Diverse impacts of day and night temperature on spring phenology in freshwater marshes of the Tibetan Plateau

Understanding the spatiotemporal variation in vegetation phenology of freshwater marshes and its response to climate change is significant to evaluate the global carbon cycling. Based on the climate and satellite-derived vegetation index data, this work investigated the temporal and spatial variation of spring phenology and its response to climatic change in freshwater marshes of the Tibetan Plateau. We found that the start date of vegetation growing season (SOS) showed a significant advancing trend of 3.4 d decade(-1) from 2001 to 2019 in freshwater marshes of the Tibetan Plateau. The increase of spring daytime and nighttime temperatures could advance the vegetation SOS over the marshes of the Tibetan Plateau. However, the effects of day maximum and night minimum temperature on freshwater marsh SOS were divergent at different altitudes: the advancing effect of warming night-time and daytime temperature on the SOS was more significant in the regions below and above 4000 m, respectively.

Automated summary

Understanding the spatiotemporal variation in vegetation phenology of freshwater marshes and its response to climate change is important. This study found that the start date of vegetation growing season in freshwater marshes of the Tibetan Plateau has been advancing. The increase in spring daytime and nighttime temperatures can advance the vegetation growing season, but the effects of temperature on different altitudes are divergent.