Studying the spatial structuring of chemical elements through the prism of community and landscape ecology

Approximatively 25 chemical elements are essential for the maintenance, growth and reproduction of all living organisms. Hence, the movement, distribution, and relative proportions of those elements on the landscape should have significant influence on the structure and functioning of biological communities. Yet our basic understanding for the spatial distribution of elements across landscapes and the drivers of those patterns are limited. Here, we propose a novel framework to apply tools from community and landscape ecology to study spatial patterns in elements. We illustrate this framework with an empirical proof of concept in the boreal forest and demonstrate how spatial grain and spatial dissimilarity of elements interact leading to predictable patterns in elemental distributions at various spatial scales. In particular, we observe that at finer spatial grains, sites with high contributions to elemental dissimilarity cluster together. As grain size increases, the landscape becomes more homogeneous with larger patches of sites with intermediate contributions to elemental dissimilarity emerging near aquatic-terrestrial boundaries. Meanwhile, an analysis revealed that the most important elemental contributors to spatial dissimilarity in this landscape are potassium and calcium, two infrequently studied elements in community ecology, raising new questions about their role in, or response to, distributions of biodiversity and ecosystem functions. Our novel framework demonstrates how we can use community metrics (e.g., dissimilarity) to investigate variability of individual elements, the building blocks of stoichiometric ratios, across landscapes. As a field, ecology is just beginning to fully acknowledge the contribution of biotic factors in shaping biogeochemical processes, but here we provide a framework for integrating abiotic and biotic processes. We conclude by hypothesizing that changes in the evenness or beta-diversity of elements should reflect the structure of biotic communities, providing a long-sought mechanistic link between community and ecosystem processes that can be measured directly in the field.