IMPACTS OF EL NIÑO ON VEGETATION STRUCTURE AND CARBON DYNAMICS IN THE AMAZON
ENSO, forest structure, mortality, recruitment, biomass
Climate regulates the integrity, growth, and functioning of vegetation and forests, so
climatic anomalies such as El Niño can compromise their functions and ecosystem
services. In this study, we investigated the effects of the 2015/16 El Niño on forest
structure and carbon dynamics across different forests in state of Acre, southwestern Amazonia, and whether these forests exhibit similar or different response patterns. We analyzed data from 17 forests with distinct phytophysiognomies, measured between 2010 and 2018 following RAINFOR or PPBio protocols. We used the paired Wilcoxon test to
compare species richness, abundance, and biomass between the pre and post El Niño
periods, and the Kruskal-Wallis test to assess differences among phytophysiognomies. We
also applied the Friedman test to compare individual and carbon change rates within and
between periods for six forests. Biomass increased significantly between periods,
especially in the FOAB phytophysiognomies, which, along with FOA, showed higher net
change rates in abundance and richness. One FOAB forest showed a reduction in mortality
rates, biomass gain, and net change in recruitment and mortality, indicating differences
both within and between physiognomies. The FOD phytophysiognomies experienced the
greatest losses and a negative net change in biomass over the period. Our results indicate
that the 2015/16 El Niño had a heterogeneous impact on forest structure and carbon
dynamics in Acre, reflecting distinct responses among phytophysiognomies and even
among forests of the same type.