Uniform spring phenology associated with non-uniform climate warming along latitudes in China

Background/Question/Methods

It is well known that spring leaf has the best relationship with latitude, especially under global warming. Some studies have found that plants in high latitudes are more sensitive to temperature changes, higher altitudes showed higher cooling trends and larger vegetation greening delays, which is the beginning of vegetation greening during 1999-2006. The date trends are consistent. Altitude of the entire study area. Plant species that are particularly sensitive to temperature signals, such as plants in high latitudes or at altitudes, may react differently with plants in temperate regions, especially in Areas with elevated temperatures. Therefore, the response of spring phenology to climate change remains uncertain. Here, based on the 23,094 observations of the leaf unfolding date for tree species located in 37 sites at various latitude in China during 1963-2008, we analyzed the variability of the spring leaf phenology and its latitudinal sensitivity (S_lat, expressed in delayed days per degree in latitude).

Results/Conclusions

The results showed the Lud has been significantly advanced at a higher latitude (0.29 day) and delayed at a lower latitude (-0.49 day) from 1963 to 2008, in keeping with the changes of temperature across latitude. Consequently, S_lat decreased by 35% from 2.38 (days °N^-1) in 1963 to 1.55 (days °N^-1) in 2008. This phenomenon can be mainly attributed to non-uniform warming with latitude. In the higher latitude, an earlier Lud has been triggered by the significant increase in the chilling hours and growing degree hours of plants. However, a significant decrease in the Chilling Hours of plants in lower latitudes causes a delay in the Lud of plants. Our results provide empirical evidence for a declining S_lat over the last 40 decades, Understanding the long-term changes in spring phenology along spatial patterns (latitude, altitude, etc.) is critical to clarifying and predicting the effects of climate warming on terrestrial ecosystems. Based on long-term and large-scale ground observations, we found differences in the latitude gradient of the leaf unfolding date, which in turn led to a decrease in the spring blade latitude sensitivity S_lat. The nonlinear response of the plants spring phenology to climate change depends on the cold and forced temperature changes of different latitudinal gradients. Therefore, it is very important to incorporate the latitudinal spring phenological information into the current dynamic vegetation model to accurately predict the impact of climate change on the structure and function of temperate forest ecosystems in future warming scenarios.