Functional traits of cryptogams in Mediterranean ecosystems are driven by water, light and substrate interactions
Article first published online: 13 SEP 2013
© 2013 International Association for Vegetation Science
Journal of Vegetation Science
Volume 25, Issue 3, pages 778–792, May 2014
How to Cite
Giordani, P., Incerti, G., Rizzi, G., Rellini, I., Nimis, P. L., Modenesi, P. (2014), Functional traits of cryptogams in Mediterranean ecosystems are driven by water, light and substrate interactions. Journal of Vegetation Science, 25: 778–792. doi: 10.1111/jvs.12119
- Issue published online: 10 APR 2014
- Article first published online: 13 SEP 2013
- Manuscript Accepted: 22 JUL 2013
- Manuscript Received: 14 JUL 2011
- Italian Ministero dell'Istruzione
- dell'Università e della Ricerca
- Functional traits;
- Photosynthetic strategy;
- Reproductive strategy
Poikilohydric organisms can survive desiccation without damage and recover soon after re-wetting. In this work we explore the realized niches of epilithic, poikilohydric organisms, i.e. lichenized and lichenicolous fungi and bryophytes, grouped into 15 functional guilds based on growth form, reproductive strategy and photosynthetic traits. We hypothesize that in Mediterranean ecosystems, the distribution of these guilds is controlled by water availability and solar radiation, together with characteristics of the substrate.
Western Sardinia (Italy). The area hosts Mediterranean Quercus ilex forests on basaltic substrata within an agroforestry landscape.
The presence or absence of species from each guild was recorded in 1025 small quadrats (10 × 10 cm). Four environmental variables were measured: solar radiation, microtopography (potential water run-off), substrate roughness and number of cracks. The occurrence of each guild was related to environmental variables using non-parametric multiplicative regression, and ecological niches of the guilds were derived from those models.
The occurrence of all functional guilds varied significantly according to the selected environmental variables. In most cases, solar radiation was the most important variable; TI was included first in the model of two sorediate guilds, whereas four sexually reproducing functional guilds had surface relief as first variable. The growth forms were separated along a gradient of increasing solar radiation, whereas water run-off and surface roughness mainly discriminated reproductive strategies and photobionts. Vegetatively reproducing guilds with other photobionts than Euphyta-like pigments were confined to the border of the ecological space, defined by gradients of environmental factors, which was largely occupied by more competitive, sexually reproducing organisms.
Functional traits of epilithic poikilohydric organisms were associated with ecological adaptations to the stressful environment of Mediterranean outcrops. We showed that their response in terms of probability of occurrence is coherent with quantitative gradients of solar radiation and water availability at the micro-scale.