Journal of Ecology

We strongly discourage the use of heuristic indices in ecological research. The majority of the 50 or so indices that have been used in competition studies have been developed with little or no regard to underlying theory or models. However, it is possible to make predictions about how competition varies along gradients from models that translate into both qualitative and quantitative conditions and metrics, and we encourage authors to do this.

Upland deforestation by European settlers triggered a cascade of ecological changes on a nutrient-poor peatland by enhancing dust deposition and nutrient delivery on the surface. These results demonstrate that indirect, unintended and often overlooked human disturbances can lead to dramatic structural and functional alterations of carbon-rich wetland ecosystems, highlighting the potential vulnerability of these systems in human-dominated landscapes.

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Our results suggest that plant diversity contributes to plant community resistance against pathogens by fostering beneficial bacterial communities. This indirect soil feedback mechanismmay contribute to the positive relationship between plant diversity and productivity and could also help the development of more sustainable and environmentally friendly agricultural management strategies.

Our findings confirmed that these ecosystems bracket a critical biological threshold below which low soil oxygen availability caused by excessive moisture becomes limiting for biological processes. Recognition of this redox threshold and its ecological implications could contribute to improved ability to manage ecosystems which may be near this threshold or become so in a changing climate.

We demonstrate here that plant traits, likely via their control on litter and topsoil decomposer community composition, have indirect effects on litter breakdown rates, not only at the interface between ecosystems but also within ecosystems, with likely implications for many other ecosystems world-wide. These results suggest functional variation in decomposer communities between ecosystems with respect to their efficiency to degrade litters with contrasting qualities, such as different lignolytic and detoxification activities but also contrasting efficiencies to degrade non-recalcitrant tissues.

Our results provide strong support for the long-term ecosystem-development model, particularly with regard to the appearance of P limitation and associated declines in productivity. However, our study also shows that N cannot be assumed to invariably be the most important limiting nutrient in young soils, and it is unlikely to be the only limiting nutrient in calcareous soils. This south-western Australian long-term chronosequence provides an excellent opportunity to explore edaphic controls over plant species diversity.

Using trait-based approach, we found that the soil resource availability was crucial determinant of habitat filtering processes in a dipterocarp tree community in a 52-ha Malaysian forest dynamics plot. Variation in soil resource availability can shape the distribution of traits through community assembly processes, promoting trait diversification and species coexistence.

Functional diversity patterns suggest that multiple assembly processes (abiotic filtering, above-ground competition and below-ground competition) operate simultaneously to structure plant communities along a stress–resource gradient in alpine tundra. These processes would be obscured by focusing on a single multivariate trait index or on phylogenetic diversity and are only evident by analyzing functional diversity patterns of individual traits.

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We measured shifts in plant trait distributions following long-term (27-year) manipulations of soil resource availability and grazing intensity. We used these trait distributions to predict species relative abundances using ‘community assembly through trait selection’ (CATS) models. These models allowed us to quantify the relative importance of different traits in determining abundance across different environmental conditions.

Our results demonstrate that at high fertility locally dominant species differ in resource-use strategy, but as soil fertility declines over the long term, dominant species increasingly converge on a resource-retentive strategy. This suggests that differentiation in resource-use strategy is required for coexistence at high-fertility but not in low-fertility ecosystems.

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We provide the most comprehensive examination to date of the relative importance of environmental filtering and limiting similarity in structuring tropical tree communities. Our results confirm that environmental filtering is the overriding influence on community assembly in these species-rich systems.

This study indicates that in the highly deforested and fragmented Los Tuxtlas rain forest, Mexico (a), the local extirpation of tree species does not occur across entire lineages (b). These novel and hopeful findings have direct implications for the ecology and conservation of fragmented rain forests. The maintenance of phylogenetic diversity in highly fragmented landscapes suggests that ecosystem function and stability may be maintained despite the loss of a number of tree species. We argue that in this unique Neotropical region, both large and small rain forest patches are critical for conserving regional tree evolutionary history.

This photo shows a tanoak stem killed by the pathogen Phytophthora ramorum that has developed basal sprouts, some of which have been killed by the pathogen. Basal sprouting maintains both the host and pathogen as part of the community which leads to reduced size and abundance of tanoak. This pattern is similar to several other forest diseases in North America.

Our results illustrate that the functional consequences of realistic species losses can differ distinctly from those of randomized species losses and that incorporation of realistic species loss scenarios can increase the relevance of experiments linking biodiversity and ecosystem functioning to conservation in the face of anthropogenic global change.

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We evaluated the covariation among wood density, xylem anatomical traits, diameter growth rate and adult stature in 40 tropical tree species. We found that xylem anatomical traits have a more significant influence on whole plant performance due to their direct association with stem hydraulic conductivity, whereas wood density is decoupled from hydraulic function due to complex variations in xylem components.

Our analysis is, to our knowledge, the first to demonstrate the critical role of species evenness, which has a saturating relationship with richness, and the importance of contrasting traits in defining net diversity effects in forest polycultures. While testing the specific mechanisms is beyond the scope of our analysis, our results should motivate future studies to link richness, evenness, contrasting traits, and life history stage to the mechanisms that are expected to produce positive net biodiversity effects such as niche differentiation, facilitation, and reduced Janzen-Connell effects.

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Natural selection on phytochromes occurs through their effects on seed germination, and maternal effects alter phytochrome contributions to germination. Therefore, maternal effects can alter natural selection on phytochromes. The results demonstrate a novel role of maternal effects in contributing to variable natural selection on specific genes associated with plant responses to climatic conditions.

There is considerable variation within populations in tree phenology, as indicated by the differences in bud-burst by the two valley oaks (Quercus lobata) shown in the photo. Studying this species in central coastal California, we found that trees that leaf out and flower early and late in the season – when fewer other trees are leafing out – produce fewer acorns in the autumn than trees that leaf out during the middle of the season, despite considerable annual variation in acorn production. This finding is consistent with the hypothesis that pollen limitation has a strong affect on within-year reproductive success in this wind-pollinated species. Pollen limitation in wind-pollinated trees affects many key aspects of their life-history including masting behaviour, spatial synchrony and within-year acorn production.

Kirwan and Guntenspergen measured rates of root production in a rapidly submerging Chesapeake Bay marsh and found that plants at low elevations produce few roots that contribute to soil building. Their results suggest that the local marsh is in a runaway feedback where sea-level rise leads to reduced root production, lower rates of soil building, and further loss of relative wetland elevation.

Our experimental data support observational studies of niche-limit conservatism in non-native plants, which has important implications for their management. Specifically, it suggests that efforts to predict the extent of an invasion based on knowledge of the native niche are likely to be accurate at the level of the species, even if populations undergo genetic changes or respond differently to climatic gradients in the new range.

Our study shows that at two structurally different tree lines, recent and initial declines in growth and losses of long-term synchrony are occurring in the latter part of the 20th century. These findings are opposite to simplistic expectations of global warming effects on tree line dynamics and call for a model reformulation that uncouples drivers of growth and recruitment.

Our results suggest that correlations between growth and resistance are context dependent and may only be apparent in populations relieved from certain natural pressures, such as in natural populations relieved from natural selection by herbivores.

Young Mallotus japonicus (Euphorbiaceae) leaves are defended against herbivores through the use of direct defence traits such as trichomes and pellucid dots. However, the plant uses indirect defence traits for middle-aged leaves. This shift from direct defence to indirect defence with leaf ageing supports the ‘optimal defence theory’: plants have evolved multiple defence traits to maximize their fitness.

In this paper, we showed that damage signalling by methyl-jasmonate (MJ) application in young pine trees involves two quick and strong induced responses putatively related with tolerance mechanisms: an intense preferential allocation of biomass to the fine roots system and a marked increase in the concentration of nutrients in the shoot. Boosting of fine roots appeared to be a generalized strategy with weak environmental modulation, whereas induced shifts in N and P to the shoots were strongly affected by soil P availability. Both tolerance mechanisms did not show significant genetic variation, that is, responses were consistent among families.

Campanula rotundifolia (Harebell) is widespread and cytologically diverse in the British Isles. Hexaploids have an oceanic, westerly/northerly distribution, tetraploids are more easterly/southern, and occasional pentaploids occur. It tolerates diverse climatic and soil conditions, becoming rare on fertile lowland clays, where there are more vigorous competitors. It is threatened by agricultural intensification, reversion of grassland to scrub, disturbance, and atmospheric pollution.