How Vegetation Spatially Alters the Response of Precipitation and Air Temperature? Evidence from Pakistan

Abstract

Precipitation, air temperature and Normalized Difference Vegetation Index (NDVI) data of 32 sites for a period of 1983 to till date in Pakistan were collected with the objective of studying the effects of vegetation on precipitation and air temperature in Pakistan. Spatial trends were assessed for NDVI, precipitation and air temperature (maximum and minimum). Increasing trends were observed at 18, 20, 24 and 26 number of monitoring stations for NDVI, precipitation and maximum and minimum temperature respectively. The trends of NDVI were compared with the trends of precipitation and maximum and minimum temperature in hilly and urban areas. NDVI and precipitation showed parallel trends in hilly areas at 64% of the monitoring stations. Whereas, only 53% of the stations displayed parallel trends in urban areas. 71% of the stations showed opposite NDVI and maximum temperature trends and 79% of the stations showed opposite NDVI and minimum temperature trends in hilly areas. However, in urban areas only 47% and 41% of the stations showed opposite trends of NDVI and maximum temperature and NDVI and minimum temperature respectively. Pearson’s correlation coefficients were calculated to determine the effects of vegetation on precipitation and air temperature (maximum and minimum) in hilly and urban areas. The results showed that there exists positive relationship between NDVI and precipitation and negative relationship between NDVI and temperature (maximum and minimum) in most of the hilly areas. However, in urban areas, the positive relationship between NDVI and precipitation exists only in 47% of the stations and negative relationships between NDVI and maximum temperature and between NDVI and minimum temperature exist only in 47% and 41% of the stations respectively. Results of the current study suggest afforestation practices at country level to reduce climate change effects.