Disentangling the effects of environment and ontogeny on tree functional dimensions for congeneric species in tropical forests

Abstract

Summary Soil water and nutrient availability are key drivers of tree species distribution and forest ecosystem functioning, with strong species differences in water and nutrient use. Despite growing evidence for intraspecific trait differences, it remains unclear under which circumstances the effects of environmental gradients trump those of ontogeny and taxonomy on important functional dimensions related to resource use, particularly in tropical forests. Here, we explore how physiological, chemical, and morphological traits related to resource use vary between life stages in four species within the genus Micropholis that is widespread in lowland Amazonia. Specifically, we evaluate how environment, developmental stage, and taxonomy contribute to single‐trait variation and multidimensional functional strategies. We find that environment, developmental stage, and taxonomy differentially contribute to functional dimensions. Habitats and seasons shape physiological and chemical traits related to water and nutrient use, whereas developmental stage and taxonomic identity impact morphological traits –especially those related to the leaf economics spectrum. Our findings suggest that combining environment, ontogeny, and taxonomy allows for a better understanding of important functional dimensions in tropical trees and highlights the need for integrating tree physiological and chemical traits with classically used morphological traits to improve predictions of tropical forests’ responses to environmental change.

Biogeographic history and habitat specialization shape floristic and phylogenetic composition across Amazonian forests

“…The higher similarity in the floristic composition between TF and SF could be explained by relatively rare flooding events and the substantial overlap of environmental conditions across these two habitats, allowing many TF species to establish on soils that are not constantly water saturated, and conversely enabling many swamp species to be competitive on soils with stronger drainage. Species distributed on TF and SF soils may also exhibit greater plasticity than WS species, which allocate costly adaptation mechanisms to survive on these relatively extreme habitats (Fortunel et al 2020).…”

Assessing invertebrate herbivory in human‐modified tropical forest canopies

“…Such differences in leaf longevity are likely to have an important effect on the impact of herbivory on the carbon and nitrogen cycles. Variation between understorey and canopy herbivory can also be affected by ontogenetic differences in leaf traits (Damián et al, 2018) mature leaves in younger individuals can be more palatable than mature leaves in older individuals of the same species, as the former tend to be less thick and tough than the latter, hence making it easier for herbivore attack (Fortunel et al, 2020). Thus, our static sampling approach may be an underestimate of the actual levels of herbivory in disturbed forests.…”

Plant functional traits explain species abundance patterns and strategies shifts among saplings and adult trees in Araucaria forests

“…The observed variability in leaf traits between sapling and adult stages can be related to ontogeny, considering that seedlings and saplings still have low reserves to produce costly leaves, and to local habitat conditions – less severe than in the canopy and high investment in leaf structure would be not necessary (Fortunel et al . 2020). Under the environmental conditions of the Araucaria forests, canopy trees must be able to acclimatise to harsh conditions imposed by lower temperatures, higher radiation and frost events (Oliveira‐Filho & Fontes 2000), featuring leaves with low SLA and high LDMC values.…”

“…Fortunel et al . 2020). Seedlings and saplings have little carbohydrate reserves and often make only soft leaves (with high SLA and low LDMC) that are more susceptible to herbivores but more efficient in terms of growth rate, especially when associated with large leaf blade (Poorter et al .…”