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Mapping Tree and Shrub Cover on Past...

Honey, Mallorie,

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Mapping Tree and Shrub Cover on Pastures in Rondonia, Brazil /

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Mapping Tree and Shrub Cover on Pastures in Rondonia, Brazil // Mallorie Honey.
作者:	Honey, Mallorie,
面頁冊數:	1 electronic resource (35 pages)
附註:	Source: Masters Abstracts International, Volume: 84-11.
Contained By:	Masters Abstracts International84-11.
標題:	Geography. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30523659
ISBN:	9798379570736

Mapping Tree and Shrub Cover on Pastures in Rondonia, Brazil /
Honey, Mallorie,

Mapping Tree and Shrub Cover on Pastures in Rondonia, Brazil /Mallorie Honey. - 1 electronic resource (35 pages)

Source: Masters Abstracts International, Volume: 84-11.

The Amazon Basin is experiencing large-scale land use conversion from primary forest to pasture. While several land cover datasets map cleared areas in the Amazon, the percent cover of woody vegetation (trees and shrubs) on cleared areas and its rate of change during clearing is poorly understood, despite its importance for carbon emissions, biodiversity, land-atmosphere interactions, and monitoring of pasture condition. This study used temporal mixture analysis on Sentinel-2 imagery from 2019 to map woody vegetation cover on cleared areas in Rondonia, Brazil. Binary woody vegetation masks were generated at 10m resolution by applying a threshold of the evergreen endmember to the temporal mixture model, which resulted in an overall accuracy of 84%. The woody vegetation masks were then aggregated to 100m to obtain fractional estimates of woody vegetation density in cleared areas. While recently cleared areas (1-2 years) had high woody vegetation cover (60% on average), woody vegetation cover decreased with pasture age, and older pastures (20-34 years) had consistently low woody vegetation cover (25% on average). We find little evidence of large-scale abandonment of pasture: most (53%) pastures in 2019 were "clean" (<10% woody vegetation cover), with 34% "dirty" (10-90% woody vegetation cover), 10% forest (90-100% woody vegetation cover), and 3% early-stage clearing (>10% woody vegetation cover, cleared 1-5 years ago). The commonly observed decrease in greenness in cleared areas, which is sometimes interpreted as an indication of decreased grass health, appears to be due to decreasing woody vegetation density as pastures are gradually cleared over a decade. These results challenge existing conceptual models of deforestation, which suggest that conversion from primary forest to pasture is a rapid process with high rates of secondary growth-we find instead gradual and permanent clearing of woody vegetation and propose a revised conceptual model of deforestation dynamics.

English

ISBN: 9798379570736Subjects--Topical Terms:

524010
Geography.
Subjects--Index Terms:

Shrub cover

Mapping Tree and Shrub Cover on Pastures in Rondonia, Brazil /
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520 $a The Amazon Basin is experiencing large-scale land use conversion from primary forest to pasture. While several land cover datasets map cleared areas in the Amazon, the percent cover of woody vegetation (trees and shrubs) on cleared areas and its rate of change during clearing is poorly understood, despite its importance for carbon emissions, biodiversity, land-atmosphere interactions, and monitoring of pasture condition. This study used temporal mixture analysis on Sentinel-2 imagery from 2019 to map woody vegetation cover on cleared areas in Rondonia, Brazil. Binary woody vegetation masks were generated at 10m resolution by applying a threshold of the evergreen endmember to the temporal mixture model, which resulted in an overall accuracy of 84%. The woody vegetation masks were then aggregated to 100m to obtain fractional estimates of woody vegetation density in cleared areas. While recently cleared areas (1-2 years) had high woody vegetation cover (60% on average), woody vegetation cover decreased with pasture age, and older pastures (20-34 years) had consistently low woody vegetation cover (25% on average). We find little evidence of large-scale abandonment of pasture: most (53%) pastures in 2019 were "clean" (<10% woody vegetation cover), with 34% "dirty" (10-90% woody vegetation cover), 10% forest (90-100% woody vegetation cover), and 3% early-stage clearing (>10% woody vegetation cover, cleared 1-5 years ago). The commonly observed decrease in greenness in cleared areas, which is sometimes interpreted as an indication of decreased grass health, appears to be due to decreasing woody vegetation density as pastures are gradually cleared over a decade. These results challenge existing conceptual models of deforestation, which suggest that conversion from primary forest to pasture is a rapid process with high rates of secondary growth-we find instead gradual and permanent clearing of woody vegetation and propose a revised conceptual model of deforestation dynamics.
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650 4 $a Geography. $3 524010
650 4 $a Remote sensing. $3 535394
650 4 $a Urban forestry. $3 704817
653 $a Shrub cover
653 $a Primary forest
653 $a Amazon
653 $a Deforestation dynamics
653 $a Older pastures
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690 $a 0799
690 $a 0281
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720 1 $a Biggs, Trent $e degree supervisor.
720 1 $a Sousa, Daniel $e degree supervisor.
773 0 $t Masters Abstracts International $g 84-11.
790 $a 0220
791 $a M.S.
792 $a 2023
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