Time-lag effects of vegetation responses to water buffered in wetland soil

Abstract Vegetation is not only immediately affected by water flow, but also has a time-lag response to water elements accumulated in the soil of the wetland ecosystem. However, extensive studies focused on the direct response of vegetation to water regimen, the time-lag effects are less considered due to lacking appropriate quantitative methods. In this study, we aimed to quantitatively determine the response of wetland vegetation to two different forms of water. We extracted three vegetation patches using long-term Landsat data and constructed two kinds of hydrological variables (immediate and time-lag), analyzing their relationship. The results showed that:(1) different vegetation patches have different spatio-temporal dynamics over time. The distribution elevation of dense and high grass patches significantly reduces, and the ecological niche expands;(2) the temporal explicit pattern of wetland vegetation response to two hydrological variables are different: the sensitivity of the response to immediate hydrological variables is sparse grass patch>dense grass patch>high grass patch, and the response duration of time-lag is dense grass patch >sparse grass patch>high grass patch; compared to vegetation patches at high elevation, sparse grass patch at lower elevation is more susceptible to the accumulation of water regimen over time. Our study clarifies that wetland vegetation has a time-lag response to water regimen, which is a supplement to evaluating and predicting vegetation dynamics under wetland water regimen changes.