Extensive mismatches between species distributions and performance and their relationship to functional traits

Abstract

Mismatches between species distributions and their optimal habitat are predicted by ecological theory and will affect species responses to changing climate. However, empirical tests lack consensus on the prevalence of such mismatches and their underlying mechanisms. Here we present a conceptual framework to quantify the mismatch between optimal conditions for species occurrence and multiple measures of population and individual performance (density, adult growth and survival, and recruitment) and the associated performance reduction, or cost. We quantified these mismatches for 59 tree species in the western US along a soil water balance gradient and found high variability in mismatches among species and among performance measures, often resulting in high costs. We used functional traits to explore how dispersal limitation, migration lags, and competitive exclusion may cause mismatches. Overall, the large variability in mismatches, their costs and the relationship with functional traits highlight the nuanced relationships between species’ performance and their distributions.

Climate‐induced variation in the demography of 14 tree species is not sufficient to explain their distribution in eastern North America

“…Our study adds to a growing body of literature on this subject (Holt, 2020, and references therein). For instance, a similar lack of correlation has been found for European trees (Csergo et al., 2017, using matrix projection models) and for western North American species along moisture gradients (Bohner & Diez, 2019). Local interactions are hypothesised to preclude species distribution models from predicting population growth rates when fitted to macroclimate data (Csergo et al., 2017).…”

Tree mortality in western U.S. forests forecasted using forest inventory and Random Forest classification

“…Sections are defined as an aggregate of geologic, soil, and vegetative properties and may include qualitative descriptors that do not continuously vary along grids (McNab et al 2007). While major improvements to modeling forest mortality may involve species-specific parameterizations, variation in demographic rates across space and between tree populations may present an additional challenge that may require detailed knowledge of tree eco-physiology (Bohner and Diez 2020).…”

Different sets of traits explain abundance and distribution patterns of European plants at different spatial scales

“…Functional traits have been used as proxies for species’ dispersal abilities (Greene and Johnson 1993; Thompson et al, 2011), environmental tolerances (Loehle, 1998; Bohner & Diez, 2020) or competitiveness (Kunstler et al, 2016). Specific functional traits have been linked to commonness and rarity on both local and large scales (see Table 1).…”