The Role of Fire on Water and Carbon Cycling Across Two Contrasting
Terra Firme Amazonian Forests
Abstract
Recently intensified forest fires in the Amazon region have led to
large-scale forest losses, particularly in Brazil, after more than a
decade of effective forest conservation policy. Analysis of the time
course of fire impacts on water and carbon cycling is required for
accurate measurement of changes in the forest-atmosphere interactions.
Moreover, measurements must also account for natural variations
associated with vegetation phenology, and generally direct and indirect
effects of environmental changes at annual, seasonal and sub-annual time
scales. Here, we study the recovery of two contrasting terra firme
forests affected by fire in eastern (sub-montane ombrophile forests) and
western (bamboo dominated forests) Amazonia in terms of water and carbon
fluxes utilizing remote sensing (Moderate Resolution Imaging
Spectroradiometer, MODIS) and climate reanalysis data (Global Land Data
Assimilation System, GLDAS). Our results showed that fires significantly
increased land surface temperature and air temperature in the forests
over different time scales. However, the forests showed an ability to
recover their original states in terms of coupling between the carbon
and water cycles based on the comparison of the periods before and after
the fires. Results from a wavelet analysis showed an intensification in
annual and seasonal fluctuations, and in some cases (e.g.,
evapotranspiration) sub-annual fluctuations. Understanding the
mechanisms controlling the forest-atmosphere interactions are essential
for assessing how forest fires will influence the exchanges of water and
carbon in the future. Improving data and theory about the impacts of
fire and other disturbances on the energy balance is essential to
improve earth systems models for forecasting the role of tropical forest
fires in climate change. Within this context, our approach and,
consequently, the results obtained here will help improve the
understanding of how fires in terra firme Amazonian forests impact
land-atmosphere coupling at different spatial and temporal scales.