Changes of Land Use/Cover and Landscape in Zhalong Wetland as “Red-Crowned Cranes Country”, Heilongjiang Province, China

<p>Hydrological and ecological role of wetlands were growing significant. Based on Landsat satellite remote sensing data collected in the years of 1990, 2000 and 2014, and integrating GIS with analytical methods of landscape ecology, research on changes of land use/cover and landscape pattern of Zhalong Wetland from 1990 to 2014 was conducted. Then, we analysed the effect of human activities and climate changes on land use/cover. The main conclusions were as follows: (1) Significant changes in land use/cover have taken place in Zhalong wetland during 1990-2014.Cultivated land, unused land and construction land increased continually, while the area of reed swamp, water swamp, grass land and water land decreased accordingly; (2) Landscape patch shape has be increasingly irregular and turned complexed, there was the tend of the growing diversification and homogenization of land use change and the growing complicate landscape pattern in Zhalong wetland; (3) There was a warm-dry climate trend from 1958 to 2014; (4) Human activities including population, construction, water land pollution and production have been threatening the wetland ecosystem. Those changes in Zhalong area were caused by nature and human activity. However, the human’s contributions are great.</p>

Does Ecological Water Replenishment Help Prevent a Large Wetland from Further Deterioration? Results from the Zhalong Nature Reserve, China

Ecological water replenishment (EWR) has been increasingly applied to the restoration and maintenance of wetland hydrological conditions across China since the beginning of the 21st century. However, little is known about whether EWR projects help protect and/or restore wetland ecohydrology. As one of the earliest and longest-running EWR projects in China, water has been released from the Nenjiang River into the Zhalong wetland since 2001. It is important to examine the ecohydrological effects of this EWR project. In this study, long time series remote sensing data were used to extract the water area, inundation frequency, and normalized difference vegetation index (NDVI) to explore how eco-hydrological conditions changed during the pre- (1984–2000) and post-EWR (2001–2018) periods in the Zhalong wetland. Results show that the inundation area decreased due to the reduced surface water inflow during the pre-EWR period. Similarly, monthly vegetation NDVI in the growing season generally exhibited a decreasing and an increasing trend during the pre- and post-EWR periods, respectively. In the post-EWR period, NDVI increased by 19%, 73%, 45%, 28%, 13% for the months of May through September, respectively. Due to EWR, vegetation growth in areas with low inundation frequency was better than in areas with high inundation frequency. We found that the EWR project, runoff, and precipitation contributed 25%, 11%, and 64% to changes in the NDVI, respectively, and 46%, 37%, and 17% to changes in inundation area, respectively. These results indicate that the EWR project has improved hydrological conditions in the Zhalong wetland. For further maximum benefits of EWR in the Zhalong wetlands, we suggest that implementing similar eco-hydrological projects in the future should focus on flood pulse management to increase the inundation area, improve hydrological connectivity, and create new habitats.