Impacts of Degradation on Water, Energy, and Carbon Cycling of the Amazon Tropical Forests

Marcos Longo, Sassan Saatchi, Michael Keller, Kevin Bowman, António Ferraz, Paul R. Moorcroft, Douglas C. Morton, Damien Bonal, Paulo Brando, Benoît Burban, Géraldine Derroire, Maiza N. dos-Santos, Victoria Meyer, Scott Saleska, Susan Trumbore, Grégoire Vincent

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Selective logging, fragmentation, and understory fires directly degrade forest structure and composition. However, studies addressing the effects of forest degradation on carbon, water, and energy cycles are scarce. Here, we integrate field observations and high-resolution remote sensing from airborne lidar to provide realistic initial conditions to the Ecosystem Demography Model (ED-2.2) and investigate how disturbances from forest degradation affect gross primary production (GPP), evapotranspiration (ET), and sensible heat flux (H). We used forest structural information retrieved from airborne lidar samples (13,500 ha) and calibrated with 817 inventory plots (0.25 ha) across precipitation and degradation gradients in the eastern Amazon as initial conditions to ED-2.2 model. Our results show that the magnitude and seasonality of fluxes were modulated by changes in forest structure caused by degradation. During the dry season and under typical conditions, severely degraded forests (biomass loss ≥66%) experienced water stress with declines in ET (up to 34%) and GPP (up to 35%) and increases of H (up to 43%) and daily mean ground temperatures (up to 6.5°C) relative to intact forests. In contrast, the relative impact of forest degradation on energy, water, and carbon cycles markedly diminishes under extreme, multiyear droughts, as a consequence of severe stress experienced by intact forests. Our results highlight that the water and energy cycles in the Amazon are driven by not only climate and deforestation but also the past disturbance and changes of forest structure from degradation, suggesting a much broader influence of human land use activities on the tropical ecosystems.

Original languageEnglish (US)
Article numbere2020JG005677
JournalJournal of Geophysical Research: Biogeosciences
Volume125
Issue number8
DOIs
StatePublished - Aug 1 2020

Keywords

  • Amazon
  • drought
  • ecosystem modeling
  • evapotranspiration
  • forest degradation
  • remote sensing

ASJC Scopus subject areas

  • Soil Science
  • Forestry
  • Water Science and Technology
  • Palaeontology
  • Atmospheric Science
  • Aquatic Science
  • Ecology

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