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Continued Declines in Mature and Secondary Forest Cover in a Previously Settled Region of Eastern Pará A.S. de Almeida 1, T.A. Stone 2, E.A. Davidson 2, and I.C.G. Vieira 1 1 Museu Paraense Emilio Goeldi 1 Museu Paraense Emilio Goeldi 2 The Woods Hole Research Center
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Most attention regarding deforestation has been focused on the deforestation frontierMost attention regarding deforestation has been focused on the deforestation frontier However, areas that have been settled by humans for decades or centuries are also still undergoing land-use change, including degradation of remaining forestsHowever, areas that have been settled by humans for decades or centuries are also still undergoing land-use change, including degradation of remaining forests Here we use Landsat imagery to quantify changes in forest cover from 1984 to 2002 in a 8000 km 2 study area east of Belém, which was first settled over a century ago.Here we use Landsat imagery to quantify changes in forest cover from 1984 to 2002 in a 8000 km 2 study area east of Belém, which was first settled over a century ago.
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8000 km 2 study area Bragantina Region Guajarina Region
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Imagery Georectification of 5 dates to a common map projectionImagery Georectification of 5 dates to a common map projection Imagery calibration to reflectivity via the COST Model (Chavez 1996)Imagery calibration to reflectivity via the COST Model (Chavez 1996) Field work with GPS data as the primary source for classification and validationField work with GPS data as the primary source for classification and validation Some limited IKONOS data also used for validationSome limited IKONOS data also used for validation Supervised classification using ERDAS Imagine SoftwareSupervised classification using ERDAS Imagine Software Map creation and overlays using ARCMap 9.3Map creation and overlays using ARCMap 9.3 Satellite Data: Landsat TM: July 27, 1984, June 21, 1994, & July 13, 1999 Landsat ETM: August 3, 2001, & September 7, 2002 Data & Methods Imagery Georectification of 5 dates to a common map projectionImagery Georectification of 5 dates to a common map projection Imagery calibration to reflectivity via the COST Model (Chavez 1996)Imagery calibration to reflectivity via the COST Model (Chavez 1996) Field work with GPS data as the primary source for classification and validationField work with GPS data as the primary source for classification and validation Some limited IKONOS data also used for validationSome limited IKONOS data also used for validation Supervised classification using ERDAS Imagine SoftwareSupervised classification using ERDAS Imagine Software Map creation and overlays using ARCMap 9.3Map creation and overlays using ARCMap 9.3
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Mature ForestMature Forest Secondary ForestSecondary Forest Young (3, 6 a 10 years) Intermediate ( 15 a 35 years) Advance (40 a 70 years) Land – useLand – use Data & Methods
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Land cover classes separated out in this 2-D plot of NDVI vs. band-5 reflectivity. Each symbol is a mean for a cover class for one Landsat image (84. 94, 99, 01, or 02).
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Note the remaining patches of mature forest in the southern part of the ‘84 image … many of which were cleared by 1994.
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Note that most of the remaining mature forest and advanced secondary growth forest occurs along river margins (igapo forest) Note the expansion of pasture (yellow)
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secondary forest cover increased from ‘84 to ‘94 while mature forest cover declined After 1994, secondary forest cover declined while pasture cover increased. The cattle herd approximately doubled during this period.
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Advanced & intermediate secondary forest cover increased from ‘84 to ‘94 as forests grew on previously cleared land After ‘94, inter- mediate secondary forest declined to create pasture
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Based on average biomass estimates for each forest age class from the literature for this region, we estimate that this 8000 km 2 region was losing about 1 teragram of C per year from 1999 to 2002, due to loss of secondary forest biomass ( about 1.3 MgC/ha on average)
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Conclusions Forest degradation is continuing in a region that is not part of the deforestation frontier.Forest degradation is continuing in a region that is not part of the deforestation frontier. While earlier land cover change (1984-1994) was mostly from mature forest to secondary forest, more recent changes (1994-2002) are mostly from secondary forest to pasture.While earlier land cover change (1984-1994) was mostly from mature forest to secondary forest, more recent changes (1994-2002) are mostly from secondary forest to pasture. Along with loss of secondary forest cover and the ecosystem services that it provides, significant losses of carbon to the atmosphere are continuing.Along with loss of secondary forest cover and the ecosystem services that it provides, significant losses of carbon to the atmosphere are continuing.
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