La disponibilidad del agua determina las propiedades funcionales de las comunidades leñosas

Guadiato_slopeUnderstanding which factors govern the processes in plant communities constitutes one of the main challenges in ecology. The functional approach is a broadly-known key tool to better understand these issues; is based on the functional trait variation along environmental gradients. Thus, the functional approach allows as to discern the filtering mechanisms and the community patterns that take place.

The IRNAS-CSIC has collaborated with the University of Córdoba in a study at local scale (Sierra Morena Mountains), analysing the functional trait variation on nine woody plant communities along moist and nutrient gradients. For this approach, several functional traits at aboveground (plant size, specific leaf area, leaf and stem dry matter content, etc.) and belowground (root dry matter content and specific root length) level were taken on 38 Mediterranean woody species. The main objectives were i) identify which environmental soil drivers (mainly nutrient and moist) were associated with functional trait variation at the community level and ii) discern if trait variation was the results of changes on species composition (turnover), changes on species abundance or such a consequence of intraspecific variability. For this last question we have developed a new formula (based on Leps et al. 2011 equation), which allows to disentangling the causes of these processes between communities.

Our results showed that the functional trait variation on the community was highly determined by soil water storage. In contrast, soil nutrient availability did not have any significant role. In addition, changes on community structures were the result of changes in species occurrence. These results highlighted the importance role of water availability on Mediterranean ecosystems (already well-known), however this study also highlighted that soil water variations at local scale may promote large changes in the community structure. These changes are not only due to species replacement on the community, but also to changes on their functional composition. These results are especially relevant on the global change context, which predict the increase of the aridity, being able to cause a strong alteration in species composition, especially on moisture sites, promoting the disappearance of species and the alteration of the ecosystem processes associated with them.

This work is part of the Ph. D. dissertation of Enrique G. de la Riva and has been published in the journal Oikos.

de la Riva, E. G., Pérez-Ramos, I. M., Tosto, A., Navarro-Fernández, C. M., Olmo, M., Marañón, T., & Villar, R. (2015). Disentangling the relative importance of species occurrence, abundance and intraspecific variability in community assembly: a trait-based approach at the whole-plant level in Mediterranean forests. Oikos. DOI: 10.1111/oik.01875.

Data deposited at Dryad: doi:10.5061/dryad.dr275

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