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Journal of Desert Research ›› 2024, Vol. 44 ›› Issue (4): 81-90.DOI: 10.7522/j.issn.1000-694X.2024.00054

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Classification and changes of vegetation in Sugan Lake wetland in the extreme arid region

Teng Zhang1,2(), Yunfa Miao1,2(), Yaguo Zou1,2, Ziyue Zhang1,2, Guoping Feng3   

  1. 1.Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
    3.Management Station of Dasugan Lake Migratory Bird Provincial Nature Reserve in Akse Kazakh Autonomous County,Akse Kazakh Autonomous County 736400,Gansu,China
  • Received:2024-03-02 Revised:2024-04-12 Online:2024-07-20 Published:2024-08-29
  • Contact: Yunfa Miao

Abstract:

Wetland is the most biodiverse ecosystem on Earth, and wetland vegetation plays a crucial role in maintaining the stability and functionality of these ecosystems, so mastering wetland vegetation types and distribution characteristics is extremely important for biodiversity conservation. Due to factors such as lacking or unsystematic vegetation community information and remote sensing resolution, the research on vegetation distribution in arid wetlands is limited. Taking the Sugan Lake wetland in the northern part of the Qaidam Basin of the extremely arid region in northwest China as the study area, based on the field vegetation survey data of 116 points and 626 unmanned aerial vehicle image sample points data, Sentinel-1 Synthetic Aperture Radar (Synthetic Aperture Radar, SAR) data and Sentinel-2 Multispectral Imager imagery (MultiSpectral Instrument, MSI) data were used to construct a new remote sensing feature database. The vegetation in Sugan Lake wetland was classified and mapped using the Random Forest algorithm. The results show that: (1) The combination of SAR and MSI data can improve the accuracy of wetland vegetation classification, with overall accuracy of wetland vegetation classification exceeding 0.81 for the years 2019-2023, and Kappa coefficients of 0.82, 0.84, 0.86, 0.82, and 0.82 respectively. (2) From 2019 to 2023, the area of Sugan Lake wetland remained stable, with a vegetation distribution area of 783.90 km2. The distribution area ofreed (Phragmites australis) communities increased by 28.49 km2, and the area of leymus (Leymus secalinus) communities increased by 27.21 km2. In contrast, the coverage of triglochin palustre (Triglochin palustre) and eleocharis palustris (Eleocharis palustris) communities decreased by 64.49 km2. It is preliminarily considered that increased runoff and grazing prohibition policies are important reasons for the changes in wetland vegetation distribution. This study provides an effective method for surveying vegetation in arid area wetlands. High-quality dynamic monitoring of wetland vegetation offers theoretical references for the construction of ecological civilization and restoration measures.

Key words: remote sensing monitoring, arid region, Sugan Lake wetland, random forest algorithm, vegetation classification

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