Vegetation phenology refers to the seasonal timing of life cycle events in plants and reflects the dynamic responses of terrestrial ecosystems to global climate change.

Global climate change has significantly changed the autumn phenology worldwide, affecting the regional and global energy balance, water flux, and carbon budget. As the highest plateau in the world, the Tibetan Plateau is highly sensitive to climate change. But until recently, the vegetation phenology is dominated by temperature or water on the Tibetan Plateau remain unclear.

Recently, a research team led by Prof. JIANG Ming from the Northeast Institute of Geography and Agroecology of the Chinese Academy of Sciences analyzed the spatiotemporal variation of autumn phenology (the end of the growing season (EOS)) of marsh vegetation on the Tibetan Plateau and its response to climate change, based on MODIS NDVI data and climate data from 2001 to 2020.

This work was published in Global Change Biology on December 12.

The researchers found that the regionally averaged EOS of marsh vegetation across the Tibetan Plateau was significantly (P < 0.05) delayed by 4.10 days/decade from 2001 to 2020.

Warming preseason temperatures were found to be the primary driver behind the delay in the EOS of marsh vegetation, whereas preseason cumulative precipitation showed no significant impact.

Interestingly, the responses of EOS to climate change varied spatially across the plateau, indicating a regulatory role for hydrological conditions in marsh phenology. In the humid and cold central regions, preseason daytime warming significantly delayed the EOS.

However, areas with lower soil moisture exhibited a weaker or reversed delay effect, suggesting complex interplays between temperature, soil moisture, and EOS. Notably, in the arid southwestern regions of the plateau, increased preseason rainfall directly delayed the EOS, while higher daytime temperatures advanced it.

The results indicate that, even in marsh ecosystems with their relatively high water contents, available water may be insufficient for vegetation growth in the drier regions of the Tibetan Plateau.

This study highlights the asymmetric influences of daytime and nighttime temperatures on the autumn phenology of marsh vegetation, particularly in the context of global diurnal asymmetric warming. It underscores the importance of considering water conditions in phenology simulations conducted by terrestrial ecosystem models in cold and dry regions worldwide.

The findings of this study can contribute to further clarification of the relationship between vegetation and climate change, and to offer valuable new insights for ecological management and conservation efforts.

Contact: SHEN Xiangjin

E-mail: shenxiangjin@iga.ac.cn

Northeast Institute of Geography and Agroecology

https://doi.org/10.1111/gcb.17097