An Integration Framework for Evaluating Vegetation Degradation in Coastal Wetlands Under the Escalating Effect of Climatic and Anthropogenic Factors

Abstract

Vegetation in coastal saltmarsh wetlands have suffered severe degradation globally due to natural and anthropogenic activities. The key issues for effective protection and restoration are quantifying the spatiotemporal dynamics of saltmarsh vegetation and exploring the driving forces. Aiming to explore the driving mechanism of natural and anthropogenic factors on vegetation degradation in costal saltmarsh, a research framework was proposed by integrating landscape pattern analysis, random forest (RF), Partial Least Squares Structural Equation Modeling (PLS-SEM) and Geographically Weighted Regression (GWR) model, then applied the methodology into saltmarsh vegetation in the Yellow River Delta, China. Results showed that saltmarsh vegetation degraded with an annual rate of 2.17% in 1990~2020, prominently characterized by decreasing distribution area, squeezing distribution range, and fragmented landscape patterns. Anthropogenic activities drastically encroached the saltmarsh vegetation areas after 2005. The whole soil properties negatively affect the landscape patterns of saltmarsh vegetation, while climate exerted the significantly individual impacts. Furthermore, potential indirect pathways shown that climatic and anthropogenic factors exhibited the escalating indirect impacts on saltmarsh vegetation by altering soil organic carbon and soil temperature. Besides, the impacts of natural and anthropogenic factors on saltmarsh vegetation exhibited significantly spatial heterogeneity. Consequently, we provide a quantitative methodology and highlight the escalating indirect effects of climatic and anthropogenic factors on vegetation degradation in coastal wetlands.

Keywords: Anthropogenic activities, climate change, coastal wetlands, Spatiotemporal evolution pattern, Vegetation degradation