Major changes in forest diversity, plant species composition and functional diversity occur along environmental gradients, and the Andes-to-Amazon gradient is Earth’s longest and highest biodiversity forest gradient. Wood density is an important functional trait related to wood properties and carbon accumulation. The few studies of this trait across altitudinal gradients have shown a decrease with increasing elevation, though this trend still unclear in the tropics. We (1) tested the effects of elevation on interspecific variation and stand-level wood density across 3.5 km altitudinal gradient and (2) looked the intraspecific variation across the gradient. More than 891 tree core samples were taken for 314 taxa at 59 sites across a 3.5 km altitudinal transect running from Andean tree line to Amazonian lowlands in Peru. We used data from 16 1-ha permanents plots (ABERG network) across the gradient to test the effects of elevation in wood density weighted by number of individuals (NI) and basal area (BA).
Results/Conclusions
Results showed a positive relationship of wood density with elevation and this trend is even stronger when wood density was weighted by NI and BA. We observed an abrupt transition in wood density at ~1500 m in the cloud base zone. The intraspecific relationship between elevation and wood density different greatly among species, with taxa showing increasing, decreasing, and no response to elevation. Turnover in species composition had a direct effect on stand-level wood density and showed a strong relationship with elevation. These results for Andean and Amazonian systems have implications in forest biomass calculations and in general understanding of ecosystem function.