Quantifying changes to ecosystem function in response to drought in an Amazon-Cerrado transitional forest

Anthropogenic deforestation drives novel climate and disturbance regimes in the Amazon. Increasing drought and forest fire frequencies and intensities can impact the gross primary productivity (GPP), ecosystem respiration (Reco), and net ecosystem CO2 exchange (NEE) of this biome. I use eddy flux data collected from an experimentally burned dry Amazon-Cerrado transitional forest to quantify the effect of the interaction between drought periods, forest disturbance (fire and control), and time of day (morning, afternoon, and night) during the wettest and driest months of the year (March and September) on ecosystem carbon fluxes (GPP, Reco, and NEE). I show that GPP and Reco are reduced during drought across both types of disturbance and all times of day in both March and September and NEE is reduced during drought across both types of disturbance and all times of day in September. Fire disturbance had no compounding effect on carbon flux during the drought year. This study demonstrates that drought contributes to forest degradation by reducing ecosystem productivity and carbon accumulation, increasing the probability of more extreme droughts and fires in the future.