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IDSB02 reading Physical and Human Dimensions of Deforestation in Amazonia.docx

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University of Toronto St. George
Political Science

IDSB02 Reading- Physical and Human Dimensions of Deforestation in Amazonia D.L. Skole et al - 1992  Tropical deforestation is important to global climate change, hydrology change and biogeochemical cycles  Brazil has the highest deforestation rates according to some  The understand of tropical deforestation is inadequate b/c: o Lack of accurate measure of its rate, geographic extent and spatial pattern o Lack of insight to its causes  Obvious that tropical deforestation is b/c of lots of social, economic & environmental factors but how they interrelate to effect deforestation vary widely -> some say chiefly pop growth others say institutions  An interdisciplinary approach to analyzing deforestation on Brazilian Amazon needed Physical Dimensional of deforestation in the Amazon  Landsat and Spot satellite remotes sensors could be used to measure the levels of deforestation would provide the best info  They could be used to develop detailed maps of rate and extent of deforestation to then document location and expansion over time  NOAA sensors could be used to locate areas of intense deforestation  The area was mapped from 1978-88 by digitized mappers and satellites which provided an analysis that was significantly lower than other previous estimates  This data shows that different regions have different levels of deforestation and different time periods also give different levels of deforestation as well  It is possible to obtain estimates using tabular summaries from government censuses  The data for these areas don’t directly report deforested area but rather on forms of permanent or temporary agriculture including pastures  Major cause of deforestation in the amazon is agriculture thus the data can be used as a proxy  They census reports also provide info on crop type, farm size, fertilizer use, & other info  When this data was plotted digitally it showed similar geographic patterns to the satellite data  Suggests important role for census data  Region wide patterns of deforestation are the result of many local activities  Net deforestation is the sum of several gross land-cover transitions: o Primary forest conversion o Abandonment of agricultural land o Re-clearing of successional vegetation  These affect biogeochemical cycles and physical processes  The analysis suggests the important and inseparable coupling between active agriculture and secondary growth  Abandonment rates tend to increase when increases in primary forest clearing produce net increases in secondary succession area (flood/fire destroyed plant life in secondary succession) Human dimensions in the Amazon  Satellite observations can provide an objective approach to measure deforestation and it’s possible to see the geographical patterns into different types of deforestation (mining/farms etc.) but these alone cannot identify why deforestation occurs or what factor influence regional trends/local dynamics  Demographic factors: FOA concluded that population growth was the cause of deforestation globally  One study by Reis and Margulis (1990) states that pop growth relates to deforestation when pop density is plotted against deforestation density -> multiple regression method related, deforestation to many anthropogenic causes; density of pop included  However this study does not find that and simple relationships to pop growth may not alone describe factors driving deforestation in the Amazon  Hecht (1983, 85) concludes that gov’t policy, fiscal incentives and the nature of individual farmers in an inflationary economy are more significant determinants of deforestation  Other studies confirm this and say that pop growth is one variable in a multiple feedback system rather than the forcing function  Economic and institutional factors: although deforestation has been occurring for a long time estimates from satellites show that 90% has happened after 1970 this is thought b/c the events and conditions happening at a national and international scale has influenced this including: o Agricultural expansion -> this is the most important agent of deforestation; during the 70s agriculture expanded esp. in states like Rondonia
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