Agricultural expansion reduces net radiation and water recycling in Amazonia

Divino V Silvério, IPAM - Amazon Environmental Research Institute, dvsilverio@gmail.com
Paulo M Brando, IPAM - Amazon Environmental Research Institute, pmbrando@ipam.org.br
Marcia N Macedo, Woods Hole Research Center, mmacedo@whrc.org (Presenter)
Pieter S Beck, European Commission - Joint Research Centre, psabeck@gmail.com
Michael T Coe, Woods Hole Research Center, mtcoe@whrc.org

The contribution of tropical deforestation to changes in the surface energy balance and water recycling strongly depends on which land uses replace forests. Here, we quantify for the first time how recent (2000-2010) transitions among common land uses (i.e. forests, croplands, and pastures) altered the water and energy balance of the 176,892 km² upper Xingu watershed in southeast Amazonia, a region that represents deforestation dynamics in ~40% of the Amazon. Our spatial-temporal analyses of multiple satellite data sets revealed that forest-to-crop and forest-to-pasture transitions decreased net surface radiation (18% and 12%, respectively) and latent heat (32% and 24%), while increasing sensible heat (6% and 9%, respectively). Integrated over the entire upper Xingu watershed, during the 2000s the expansion of croplands and pastures into forests reduced evapotranspiration by 7 km³ and 25.5 km³, and warmed regional land surface temperatures by 0.07°C and 0.2°C, respectively. Simultaneous pasture-to-crop transitions further reduced evapotranspiration (2.5 km³) and increased temperature (0.03 ºC). Such regional climate changes could decrease precipitation, triggering negative feedbacks on forest and agricultural productivity. Our results indicate that, at regional scales, private and public protected forests may play a critical role in buffering against climate changes caused by tropical land use change.

Presentation Type:  Poster

Session:  Theme 4: Human influence on global ecosystems   (Mon 4:30 PM)

Associated Project(s): 

• Coe, Michael: Climate and land use change at the Amazonian agro-frontier: Historical and future effects on the surface energy balance ...details

Poster Location ID: 70