Historical trajectory in vegetation cover in Northeastern Namibia based on AVHRR satellite imagery (1982-2015)

Abstract

The negative impact of the reduction of vegetation cover is already being felt in the Zambezi Region in northeastern Namibia. The region has been undergoing various land cover changes in the past decades. To understand the historical trend of vegetation cover (increase or decrease), we analyzed 8-km resolution Global Inventory Monitoring and Modeling Studies (GIMMS) from the Advanced Very High Resolution Radiometer (AVHRR) and 0.25° x 0.25° (resampled to 8 km) resolution Global Precipitation Climatology Center (GPCC). We used the Time Series Segmented Residual Trends (TSS-RESTREND) method. We found that the general trajectory of vegetation cover was negative. Pixel-wise analysis and visual interpretation of historical images both revealed clear signs of vegetation cover change. We observed a single breakpoint in the vegetation trajectory which correlated to the 1991-1992 drought in southern Central Africa. Potential drivers of land cover change are the (il)legal expansion of subsistence farming, population growth, and wood extraction. These findings will serve as a reference for decision makers and policymakers. To better understand the human-induced land cover change at the micro scale and sub-regional level, we recommend using higher resolution remote sensing datasets and historical documents to assess the effect of demographic change, disease, civil unrest, and war.