The Underpinnings of Land Use History
Date: Wednesday, September 28 @ 08:00:00 MDT
Topic:
by George Hurtt
To accurately assess the
impacts of human land-use on the Earth System, information is needed on the
current and historical patterns of land-use activities. Previous global
studies have focused on developing reconstructions of the spatial patterns of
agriculture. Here, we provide the first global gridded estimates of the
underlying land conversions (land-use transitions), wood harvesting, and
resulting secondary lands annually, for the period 1700-2000. For input, we
used two existing datasets of global gridded land-use history—HYDE [Klein Goldewijk 2001] and SAGE [Ramankutty & Foley 1999], a new
reconstruction of national wood harvest that we spatially disaggregated to a
global gridded product, and model estimates of the spatial distribution of
plant carbon density and its recovery. Since these do not fully constrain the
problem, we added assumptions related to four additional factors: the residence
time of agricultural land, the inclusiveness of wood harvest statistics, the
priority for land conversion and logging (e.g. primary- or secondary-land), and
the spatial pattern of wood harvest within countries. In order to estimate
uncertainty and characterize model sensitivity, a set of 216 alternative reconstructions
was derived using different assumptions. We estimate that the accumulated
global wood harvest 1700-2000 was approximately 112 Pg C including slash.
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