Content uploaded by Christian Piedallu
Author content
All content in this area was uploaded by Christian Piedallu on Jan 08, 2016
Content may be subject to copyright.
A preview of the PDF is not available
The SILVAE portal provides access to ecological and forestry maps for France
ResearchGate has not been able to resolve any citations for this publication.
Aim
Soil water is essential for the physiological processes of plant growth and fitness. Owing to the difficulty of assessing wide variations in soil water reserves, plant distribution models usually estimate available water for plants through such climatic proxies as precipitation data ( P ) or climatic water balance ( P minus potential evapotranspiration). We evaluated the ability of simple climatic proxies and soil water balance indices to predict the ecological niches of forest tree species.
Location
F rance.
Methods
Soil water content and deficits were computed and mapped at a resolution of 1 km × 1 km throughout F rance. The predictive abilities of these indices were compared with those of P and climatic water balance to model the distributions of 37 of the most common E uropean tree species. We focused on two species with contrasting water tolerance, Q uercus robur and Q uercus pubescens , to illustrate the differences between climatic proxies and soil water balance in species response curves and distribution maps.
Results
Throughout F rance, soil water content was poorly correlated with P and climatic water balance, because low P in the lowlands can be compensated for by water provided by deeper soils, which is not the case in most mountainous areas. Soil water balance performed better than simple climatic water variables for explaining tree species distribution, improving 82% of the models for hygrophilous, meso‐hygrophilous, meso‐xerophilous and xerophilous species.
Main conclusions
Our results showed that simple climatic values do not accurately represent available water for trees and that soil water balance indices perform better than do climatic proxies for most species. This point is crucial to avoid underestimating the importance of water in studies aimed at determine the ecological niches of plant species and their responses to climate change.
A new database is described, named EcoPlant, that currently holds data from 6432 phytosociological relevés of French forests. The aim of the database is to investigate and model the distribution of forest plant species, and their response to ecological factors, i.e. their ecological niche. Unlike other similar databases, a full environmental description is stored with the floristic data of each site. The climatic data at the site are included, and access to direct climatic variables is possible through geographic information system (GIS) modelling. Precise data on the soil are also stored for each site (soil profile and horizon descriptions, physical and chemical analyses of soil samples). The database is designed to enable linkages to existing soil, floristic or plant-trait databases.