Data from: Niche construction by growth forms is as strong a predictor of species diversity as environmental gradients

We present a conceptual framework that describes how species belonging to
a growth form collectively can be niche constructors (i.e. modify niches)
and affect species diversity in plant communities. We use an empirical
assessment of tundra plant communities to illustrate the framework's
utility. In doing so, we make a first investigation of collective niche
construction in ecological communities. In tundra plant communities,
growth forms differently affect ecosystem process rates and cause
environmental modifications; thus, growth forms are strong candidates for
being niche constructors. To assess the impact of growth form niche
construction on plant species diversity, we excluded the species of the
growth form applied as niche constructor when estimating the community
species diversity. We assessed niche construction in 70 tundra meadow
communities and 1450 randomly selected tundra plant communities that are
distributed along ecological gradients in temperature, resource
availability, competitive interference and herbivory. These gradients
allowed us to concomitantly assess to what extent the niche construction
is independent of environmental conditions. Growth forms varied from
strong positive to neutral predictors of both species richness and Simpson
index in the order of forbs, grasses, sedges, deciduous shrubs and
evergreen shrubs, suggesting that growth forms have important roles as
niche constructors in tundra plant communities. Also, the environmental
conditions were strong predictors of species diversity, but they did not
interact with or confound the effects of growth forms. Forbs and grasses
were the least abundant growth forms, yet they were the strongest positive
predictors of species diversity. Therefore, our results suggest a
particular niche-constructing role of these growth forms for enhancing
species diversity in tundra plant communities. Synthesis. In this study,
we provide conceptual and empirical evidence for collective niche
construction as a powerful ecological process that affects species
diversity and that can act independently of environmental conditions.
Species sharing a single trait or species belonging to a growth form can
act as collective niche constructors, and as exemplified for growth forms
in this study, be important predictors of species diversity in ecological
communities.