Jahelnabi, AE; Wu, WC; Boloorani, AD; Salem, HM; Nazeer, M; Fadoul, SM; Khan, MS (2020). Assessment the Influence of Climate and Human Activities in Vegetation Degradation using GIS and Remote Sensing Techniques. CONTEMPORARY PROBLEMS OF ECOLOGY, 13(6), 685-693.

Vegetation net primary productivity (NPP) reveals the plants capability to transform solar energy to photosynthesis. It can be used as an indicator of status of environmental processes affected by climate changes and human activities, especially in degraded areas such as Gadarif State, Sudan, where vegetation degradation has progressively taken place. In this study, three types of net primary productivity from 2000 to 2017 were used to assess the relative roles of climate variables and human activities on vegetation variability in the eastern part of Sudan (Gadarif State) by ordinary least-square regression technique. The three types of NPP are the actual NPP derived from MODIS data, potential NPP estimated using Thornthwaite memorial model and human-related NPP, the difference between the Potential NPP and actual NPP. The correlations between NPP and climate variables are calculated using Pearson's correlation coefficient. The results revealed that 91.7% of the study area has experienced vegetation degradation caused by human activities with a variation of 97.95% in NPP. In contrast, 8.3% of the study area has a recovery by 2.05% of increase in NPP favored by climate change. The main driving forces of vegetation degradation are human activities, and the dominant factor for vegetation reversion is climate. No clear interaction between the two factors (climate change and human activities) was observed in the study area throughout the period of study. Thus, we concluded that NPP is a good indicator for assessing the relative roles of climate changes and human activities in vegetation cover dynamics that has obviously occurred in almost all districts of Gadarif, Sudan.