Abstract
Hydrological connectivity is important for maintaining the stability and function of wetland ecosystems. Small-scale hydrological connectivity restricts large-scale hydrological cycle processes. However, long-term evolutionary studies and quantitative evaluation of the hydrological connectivity of wetlands in the Poyang Lake area have not been sufficiently conducted. In this study, we collected 21 Landsat remote sensing images and extracted land use data from 1989 to 2020, introducing a morphological spatial pattern analysis model to assess the wetland hydrological connectivity. A comprehensive method for evaluating the hydrological connectivity of wetlands was established and applied to the Poyang Lake area. The results showed that, over the course of 31 years, the wetland landscape in the Poyang Lake area changed dramatically, and the wetland area has generally shown a decreasing and then increasing trend, among which the core wetland plays a dominant role in the hydrological connectivity of the Poyang Lake area. In addition, the hydrological connectivity decreases as the core wetland area decreases. From 1989 to 2005, the landscape in the Poyang Lake area focused mainly on the transition from wetland to non-wetland. From 2005 to 2020, the conversion of wetland landscape types shows a clear reversal compared to the previous period, showing a predominant shift from non-wetland to wetland landscapes. The eco-hydrological connectivity of the wetlands in the Poyang Lake area from 1989 to 2020 first decreased, and then increased after 2005. In the early stage of the study (1989−2005), we found that the connectivity of 0.3444 in 2005 was the lowest value in the study period. A resolution of 30 m and an edge effect width of 60 m were optimal for studying the hydrological connectivity of wetlands in the Poyang Lake area. The main drivers of the changes in hydrological connectivity were precipitation and the construction of large-scale water conservation projects, as well as changes in land use. This study provides a good basis for assessing hydrological connectivity in a meaningful way, and is expected to provide new insights for maintaining and restoring biodiversity and related ecosystem services in the Poyang Lake area.
Highlights
Material and energy exchanges between patches were more frequent, which favored maintaining the stability and biodiversity of wetland ecosystems. Both spatially and in terms of area, the core wetlands exhibited gradual fragmentation followed by recovery from 1989 to 2020 (Figure 5C); Branches, bridges, and loops all play the role of corridors in the wetland connectivity functions
The area of perforation wetlands was more stable, and was the smallest of the foreground wetlands; the largest was less than 50 km2, and had little impact on the wetland hydrological connectivity (Figure 5B)
We focused on the spatial and temporal evolution of hydrological connectivity in the Poyang Lake area over the past 31 years, and introduced a method of morphological spatial pattern analysis
Summary
Along with forests and oceans, are among the three dominant ecosystems in the world. They are an important part of the natural ecological space, and play an important role in water conservation, water purification, flood and drought control, climate regulation, and biodiversity maintenance. They support the sustainable development of human economies, societies, and living environments [1,2]. Hydrological connectivity refers to the process of transferring various materials, energies, and organisms within or between elements of a hydrological cycle, using water as a medium [3,4], including spatial
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