Hydrothermal change regulates spring phenology of different life forms of plants

Plant spring phenology is influenced by multiple climatic variables. Climate warming has significantly advanced spring phenophases over recent decades. However, the differences in responses to climatic variables among various life forms of plants remain unclear. We analyzed spring phenophases of different life forms by integrating approximately 20 years of spring phenological observation data for 82 species from 29 sites in China from 1964 to 2022, combined with contemporary climate data. The results indicated that the correlation between spring phenophases and temperature of trees and shrubs was stronger than that of herbs. Most of the plant phenophases were significantly correlated with temperature, but showed no remarkable correlation with sunhours or humidity. However, some trees and shrubs displayed significant correlations with precipitation. Spring phenophases of trees and shrubs were more sensitive to mean temperature ( S T = −3.62 and −3.59 days ℃ −1 , respectively), whereas those of herbs was more sensitive to minimum temperature ( S T = −1.91 days ℃ −1 ). Spring phenophases of trees and shrubs demonstrated higher S H values (0.48 and 0.43 %RH −1 , respectively), while those of herbs showed lower S H (0.31 days %RH −1 ). Precipitation and sunhours had a significant impact on S T and S H of trees and shrubs. Wind speed had a greater effect on S T and S H of trees than on those of shrubs. In the northern sites, there were significant differences in the sensitivity of phenology to mean temperature between trees and herbs. Spring phenophases for herbs showed the strongest response to maximum temperature compared with those for trees and shrubs.