Trait-based modelling in ecology: lessons from two decades of research

Abstract

Trait-based approaches are an alternative to species-based approaches for functionally linking individual organisms with community structure and dynamics. In the trait‑based approach, the focus is on the traits, the physiological, morphological, or life-history characteristics, of organisms rather than their species. Although used in ecological research for several decades, this approach only emerged in ecological modelling about twenty years ago. We review this rise of trait-based models and trace the occasional transfer of trait-based modelling concepts between terrestrial plant ecology, animal and microbial ecology, and aquatic ecology. Trait-based models have a variety of purposes, such as predicting changes in species distribution patterns under climate and land-use change, planning and assessing conservation management, or studying invasion processes. In modelling, trait-based approaches can reduce technical challenges such as computational limitations, scaling problems, and data scarcity. However, we note inconsistencies in the current usage of terms in trait-based approaches and these inconsistencies must be resolved if trait-based concepts are to be easily exchanged between disciplines. Specifically, future trait-based models may further benefit from incorporating intraspecific trait variability and addressing more complex species interactions. We also recommend expanding the combination of trait-based approaches with individual-based modelling to simplify the parameterization of models, to capture plant-plant interactions at the individual level, and to explain community dynamics under global change.

Trait-based modelling in ecology: lessons from two decades of research

“…Functional traits well-defined morpho-physio-phenological characteristics of individual organisms that relate to the patterns of growth, reproduction, and survival of the species (McGill et al, 2006;Violle et al, 2007), and that evolved in response to abiotic environmental conditions and interactions with other species (Reich et al, 2003;Clark et al, 2012).…”

“…Intraspecific trait variability (variation) is the difference in the values of functional traits within one species that results from the development and adaptation of species to environmental change (Albert et al, 2011;Schirpke et al, 2017). There are two sources for this variation.…”

“…For instance, process-based models are based on a theoretical understanding of the relevant ecological processes. They are built on explicit assumptions about how a system works, and these models are especially well-designed to predict the effects of global change (Cuddington et al, 2013). Dynamic Global Vegetation Models (DGVMs) and Earth System Models (ESM) also fall in this category.…”

“…Therefore, when the environment changes rapidly, trait-based models become inaccurate because the traits measured were selected for by a previous, different, environment (Welsh et al, 2016). A statistical approach uniting trait-based and species distribution models was also applied to model the distribution of wood-inhabiting fungi (Abrego et al, 2017).Finally, the only equation-based model in this section was a model that incorporated plant physiology to predict tree distributions along resource gradients (Sterck et al, 2014).…”

“…The group of models of community assembly partially overlapped with models of species distribution and was thus already partly discussed in section 1.2.Trait-based models on species distributions. Three groups of studies emerged: First, a large group of publications where the intention was to identify traits that affect community assembly; second, a group of four papers studying intraspecific trait variability (Pachepsky et al, 2007;Laughlin et al, 2012;Schliep et al, 2018) ; and, third, another group of three papers where traits were used as response traits to distinguish between biotic and abiotic filtering (Bhaskar et al, 2014;Chauvet et al, 2017) and to assess effects of environmental change (Losapio and Schöb, 2017).…”