Responses of Urban Wetland to Climate Change and Human Activities in Beijing: A Case Study of Hanshiqiao Wetland

Abstract

Hydrological connectivity is an essential indicator of wetland pattern and functional stability. The reduction of connectivity usually means the degradation of wetland ecological function, internal energy flow, and nutrient cycle disturbance. Taking Hanshiqiao wetland as a case, we used Morphological Spatial Pattern Analysis (MSPA) with the Connectivity Index (IIC, Integral Index of Connectivity; PC, Probability of Connectivity) to analyze the change in hydrological connectivity of Hanshiqiao Wetland from both spatial and temporal aspects. The results showed that the hydrological connectivity of Hanshiqiao Wetland significantly improved with the implementation of the wetland restoration project. According to the changes in MSPA function types, the spatial morphological evolution of Hanshiqiao Wetland can be divided into two stages: the recovery stage and the stable stage. In the restoration stage, the area of the core wetland gradually increased, and many croplands and islet wetlands were transformed into the core wetland. The area of the core wetland recovered from 33 hm2 in 2005 to 119 hm2 in 2020. However, during the stable period, the landscape pattern of Hanshiqiao Wetland did not change significantly, and the hydrological connectivity of the wetland was mainly affected by water resource supply. In general, during the restoration period of Hanshiqiao Wetland, the changes in core wetlands played a leading role in the hydrological connectivity of Hanshiqiao Wetland. In the stable period, the main factors affecting the hydrological connectivity of Hanshiqiao Wetland are upstream recharge water, land-use change, and climate change. However, with climate warming and population surge, upstream water supply gradually decreases, and Hanshiqiao Wetland faces an increasingly severe water resource crisis. Therefore, to maintain the hydrological connectivity of Hanshiqiao Wetland, it is necessary to increase the artificial ecological water supply. The combined MSPA model and grey relational analysis method can better reveal the evolution characteristics and driving mechanism of wetland hydrological connectivity, which can provide a methodological reference for other wetland-related research.