Landscape pattern change of marsh in the Nanmoqie Wetland National Nature Reserve of Sichuan Prov-ince
Alpine wetlands are typical wetland types on the Qinghai-Tibet Plateau,playing important roles in biodi-versity maintenance and water conservation.Understanding the changes and driving factors for their landscape pat-tern is of great significance for the conservation and restoration of alpine wetlands in China.Based on GEE and Landsat satellite images,we used the random forest classification method to extract information on the distribution of marsh in the Sichuan Nanmoqie Wetland National Nature Reserve,for 12 periods from 1987 to 2022,and analyzed the spatial and temporal marsh landscape patterns and the driving factors.The results showed that:(1)the area of marsh first decreased and then increased,with an overall decrease of 10.29％;(2)the area conversion between marsh and meadow was highest,with a cumulative shift of 4349.44 hm2 from marsh to meadow;(3)the centroid of marsh moved to the northeast first and then to the southwest,and the distribution range of marsh moved to the southwest as a whole;(4)the degree of fragmentation decreased and then increased,and the connectivity in-creased and then decreased instead.The shape of patches tended to be complex,and the landscape tended to deve-lop from a compact state to a dispersed state;(5)the cumulative precipitation and average temperature during the growing season were the main factors affecting the pattern of marsh distribution.The results can provide a scientific basis for the conservation and restoration of alpine wetlands in the reserve and for the ecological security construc-tion of alpine wetlands on the Qinghai-Tibet Plateau.
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