One of the fundamental questions currently challenging ecology is predicting future states of biological diversity. For vegetation, such an issue is timely as information has practical application for decision-makers. For example, understanding future biodiversity states is compelled either in the context of how responsive ecosystems may be to global change or in understanding the consequence of different conservation/restoration approaches to managing nature. Recently, trait-based approaches, derived either from documenting known character variation associated with broad-scale macroecological patterns or inferring features of physical constraints on biological systems, have been used to predict and evaluate large-scale spatial and temporal patterns of vegetation. For decision-making, much more fine -scale dynamics (e.g., plot-based demography, local composition, etc.), may be important, yet also much more difficult to produce. In order to develop a better understanding of such fine-scale dynamics of plant populations and community composition, we have focused on linking long-term demographic and production data sets with detailed ecophysiology and growth analysis to discover trait-combinations that are based on functional relationships to the environment.
Results/Conclusions -
Emerging from this approach is the importance of known life history trade-offs that have proven successful in predicting life history evolution and population dynamics in the context of the variable southwestern deserts. Carefully considering how species organize around a general trade-off between growth rate and stress tolerance in arid-land systems has illuminated a number of trait-combinations that are useful at making predictions of vegetation response to long-term diversity trends and species response to contemporary climate change. We find that plants often can be categorized by their response to resource input, either employing morphological versus physiological approaches to translate resources into biomass (and thus fecundity). At the same time, in a variable environment, phenological constraints can reduce the risk of poor performance in a given year, which when combined with the strategies above, result in unique sets of trait combinations that provide a diversity of distinct approaches to establishment, growth, survival, and reproduction in deserts.