Ecosystem dynamism: exploring the role of primary functional diversity in ecosystem functioning

Abstract

Ecosystem functioning depends on many processes whose dominance over function varies across space and time. Carbon sequestration is a crucial function in tropical forests, contributing to global climate regulation. It is performed in great part by primary producers via production/maintenance of above-ground biomass (AGB), being modulated by physical and physiological characteristics known as "functional traits" that dictate plant development. Hypotheses pertaining to the mechanisms driving AGB accumulation include modulation by climate conditions, by functional diversity (niche complementarity hypothesis), by the most abundant species in the landscape (biomass ratio hypothesis), and by self-regulatory processes. Trophic chain effects may also affect primary production. Frugivorous birds modulate seed dispersal in tropical forests, affecting and being affected by changes in its AGB due to dependence on its food resources. Insectivorous birds modulate insect populations that may consume and diminish AGB, while carnivore fauna may reduce the abundance of other herbivores, indirectly affecting AGB. Anthropic activities, such as deforestation to establish plantations/pastures, change the primary community composition and functional diversity, also affecting AGB as well as habitat structure throughout all trophic levels. Our aim is to develop a framework for investigating and monitoring ecosystem functioning remotely by (1) identifying seasonal effects over primary production and carbon storage, (2) analysing mechanisms driving AGB production/maintenance, (3) assessing the relationships between primary producers and avifauna, and (4) evaluating whether the aforementioned processes and mechanisms differ between areas of native vegetation and of anthropic use.