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Management intensification maintains wood production over multiple harvests in tropical Eucalyptus plantations
Author(s) -
McMahon Devin E.,
Jackson Robert B.
Publication year - 2019
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1002/eap.1879
Subject(s) - eucalyptus , wood production , vegetation (pathology) , productivity , environmental science , agroforestry , forest management , forestry , short rotation forestry , production (economics) , tropics , silviculture , geography , woody plant , ecology , biology , coppicing , medicine , macroeconomics , pathology , economics
Abstract Plantation forestry, in which trees are grown as a crop, must maintain wood production over repeated harvest cycles (rotations) to meet global wood demands on a limited land area. We analyze 33 yr of Landsat observations across the world's most productive forestry system, Eucalyptus plantations in southeastern Brazil, to assess long‐term regional trends in wood production. We apply a simple algorithm to time series of the vegetation index NIR v in thousands of Eucalyptus stands to detect the starts and ends of rotations. We then estimate wood production in each identified stand and rotation, based on a statistical relationship between NIR v trajectories and inventory data from three plantation companies. We also compare Eucalyptus NIR v with that of surrounding native vegetation to assess the relative influence of management and environment on plantation productivity trends. Across more than 3,500 stands with three complete rotations between 1984 and 2016, modeled wood volume decreased significantly between the first and second rotation, but recovered at least partially in the third; mean wood volumes for the three rotations were 262, 228, and 247 m 3 /ha. This nonlinear trend reflects intensifying plantation management, as rotation length decreased by an average of 15% (decreasing wood volume per rotation) and NIR v proxies of tree growth rates increased (increasing volume) between the first and third rotation. However, NIR v also increased significantly over time in unmanaged vegetation around the plantations, suggesting that environmental trends affecting all vegetation also contribute to sustaining wood production. Management inputs will likely continue to be important for maintaining wood production in future harvests.