## 3 Results
### Differences in Sensitivity to Precipitation in Land Cover Types  
The sensitivity to trace precipitation increased in spring and autumn but decreased in summer and winter (Figure 7). Trace rainfall sensitivity is highest in most areas across seasons (Figure S3); for example, sensitivity increased significantly in the southern Sahara Desert. Most areas exhibited an increasing sensitivity to small precipitation amounts, except for the southern Sahara, where a decrease in this parameter was observed. The sensitivity to precipitation frequency decreased in more than half of the areas in northern latitudes (Figures S4-S8). Generally, the greater the amount of precipitation, the smaller the sensitivity variation. Figure 7: Decade M–K trends of sensitivity to different precipitation frequencies during each season from 1982 to 2015 in every vegetation type. The error bars (mean \(\pm\) 1.96 \(\times\) SE) represent 95% confidence intervals. The sensitivity to precipitation frequency in most land cover types decreased at rates between \(-0.1/\)decade and \(0.1/\)decade, although it remained unaltered for large precipitation intensities. In some exceptional cases, the areas with increased sensitivity to heavy and very heavy precipitation in winter were approximately 10.2% and 25.8% larger, respectively, than those with decreased sensitivity. A similar trend was observed in summer, autumn, and winter for the frequency of very heavy precipitation. For all vegetation in winter, the sensitivity to moderate precipitation increased while that to trace precipitation decreased. In terms of different land cover types, shrubland vegetation was shown to be more sensitive to precipitation frequency than forest, tundra, and barren land vegetation. The average sensitivity of shrub vegetation increased by 0.03/decade and 0.06/decade in spring and summer, respectively, as trace precipitation increased in spring, summer, and autumn, but it decreased in winter. On the contrary, other precipitation categories in shrubland, cropland, forest, and tundra showed a completely opposite trend. Trace precipitation decreased by 0.04/decade on average in winter in all land cover types. The sensitivity of cropland and shrubland to precipitation frequency in summer and autumn decreased, while that of forests increased. The sensitivity of grassland slowly decreased throughout the year except in spring. However, the sensitivity of GPP to precipitation frequency in barren land decreased across seasons. The results suggested that sensitivity to precipitation varied greatly among land cover types. Cropland was crucially impacted by soil water content during the growing season, which led to variations in yield [48]. This land cover type was also affected by human activity, especially in summer and autumn during harvesting, when GPP values dropped dramatically. Thus, the GPP value of cropland would remain constant as precipitation frequency decreased, and then crops planted for the next year's harvest and grown in winter. Thus, GPP is negatively correlated with the decrease in precipitation frequency. Taiga forests cover 17 million square kilometers (11% of the Northern Hemisphere). The interception effect of forest leaves [49] may explain why forest growth was scarcely impacted by trace precipitation. In addition, the greater biodiversity found in these forest ecosystems makes them more resistant to climate change. In most land cover types, large precipitation events would increase moisture availability more easily than small ones. Plant production would therefore benefit more from heavy precipitation, particularly during the growing season, which is characterized by relatively high temperatures [50]. Grassland, herbaceous, and gramineous plants seem to retain soil moisture in their dense roots, which create impermeable underlying surfaces where precipitation is collected in streams instead of soil. Therefore, variations in the frequency of heavy precipitation events in grassland are unable to control grassland growth.