Hat die Erde seit 1950 mehr als ca. die Hälfte ihrer 'Baumdecke' verloren?

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  United Nations Forum on Forests: http://www.un.org/esa/forests
  
  FAO releases Global Forest Resources Assessment 2010 - Forest biodiversity at risk, but conservation efforts are growing: http://www.fao.org/news/story/en/item/45904/icode
  
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  "The world's total forest area is just over four billion hectares or 31 percent of the total land area. The net annual loss of forests (when the sum of all gains in forest area is smaller than all losses) in 2000-2010 is equivalent to an area about the size of Costa Rica
  
  ...
  
  Biggest losses in South America, Africa
  
  South America and Africa had the highest net annual loss of forests in 2000-2010, with four and 3.4 million hectares respectively. Oceania also registered a net loss, due partly to severe drought in Australia since 2000.
  
  Asia, on the other hand, registered a net gain of some 2.2 million hectares annually in the last decade, mainly because of large-scale afforestation programmes in China, India and Viet Nam, which have expanded their forest area by a total of close to four million hectares annually in the last five years. However, conversion of forested lands to other uses continued at high rates in many countries. "
  
  http://www.fao.org/news/story/pt/item/40893/icode/en
  
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  Mal versuchen, es auszurechnen:
  - Costa Rica: https://www.cia.gov/library/publications/the-world-factbook/geos/cs.html ca 51000 km2 = 51000 * 100 ha = 5.100.000 ha
  - Welt-Waldfläche: 4 billion (4 Milliarden) ha.
  - Die Waldvernichtung hat abgenommen, d.h. die 5.100.000 ha jährlich sind eine untere Abschätzung.
  - In 50 Jahren gingen demnach minimal 5.100.000 ha * 50 = 255.000.000 ha verloren
  - 4.000.000.000 ha / 255.000.000 = minimal 6% Verlust der "Waldfläche":
  
  Problem dabei: Waldacker zählt zum Wald dazu, d.h. vernichtete Urwälder gelten als Wald, auch wenn pestizidvergiftete artentote Palmen- oder Eukalyptusplantagen dort stehen und in Deutschland wächst der "Wald" sogar (trotz zunehmender Zersiedelung und Versiegelung), weil ehemalige Moore mit Wald bewirtschaftet werden. Für ein detaillierteres Bild muss ich selbst erst recherchieren bzw den FAO-Waldbericht lesen ..., z.B. "Primary forests account for 36 percent of total forest area but have decreased by more than 40 million ha since 2000. This is largely due to reclassification of primary forest to "other naturally regenerated forests" because of selective logging or other human interventions. "

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  Beantwortet von inaktiver User 1038 am 06.Dezember 2010, 13:58

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    PS: http://www.wwf.de/fileadmin/fm-wwf/new-images/Waldstudie_MAI2011_lowres.pdf...mehr

    inaktiver User 1038 am 27.Mai 2011, 22:59

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