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Scientia Silvae Sinicae ›› 2024, Vol. 60 ›› Issue (8): 1-13.doi: 10.11707/j.1001-7488.LYKX20240048

• Technology and application of smart forestry and grassland • Previous Articles     Next Articles

Spatiotemporal Patterns and Driving Forces of Vegetation Restoration and Degradation in Dongting Lake Wetland

Yutian Zhang1,2,3,Junnan Shi2,Huaiqing Zhang1,3,*,Binglun Wu4   

  1. 1. Institute of Forest Resource Information Techniques, Chinese Academy of Forestry Beijing 100091
    2. Central South University of Forestry & Technology Changsha 410004
    3. Key Laboratory of Forestry Remote Sensing and Information System, National Forestry and Grassland Administration Beijing 100091
    4. Changsha General Survey of Natural Resources Center, China Geological Survey Changsha 410600
  • Received:2024-02-18 Online:2024-08-25 Published:2024-09-03
  • Contact: Huaiqing Zhang

Abstract:

Objective: Wetland vegetation can purify the environment, regulate climate, and improve the soil, which is of great significance to the ecological security and stability of the wetland system. Wetland vegetation communities are, however, under serious threat from accelerated global warming and human disturbance. Probing the long-term spatial-temporal pattern of wetland vegetation cover change and its response to climate change and human activities are important for informing decisions on wetland protection. Method: It is difficult to collect long-term, reliable optical observations with high spatiotemporal resolution in the Dongting Lake wetland due to its location in the subtropical monsoon climate zone and its frequent cloud and rainy conditions. Firstly, this study used the flexible spatiotemporal data analysis fusion (FSDAF) algorithm to fuse Landsat and MODIS images to obtain the monthly normalized difference vegetation index (NDVI) time series during the study period (2000—2019). To quantify the response of wetland vegetation cover to environmental changes and human disturbance at different time scales, the seasonal and trend components of wetland vegetation NDVI in Dongting Lake were separated by an improved seasonal-trend decomposition procedure based on the loess (STL) time series decomposition method. Based on the linear trend analysis and NDVI seasonal and trend component data with a high spatiotemporal resolution, the spatiotemporal dynamic patterns of wetland vegetation at different scales were identified. Finally, a partial correlation-based approach was used to quantitatively assess the contributions of three major climatic factors (i.e., temperature, precipitation, and solar radiation) and anthropogenic factors to seasonal and trend vegetation changes from 2000 to 2019. Result: 1) From 2000 to 2019, the trend component and seasonal component of NDVI vegetation in Dongting Lake wetland showed spatial differentiation patterns, but overall exhibited a “greening” trend, with a change rate of 4.8×10?3 a?1 and 0.4×10?3 a?1, respectively. 2) Vegetation growth has a significant positive correlation with temperature and solar radiation, and its seasonal correlation with vegetation change is generally greater than trend correlation. The correlation between precipitation and vegetation is relatively low, and it has a negative correlation with rice (trend component R=?0.27; seasonal component R=?0.42). 3) From 2000 to 2019, human factors and climate change have driven 58% and 42% of the NDVI vegetation changes in the Dongting Lake wetland, respectively. Among them, the relative contribution rates of human factors to the long-term and seasonal growth and restoration of wetland vegetation are 55% and 62%, respectively, while the relative contribution rates of climate change to the long-term and seasonal degradation of wetland vegetation are 53% and 56%, respectively. Conclusion: Human factors have promoted the growth of wetland vegetation and are the main driving force behind the greening of Dongting Lake wetland vegetation from 2000 to 2019, while climate change poses a threat to wetland ecosystems. Adopting appropriate ecological protection and restoration measures is still an important means to achieve sustainable development of the Dongting Lake wetland ecosystem in the future. This study elucidates the response mechanism of Dongting Lake wetland vegetation to climate change and human activities, providing a scientific basis for spatial decision-making on wetland conservation.

Key words: wetland vegetation, climate change, spatiotemporal fusion, times series NDVI, Dongting Lake wetland

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