Identifying the drivers of community diversity and dynamics can be achieved by empirically linking functional traits, that constitute a whole-plant phenotype, environmental gradients, and demographic rates. However, current approaches often fail to explicitly consider trait-trait and trait-environment interactions, which may lead to an incomplete understanding of the drivers of demographic rates and diversity of form and function seen in ecological communities. Here, we determined whether interactions between multiple functional traits and environmental gradients impacted tropical tree seedling performance by modeling growth performance landscapes that span a multidimensional trait space along environmental gradients. We asked two main questions: 1) Do alternative phenotypic designs have similar demographic outcomes within an environment?, and 2) how do the peaks of growth performance landscapes change across environmental gradients? We utilized individual-level leaf, stem and root trait data combined with growth data from 1,559 tree seedlings from 122 species in a hyper-diverse Chinese tropical rainforest along soil nutrient and light gradients.
Results/Conclusions
We found that multiple trait combinations in phenotypic space (i.e. alternative designs) lead to multiple growth performance peaks that shift along light and soil axes. Further, we found evidence that above and below ground functional strategies often combine to produce optimal growth performance in such a way that acquisitive above ground strategies can align with conservative below ground strategies and vice versa. These results help explain how functional diversity is maintained in ecological communities and question the practice of utilizing a single trait or environmental variable in isolation to predict the growth performance of individual trees.