Soil water storage appears to compensate for climatic aridity at the xeric margin of European tree species distribution

Karl H Mellert,Joerg Ewald,Steffen Täger,Andraž Čarni,Christian Kölling,Jean-Claude Gégout,Dejan Stojanović,Eckart Kolb,Daniel Hornstein,Susanne Winter,Matthias Jantsch,Annette Menzel,Thomas Wohlgemuth,Axel Göttlein,Isabel Dorado-Liñán,Ioannis Tsiripidis,Nina Juvan,Jonathan Lenoir,Eduardo López-Senespleda

doi:10.1007/s10342-017-1092-x

Abstract

Based on macroecological data, we test the hypothesis whether European tree species of temperate and boreal distribution maintain their water and nutrient supply in the more arid southern margin of their distribution range by shifting to more fertile soils with higher water storage than in their humid core distribution range (cf. soil compensatory effects). To answer this question, we gathered a large dataset with more than 200,000 plots that we related to summer aridity (SA), derived from WorldClim data, as well as soil available water capacity (AWC) and soil nutrient status, derived from the European soil database. The soil compensatory effects on tree species distribution were tested through generalized additive models. The hypothesis of soil compensatory effects on tree species distribution under limiting aridity was supported in terms of statistical significance and plausibility. Compared to a bioclimatic baseline model, inclusion of soil variables systematically improved the models’ goodness of fit. However, the relevance measured as the gain in predictive performance was small, with largest improvements for P. sylvestris, Q. petraea and A. alba. All studied species, except P. sylvestris, preferred high AWC under high SA. For F. sylvatica, P. abies and Q. petraea, the compensatory effect of soil AWC under high SA was even more pronounced on acidic soils. Soil compensatory effects might have decisive implications for tree species redistribution and forest management strategies under anthropogenic climate change. Therefore, soil compensatory effects deserve more intensive investigation, ideally, in studies combining different spatial scales to reduce the uncertainty associated with the precision of soil information.

Highlights

Contemporary forest management planning increasingly relies on projections from tree species distribution models (SDMs) under future climate conditions (Attorre et al, 2011; Falk and Mellert, 2011; Hlásny et al, 2014; Hanewinkel et al, 2014; Mellert et al, 2015; Zimmermann et al 2013)
The result of modeling is shown in the mosaic plot in Fig. 3, where species define rows and summer aridity levels (SA1-SA3) columns
The effect of the soil physical (AWC, x-axis) and chemical gradients (SNS, y-axis) on the probability of occurrence (Pocc, z-axis) at a specific summer aridity level is shown as response surface

Summary

Introduction

Contemporary forest management planning increasingly relies on projections from tree species distribution models (SDMs) under future climate conditions (Attorre et al, 2011; Falk and Mellert, 2011; Hlásny et al, 2014; Hanewinkel et al, 2014; Mellert et al, 2015; Zimmermann et al 2013). To avoid misspecification (e.g. due to model extrapolations), SDMs should be calibrated across the entire species range to ensure that climatic limits are properly covered by the data (Mellert et al, 2011, Beauregard and de Blois 2014), but tree SDMs should consider soil properties (Thuiller, 2013; Diekmann et al, 2015). Soil is a key compartment for forest productivity (Cajander, 1949; Barnes et al, 1982; Bailey 1987) Both water and nutrient availability in soils matter for tree growth Previous SDMs for plants relied on qualitative soil data (e.g. soil type, Brus et al, 2011; Dolos et al, 2015) as indirect environmental factors in the sense of Austin (1980) or considered only topsoil properties (e.g. Dubuis et al, 2013) which are less relevant for deeper rooting trees than for herbs (Beauregard and Bois, 2014)

Objectives

Methods

Results

Discussion

Conclusion