Spatial and temporal trends of forest cover as a response to policy interventions in the district Chitral, Pakistan

摘要

Forest protection policies potentially reduce deforestation and forest degradation. Using satellite imagery, a supervised classification method and a post-classification change detection technique, this study quantifies forest cover changes prior (1973-1993) and after (1993-2015) a nation-wide logging ban in 1993. Using logistic model, we also assess and compare the relative importance and patterns of drivers of deforestation and forest degradation between the two periods. We show that despite a complete ban on green felling, total forest in the study area has decreased from 89,938 ha in 1973 to 68,904 ha in 2015. Proportionally more forest (13,636 ha) disappears during the post-logging ban as compare to the pre-logging ban period (7398 ha) with annual conversion rate of 0.43% and 0.82% respectively. In particular, forest degradation has accelerated in the region after the imposition of the logging ban policy. However, sparse forest conversion appears to slightly slowdown after the imposition of the logging ban. The logistic analysis shows that most of the deforestation in the pre-ban period occurred in the high elevation range (3000 to 4000 m), while during the post-ban period more can be observed in the low elevation range (2500 and 3500 m). Opposite to deforestation, forest degradation shifted from low elevation range (2500 to 3000 m) during the pre-ban period to high elevation range (3000 to 3500 m) of mature and old growth stands during the post-ban period. Distances to political boundary and forest edge were the other significant variables that behaved differently between the two periods. We found that factors influencing deforestation and forest degradation were not only time and space specific but also varied with the policy setting.