Critical role of water conditions in the responses of autumn phenology of marsh wetlands to climate change on the Tibetan Plateau

Abstract

The Tibetan Plateau, housing 20% of China's wetlands, plays a vital role in the regional carbon cycle. Examining the phenological dynamics of wetland vegetation in response to climate change is crucial for understanding its impact on the ecosystem. Despite this importance, the specific effects of climate change on wetland vegetation phenology in this region remain uncertain. In this study, we investigated the influence of climate change on the end of the growing season (EOS) of marsh wetland vegetation across the Tibetan Plateau, utilizing satellite‐derived Normalized Difference Vegetation Index (NDVI) data and observational climate data. We observed that the regionally averaged EOS of marsh vegetation across the Tibetan Plateau was significantly (p < .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. Our results emphasize the critical role of hydrological conditions, specifically soil moisture, in shaping marsh EOS responses in different regions. Our findings underscore the need to incorporate hydrological factors into terrestrial ecosystem models, particularly in cold and dry regions, for accurate predictions of marsh vegetation phenological responses to climate change. This understanding is vital for informed conservation and management strategies in the face of current and future climate challenges.

Spatial and temporal variation of net primary productivity of herbaceous marshes and its climatic drivers in China

“…The compensatory effect is a phenomenon that vegetation produces more organic matter the next day after consuming organic matter due to nighttime warming, resulting in some recovery of vegetation growth ( Peng et al., 2013 ; Ulrich et al., 2019 ). Previous studies have shown that environments with sufficient water easily lead to a compensatory effect and even a super compensatory effect ( Liu et al., 2023b ; Shen et al., 2024 ), which can recover and even exceed the original state of the vegetation ( Wang et al., 2023 ; Liu et al., 2023a ). The subject of this study was marsh wetland with sufficient water and nutrients ( Shen et al., 2022b ); therefore, a super compensatory effect may have occurred in this region.…”

“…The environment of TAS are more arid, and precipitation is the limiting factor for the growth of vegetation in this region ( Wang et al., 2023 ). Increased spring precipitation can effectively alleviate the drought stress suffered by the vegetation, and is beneficial to the growth of the vegetation ( Abel et al., 2023 ; Zhu et al., 2023 ; Shen et al., 2024 ). This could explain why the increase in spring precipitation leads to an increase in NPP in the temperate semi-arid and arid marsh regions.…”

“…The regional mean value of each variable was calculated from the average of all the pixels in herbaceous marshes of this region ( Shen et al., 2022a ). Consistent with previous studies ( Ma et al., 2023 ; Liu et al., 2023b ; Shen et al., 2024 ), a linear regression analysis was used to calculate the trends of NPP and meteorological factors over time, using the following formula ( Equation 1 ):…”

“…Consistent with a number of earlier research ( Shen et al., 2016 ; Huang et al., 2020 ), we calculated partial correlations between NPP with meteorological factors in order to assess the impact of climatic change on NPP. This partial correlation method can effectively exclude the interference of other factors ( Li and Qin, 2019 ; Ren et al., 2023 ; Shen et al., 2024 ), thus accurately reflecting the relationship between meteorological factors and NPP.…”

Variation of the Start Date of the Vegetation Growing Season (SOS) and Its Climatic Drivers in the Tibetan Plateau

“…These characteristics of remote sensing data compensate for the shortcomings of traditional vegetation phenology observation methods, rendering them extensively applied in regional and worldwide vegetation phenology research [ 3 , 4 , 12 ]. The Normalized Difference Vegetation Index (NDVI) has been extensively utilized in quantitative research of vegetation phenology due to its robustness and simplicity [ 13 , 14 , 15 ]. According to the majority of previous vegetation phenology studies based on satellite data, the SOS advanced owing to global warming [ 16 ].…”