Impacts of degradation on water, energy, and carbon cycling of the Amazon tropical forests

Longo Marcos, Saatchi Sassan, Keller Michael, Bowman Kevin, Ferraz Antonio, Moorcroft Paul R., Morton Douglas C., Bonal Damien, Brando Paulo, Burban Benoit, Derroire Géraldine, dos‐Santos Maiza N., Meyer Victoria, Saleska Scott, Trumbore Susan, Vincent Grégoire. 2020. Impacts of degradation on water, energy, and carbon cycling of the Amazon tropical forests. Journal of Geophysical Research. Biogeosciences, 125 (8):e2020JG005677, 27 p.

https://doi.org/10.1029/2020JG005677

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Quartile : Q2, Sujet : ENVIRONMENTAL SCIENCES / Quartile : Q2, Sujet : GEOSCIENCES, MULTIDISCIPLINARY

Résumé : 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.

Mots-clés Agrovoc : dégradation des forêts, dégradation de l'environnement, modélisation environnementale, forêt tropicale, préservation de l'écosystème, écosystème forestier, cycle du carbone, cycle hydrologique, impact sur l'environnement, évaluation de l'impact

Mots-clés géographiques Agrovoc : Guyane française, Brésil, Amazonie, France

Mots-clés libres : Amazon, Remote Sensing, Ecosystem modeling, Forest degradation, Evapotranspiration, Drought

Classification Agris : P01 - Conservation de la nature et ressources foncières
K70 - Dégâts causés aux forêts et leur protection
K01 - Foresterie - Considérations générales

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

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