Functional traits partially mediate the effects of chronic anthropogenic disturbance on the growth of a tropical tree

Abstract

Understanding how trees mediate the effects of chronic anthropogenic disturbance is fundamental to developing forest sustainable management strategies. The role that intraspecific functional diversity plays in such process is poorly understood. Several tree species are repeatedly defoliated at large scale by cattle breeders in Africa to feed livestock. In addition, these tree species are also debarked for medicinal purposes. These human-induced disturbances lead to biomass loss and subsequent decline in the tree growth. The main objective of this work is to investigate how functional traits mediate tree response to chronic anthropogenic disturbance. We used a unique data set of functional traits and growth rate of 503 individual tree of Afzelia africana. We collected data on leaf mass per area (LMA), wood density (WD) and growth rate, and recorded history of human disturbances (debarking, pruning) on individual tree from 12 populations of A. africana distributed in two ecological zones in Benin (West Africa). We tested the effect of disturbances on absolute growth rate across ontogenetic stages, assessed the role of intraspecific trait variability on growth and tested the role of tree functional strategy on the tree growth response to debarking and pruning. We found that debarking did not affect stem growth, suggesting a fast compensatory regrowth of bark wounded. Moreover, tree response to debarking was independent of the functional strategy. By contrast, we found that pruning reduced tree absolute growth; however, trees with low WD were more strongly affected by pruning than trees with high WD. Our results emphasize the importance for plant functioning of the interplay between the availability of leaves for resource acquisition and a resilience strategy by mobilizing stored resources in stem wood to be reinvested for growth under severe disturbances.

Long‐term influence of early human occupations on current forests of the Guiana Shield

“…But species that have useful bark are also closely associated to NAs, giving credit to the idea that using bark on a regular basis is negatively impacting individual demographic performance (but see Amahowe et al. ). Conclusions are more difficult to draw for species belonging to the “medicine and magic” and “arts and crafts” categories, which showed no clear pattern.…”

Functional perspectives on tropical tree demography and forest dynamics

“…Despite the large number of traits that could impact plant fitness or performance, the functional trait research program typically focuses on a set of commonly and easily measured traits (e.g., Westoby 1998;Westoby et al 2002;Westoby and Wright 2006). It is thought that these traits represent fundamental tradeoff axes that indicate life history strategies, the abiotic and biotic interactions of individuals and species, and their overall fitness or performance given the abiotic and biotic contexts (Ackerly 2003;Swenson 2012;Adler et al 2014;Funk et al 2017;Amahowe et al 2018). To begin the review, we will focus on the most commonly measured functional traits (i.e., the wood economics spectrum, the leaf economics spectrum, and seed economics spectrum) and later in the text we will expand our discussion of functional diversity to include a larger variety of traits and functions.…”

“…The other end of the spectrum represents longer-lived, slower-growing trees with low SLA, nitrogen, and phosphorus (Wright et al 2004;Donovan et al 2011). Some work has shown that the wood economics spectrum is orthogonal to the leaf economics spectrum (Baraloto et al 2010;Dwyer and Laughlin 2017;Amahowe et al 2018). This contrasts with other work demonstrating a tight coordination between leaf and wood hydraulic traits (e.g., Santiago et al 2004).…”

Characterization of 15 nuclear microsatellite markers for Afzelia africana (Fabaceae) and related species

“…africana is listed as a vulnerable tree species on the International Union for Conservation of Nature (IUCN) Red List (African Regional Workshop, ). In West Africa, much research effort has been invested in promoting the sustainable management and conservation of the species by assessing the local importance of its uses (Houehanou et al., ; Balima et al., ) and the variation of its population attributes in relation to climatic condition and anthropogenic disturbance (Nacoulma et al., ; Mensah et al., ; Amahowe et al., ). However, little is known of the population genetics of A. africana , as is the case for most endangered African tree species (Houehanou et al., ).…”