The co-existence of woody plants and grasses characterize savannas, with the horizontal and vertical spatial arrangement of trees creating a heterogeneous biotic environment. To understand the influence of biogeophysical drivers on the spatial patterns of 3-D structure of woody vegetation, these patterns need to be explained over large areas to capture the context. Is there a spatially explicit, ecologically meaningful way to capture the patterns and context of 3-D woody vegetation structure?

Classification development and testing sites: landscapes in Bushbuckridge Municipality, Sabi Sand Wildtuin and Kruger National Park, Mpumalanga province, north-east South Africa.

The aforementioned structural classification approach requires appropriate 3-D and spatially explicit remote sensing data. A LiDAR-based canopy height model (CHM) and volumetric pixel (voxel) data from the Carnegie Airborne Observatory Alpha system were used to create the structural classification. First, we segmented the CHM images using multi-threshold and multi-resolution image segmentation techniques, and classified the image segments into four height classes, namely shrub (1–3 m), low tree (3–6 m), high tree (6–10 m) or tall tree (>10 m). A hierarchical a priori approach was used to develop classification criteria. The following metrics were calculated for 0.25-ha grid cells based on the cover and spatial arrangement of the four height classes: canopy cover, sub-canopy cover, canopy layers, Simpson's diversity index and cohesion. Top of canopy vegetation was classified using each metric at the 0.25-ha scale, with canopy cover being the primary classification metric. Subsequently, individual layers identified within the canopy were classified using the voxel data. We use a code system for describing classes to ensure standardization between different regions; a more traditional naming system may be used in addition for interpretation.

This system provides a more comprehensive classification of the horizontal and vertical structural diversity of savannas compared to the traditional vegetation classification systems. The description of multi-layers within the canopy should allow for a sensitive change detection method. The classification can be used in many current focus areas, including habitat suitability mapping for biodiversity conservation, strategic adaptive management and monitoring land-cover change.

Ancient woodland indicator species (AWIs) are plant species which are thought to be restricted to areas of long-continuity woodland habitat. In many cases, however, these species have been identified on the basis of personal, to some extent, subjective experience. Do the species proposed as AWIs according to these lists have traits in common, and how distinct is their trait profile from that of other woodland plant species?

United Kingdom.

We applied classification tree analysis to a plant trait database to assess the extent to which proposed AWI species can be clearly separated from other woodland plants based upon their traits. We contrasted AWI species with an objectively defined list of plants that are not considered to be AWIs but that have been commonly recorded in woodlands. We also investigate the effects of phylogeny and region specificity on species' proposed AWI status.

The results provide support for the distinctiveness of plant species thought to be associated with ancient woodland; they were found to be almost exclusively short, perennial species, usually with a high seed weight. Results also indicate that rarer AWIs have a more distinguishable trait profile than more common species. No link was found between phylogeny and AWI status.

AWI species do have a distinguishable trait profile, despite their often partially subjective selection. The results of the classification tree analysis suggest that traits reflecting poor dispersal ability may be partly responsible for confining these species to ancient woodlands. This confirms other studies that emphasize their low ability to colonize secondary woodland sites and hence vulnerability to habitat conversion.

Removal of vegetation and disturbance of the soil profile during mining reduce nutrient pools available for plants during mine site restoration. Thus, fertilizer is needed to replace the loss of nutrients available to support vegetation establishment. Yet the application of fertilizer can promote the establishment of competitively dominant species to the exclusion of others, particularly in low-fertility ecosystems. Here, we test effects of fertilizer application rates on the establishment of jarrah forest.

Five restored mine pits in the jarrah forest that grows on low-fertility soils in southwest Western Australia.

Nitrogen (0 and 20 kg elemental N·ha⁻¹) and phosphorus (0, 10, 20 and 40 kg elemental P·ha⁻¹) were applied factorially to 20 m × 20 m field plots at five sites restored after bauxite mining with seeds and seedlings of jarrah forest species.

Two and a half years after the experiment was established, there were no effects of N application rates on species richness, percentage vegetation cover or community composition of the restored jarrah forest. In contrast, P application had a number of effects on the restored jarrah forest. Species richness was highest at intermediate P application rates (10–20 kg·ha⁻¹) and lowest at the two extreme treatments (0 and 40 kg·ha⁻¹). Higher rates of P application resulted in a higher seedling density (2.5 vs 5.0 m⁻² for 0 and 40 kg P·ha⁻¹, respectively) and increased plant cover. Fertilizer P also significantly affected community composition, favouring ephemerals and weeds at high application rates and re-sprouting species at lower application rates. Community composition was more similar to the restoration target (unmined jarrah forest) at 0 kg·P·ha⁻¹ (similarity value of 36%) than at higher P application rates.

The data suggest that, in terms of maximizing species richness and percentage cover, a P application rate of between 10 kg·P·ha⁻¹and 20 kg·P·ha⁻¹is optimal for jarrah forest restoration after bauxite mining. Additionally, the data suggest no benefit of N application at a rate of 20 kg·N·ha⁻¹.

How do different weed management systems based on glyphosate-resistant (GR) crops affect weed community structure and composition?

A total of 156 agricultural fields across six US states.

Fields were selected and categorized into three weed management systems based on a 3-yr history: (1) a single continuous GR crop; (2) a rotation of two GR crops; and (3) a GR crop rotated with a non-GR crop. Weed species population density was surveyed in 20 0.5-m² plots per field four times each season from 2006 to 2010. Weed population density, species richness and diversity were analysed using repeated measures mixed models to test the effect of year, geographic location (based on plant hardiness zone) and weed management system (as described above). Weed community composition was analysed using NMDS ordination. The importance of geographic location, planted crop and weed management system were analysed using analysis of similarity and permutational ANOVA based on the Bray–Curtis similarity among sites calculated from the maximum weed species population density per site per year.

A total of 329 weed species were identified across the six states and all time periods. Weed communities were most strongly correlated with geographic location and secondarily to the crop planted. Weed management system affected similarity among weed communities through an interaction with site location but not every year. The weed management systems of crop rotation and GR trait rotation generally reduced weed population density and species diversity, but the effect of crop rotation varied by geographic location.

The overall effects of weed management systems in fields including the GR trait on arable weed communities reinforce the need for locally adapted weed management programmes to steward the GR crop trait to manage for high weed diversity while reducing crop–weed competition and maximizing yield.

We investigated the effects of human-induced fires on woody plant components of dry deciduous forest in Madagascar. Specifically, we addressed the following questions: (1) which forest layers are most affected by fire; (2) how is forest structure, species richness, diversity and composition affected by fire disturbance; and (3) does the forest recover after fire disturbance?

Kirindy Forest in Central Menabe, western Madagascar.

We conducted our investigations in seven areas of the Kirindy Forest, which was burned between 1984 and 2009. Vegetation data were collected in nested plots for the different forest layers in the burned and unburned forest. Using GLM, we assessed fire impact on forest structure, species richness and diversity of the different forest layers. The recovery of burned forest was investigated using correlation analysis. In addition, we used descriptive methods to analyse fire impact on species composition.

Fire mainly influenced the middle forest layers, trees >1.50-m high and diameters <15 cm, and significantly reduced tree density, basal area, species richness and diversity. Fire had no significant impact on the measured parameters of the shrub and top layers. Despite the severe impact of fire on the middle forest layers, most of the measured parameters of these layers were able to recover from fire disturbance within a short time. Twelve years after fire disturbance, tree density, basal area, species richness and diversity in burned forest areas no longer differed from unburned forest areas. However, species composition differed substantially between burned and unburned forests.

We conclude that fire severely impacts the middle forest layers and alters forest structure, i.e. species richness and tree diversity, of the dry deciduous forest of Central Menabe.

Ecological restoration has traditionally been evaluated with analyses focused on species identities and abundances. These analyses provide no ecological explanation to why certain species change in abundance. One solution may be a functional trait analysis. We asked whether shifts in functional traits could explain vegetation changes in fens restored through tree cutting and rewetting, and how the functional traits in the restored sites compare to those of the reference site?

Three former rich fens in east-central Sweden.

Tree cutting and rewetting were applied in a factorial design, and species and abundance data were recorded for 8 yrs. Abundance data and trait data of canopy height, specific leaf area (SLA) and diaspore mass were used to calculate functional richness (FRic), functional divergence (FDiv), functional dispersion (FDis) and community-weighted mean (CWM) of functional traits. Data were analysed in a linear mixed effect model for vascular plants and bryophytes jointly, and for vascular plants separately. Results of restoration treatments were compared to data from a reference site.

Among vascular plants, tree cutting caused a decrease in SLA, as shade-sensitive species increased. In accordance with the change in SLA, FDis increased. In the joint analysis, tree cutting led to increased FDis, FDiv and FRic, indicating reduced filtering caused by the removal of the shading canopy, which allowed shade-sensitive species to establish. The comparison to the reference site shows that even after 8 yrs, the restoration treatments have higher trait diversity than the reference site, indicating that the restoration sites have a too relaxed trait filter compared to conditions in an undisturbed fen. Our interpretation is that this is primarily caused by insufficient rewetting (and increased nutrient availability) that allow species of both natural and degraded fen conditions to co-exist, and which failed to suppress the regrowth of trees.

Analysis of functional diversity improves our understanding of the ecological mechanisms affecting restoration results, and allows comparison among regions and communities with different species composition.

How do recent patterns of drought-induced woody plant mortality in Texas semi-arid savanna compare to the extended drought of the 1950s? Does the relative composition of the woody plant community shift ubiquitously across the landscape following woody plant mortality and dieback or are shifts dependent on differences among species, soils, land use and plant demography?

Texas Agrilife Research Station, Sonora, Texas, USA (30.1° N 100.3° W).

Following an exceptional drought from 1951 to 1957, a study was conducted to quantify rates of mortality for various woody plant species. In 2011, we repeated this study within three long-term grazing treatments that were established in 1948. Ten transects were established in each treatment to quantify the frequency and cover of live and dead woody individuals for all woody species. Rates of woody plant dieback were determined for each species and tested for differences among height classes, soil categories, total woody densities and pastoral treatments.

Flash droughts (defined as rapidly intensifying droughts characterized by moisture deficits and high temperatures) from 2000 to 2011 were the second most severe since 1919 (low PDSI = −4) and were only surpassed by the prolonged drought from 1951 to 1957 (low PDSI = −5.17). Drought-induced shifts from one woody plant community to another did not occur uniformly across the landscape. Instead, high mortality rates of mature Juniperus ashei trees in deep soils (67.3%, 33 of 49 trees), combined with the recruitment of Quercus species where grazing had been excluded for the last 60 yr, were the only patch types to shift from a Juniperus–Quercus woodland to an alternate state.

Flash droughts since 2000 resulted in significant mortality and dieback, but dieback in cover was 28% higher following the more severe drought of the 1950s. Legacies from long-term land management practices interacted with localized differences in topoedaphic factors to drive patch-level shifts in woody vegetation following drought.

Tree line ecotone regions are expected to respond swiftly to climate changes. In this paper, remote sensing- and ground-based tree population data are used to examine past and on-going changes of the tree line ecotone in a sub-arctic region characterized by precipitation increase. Questions addressed are: (1) at what rate has the tree line ecotone changed since the mid-20th century; (2) can specific temporal dynamics be identified; and (3) do combined remote sensing and tree population analyses add essential knowledge for the interpretation of tree line changes?

Khibiny Mountains, Kola Peninsula, northwest Russia.

Aerial photos from 1958, high-resolution satellite imagery from 2006/2008 and age structure data for dominant tree line species (birch and pine) were used to analyse rate of change and temporal and species-specific tree line recruitment patterns. This was accomplished using digital elevation models, resolution-merging procedures, visual interpretation and dendroecological methods.

Mean tree line advance for birch and pine was recorded as 29 and 27 altitudinal metres (0.6 and 0.5 m·yr⁻¹), respectively. The advance was accompanied by an apparent infilling of pre-established tree populations and by recruitment beyond the tree line. Evident increased recruitment occurred in the late 1980s for birch and in the 1970s and 1990s for pine. Establishment showed no strong correlations with climate variables, but the importance of non-growing season variables was indicated.

The recorded tree line advance is modest compared to global model predictions for advance at high latitudes, but in accordance with results from a number of high-latitude areas. Concomitantly, the apparent increased recruitment is indicative of a more rapidly advancing tree line zone. Studies combining remote sensing and ground-based data minimize the risk of under- or overestimating potential tree line advance. Low detectability of small seedlings and saplings by remote sensing can cause underestimation of the current potential, while ground-based data used alone can overestimate potential advance. A balance between the two approaches is beneficial and enhances quality in production of change scenarios related to high latitudinal tree line areas at local to large regional scales.

How are plant species richness and diversity related to spatial autocorrelation under grazed and ungrazed conditions in grassland communities? Is spatial autocorrelation dissimilar within different plant communities?

The grasslands of southeast North Dakota, USA.

The study was conducted during the summer of 2009 in six grasslands under different management (grazed vs ungrazed with fire) along a moisture gradient. Spatial autocorrelation at each site was measured along 50-m transects among three different landscape positions representing different moisture levels. Dissimogram multivariate analysis was used to measure the nugget, dissimilarity and patch diameter. Additionally, richness and Shannon diversity indices and nonmetric multidimensional scaling analysis were compared to the dissimogram results.

Mean patch diameter was significantly higher in grazed mid-slope sites than in ungrazed sites. Spatial autocorrelation was not different between the landscape positions (higher, dry areas were not different from lower, mesic areas). However, plant species richness, diversity and community composition were found to be different between landscape positions and management, with key differences in the presence of certain invasive species.

Disturbance and moisture level were reflected differently in the spatial autocorrelation analysis compared to the richness, diversity and ordination analyses. This indicates that disturbance and management impacted spatial autocorrelation separate from plant community composition and species diversity. This also highlights changes in the plant community caused by different management actions and the spread of invasive species.

What is the precision of five methods of measuring vegetation structure using ground-based digital imagery and processing techniques?

Lincoln, Nebraska, USA

Vertical herbaceous cover was recorded using digital imagery techniques at two distinct locations in a mixed-grass prairie. The precision of five ground-based digital imagery vegetation analysis (DIVA) methods for measuring vegetation structure was tested using a split-split plot analysis of covariance. Variability within each DIVA technique was estimated using coefficient of variation of mean percentage cover.

Vertical herbaceous cover estimates differed among DIVA techniques. Additionally, environmental conditions affected the vertical vegetation obstruction estimates for certain digital imagery methods, while other techniques were more adept at handling various conditions. Overall, percentage vegetation cover values differed among techniques, but the precision of four of the five techniques was consistently high.

DIVA procedures are sufficient for measuring various heights and densities of standing herbaceous cover. Moreover, digital imagery techniques can reduce measurement error associated with multiple observers' standing herbaceous cover estimates, allowing greater opportunity to detect patterns associated with vegetation structure.

(1) What is the utility of the soil seed bank in passive restoration of a suburban secondary successional temperate deciduous forest? (2) What is the composition and structure of the seed bank? (3) How abundant are woody and exotic species and how are they distributed in the seed bank? (4) Are edge effects evident in seed bank composition? (5) What is the influence of a suite of abiotic and biotic variables, including deer browse, on seed bank richness and abundance?

A 413-ha suburban forest near Baltimore, Maryland, USA.

We sampled the seed bank and vegetation of 100 permanent plots in a Liriodendron–Fagus–Acer–Quercus dominated secondary successional forest. Information on soil chemistry, canopy cover, leaf litter cover and depth, deer browse severity and distance to the nearest urban edge and path was also collected for each plot. Seedling emergence was monitored in a greenhouse over 2 yr.

A total of 76 species emerged from the seed bank, including 16 woody species and 22 exotic species. Compositional similarity between the seed bank and vegetation was low. Woody species were under-represented and exotic species were over-represented, with exotic species found in the seed bank of 94 of 100 plots. Species composition and exotic species richness and abundance were similar between edge or path and interior plots. Leaf litter cover, vegetation cover, browse severity and variables related to soil fertility were included in top models explaining patterns in seed bank richness and abundance.

Reliance on the soil seed bank as a passive restoration strategy will be insufficient for restoring a mature secondary successional suburban forest community. However, a suite of shade-tolerant exotic shrubs and vines that are of concern to management do not appear to use the seed bank, indicating that targeted removal of these species may be successful. Increased deer browse was associated with decreased seed bank abundance and richness, suggesting that deer may directly reduce inputs to the seed bank. If deer are impacting seed bank composition, active restoration will need to include understorey herbs in addition to overstorey species.

Does a reduction in size class of soil biota aggravate the impacts of soil compaction on plant communities?

Controlled mesocosm study with a European ruderal plant community exposed to soil compaction and soil biota communities of different size classes.

We evaluated the individual and combined effects of soil compaction and soil biota communities of different size classes (<2000, <212, <20 μm, natural control) on the structure and productivity of a ruderal plant community, and the establishment of a neophyte (Lupinus polyphyllus) in a full-factorial mesocosm study.

Soil compaction reduced the productivity of the plant community, but the negative effect decreased in magnitude as the size class of the soil biota community was reduced. Consistently, shoot growth of the dominant grasses was most reduced by soil compaction when bigger soil biota were present; the shoot growth of forbs showed an opposite pattern. In contrast, legumes seem to profit from soil compaction independent of the size class of the soil biota community, and were detrimentally affected only in the natural control soil. Establishment of the neophyte L. polyphyllus was best under natural soil conditions and was not affected by soil compaction.

A reduction in soil biota size due to intensified management may change the impacts of soil compaction on plant communities. The results indicate that soil compaction has the most detrimental effect on primary productivity in soil communities where a range of size classes of soil biota is present and the functional complexity of the soil biota community is therefore high.

Diversification of grassland management is recommended as a tool for conservation of different taxonomic groups living in those habitats. How resistant and resilient are species-rich grasslands in terms of plant species richness and vegetation composition to short-term, small-scale perturbations caused by changes in management practice?

Bílé Karpaty Mountains, SE Czech Republic.

The experiment included the effect of six management regimes (mowing in June; mowing in September; mowing in June and September; mowing in June and high stubble left; no management; mowing in June and mulching). It was conducted in species-rich wooded grasslands in the White Carpathians Mts., Czech Republic, represented by three types of plant community: a Bromus erectus community (with high species richness and low productivity), a Molinia arundinacea community (with high species richness and high productivity), and a Calamagrostis epigejos community (with low species richness and high productivity). After 3 yr, resistance was assessed, and traditional management (mowing once each year in June) was resumed; resilience was evaluated after three more years.

While the species-rich, unproductive Bromus community was relatively resistant to less intensive management in terms of species richness, and therefore its resilience could not be assessed, it changed substantially in terms of vegetation composition (maximum dissimilarity between control and abandoned plots was 63%). The more productive Molinia and Calamagrostis communities lost up to 37% of species due to abandonment, but not as a consequence of other changes management regimes. After the traditional management was resumed, resilience was higher in the Calamagrostis community than in the Molinia community. Vegetation composition was not affected by treatments.

The results show that short-term abandonment causes loss of plant diversity in productive grasslands but not in less productive, species-rich grasslands in the short term. Other relaxed management regimes (e.g. high stubble and delayed mowing) were comparable with the control and can be used for a short time to increase diversity of management without an effect on plant species richness. However, further research is needed to assess the effects of these management practices when they are applied repeatedly or over the long term.

The importance of silvicultural site preparation techniques in determining vegetation succession is increasingly recognized. We studied the effects of mechanical site preparation (MSP) on post-fire vegetation regeneration within reforested sites in Mediterranean Israel.

Upper Galilee region, Israel.

Vegetation cover and composition, ruderal species colonization and pine regeneration were monitored in four reforested sites for 3 yr following wildland fires that burned mature Pinus brutia and P. halepensis plantations. In each reforested site, a 50 m × 50 m monitoring area was assigned and measurements were conducted within five subplots (2 m × 50 m) encompassing three MSP patch types: ploughed patches (P), unploughed patches (UP) and planting mounds (M) that combined ploughing, pit digging and wood-chip mulching.

Recovery of vegetation cover (excluding pines) was rapid. The MSP patch type significantly affected vegetation cover in the first spring following the fire: cover was lowest on M, intermediate on P and highest on UP. However, these differences became minor by the third spring following the fire. Total woody species richness was not affected by MSP patch type, although there were minor effects on relative abundance of woody species. Two ruderal species were found, but their abundance became untraceable by the third year. Patterns of MSP effects on pine regeneration were similar for P. halepensis and P. brutia. Density of emerging seedlings of both pine species during the first year following the fire was significantly affected by MSP patch type: lower in P and M than in UP by more than 50% and 90%, respectively. However, emergence and/or survival during the following 2 yr was higher in P and M than in UP, with overall outcome of pine regeneration still about 50% lower in P and M than in UP.

The MSP treatments had only a minor, short-term effect on post-fire regeneration and colonization of vegetation, except for pine recruitment, which was more severely affected.

We identify the main forest vegetation types in Taiwan, provide their formal definitions and describe their species composition, habitat affinities and distribution.

Taiwan.

A data set of 9822 vegetation plots with environmental characteristics recorded in the field or derived from digital maps in GIS was compiled from historical literature and an extensive field survey. Using expert knowledge, 6574 of these plots were used to build a classification into broad vegetation types. The units of the resulting classification were formally defined using a Cocktail determination key, which can be used for the automatic assignment of new vegetation plots to these vegetation types.

Twelve vegetation types of zonal forests and nine types of azonal forests were distinguished. Zonal types in the subtropical region, from high mountains to foothills, are Juniperus subalpine coniferous woodland, Abies–Tsuga upper-montane coniferous forest, Chamaecyparis montane mixed cloud forest, Fagus montane deciduous broad-leaved cloud forest, Quercus montane evergreen broad-leaved cloud forest, Machilus–Castanopsis sub-montane evergreen broad-leaved forest, Phoebe–Machilus sub-montane evergreen broad-leaved forest and Ficus–Machilus semi-evergreen foothill forest. Zonal types in the tropical region, from high mountains to foothills, are Pasania–Elaeocarpus montane evergreen broad-leaved cloud forest, Drypetes–Helicia sub-montane evergreen broad-leaved forest, Dysoxylum–Machilus foothill evergreen broad-leaved forest and Aglaia–Ficus foothill evergreen broad-leaved forest. Azonal types are Illicium–Cyclobalanopsis tropical winter monsoon forest, Pyrenaria–Machilus subtropical winter monsoon forest, Diospyros–Champereia tropical rock-outcrop forest, Zelkova–Quercus subtropical rock-outcrop forest, Pinus successional woodland, Alnus successional woodland, Trema–Mallotus successional woodland, Scaevola–Hibiscus seashore woodland and Kandelia mangrove.

The diversity of forest vegetation in Taiwan is strongly structured by the temperature and moisture gradient. Along the temperature gradient, five altitudinal zones can be recognized. Azonal forest types develop at sites affected by the winter monsoon, on steep slopes, rocky soils, in seashore saline habitats and in places disturbed by fire, landslides and human activities. Zonal vegetation contains a higher ratio of endemic and Pacific species and occurs in wetter habitats, whereas azonal vegetation contains co-existing species from different regions and usually occurs in drier habitats.

The vegetation of high-alpine and subnival scree habitats in Iranian mountains has been poorly investigated so far despite the large variety of narrowly distributed vascular plant species and the expected vulnerability of these ecosystems to global warming. Which plant communities occupy these ecosystems and what is their syntaxonomic position? Which environmental factors determine the species composition of these habitats?

Alborz and Azerbaijan Mountains in N and NW Iran.

A total of 141 phytosociological relevés were collected from 3200 to 4800 m a.s.l. This data set was classified using TWINSPAN, and the numerical classification was translated into a syntaxonomic system. Floristic differences between vegetation types were evaluated with detrended correspondence analysis (DCA). We determined the means and SD of measured environmental and vegetation parameters for all associations. Differences in the major environmental parameters among associations and alliances were analysed using ANOVA and post-hoc tests. Moreover, we determined the mean cover percentage of life forms in all associations.

All high-alpine and subnival scree communities are arranged in one class (Didymophyso aucheri-Dracocephaletea aucheri), two orders (Physoptychio gnaphalodis-Brometalia tomentosi, Didymophysetalia aucheri), three alliances (Elymo longearistati-Astragalion macrosemii, Erigerontion venusti, Didymophysion aucheri) and ten associations, which are new to science, except for one association. The territory of the class extends from Alborz to NW Iran and probably to E Anatolia, Transcaucasia and the Zagros Mountains. Altitude, aspect and edaphic qualities are the major ecological factors influencing the species composition and vegetation mosaic.

Our study introduces a formal syntaxonomic classification of the scree vegetation at high altitudes in Iran, thus providing a scheme for ongoing ecological surveys and monitoring programmes to assess the impacts of climate warming and of human land use on these unique ecosystems.

Dominance of the widespread fire-altering invasive grass, Bromus tectorum, is markedly reduced at upper elevations in the Great Basin Desert. Here, we evaluated whether increased anthropogenic nitrogen (N) deposition would have an effect on species composition and ecosystem invasibility by B. tectorum at high elevations, and whether B. tectorum cover was associated with decreased native plant diversity.

Sagebrush steppe of the eastern Sierra Nevada, CA, US, at the western edge of the Great Basin Desert.

We set up 54 paired plots, half of which were exposed to elevated N deposition (50 kg·ha⁻¹·yr⁻¹ at the time of snowmelt for 4 yr) and half acted as controls, in areas differing in disturbance history (grazed, burned and grazed–burned). We monitored species composition each summer from 2008 to 2011 and then compared species richness, Shannon's diversity (H'), Simpson's dominance (D'), Simpson's evenness (E_1/D), B. tectorum dominance and community similarity (with ANOSIM and SIMPER analyses) by N treatment and disturbance history.

Species composition differed by disturbance history in all years (ANOSIM, P < 0.05), and the grazed–burned plots consistently had the highest levels of B. tectorum dominance (P ≤ 0.0003) and cover (P ≤ 0.0001). Bromus tectorum cover was inversely related to native forb species richness (r = −0.44, P < 0.0001), H'(r_s = −0.73, P < 0.0001), -ln(D') (r_s = −0.75, P < 0.0001) and E_1/D'(r_s = −0.49, P < 0.0001). We found no evidence that increased N deposition would affect native plant diversity after 4 yr in this arid montane ecosystem, but the possibility of longer-term effects cannot be eliminated.

Results suggest that high-elevation plant communities are already experiencing invasion impacts even though changes to the fire cycle have not yet occurred. In the most disturbed areas, B. tectorum cover is approaching the threshold for increased fire risk, which could result in more severe impacts at high elevations.

Can predictors derived from air- and space-borne high-resolution remote sensing data improve models of species richness commonly built using coarser-scaled environmental variables?

Switzerland, covering 41 244 km² of Central Europe.

We applied linear regressions to model species richness of woody species, herbs, edaphic bryophytes and epiphytic lichens in Swiss forests. We included high-resolution predictors derived from digital height models and from satellite spectral images. Coarser-scaled predictors characterizing climatic and topographic conditions were also included, as were soil properties and geology. We applied hierarchical partitioning to regression models to investigate the independent contribution of each predictor set to species richness models.

Predictors derived from high-resolution remote sensing data substantially improved the species richness models (increase 14–55% of R²). However, coarse-scaled climatic and topographic predictors still explained a high proportion of the variance in the species richness data in all models, independently of other predictors commonly used. The importance of the remotely sensed variables was strongly dependent on the biogeographic region considered. The species richness models of smaller organisms of the forest floor (herbs and edaphic bryophytes) benefited greatly from adding high-resolution topographic predictors, indicating the importance of microtopographic heterogeneity for these groups. Both epiphytic lichens and herbs responded strongly to indicators of structural properties of the forest stand.

High-resolution remote sensing data is a proxy for micro-environmental structures and variation in these structures. Our results show that predictors derived from such data can improve species richness models considerably, especially in regions with low climatic and/or topographic variation. High-resolution remote sensing variables excellently complement coarser-scaled predictors, as they are available over large areas at low cost.

What are the characteristics of soil seed banks in highly endangered renosterveld vegetation and adjacent degraded sites? What is the contribution of the soil seed bank to restoring renosterveld vegetation after degradation through agriculture or afforestation?

Tygerberg Nature Reserve – one of the largest remaining fragments of Swartland Shale Renosterveld, Cape Floristic Region, South Africa.

Assessment of vegetation, soil parameters and soil seed banks in three renosterveld sites, two adjacent abandoned fields, one pine plantation and one pine plantation clear-cut site. Smoke primer (i.e. fire surrogate) was applied to soil seed bank samples to evaluate fire as a possible management and restoration tool.

Abandoned agricultural fields adjacent to renosterveld remnants are characterized by alien grass cover, nutrient enrichment of the soil and depletion of the indigenous soil seed bank. In contrast, pine plantations show less alien species infestation, soil nutrient alteration and have a viable soil seed bank as well as re-development of indigenous renosterveld vegetation after clearance. Seedling recruitment was not significantly influenced by application of a smoke primer compared to the magnitude of fire response in fynbos.

Abandoned agricultural fields (previously renosterveld) at Tygerberg have a very low restoration potential. In contrast, pine plantation sites should be given priority in restoration, because soil chemistry is less significantly altered and a viable indigenous soil seed bank is still present, which can be successfully activated through clearance management.

The aim of this study was to establish the potential of domestic goats to act as cactus seed dispersers by assessing: (1) the proportion of cactus seeds that can pass undamaged through the domestic goat gut, (2) the temporal pattern of seed defecation, (3) whether ingestion by goats enhances or depresses cactus seed germination, and (4) whether the viable cactus seeds contained within goat faecal pellets can germinate directly from the faeces.

River basin of Zapotitlán, Tehuacán-Cuicatlán Biosphere Reserve, Mexico.

Four groups of goats, each comprising three females of similar size and age, were fed the fruits of four endemic cactus species (Echinocactus platyacanthus f. grandis, Ferocactus flavovirens, F. robustus and F. latispinus var. spiralis). The percentage of undamaged seeds in the goat faeces was calculated at different times of collection following ingestion. Recovered seeds were tested for germination and viability, alongside seeds taken directly from the fruit. Intact and artificially cracked faecal pellets, collected from grazed natural areas, were kept in a greenhouse while seedling emergence was quantified. After 103 d, all cactus seeds that remained within the faecal pellets were recovered and their germination capacity was compared to that of the seeds taken directly from fruits.

For the four species, between 28% and 61% of the seeds ingested were later recovered in the faecal pellets. No significant differences were found between species in the proportion of seeds retrieved during each collection time point. However, the time interval between ingestion and collection significantly influenced the number of seeds retrieved, peaking at between 16–32 hr. The digestion process significantly decreased the seed germination rate. Cactus germination from cracked faecal pellets was significantly higher than from intact pellets. Both contained viable seeds of all four cactus species, but particularly E. platyacanthus f. grandis.

Domestic goats are potential dispersers of the studied cactus species, although degradation of the faecal pellets is necessary to fully permit seedling emergence. These findings should be taken into account when designing management plans to conserve these endangered species.

How did post-wildfire understorey plant community response, including exotic species response, differ between pre-fire treated areas that were less severely burned, and pre-fire untreated areas that were more severely burned? Were these differences consistent through time?

East-central Arizona, southwestern US.

We used a multi-year data set from the 2002 Rodeo–Chediski Fire to detect post-fire trends in plant community response in burned ponderosa pine forests. Within the burn perimeter, we examined the effects of pre-fire fuels treatments on post-fire vegetation by comparing paired treated and untreated sites on the Apache-Sitgreaves National Forest. We sampled these paired sites in 2004, 2005 and 2011.

There were significant differences in pre-fire treated and untreated plant communities by species composition and abundance in 2004 and 2005, but these communities were beginning to converge in 2011. Total understorey plant cover was significantly higher in untreated areas for all 3 yr. Plant cover generally increased between 2004 and 2005 and markedly decreased in 2011, with the exception of shrub cover, which steadily increased through time. The sharp decrease in forb and graminoid cover in 2011 is likely related to drought conditions since the fire. Annual/biennial forb and graminoid cover decreased relative to perennial cover through time, consistent with the initial floristics hypothesis. Exotic plant response was highly variable and not limited to the immediate post-fire, annual/biennial community. Despite low overall exotic forb and graminoid cover for all years (<2.5%), several exotic species increased in frequency, and the relative proportion of exotic to native cover increased through time.

Pre-treatment fuel reduction treatments helped maintain foundation overstorey species and associated native plant communities following this large wildfire. The overall low cover of exotic species on these sites supports other findings that the disturbance associated with high-severity fire does not always result in exotic species invasions. The increase in relative cover and frequency though time indicates that some species are proliferating, and continued monitoring is recommended. Patterns of exotic species invasions after severe burning are not easily predicted, and are likely more dependent on site-specific factors such as propagules, weather patterns and management.

Can UAV-based NIR remote sensing support restoration monitoring of cut-over bogs by providing valid information on species distribution and surface structure?

Restored polders of the Uchter Moor, a bog complex in NW Germany.

We used autonomously flying quadrocopters, supplied with either a panchromatic or colour infrared calibrated small frame digital camera to generate high resolution images of the restored bog surface. We performed a two-step classification process of automatic image segmentation and object-based classification to distinguish between four pre-defined classes (waterlogged bare peat, Sphagnum spp., Eriophorum vaginatum and Betula pubescens. An independent validation procedure was performed to evaluate the accuracy of the classification.

A set-up composed of decision rules for reflectance, geometry and textural features was applied for identification of the four classes. The presented classification revealed an overall accuracy level of 91%. Most reliable attribution was obtained for waterlogged bare peat and Sphagnum-covered surfaces, revealing producer accuracies of 95% and 91%, respectively. Lower but still feasible accuracy levels were obtained for Eriophorum vaginatum and Betula pubescens individuals (89% and 84%, respectively).

UAV-based NIR remote sensing is a promising tool for monitoring the restoration of cut-over bogs and has the potential to significantly reduce laborious field surveys. UAVs may increasingly play a significant role in future ecological monitoring studies, since they are small in size, highly flexible, easy to handle, non-emissive and available at a comparatively low cost.

How can conservation status of rich fen and alkaline spring areas be assessed most cost-effectively based on existing monitoring data? What is the precision and accuracy of available indicators?

Rich fen and alkaline spring areas in Denmark.

Potential indicators of conservation status were evaluated based on: accuracy, measured as the ability to predict the number of typical species in monitoring plots; precision, measured as variation over years of indicators in repeated plots; and cost of obtaining data for the indicator. Indicators were derived using data from the Danish National Monitoring and Assessment Programme for the Aquatic and Terrestrial Environment from 2000 to 2009. Indicators included biotic indices derived from species lists, abiotic measurements of pH and nutrients and structural measurements of vegetation height and tree cover.

The majority of indicators showed a significant correlation with the number of typical species. Floristic indicators, especially based on Ellenberg nutrient values, showed superior correlation and were furthermore very stable over years. Structural indicators were generally accurate, but were highly imprecise with high between-year variation. Among the abiotic indicators, pH and soil P were inaccurate, whereas tissue N content and nitrate in water were accurate but with low precision. When balancing efficiency of indicators with monitoring costs, laboratory analyses stand out as expensive compared to recording of a species list, the latter providing up to five valuable indicators.

Floristic indicators derived from Ellenberg values, and especially those related to nutrient availability, are cost-effective indicators of conservation status. The method is applicable to all regions where Ellenberg indicator values have been calibrated to fit local conditions.

Which are the most effective plant communities for honeybee foraging and honey production in Mediterranean sylvo-pastoral systems? What is the relationship between flowering phenology and pollen occurring in honey sediments?

Mediterranean sylvo-pastoral system in Gallura, Sardinia, Italy.

Phytosociological and phenological surveys were performed in a circular area of 1.5 km radius with a small apiary placed in the centre. Polleniferous and nectariferous values of plant communities were assessed based on the cover and the polleniferous and nectariferous value of each constituting species. Honey production was quantified during the main flow (March–June) and subjected to melissopalynological analysis. Data were evaluated by ordination through principal components analysis and principal coordinates analysis. The latter utilized a new index, developed for calculating the phenological distances based on the individual distributions of flowering frequencies.

Plant communities richest in species providing pollen and nectar were Rhamnus hedges. There was a close correlation between polleniferous and nectariferous values, suggesting that plant communities are important for honeybee foraging of both resources. The temporal flowering sequence ensured the supply of nectar and pollen throughout the spring season. Pollen foraged from 12 Trifolium species with different flowering phenology was the most abundant. Salix purpurea and Rhamnus alaternus were productive at the beginning of the season, followed by Lavandula stoechas, Echium plantagineum and E. italicum.

Plant communities vary in importance for honeybee foraging mainly due to differences in floristic composition and flowering phenology. Communities characterized by human presence (e.g. semi-natural grasslands and hedges) are the most relevant. Some target species (e.g. Trifolium spp.) favoured by grazing livestock ensure foraging for honeybees throughout the season. Plant communities of wild areas, such as the garrigue vegetation, provide foraging for unifloral valuable honey (i.e. ‘Lavandula’ honey).

(1) At what rate does succession take place in active and more stabilized drift sands in regions with low and high N deposition in the Netherlands? (2) What is the present composition of pioneer vegetation in active and more stabilized drift sands in regions with low and high N deposition? (3) What efforts are necessary to conserve bare sand in drift sands?

Eight inland dunes in the Netherlands, which represent four active and four more stabilized drift sands in regions with low and high N deposition.

Aerial photographs from 1950, 1981, 1995 and 2007 were used to compare rates of succession from bare sand towards forest. For each site, a detailed vegetation map was made in 2007.

In all studied sites, bare sand decreased, especially in regions with high N deposition. This decline was significantly higher between 1981 and 2007 than between 1950 and 1981. The loss of bare sand did not lead to an increase of pioneer vegetation, which remained more or less stable; it led, however, to an increase of heath and forest. In active drift sands, pioneer vegetation was characterized by Corynephorus canescens and Polytrichum piliferum, while lichens, lichen-rich grassland and Campylopus introflexus were more common in stabilized drift sands. In regions with high N deposition, the proportion of Campylopus introflexus to older pioneer stages was significantly higher, and the contribution of forest to the ‘heath/forest’ vegetation class was also higher. The calculated life span of bare sand decreased in all sites. Extrapolation of the results suggests that in the absence of restoration measures, bare sand will vanish by 2035.

In both active and more stabilized drift sands, a generic loss of bare sand and an increase in forest area was found. The increase was higher in regions with high N deposition. Conservation management should include the annual transformation of 43 ha of forest into bare sand in order to stop the loss of bare sand.

How does the plant species composition of Pontic–Pannonian salt-rich habitats vary on a large geographical scale? Do the floristic differences between Pannonia and the Balkans correspond to the current phytosociological classification?

Pannonia (Hungary, Slovakia, Austria, Czech Republic, Croatia, Serbia, Romania) and the Balkans (Bulgaria, Macedonia, Greece).

Two thousand four hundred and thirty-seven relevés from halophytic and sub-halophytic habitats were classified using a modified TWINSPAN. The crispness of classification was checked. DCA and CCA with climate data as explanatory variables were applied.

The classification was best interpreted at the level of 15 clusters. The vegetation changed along the salinity gradient from sub-halophytic grasslands (including Trifolion resupinati alliance of the Molinio-Arrhenatheretalia class and Beckmannion eruciformis and Festucion pseudovinae p. p. alliances of the Festuco-Puccinellietea class) and reed beds (Bolboschoenion maritimi p. p. alliance; the Phragmito-Magnocaricetea class), through steppe and wet inland halophytic vegetation (Festucion pseudovinae p. p., Puccinellion limosae, Pucinellion convolutae, Bolboschoenion maritimi p. p. and Juncion gerardii of the Festuco-Puccinellietea class) towards the extreme halophytic vegetation of the Thero-Salicornietea, Crypsietea and Juncetea maritimi classes. This gradient was longer in the Balkan region, where it spanned from the sub-mediterranean salt-rich grasslands to the extremely halophytic vegetation at the Black Sea coast. The second most important gradient coincided with the water regime. Some vegetation types appeared to be confined to either the Pannonian or the Balkan region (especially within dry sub-halophytic and steppe halophytic grasslands), while others were distributed across the entire study area. The above-mentioned pattern did not always correspond with current classification systems.

Variation in salt-rich vegetation predominantly follows the salinity and water regime gradients. Geographical variation, generally coinciding with climatic and historical effects, is also important, especially in drier salt-rich habitats. Our large-scale analysis of the floristic variation of salt-rich habitats might be useful for the unification of classification systems that differ substantially between the countries involved. In addition, the analysis may be useful for adjustment of a classification system in the poorly explored Balkan region, where particular vegetation types were identified with, or delimited from, Central European vegetation types without detailed comparative analysis until now.

What are the main drivers of variation in beta-diversity for Bromus erectus semi-natural dry grasslands of habitat 6210(*) at different scales? How should environmental variables and spatial patterns be taken into account to conserve the maximum possible beta-diversity within the habitat?

Central Italy.

We used 195 vegetation relevés distributed in three nested extents: a single mountain, a mountain chain and southern Lazio. Multiple regression on distance matrices was performed using dissimilarity matrices based on: (1) species abundances as response variables; (2) spatial coordinates and environmental parameters (altitude, slope, percentage of rock and stone coverage, aspect, annual rainfall) as explanatory variables. The two groups of explanatory variables were used separately to partition the variation, and jointly to assess the relative contribution of each individual variable. Those variables found to significantly affect beta-diversity were used to: (1) compare beta-diversity levels between a set of randomly selected and a set of stratified relevés; and (2) analyse the habitat distribution across environmental gradients. These analyses, together with the curves describing the relationships between spatial distances and composition dissimilarities, were used to inform management decisions for the habitat.

Most of the variance was explained by environmental variables, whose share was higher in the smallest and intermediate extent than in the broadest extent. Community dissimilarity increased in proportion to differences in altitude and spatial distances at every extent. Accordingly, at all the extents, the selection of relevés stratified by altitude or selected taking into account a minimum spatial distance included significantly higher levels of within-habitat beta-diversity, than randomly selected relevés. The relation of beta-diversity to the variation in aspect and annual rainfall varied at different extents.

Our results demonstrate that dry grassland management plans aimed at conserving the maximum within-habitat beta-diversity should take into account variation in environmental variables, among which altitude proved to be a critical factor at every extent. Also, spatial distances positively affect within-habitat beta-diversity levels, and scale-dependent minimum distances among habitat patches should be taken into account when selecting patches of habitat 6210(*) to be conserved in the study area.

How did the presence of forest roads modify plant diversity and composition in a nutrient-poor environment? What was the effect of the use of limestone gravel as road surfacing material? How did floristic succession vary between roadside and forest interior?

State Forest of Orléans, Loiret, northern France.

We sampled 30 pairs of 2000-m² plots, one on a road and the other 30 m inside the forest, on two road surfacing materials (limestone gravel and bare soil) and three stand ages (young, middle-aged and mature) in Scots and Corsican pine stands in a large managed forest. Plant diversity was analysed according to life-history traits (protection status, indigenousness, life form, habitat and ecological preferences). We tested the effects of plot position, road type and stand age on species richness, species composition and individual species response.

The species richness of all plant groups was always higher on roads compared to forest stands, and the forest plot communities were nearly completely nested within the roadside plot communities. Seven protected species and four non-native potentially invasive species were observed on roadsides. Limestone-gravelled roads hosted more species than bare soil roads, but acidophilous forest and grassland species richness was higher on bare soil roads. Plant composition similarity between the roadside and forest were higher at early successional stages and lower in older stages.

Roads have inseparable positive and negative effects on plant communities, but the negative ones are of great concern. To prevent further damage in these nutrient-poor ecosystems, we recommend monitoring road sections hosting protected acidophilous species, not increasing road density, and replacing limestone gravel with a low pH endogenous material.

How is the magnitude and seasonality of carbon uptake affected by the replacement of native grasslands by eucalyptus plantations?

Río de la Plata Grasslands in Argentina and Uruguay.

A total of 115 paired sites of fast-growing Eucalyptus grandis plantations and adjacent grasslands were used to characterize the magnitude and seasonality of (1) radiation interception by canopies and (2) above-ground net primary productivity based on a time series of MODIS-derived normalized difference vegetation index (NDVI). The response of NDVI to precipitation was explored across temporal scales.

NDVI in afforested vs. grassland plots presented higher annual averages (1.3-fold), lower seasonal ranges (average relative range of 0.11 vs. 0.29) and delayed growing seasons (2-month shift). Temporally, NDVI was positively associated with precipitation input, showing a correlation with longer periods of precipitation accumulation in tree plantations compared to grasslands (> 7 vs. 2–3 months). Estimated average annual above-ground net primary productivity (ANPP) almost quadrupled as a consequence of replacing grasslands by tree plantations (∼4 vs. ∼17 Mg dry matter. ha^−1·yr⁻¹), and this difference was evidenced throughout the whole study period.

Afforested grasslands intercept more radiation and have higher and more stable ANPP throughout the year, probably as a result of major changes in leaf phenology and root distribution patterns, which in turn allowed better access to water. Changes in carbon uptake can influence climate/biosphere feedbacks and should be considered in land-use planning, especially when grassland afforestation is recommended as a tool to mitigate global warming.

How do fragment-level characteristics affect remnant grassland functioning in a highly transformed landscape? Are artificial neural networks (ANNs) a better statistical tool to model variations in grassland functioning compared to linear regression models (LRMs)?

Tandilia Range, Southern Pampa, Buenos Aires Province, Argentina.

We characterized the dynamics of the vegetation functioning in 60 remnant grasslands using enhanced vegetation index (EVI) data provided by MODIS/Terra images from July 2000 to June 2005. First, we performed a principal components analysis (PCA) on the fragment mean monthly values of EVI in order to obtain synthetic measures (i.e. the PCA axes) of grassland functioning. Grassland fragments were also characterized by size, vegetation structure (abundance of the tall-tussock grass Paspalum quadrifarium) and physical environment (soil type – abundance of litholitic soils – elevation, aspect and slope). The relationship between grassland functioning and these explanatory variables was explored using linear regression models (LRMs) and artificial neural networks (ANNs).

The first and second PCA axes were related to the annual integral of EVI (EVI-I) and EVI seasonality (EVI-S), respectively; these explained jointly ca. 80% of total variability in mean EVI values. ANNs captured better than regression models the relationships among the proposed controls and the spatial variability of grassland functioning in Southern Pampa. Results showed that EVI-I variability was related to all independent variables except aspect. While fragment size, litholitic soils and slope were negatively related to EVI-I, the abundance of P. quadrifarium had a positive effect on the spectral index. Grasslands with high seasonality were large and had high slope and aspect, low abundance of P. quadrifarium and increased abundance of litholitic soils.

Our results showed that grassland functioning in Southern Pampa, as estimated by EVI, depends on fragment size, vegetation structure and physical factors (soil type, aspect and slope). Paspalum quadrifarium may have an important functional role in this grassland system.

(1) To investigate the temporal response of semi-arid Mediterranean grasslands to multiple disturbances as well as P fertilization and irrigation; and (2) to determine the reaction of single species or groups of species as well as the extent of recovery of the grassland community following cessation of the above interventions.

North Greece.

In a fenced area, six treatments (burning, irrigation, digging, cutting, P fertilization and control) were applied, for three growing seasons, in a completely randomized block design with four blocks. Biomass was sampled in five (0.5 × 0.5 m) quadrats per plot at the end of the growing season and sorted into the following functional groups: annual grasses, perennial grasses, annual legumes and forbs (that included all the other species). Measurements were repeated 1 and 7 yr after cessation of the treatments.

Annual grasses and legumes were positively favoured by cutting, burning and digging, which produced changes in vegetation composition over time. P fertilization had a positive influence on total legume biomass. Effects on individual species were not uniform. Plant composition after cessation of the disturbance treatments was quite different. Total legume biomass remained high 1 yr after the cessation of P fertilization but declined thereafter. Annual grasses and legumes constituted the largest portion of the total biomass in the first year of the experiment. Disturbance (burning, cutting and digging) gradually reduced their biomass in favour of forbs. Seven years after cessation of the treatments, the tall annual, as well as perennial grasses constituted more than 80% of the total biomass. Under conditions of disturbance, short annual species had an advantage over perennials, while cessation of disturbance enables perennial grasses to dominate.

Disturbance promotes the dominance of annuals, especially species with a persistent seed bank. Repeated disturbance encourages an increase of small or prostrate species. Cessation of disturbance leads to the rapid recovery of biomass production. Tall annuals are promoted. P fertilization clearly favours legumes in the short term.

Is valuable information lost when plant trait group composition is used, rather than species composition, to describe plant community response to range management?

Elkhead Watershed, Colorado, US.

Current model-building efforts use species composition to define changes in ecosystem state, but plant traits may offer a faster and more broadly applicable alternative. We (1) compare states defined by species composition to those defined by trait-based groups of differing complexity and (2) determine how management and environmental site characteristics relate to species- and trait group-defined states. We sampled 72 plots with different grazing and chemical shrub treatment histories on two soil types. We measured plant species composition in each plot and categorized species into trait groups using three classification schemes, which represented increasing numbers of traits and levels of classification complexity. The classifications employed easily measured traits that affect plant response to range management: life form, life history, resprouting ability, height, vegetative reproduction and N-fixation. Using hierarchical cluster analysis, we identified states with similar species or trait group composition. We explored relationships between each set of potential states and management history and environmental factors using logistic regression.

Trait-based group composition and species composition identified many of the same potential states and responses to grazing and chemical shrub treatment. Relationships between species and trait group composition and management and environmental characteristics differed on the two soil types. Species composition was sensitive to more different management practices, on average, than trait group composition. Trait group composition revealed some relationships to management and environmental drivers that were not detected using species composition.

This study confirms that species composition is a more sensitive indicator of sagebrush steppe response to range management, and some information is lost with a trait-based approach. However, traits also add to depth of understanding by revealing additional community patterns related to different drivers. Using the most complex trait grouping scheme that is feasible in a particular study, and also looking for patterns based on simpler trait groups, will provide the most complete understanding of sagebrush steppe response to range management.

Do soils impacted by Tamarix spp. affect the growth of plants used for restoration through altered soil chemistry and/or plant-soil feedbacks?

The Bighorn River, the Yellowstone River and the Fort Peck Reservoir, Montana, western USA.

Soil was collected from paired subsites where Tamarix was either present or absent along three water bodies. To evaluate chemical and biological soil effects on plant growth, eight plant species (Achnatherum hymenoides, Astragalus cicer, Dalea candida, Elymus lanceolatus, Leymus cinereus, Pascopyrum smithii, Ratibida columnifera and Trifolium pratense) commonly used in restoration projects at Tamarix-invaded sites were grown in the collected soil. Plant-soil feedbacks were evaluated by growing two species (D. candida and P. smithii) in greenhouse soils inoculated with small amounts of the field soils. Germination, emergence and growth characteristics were compared between Tamarix-invaded and un-invaded subsites and across water bodies.

Seedling emergence and plant relative growth rate, total biomass production and allocation of resources to roots and shoots were not negatively affected in field soils or in greenhouse soil inoculated with soil from areas where Tamarix was present. In fact, overall, plants emerged earlier and produced more biomass in soils affected by Tamarix than in soils from where Tamarix was not present. These results indicate that for sites in the northern range of Tamarix, restoration would not be inhibited by Tamarix-induced soil changes.

Tamarix is a relatively new invader in the northern USA, and little is known about its impacts in this area or the potential implications for restoration. However, our results indicate that neither altered soil chemistry nor plant-soil feedbacks negatively impact native plant growth, and restoration efforts would not be hindered by Tamarix-induced changes to soil chemistry or microbiota.

How does salinity affect germination, seedling performance and survival of the critically endangered Limonium barceloi, compared to ruderal species invading its salt marsh habitat? Is salt application an effective management tool for controlling invaders and favouring endangered halophytes?

Ses Fontanelles, Mallorca, Balearic Islands, Spain.

The germination of seeds of L. barceloi and nine ruderal species was tested in five salinity levels (0–37 g·L⁻¹), and also in freshwater after a pre-treatment with seawater. The ruderal study species were: Asphodelus fistulosus, Avena barbata, Geranium molle, Hypochoeris achyrophorus, Oryzopsis miliacea, Plantago coronopus, Reichardia picroides, Sonchus asper and Sonchus tenerrimus. Two salt concentration levels (18 and 37 g·L⁻¹) were applied twice monthly, weekly or twice weekly to examine the effect of salt irrigation schemes on the performance and seedling survival of L. barceloi compared to two of the principal species invading these salt marshes, S. tenerrimus and A. fistulosus.

Germination of L. barceloi and most ruderal species was highest at low salinity (0–8 g·L⁻¹). Seeds of L. barceloi, A. fistulosus and S. tenerrimus were also able to germinate at the highest salinity level, in contrast to the other species. Germination in freshwater after seawater pre-treatment was highest in L. barceloi (72 ± 6%). Seedling performance and survival of A. fistulosus and S. tenerrimus decreased with frequency and concentration of the salt treatment. An application of 37 g·L⁻¹ salt twice a week reduced seedling survival of A. fistulosus and S. tenerrimus by 83.3 and 91.6%, respectively. In contrast, 100% of the L. barceloi seedlings survived and showed similar performance among treatments.

Limonium barceloi had higher seedling growth and survival than ruderal invaders when salinity levels were high (37 g·L⁻¹). Nevertheless, at lower salinity, ruderal species may germinate and grow better and thus salinity level changes may represent a threat to the survival of this critically endangered species. Although further field testing is required, our experiments suggest that salt application could be an effective measure to protect L. barceloi and other endangered halophytic plant species from less salt-tolerant invaders.

How do different substrate types and soil nutrient levels influence species composition and successional sequences, as represented by different life-history traits? Is the rate of succession increasing or decreasing along a gradient from low to high fertility?

Ecological field station Dahlem, Berlin, Germany.

An 18-yr permanent plot study of succession on soils of differing fertility. The original substrates were a nutrient-poor sandy soil from a sandpit, ruderal subsoil of moderate fertility and nutrient-rich topsoil.

In plots with sand, monocarpic perennials were dominant at the beginning, which were then replaced by perennial grasses, those being then replaced by woody perennials. On ruderal soil, monocarpic perennials were co-dominant with perennial herbs at first, then were replaced by perennial herbs, which were then also replaced by woody plants. Dominance of woody species was attained after about 10 yr, both on sand and on ruderal soil. In plots with topsoil, there was a short phase at the start where monocarpic perennials were co-dominant with perennial herbs, followed by a relatively long period of perennial herb dominance. There were about twice as many woody species growing on the substrates of low and intermediate fertility compared to the nutrient-rich soil. If we compare the time necessary for woody species to reach 10% and 50% cover, woody colonization was much slower on the resource-rich site. DCA ordination revealed a clear separation of samples along the nutrient gradient. It also showed slower community change with increasing soil fertility.

This study demonstrates that woodlands can be created on bare ground in a temperate climate through natural colonization in a relatively short time, if substrates are not too nutrient-rich. The assumption that the rate of succession increases with increasing productivity could not be confirmed. Succession towards woodland can be rapid on soils of low and intermediate fertility. In contrast, a nutrient-rich substrate favours perennial herbaceous vegetation, which inhibits woody colonization and arrests succession.

What are the effects of traditional drove roads on landscape pattern and plant communities?

Madrid Autonomous Region, Central Spain.

We selected four study localities in different landscape units. Within each locality, we selected eight sites and within each site, we established three 1-ha plots, each corresponding to one of three situations: drove road, adjacent matrix or distant matrix. The landscape pattern of each plot was characterized by the cover of the different patch types, the patch type richness ha⁻¹ and the patch type evenness ha⁻¹. At one site per locality, we also recorded vegetation by randomly distributing twenty 20 cm × 20 cm quadrats per plot. We characterized each quadrat by its species richness, plant species composition and plant functional composition. We also analysed species richness by constructing rarefaction curves for each plot.

In the localities situated in croplands, sub-mediterranean forests and coniferous forests, drove roads were found to be an important source of spatial heterogeneity and a reservoir for a large number of plant species. In contrast, drove roads did not differ from the matrix habitats in rangelands, suggesting that the processes shaping drove road vegetation are similar to the general processes that shape grazed systems. Drove roads did not imply a significant increase in functional diversity. Our results were heavily scale-dependent: while drove roads provided heterogeneity at the local scale, they showed a remarkable similarity at the large scale.

Drove roads act as authentic local biodiversity reservoirs, especially in environments with low grazing levels. At the same time, drove roads imply structural and functional continuity on a large scale, increasing potential connectivity at the regional level. We recommend the preservation of drove roads in a functional state, because of their benefits to plant biodiversity conservation, and claim that these benefits should be considered when designing livestock policies with different intensification scenarios.

How well does a time-saving, qualitative sampling method compare with an intensive, quantitative sampling method in identifying the effects of reduction and cessation of cattle grazing on compositional change in a Mediterranean grassland?

Upper Galilee, northern Israel.

Experimental treatments involved two levels of grazing intensity and protection from grazing for different time periods. Sampling methods included a quantitative method, involving harvesting of vegetative biomass from small (25 × 25 cm) quadrats within 10 × 10 m exclosures, and a qualitative method, involving recording presence only of plant species within the same exclosures.

Both sampling methods revealed differences between protected vegetation and grazed vegetation; however they were not comparable in the way they described differences in species composition between grazed and ungrazed vegetation, and neither method could discriminate between the two levels of grazing intensity. The discrepancy between the two methods in the number and identity of species recorded ranged from 37% to 51% per plot for species recorded by both methods.

Qualitative sampling highlighted species that are indicative of protection from grazing; however it did not satisfactorily describe alteration in community composition, since the studied grassland is characterized by changing dominance of common species among treatments, instead of major species turnover. Suitable methods of data collection and monitoring will depend primarily on manpower and the specific characteristics of the studied community.

What is the effect of invading individuals of the widely invasive species Pinus radiata D. Don on regeneration of native woody species in a semi-arid ecosystem?

A semi-arid ecosystem in central Chile.

We sampled natural regeneration of native woody species in 40 plots in each of three canopy types: (1) under young adult invading trees of P. radiata located in formerly open (disturbed) sites; (2) in patches of native trees; and (3) in open (disturbed) sites, in two localities where this exotic tree is invading. Additionally, we carried out a field experiment in one of these localities; in eight of each of these canopy types we sowed seeds of ten widely distributed woody native species and monitored their recruitment. We also assessed different biotic and abiotic variables in these canopy types.

We found that soil water content, depth and cover of leaf litter were higher and photosythetically active radiation was lower under P. radiata trees and native patches than in open sites. In the natural regeneration study, species richness of seedlings was higher in native patches and under P. radiata trees than in open sites, and total abundance of seedlings (including all species) was higher only in native patches than in open sites. In the field experiment, both species richness and total abundance of seedlings were higher in native patches and under P. radiata trees than in open sites. Moreover, in the field experiment species richness recruiting in native patches was higher than under P. radiata trees.

We suggest that native patches as well as P. radiata trees invading open sites facilitate or have the potential to facilitate regeneration of native species, although facilitation produced by native trees was stronger than that produced by P. radiata. Thus, in sites where nurse plants are not available, invasion by this exotic tree may be exploited in restoration processes through sowing or planting native species under the canopy of invading young trees of P. radiata, eliminating P. radiata individuals after native regeneration has established.

The relative importance of environmental vs. biotic resistance of recipient ecological communities remains poorly understood in invasion ecology. Acer negundo, a North American tree, has widely invaded riparian forests throughout Europe at the ecotone between early- (Salix spp. and Populus spp.) and late-successional (Fraxinus spp.) species. However, it is not present in the upper part of the Rhône River, where native Alnus incana occurs at an intermediate position along the successional riparian gradient. Is this absence of the invasive tree due to environmental or biotic resistance of the recipient communities, and in particular due to the presence of Alnus?

Upper Rhône River, France.

We undertook a transplant experiment in an Alnus-dominated community along the Upper Rhône River, where we compared Acer negundo survival and growth, with and without biotic interactions (tree and herb layer effects), to those of four native tree species from differing successional positions in the Upper Rhône communities (P. alba, S. alba, F. excelsior and Alnus incana).

Without biotic interactions Acer negundo performed similarly to native species, suggesting that the Upper Rhône floodplain is not protected from Acer invasion by a simple abiotic barrier. In contrast, this species performed less well than F. excelsior and Alnus incana in environments with intact tree and/or herb layers. Alnus showed the best growth rate in these conditions, indicating biotic resistance of the native plant community.

We did not find evidence for an abiotic barrier to Acer negundo invasion of the Upper Rhône River floodplain communities, but our results suggest a biotic resistance. In particular, we demonstrated that (i) additive competitive effects of the tree and herb layer led to Acer negundo suppression and (ii) Alnus incana grew more rapidly than Acer negundo in this intermediate successional niche.

Most rivers in the Western Cape Province of South Africa are heavily invaded by alien trees, often resulting in profound changes in biodiversity and ecosystem functioning. Although large-scale management operations are underway to clear invasive trees and restore ecosystem function, little is known regarding native species recovery after alien clearing. Has Eucalyptus invasion along the Berg River altered the distribution and composition of native vegetation? How does the removal of invasive trees through complete clearing and thinning facilitate the recovery of native vegetation?

Berg River, Western Cape, South Africa.

We assessed the recovery of native vegetation after 4 yr of complete clearing of the invasive tree Eucalyptus camaldulensis (100% alien cover removal) and thinning (40–50% alien cover removal) along the Berg River in the Western Cape, South Africa. Native and alien plant cover, species richness and diversity were recorded on completely cleared and thinned sites and compared to natural (non-invaded control sites) and E. camaldulensis invaded sites.

Species richness and diversity were significantly higher in both completely cleared and thinned sites compared to natural and invaded sites. Increases in species richness and diversity in completely cleared and thinned sites were a result of re-invasion by alien herbaceous and graminoid species, which have the potential to hinder native species recovery. Cover of native trees and shrubs was higher in both completely cleared and thinned sites compared to invaded sites. Species composition (relative cover) in completely cleared and thinned sites was similar to species composition in natural sites.

Both complete clearing and thinning methods promote indigenous vegetation recovery and a positive trajectory towards recovery of ecosystem structure and composition can be expected in future. To improve management operations, a four-stage thinning process that has the potential to facilitate native species recovery is suggested.

In the past decades, the tall native invasive grass, Elytrigia atherica, has been increasing in frequency and dominance on salt marshes along the Wadden Sea coast. Is this rapid expansion an outcome of natural succession or is it driven by anthropogenic eutrophication resulting from atmospheric deposition?

Salt marshes on four back-barrier islands, Wadden Sea on the coast of the Netherlands and Germany.

We used a combination of time series of vegetation maps and chronosequence data of four naturally developed salt marshes to address our questions. These salt marshes have not been grazed by livestock or subject to other management regimes. By comparing development within and between four different salt marshes, we were able to study the spatial and temporal dynamics of the community dominated by E. atherica on natural salt marshes.

The expansion rate of the E. atherica community was highest on young salt marshes (up to 30 yr old) with vertical accretion rates of 0.35 cm·yr⁻¹. The rate of expansion decreased on older marshes and the direction reversed, becoming negative, on the oldest marshes (around 90 yr old), which have no vertical accretion and are under waterlogged conditions.

The expansion of E. atherica on natural, back-barrier islands along the Wadden Sea coast is more influenced by the age of the salt marsh and patterns in vertical accretion of soil than by uniformly spread atmospheric deposition.

What changes in character and extent of land use have occurred during the last 200 yr in the Białowieża Primeval Forest (BPF)? Are the landscape transformations described from the multi-temporal analysis of historical maps coherent with vegetation changes expressed by the previous palynological analyses?

Białowieża Primeval Forest, Polish–Belarusian border.

We used five historical maps (from 1793 to 1936) and one digital land-use map (1999–2000) to quantify the landscape changes. Land-use types according to historical maps were digitized and georeferenced. The maps were then used for both comparing the extent of cover types in each time step and analysing the nature of change through transition matrices. The sequence of changes concerning the proportion of land-use types was then compared with classes of pollen, which were assumed to represent corresponding vegetation types.

Most of the area (>70%) has been continuously covered with forest. In the period between 1793 and 1830, the forest declined, being the main donor to agricultural land and villages. In the 20th century, the trend was reversed. We found a significant correlation between the percentage of the main vegetation types derived from historical maps and the corresponding vegetation types, as indicated by pollen, with a mean time lag of 20 yr.

The BPF landscape has been quite stable throughout the last 200 yr, mainly due to the high continuity of forest cover. The results obtained from landscape analysis based on maps are coherent with pollen data collected in the same area.

Can we predict where forest regrowth caused by abandonment of agricultural activities is likely to occur? Can we assess how it may conflict with grassland diversity hotspots?

Western Swiss Alps (400–3210 m a.s.l.).

We used statistical models to predict the location of land abandonment by farmers that is followed by forest regrowth in semi-natural grasslands of the Western Swiss Alps. Six modelling methods (GAM, GBM, GLM, RF, MDA, MARS) allowing binomial distribution were tested on two successive transitions occurring between three time periods. Models were calibrated using data on land-use change occurring between 1979 and 1992 as response, and environmental, accessibility and socio-economic variables as predictors, and these were validated for their capacity to predict the changes observed from 1992 to 2004. Projected probabilities of land-use change from an ensemble forecast of the six models were combined with a model of plant species richness based on a field inventory, allowing identification of critical grassland areas for the preservation of biodiversity.

Models calibrated over the first land-use transition period predicted the second transition with reasonable accuracy. Forest regrowth occurs where cultivation costs are high and yield potential is low, i.e. on steeper slopes and at higher elevations. Overlaying species richness with land-use change predictions, we identified priority areas for the management and conservation of biodiversity at intermediate elevations.

Combining land-use change and biodiversity projections, we propose applied management measures for targeted/identified locations to limit the loss of biodiversity that could otherwise occur through loss of open habitats. The same approach could be applied to other types of land-use changes occurring in other ecosystems.

Given the significance of the herbaceous understorey layer for temperate forest ecosystem biodiversity and functioning, it is important to have a thorough understanding of its dynamics in response to environmental change. However, site-specific factors such as soil type may cause differential temporal herb layer changes within a single study area under comparable external pressure. Surprisingly, relatively few studies have examined herb layer changes on different site types within the same forest complex. The aim of this study is to determine the temporal differences in herb vegetation and to compare these for two differing site types in the same forest complex.

Ancient broad-leaved woodlands traditionally managed as coppice with standards in South Belgium, an area with secondary deposits and a mild temperate climate.

In 2008 we re-inventoried 43 vegetation recordings from 1953 to 1954 in forests on two site types (acid and neutral forests). First, we described differences in soil pH, litter and overstorey characteristics between the sites. Next, multivariate analysis, Ellenberg indicator value and CSR signature were used to determine differences in herb layer diversity and composition between both the two survey times and the two site types. Finally, we analysed temporal differences in individual species abundances and frequencies.

The two site types clearly differed with respect to soil, litter and overstorey characteristics. Temporal changes between the surveys were mostly highly significant on the neutral sites and mostly not significant on the acid sites. On both site types, the species pool size declined. On the neutral site, the mean plot species richness also declined. Based on the plant-derived characteristics (Ellenberg indicator values) of the plots, light availability decreased and nitrogen availability significantly increased on the neutral sites.

Input of eutrophying deposits and management changes are seen as key drivers of herb layer changes in the study area over the last half-century. However, our study suggests that site characteristics such as parent material and soil pH should also be considered. Together with the key drivers, incorporating differences in site characteristics may improve our understanding of temporal shifts in herb layer vegetation in response to environmental change.

How resilient is boreal forest vegetation growing on acidic podzols to the environmental change caused by alkaline kiln dust pollution? How adaptive is the vegetation, when species pool and time for dispersal do not limit? How constant is the species niche breadth along the soil pH gradient?

Region of 30 km around the Kunda cement plant, northern Estonia (59°30′ N, 26°32′ E), which has been continuously polluted last 140 years.

We sampled 20 forest stands on sandy gleyic podzols at various distances from the pollution source, leeward and windward of prevailing winds. Data processing: principal components analysis for gradient generalization, indicator species analysis for grouping species along the pollution gradient and generalized linear model analyses to estimate species reaction to pollution, considering covariates.

The impact of alkaline dust accumulated over a century persisted despite resolute reductions of pollution. Forest soil conditions changed 10 km leeward and 5 km windward from the source: the litter pH level changed from 3.6 to 4.5 in unpolluted forests to 7.1–7.4 in the heavily polluted forests, and soil Ca content increased ten-fold. Soil alkalization has induced a remarkable succession from typical boreal vegetation toward vegetation of boreo-nemoral or calcareous habitats. We detected a linear increase of species richness from habitats on acidic soils (unpolluted) to newly formed alkaline soils (polluted habitats), reflecting the species pool composition and size, which is known to be large for calcicolous species. The establishment of several endangered calcicolous species shows the lack of dispersal limitation and points on their narrow soil pH niche. The niche breadth of species along the pH gradient varied among species, but only a few species appeared to be pH generalists.

Species ranking along the pH and/or Ca gradients indicates (1) the existence of different ecological guilds in terms of ecological niche use, and (2) the formation of a new community is dictated by the tolerance level of each species. This supports the individualistic community assembly rule suggested by Gleason. We find that such polluted regions with disturbed communities have high scientific value as long-term ecological experiments, but this might lead to conflict between the peculiar biodiversity complex and human well-being.

(1) to compare two series of precipitation data from different periods (1930–1950 and 1950–2000) in three sectors of the southern dry Chaco in the arid and semi-arid sub-regions; (2) construct maps showing the distribution of land-cover units for 1979, 1999, 2004 and 2010 for the same three sectors; and (3) assess the changes in land-cover units occurred between 1979 and 2010 in the three sectors.

Southern extreme of the dry Chaco in NE and NW Córdoba Province, central Argentina.

We compared annual and growth period (November–March) precipitation among the three sectors and between two series of data corresponding to different periods (1930–1950 and 1950–2000) using repeated measures ANOVA, with the station as the subject variable, period as the within-factor and sector as the between factor. Using three Landsat MSS (1979) and nine Landsat TM (1999, 2004 and 2010) images we mapped the distribution of eight land-cover units for the whole study area. For each sector (NE, NW and W), we performed a change detection analysis between 1979 and 2010.

The classification of Landsat MSS and TM images resulted in reliable land-cover maps (overall accuracy 80%). Our results showed that vegetation cover in the area is highly disturbed and that the present status of vegetation cover differs among the three sectors. In the more humid sector, the land-cover changes have been dominated by replacement of closed forests by crops, while in the driest portion of the study area forest loss was not related to agriculture. Additionally, we found that significant increases in precipitation have occurred in all three sectors, but the increase was highest in the humid sector.

The differences observed among the three sectors suggest that precipitation may have effectively played a dominant role in the process of forest conversion to agriculture.

Which plant traits characterize successful and failed target species in urban grassland restoration? Do traits of successful target species differ from those of resident species? How do plant traits relate to environmental constraints?

In-situ experimental sites on wastelands in shrinking residential areas in Berlin, Germany.

We established grassland restoration treatments and explored plant traits of successful and failed target species (plant height, specific leaf area, seed mass, seed shape, seed longevity index, CSR strategy type, plant life form). To shed light on mechanisms that shape restoration success, we also analysed the same traits of species originating from the soil seed bank and species immigrating from the surroundings. We compared both trait sets to those of resident species. With RLQ analyses we related the trait data to abundance data of species and to variables describing the environmental setting of the sites.

In the third year after treatment, several plant traits differed between the successful or failed target species and the resident vegetation, e.g. successful target species tended to be as tall as resident species, whereas failed target species were smaller, suggesting insufficient competitive ability of the latter. Species that successfully recruited from the soil seed bank were taller than resident species. Small specific leaf area was important for the establishment success of target species. Trait composition of the species assemblage clearly related to the environmental setting: mean specific leaf area and the proportion of annuals increased and the proportion of C-strategists decreased with increasing human-mediated impacts on the restoration sites.

Our results reveal clear trait differences between successful and failed target species in grassland restoration on urban wasteland sites, demonstrating that high competitive ability is crucial for success in target species. Grassland species that are successfully integrated into urban wasteland vegetation may thus fill well-defined vacant niches, while resembling the traits of the resident species in other ways. Our results may allow generalizations and transfer to similar urban settings, as the analysed trait states were assessed as relative values compared to resident species.

(1) How do various mowing regimes used for the preservation of diverse meadow biota affect the occurrence of plant seedlings? (2) Does the effect of mowing regime on seedlings differ among vegetation types? (3) Are the seedlings occurring under a particular management type characterized by distinct functional traits? (4) Do the traits of seedlings differ from those of resident adult plant species?

White Carpathians (Bílé Karpaty) Mountains, Czech Republic.

In a species-rich meadow, seedlings (non-graminoids only) were identified to species and counted in an experiment that included management cessation and five mowing regimes in three types of vegetation for 2 yr. The abundance-weighted averages of functional traits were compared between seedling and adult plant communities.

Seedling occurrence was suppressed by management cessation (abandonment) but differences among the five mowing treatments were small for all vegetation types. Seedling density and species richness were highest in vegetation dominated by Bromus erectus, intermediate in vegetation dominated by Molinia arundinacea, and lowest in vegetation dominated by Calamagrostis epigejos. Comparison of functional trait composition of seedlings with that of adult plants revealed that seedlings were largely produced by species with no or limited clonal growth and with low stature, and therefore with lower competitive ability.

The results indicate that short-term alteration of the mowing regime does not change conditions conducive to seedling occurrence, but even short-term abandonment hinders the establishment of small, non-clonal species. Rapid changes in species composition after abandonment in temperate meadows are therefore due not only to competitive exclusion of subordinate plant species, but also to their inability to establish from seeds.

Does the presence of grasses affect the establishment (survival and growth) of tree saplings in an abandoned tropical pasture, and what is the potential of established saplings to modify pasture microenvironmental conditions, particularly light incidence?

Abandoned cattle pasture, in the humid tropics of SE Mexico (18°25′–18°45′ N, 95°00′–95°18′ W).

The establishment of four native fast-growing tree species in a tropical abandoned pasture was evaluated. Saplings of Cecropia obtusifolia, Hampea nutricia, Omphalea oleifera and Erythrina folkersii were transplanted using a split-plot design. Plant survival and growth were evaluated over 12 mo under two experimental treatments: presence and absence of grasses. Light incidence at ground level was used to evaluate microclimate conditions under the grass matrix, compared to light incidence under saplings established in the pasture.

Saplings had high survival (49–88%) regardless of the presence of grasses. In the presence of grasses, growth of surviving saplings either increased or was not impacted, and in only one out of eight comparisons did grasses negatively affect growth. The impact of saplings on light incidence in abandoned pastures depended on sapling species architecture: species with large total leaf area and canopy area ( H. nutricia and E. folkersii) significantly reduced light incidence (12–29% of total incidence), while narrow-canopy species ( C. obtusifolia and O. oleifera) generated less intense shade (37–89% of total incidence).

Grasses did not seem to represent a crucial limiting factor in sapling establishment of fast-growing native species in the short term. In addition, shading by recruited saplings of some native species could be important to out-compete grasses in the future, as well as for ‘facilitating’ regeneration of more shade-tolerant species. Transplantation of fast-growing native saplings into abandoned pastures, even without manipulation of the grasses, could be a useful practice for landscape-scale restoration programmes in tropical areas. Evaluation of the longer-term consequences (beyond the 1-yr span of this study) warrants further research.

Resources quality and quantity are both important determinants of habitat use for large herbivores. We aim to understand how these two variables vary throughout the growing season in sub-alpine grasslands. How do productivity and phenology (quality) of different plant communities within a landscape vary over time? Do productivity and phenology co-vary? Which environmental constraints or growth form composition best explain differences in productivity and phenology among plant communities?

Calcareous sub-alpine grasslands, the external Alps, France.

We assessed how productivity (above-ground biomass) and phenology varied with date, slope, radiation and altitude among seven plant communities. Then we explored (1) co-variation among maximum biomass, the date of maximum biomass and average community flowering date for each plant community, and (2) whether these variables were related to snow regime or growth form composition.

Temporal dynamics of biomass and phenology varied markedly among plant communities. More productive communities reached their maximum biomass later. Flowering occurred after the biomass peak, except for one plant community. However, the later the biomass peak, the shorter the lag to flowering peak. The timing of flowering and date of maximum biomass were best explained by differences in snow regimes among communities. The impact of growth form composition was marginal.

Plant communities are under strong time constraints to grow and flower. Snowmelt regime plays a crucial role at one end of the growing season, while time left for fruiting and maturing is likely to influence the other end. Sub-alpine grassland communities are highly heterogeneous in productivity, timing of maximum productivity and flowering phenology, creating small-scale variability in the forage quality and quantity available to large herbivores.

Can repeat (time-lapse) photography be used to detect the phenological development of a forest stand, and linked to temporal patterns in root nutrition for Hedysarum alpinum (alpine sweetvetch) an important grizzly bear food species?

Eastern foothills and front ranges of the Rocky Mountains in Alberta, Canada. The area contains a diverse mix of mature and young forest, wetlands and alpine habitats.

We deployed six automated cameras at three locations to acquire daily photographs at the plant and forest stand scales. Plot locations were also visited on a bi-weekly basis to record the phenological stage of H. alpinum and other target plant species, as well as to collect a root sample for determination of crude protein content.

Repeat photography and image analysis successfully detected all key phenological events (i.e. green-up, flowering, senescence). Given the relation between phenology and root nutrition, we illustrate how camera data can be used to predict the spatial and temporal distribution and quality of a key wildlife resource.

Repeat photography provides a cost-effective method for monitoring vegetation development, food availability, and nutritional quality at a forest stand scale. Since wildlife responds to the availability and quality of their food resources, detailed information on changes in resource availability helps with land-use management decisions and furthers our understanding of grizzly bear feeding ecology and habitat selection.

Do leaf functional traits describe variation in the intensity of management in semi-natural grasslands?

Mugello, North Apennines, Italy.

In an ecologically homogeneous area, we identified four grassland management practices (three different stocking rates and abandonment for 10 or more years). We measured leaf functional traits (LFT) of three dominant grass species – leaf dry matter content (LDMC), specific leaf area (SLA) and leaf N concentration (LNC) – in two permanent sampling plots per treatment for two consecutive years. Statistical tests and multivariate analysis were employed to compare the traits and analyse their sensitivity in responding to the different management intensities.

The robustness of LDMC and SLA in grass species ranking was confirmed. Weighted LDMC and SLA were able to differentiate the most intensely managed site from the others.

The results of the weighted LDMC and the weighted SLA encourage further studies aimed at the development of a LFT database for the most common grass species of Apennine semi-natural grasslands. This could be of great help in the development of indicators able to support the formulation of rational management plans for conservation and sustainable animal production.

How can the conservation status of Mediterranean coastal dunes be assessed? What is the effect of disturbance factors on it?

Tyrrhenian coast of Central Italy.

Vegetation relevés along 164 transects lying perpendicular to the shoreline along the Tyrrhenian coast of Central Italy were used to identify the presence of dune habitats by means of TWINSPAN classification and detrended correspondence analysis. Multiple correspondence analysis was used to analyse relationship between habitats and disturbance factors. The resulting Burt's table was used to build an index (habitat-disturbance, HDi) for analysing this relationship. Based on HDi values, a correspondence analysis (CA) between presence/absence of habitats and disturbances was performed. The overall plant species diversity of dunes was measured with NH_DUNE, a modified version of the Shannon index. Multi-way ANOVA procedure was used to investigate effect of single disturbance factors and their interactive effect on NH_DUNE.

Classification and ordination procedures identified four sequential habitats moving from the shoreline to inland: annual vegetation on drift lines characterized by Cakile maritima; embryonic shifting dunes dominated by Elymus farctus; shifting dunes with Ammophila arenaria subsp. australis; back dune grasslands characterized by Ononis variegata. CA showed that disturbance factors influence dune habitats differently. In particular, the Cakile community had a negative relationship with beach tourism and mechanical cleaning; the Elymus community had a positive relationship with beach tourism and mechanical cleaning and a negative relationship with erosion and bathing establishments; the Ammophila community had a negative relationship with mechanical cleaning and bathing establishments and a positive relationship with dune cross-trampling; and the Ononis community had a negative relationship with bathing establishment. According to multi-way ANOVA, single disturbance factors can have different effects on plant species diversity as measured by NH_DUNE. However, the overall effect is negative, with erosion as a single factor and the combination of mechanical cleaning and bathing establishments significantly lowering the plant diversity of coastal dune systems.

The proposed method allows a fast and replicable evaluation of the effects of disturbance factors on the conservation status of Mediterranean coastal dunes, providing the information necessary for development of conservation strategies focusing on a single habitat or on the overall dune system.

Is the satellite-derived Normalized Difference Vegetation Index (NDVI) an adequate proxy for the timing of the peak in plant nitrogen concentration in an Arctic tundra system? Can NDVI be used to reliably assess seasonal changes in aboveground plant biomass?

The south plain of Bylot Island, an Arctic tundra ecosystem north of Baffin Island, Nunavut, Canada (73°08′ N, 80°00′ W).

Using plant data collected every 2 wk throughout the summer in 1991, 1993–1996 and 2006–2008, we assessed the relationship between four NDVI indices (AVHRR satellite data at 1-km² spatial resolution) and the date of peak nitrogen concentration in wetland graminoid plants, which represents seasonal variability in plant quality. We also examined the relationship between NDVI and the seasonal changes in aboveground live plant biomass.

Three out of the four NDVI metrics that we tested were significantly related to date of peak nitrogen concentration. The strongest relationship was found with the date at which NDVI values reached 50% of their annual maximum (r² = 0.87). We also found a positive exponential relationship between NDVI and aboveground biomass of plants (r² = 0.58), though this relationship was strongest early in the growing season.

NDVI can be used as a proxy to determine date of peak nitrogen concentration in some tundra plants, and can thus be a reliable measure of the yearly changes in the timing of the availability of high quality food for herbivores. To a lesser extent, NDVI can also be used to assess seasonal change in plant biomass. This study provides additional support for the use of broad-scale satellite-derived NDVI to assess seasonal changes in habitat quality for herbivores.