Dynamic pattern-effect relationships between precipitation and vegetation in the semi-arid and semi-humid area of China

Explicating the relationship between vegetation and precipitation changes with different spatial dimensions is critical for clearly identifying the interaction mechanism between climate change and ecosystem health in the semi-arid and semi-humid (SASH) area, China. Due to investigating the dynamic pattern-effect relationships between precipitation and vegetation in the directions of longitude and latitude in the SASH area of China, the division method of SASH area, the identifying method of spatial distribution change of NDVI and precipitation, and the sensitivity index of NDVI to precipitation were developed in this study, based on the NDVI data and monthly precipitation data from 1991 to 2020. The research results showed that the NDVI was significantly related with precipitation in the whole SASH area. The relationship between NDVI and precipitation in the semi-arid area was higher than that in the semi-humid area between 1991 and 2020. The response of NDVI to pre-cipitation (R-(NDVI,R-Pre) = 0.90, P < 0.01) in the longitude direction was more than that (R-(NDVI,R-Pre) = 0.55, P < 0.01)in the latitude direction. The sensitivity of 79% NDVI to precipitation was increased with increasing latitude within the same longitude range, and the sensitivity of 97% NDVI to precipitation was decreased with increasing longitude within the same latitude range. The NDVI was more sensitive to precipitation in the semi-arid area than that in the semi-humid area. In summary, the responses of NDVI to precipitation showed significant heterogeneity between 1991and 2020 in the whole SASH area. Thus, the planning of ecological protection should give more consideration to the precipitation condition in the SASH area in the future.

Automated summary

This study investigated the dynamic pattern-effect relationships between precipitation and vegetation in the semi-arid and semi-humid (SASH) area of China. It developed methods to divide the SASH area, identify spatial distribution changes of NDVI and precipitation, and measure the sensitivity of NDVI to precipitation. The results showed a significant correlation between NDVI and precipitation, with a stronger relationship in the semi-arid area compared to the semi-humid area. The study also found that NDVI had a higher sensitivity to precipitation in the longitude direction than in the latitude direction.