A study of the variation of rainfall patterns with tree cover change

Abstract

According to statistical results, 20% of the Amazon basin’s original forest has been converted to pastures or croplands by 2018 due to the deforestation since 1970. Studies with large spatial scale demonstrate that these changes lead to a decrease in evapotranspiration and contribute to a decline in rainfall. However, the effect of this transformation on local precipitation is far from clear. In addition, it still remains unclear that the effect of afforestation on local precipitation. Through the study, it is expected that the results could contribute to a deeper understanding of response of precipitation to vegetation change. By this way, the present study performs the temporal trend analysis and neighboring effect analysis of the annual time-series of Amazonia and southeastern China local precipitation and tree cover data over the period of 1998-2016 (except 2000) and 2001-2016 with the resolution of 0.25o by 0.25o, respectively. The Mann-Kendall (MK) test was applied to quantify the significance of trend and then regression analysis was implemented to explore if there were significant correlations between center position’s tree cover and its neighbor’s precipitation. In relation to tendencies, downward tree canopy trends were detected in the southeastern Amazonia. In addition, upward tree canopy trends were identified for half of the southeastern China. The neighboring effect is not obvious in both research area. For Amazonia, only 5% results show moderate correlations in each month and this number varies from 3 to 10% in southeastern China of each month. Generally, basing on the research results, it can’t be concluded that the local precipitation is associated with local and around tree cover ratio and studies with finer resolutions are expected in the future.