/ Results from time-series analysis of 654,178 Landsat images in characterizing forest extent and change, 2000â2012. / Trees are defined as all vegetation taller than 5m in height and are expressed as a percentage per output grid cell as â2000 Percent Tree Coverâ. âForest Lossâ is defined as a stand-replacement disturbance, or a change from a forest to non-forest state. âForest Gainâ is defined as the inverse of loss, or a non-forest to forest change entirely within the study period. âForest Loss Yearâ is a disaggregation of total âForest Lossâ to annual time scales. / Reference 2000 and 2012 imagery are median observations from a set of quality assessment-passed growing season observations.