ASNER, G. P.

DAVIDSON, E. A.

FIGUEIREDO, R. de O.

NEILL, C.

STONE, T. A.

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C lose WindowObjective Indicators of Pasture Degradation from Spectral Mixed Model Analysis ofLandsat ImageryEric A. Davidson, Woods Hole Research Center, edavidson@whrc.org (Presenting) Gregory P. Asner, Carnegie Institute, gpa@stanford.edu Thomas A. Stone, Woods Hole Research Center, tstone@whrc.org Christopher Neill, Marine Biological Laboratory, cneill@mbl.edu Ricardo de O. Figueiredo, Embrapa Amazônia Oriental, ricardo@cpatu.embrapa.br Degradation of cattle pastures is a major concern for management and for understanding thefuture land cover/land use consequences of ongoing Amazonian deforestation. Unfortunately,“degradation” is not well defined and may have different meanings for ranchers, ecologists,and policy makers. The objective of this study is to quantify pasture degradation usingobjective scalars of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV),and exposed soil derived from spectral mixture analyses of Landsat imagery. The amount ofexposed soil and NPV, such as senescent grass foliage, increases as pastures age and as thegrasses become less productive. We employed a general, probabilistic spectral mixture model(AutoMCU) for decomposing satellite spectral reflectance measurements into sub-pixelestimates of PV, NPV, and bare soil covers at Fazenda Nova Vida in Rondonia and FazendaVitoria in Pará. These two ranches vary by size, age, soils, and management practices. TheNova Vida ranch had higher stocking densities, was more intensively managed, and hadlarger values of estimated exposed soil than did Fazenda Vitoria. The number of management“treatments” at Nova Vida, which included liming, herbiciding, and disking, was weakly, butsignificantly positively correlated w ith exposed soil and negatively correlated w ith PV acrosspasture management units. At both ranches, PV and NPV were strongly negatively correlated,and PV values were generally lower at the more intensively managed Nova Vida ranch.Although this analysis demonstrates that Nova Vida ranch shows signs of pasturedegradation as defined by these objective criteria, it nevertheless has been maintained as ahighly productive pasture system through intensive management and relatively high inputs.This remote sensing technique successfully reveals variation in objectively defineddegradation indicators between and w ithin ranches, but these degradation indicators do notnecessarily imply reduced current cattle production.Science Theme:  LC (Land Use and Land Cover Change)Session:  1A: Remote Sensing and the Carbon CyclePresentation Type:  Oral (view presentation (1565 KB))Abstract ID: 68C lose Windowconverted by Web2PDFConvert.com

Objective indicators of pasture degradation from spectral mixed model analysis of landsat imagery.

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