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