Spatiotemporal Variation of Siberian Crane Habitats and the Response to Water Level in Poyang Lake Wetland, China

Lin Zou,Qianqian Zhang,Bisong Hu,Shuhua Qi,Pan Ning

doi:10.3390/rs13010140

Abstract

The Poyang Lake wetland in China is the largest wintering destination for Siberian cranes worldwide. Understanding the spatiotemporal characteristics of crane habitats is of great importance for ecological environment governance and biodiversity protection. The shallow water, grassland, and soft mudflat regions of the Poyang Lake wetland are ideal habitats for wintering Siberian cranes. Based on Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI) remote sensing images, habitat areas were extracted and associated with various water levels taken on multiple dates. Landscape metrics were applied to describe the spatial structural characteristics of the crane habitats, and spatial statistics are used to explore the cold and hot spots of their distribution. Moreover, three indicators including sustainability, stability, and variety were applied to evaluate the vulnerability of the crane habitats under different hydrological conditions. Our findings indicate: (a) The main crane habitats exhibit a gradual decreasing degree of fragmentation in time, an obvious uncertainty of shape complexity and a relatively stable connectivity. (b) The crane habitats have a consistent spatial pattern of highly aggregated distributions associated with various water levels. (c) The hot spots of the habitats formed multiple “sheet” belts centered on the “Lake Enclosed in Autumn” regions, while the cold spots indicate a spatial pattern of axial distributions. (d) The majority of the hot spots of the habitats were distributed in sub-lakes found in the southeast part of the Poyang Lake watershed and the Nanjishan and Wucheng nature reserves, while the cold spots were mainly distributed in the main channels of the basins of Poyang Lake. (e) The sustainable habitats were mainly distributed in the “Lake Enclosed in Autumn” regions and intensively aggregated in two national nature reserves. (f) Under conditions of extremely low to average water levels (5.3–11.46 m), an increase of water level causes a decrease of the stability and variety of the crane habitats and weakens the aggregation structure.

Highlights

It is of great importance for ecological environment protection and management of the Poyang Lake wetland to study the spatiotemporal variation of Siberian crane habitats and their corresponding response to water level changes
The landscapes of the Poyang Lake wetland associated with various water conditions help describe the spatiotemporal patterns of the Siberian crane habitats
The majority of the aggregated habitats for the wintering Siberian cranes were found to be located in the “sheet” belts centered on the “Lake Enclosed in Autumn”

Summary

Introduction

The “Lake Enclosed in Autumn” project, a long-term fishing operation mode adapted to the seasonal hydrological changes of Poyang Lake, has been identified to have a negative impact on the local ecological environment [11,12]. It is formed by constructing low dams during the dry seasons and enclosing shallow beaches on the spot, which are located around the sub-lakes of Poyang Lake, to intercept more fish and water when the water recedes in autumn [13,14]. It is of great importance for ecological environment protection and management of the Poyang Lake wetland to study the spatiotemporal variation of Siberian crane habitats and their corresponding response to water level changes

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Discussion

Conclusion