The Impacts of Climate Change on Vegetation Productivity and the Trends of the Impacts in Pakistan over the Last Two Decades

The land territory of Pakistan extends from the coastal area towards the Karakoram, rising vertically by more than 8,600 metres within a distance of 1,600 kilometres. The net primary productivity (NPP) has been affected by climate change, but the regional differentiation of climatic impacts on vegetation productivity and the trends of these impacts over the last two decades remain unclear. Using the ERA5-Land climate dataset and the MODIS NPP dataset via partial regression and moving correlation analyses, we identified the main climatic driver of the NPP and assessed the potential climatic forces faced by local vegetation in the future. Our results were as follows: (1) The NPP showed an overall increasing tendency across Pakistan from 2001 to 2022. (2) The areas where the changes in NPP were driven mainly by temperature and NPP benefitted from the temperature change were located in the northern mountainous regions approximately north of 35°N and east of 72°E, and the northern Upper Indus Plain. With temperatures changing over time, the increase in NPP intensified in the northern mountainous regions above approximately 3,500 m a.s.l., whereas the increase in NPP diminished below this zone and in the northern Upper Indus Plain. (3) The areas where the changes in NPP were driven mainly by precipitation and NPP benefitted from the precipitation change were located in the Gandhara Plain, the northern Potwar Plateau and in the middle to southern parts of Pakistan south of approximately 32°N. With precipitation changing over time, the increase in NPP intensified in the region between approximately 26°N and 32°N, whereas the increase in NPP diminished in the Gandhara Plain, the northern Potwar Plateau and south of approximately 26°N. Our findings indicated spatial differentiation in the responses of NPP to climate change. If climate change continues at its current pace, vegetation in the northern mountainous regions below 3,500 m a.s.l., the Gandhara Plain, the northern Potwar Plateau, the northern Upper Indus Plain and regions south of approximately 26°N may undergo risks of degradation.