Massive tree mortality from flood pulse disturbances in Amazonian floodplain forests: The collateral effects of hydropower production

Autor(es)

de Resende, Angelica Faria ^{[1, 2]} ; Schongart, Jochen ^[1] ; Streher, Annia Susin ^[3] ; Ferreira-Ferreira, Jefferson ^{[3, 4]} ; Fernandez Piedade, Maria Teresa ^[1] ; Freire Silva, Thiago Sanna ^[3]

Afiliação do(s) autor(es)

^[1] Natl Inst Amazonian Res INPA, Coordinat Environm Studies CDAM, Ave Andre Araujo 2936, BR-69060001 Manaus, Amazonas - Brazil

^[2] Natl Inst Amazonian Res INPA, Ave Andre Araujo 2936, BR-69060001 Manaus, Amazonas - Brazil

^[3] Univ Estadual Paulista Unesp, Inst Geociencias & Ciencias Exatas, Ecosyst Dynam Observ, Ave 24-A 1515, BR-13506900 Rio Claro - Brazil

^[4] Inst Desenvolvimento Sustentavel Mamiraua, Estr Bexiga 2584, BR-69470000 Tefe, AM - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Science of The Total Environment; v. 659, p. 587-598, APR 1 2019.
• Citações Web of Science: 5

Resumo

Large dams built for hydroelectric power generation alter the hydrology of rivers, attenuating the flood pulse downstream of the dam and impacting riparian and floodplain ecosystems. The present work mapped blackwater floodplain forests (igapo) downstream of the Balbina Reservoir, which was created between 1983 and 1987 by damming the Uatuma River in the Central Amazon basin. We apply remote sensing methods to detect tree mortality resulting from hydrological changes, based on analysis of 56 ALOS/PALSAR synthetic aperture radar images acquired at different flood levels between 2006 and 2011. Our application of object-based image analysis (OBIA) methods and the random forests supervised classification algorithm yielded an overall accuracy of 87.2%. A total of 9800 km(2) of igapo forests were mapped along the entire river downstream of the dam, but forest mortality was only observed below the first 49 km downstream, after the Morena rapids, along an 80-km river stretch. In total, 12% of the floodplain forest died within this stretch. We also detected that 29% of the remaining living igapo forest may be presently undergoing mortality. Furthermore, this large loss does not include the entirety of lost igapo forests downstream of the dam; areas which are now above current maximum flooding heights are no longer floodable and do not show on our mapping but will likely transition over time to upland forest species composition and dynamics, also characteristic of igapo loss. Our results show that floodplain forests are extremely sensitive to long-term downstream hydrological changes and disturbances resulting from the disruption of the natural flood pulse. Brazilian hydropower regulations should require that Amazon dam operations ensure the simulation of the natural flood-pulse, despite losses in energy production, to preserve the integrity of floodplain forest ecosystems and to mitigate impacts for the riverine populations. (c) 2018 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 15/17534-3 - Controles bióticos e abióticos sobre a diversidade de espécies em um gradiente altitudinal: testando teorias ecológicas através de atributos óticos
• Beneficiário: Annia Susin Streher
• Modalidade de apoio: Bolsas no Brasil - Doutorado