A global evaluation of forest interior area dynamics using tree cover data from 2000 to 2012

Abstract

Context: Published maps of global tree cover derived from Landsat data have indicated substantial changes in forest area from 2000 to 2012. The changes can be arranged in different patterns, with different consequences for forest fragmentation. Thus, the changes in forest area do not necessarily equate to changes in forest sustainability. Objective: The objective is to assess global and regional changes in forest fragmentation in relation to the change of forest area from 2000 to 2012. Methods: Using published global tree cover data, forest and forest interior areas were mapped in 2000 and 2012. The locations of forest interior change were compared to the locations of overall forest change to identify the direct (pixel level) and indirect (landscape level) components of forest interior change. The changes of forest interior area were compared to the changes of total forest area in each of 768 ecological regions. Results: A 1.71 million km2 (3.2 %) net loss of global forest area translated to a net loss of 3.76 million km2 (9.9 %) of forest interior area. The difference in loss rates was consistent in most of the 768 ecological regions. The indirect component accounted for 2.44 million km2 of the net forest interior change, compared to 1.32 million km2 that was attributable to the direct component. Conclusion: Forest area loss alone from 2000 to 2012 underestimates ecological risks from forest fragmentation. In addition to the direct loss of forest, there was a widespread shift of the remaining global forest to a more fragmented condition.