| As a direct reflection of human activities and climate change,land use/cover change(LUCC)is closely related to ecosystem change.The research on land use/cover change helps to understand the intensity and scope of human activities and the results of climate change,and is an important link in exploring ecological environment changes,regional ecosystem balance and sustainable development.As one of the world's important biodiversity hotspots and climate change sensitive areas,the Himalayas are facing serious ecological risks due to the accelerated degradation of regional ecosystems and a substantial decline in ecosystem services under the background of climate change.The establishment of nature reserves to reduce the damage to the natural environment caused by human activities is an important means to maintain the stability of the natural ecological environment and biodiversity within the region.With the rapid increase in the scale of protected areas in the Himalayan region,assessing the effectiveness of current nature protection is an important task that needs to be done at this stage.In this research,through the Google Earth Engine cloud platform,the 1992,2000,2010,and 2020 Landsat TOA reflectance images are used as the basis for image classification.Based on multi-source land cover sample data,some auxiliary classification data are added.Nine types of land use/cover types including forest land,shrubland,grassland,construction land,cultivated land,water bodies,wetlands,glaciers and snow cover,and bare land are classified by Random Forest algorithm and extracted.The LULC data sets with spatial resolution of 30 m were produced in 1992,2000,2010 and 2020.Based on the acquired datasets,the characteristics of land use/cover differences and changes in the Himalayan region,protected areas,and inside and outside protected areas from 1992 to 2000 were analyzed.Combining the changes of the landscape-scale landscape pattern index and NDVI index to reveal the ecosystem pattern and change status of the protected area,so as to study the ecological pattern,change and protection effect of the protected area,and provide a basis for the construction and evaluation of local and global protected areas in the future,so as to promote regional ecological sustainable development and better provision of ecological service value.Research indicates:(1)The four-phase land use/cover data in the Himalayan region obtained in this study have high accuracy,the overall verification accuracy is about 0.88-0.90,and the Kappa coefficient is about 0.86-0.87.Based on the 2020 land use/cover dataset,the overall accuracy,Kappa coefficient,and producer accuracy and user accuracy for each cover type are significantly better than the nine global data products of GLC2000,MCD12Q1?2020,GLCNMO?2013,Glob Cover,CCI-LC?2015,CGLS?LC100,Globe Land30?2020,GLC?FCS30?2020 and FROM-GLC?2017.(2)In 2020,the Himalayan region will be dominated by forest land,grassland and bare land,accounting for 34.98%,18.82% and 18.41% of the total area of the region,respectively,while water bodies,wetlands and construction land account for less than1%.From 1992 to 2020,the area of shrubs,construction land,wetlands,and glaciers and snow in the Himalayan region increased,while the areas of woodland,grassland,cultivated land,water bodies,and bare land decreased,The main interchanges are between woodland-scrub,scrub-grassland,woodland-cultivated land,grassland-naked land,and glacial snow-bare land.From the perspective of landscape pattern index and changes,ecological landscape diversity increased,connectivity decreased,fragmentation increased,and the overall ecological environment continued to deteriorate.At the junction of the north and south slopes of the Himalayan region,the parts with severe elevation fluctuations were particularly prominent.The NDVI results show that the vegetation greenness in the Himalayan region has improved overall,and the southern slope has improved more significantly than the northern slope.(3)The proportion of construction land and cultivated land in protected areas in the Himalayan region is very small,indicating the low-intensity human activities.The main changes of area in the Himalayan region from 1992 to 2020 are woodland to shrub,shrub to grassland,grassland to bare land,and bare land to glacier and snow cover.The area of shrub,construction land,water body,wetland and glacier and snow cover increases as a whole.The area of forest land,grassland and cultivated land decreased as a whole,and the changes of forest land,shrub,water body and wetland,which are important related to ecological environment,tended to be more favorable than that of Himalayan region as a whole.According to the change of landscape pattern index,the deterioration degree of landscape ecology is significantly slower than that in the Himalayan region as a whole.A comprehensive comparison of the ecological landscape status and changes shows that the protected area is better than the Himalayan region as a whole,and the buffer zone inside the protected area is better than the buffer area outside the protected area.(4)Comparing the differences and changes of protected areas with different attributes in the Himalayan region at the scale of landscape pattern: According to the national differences of protected areas,the ecological landscape of protected areas in Bhutan in 2020 is the best,Pakistan is the worst,and among the changes from 1992 to2020,India Protected areas performed best,while Bhutan and Pakistan performed less well.From the perspective of the protected area level,in 2020,the ecological landscape of category IV protected areas is the best,and category V is the worst.In the changes from 1992 to 2020,the protection effect of category II is the best,and the effect of category Ia and VI is poor.From the perspective of protected area types,the ecological landscape of the biological corridor in 2020 is the best,and the UNESCO-biosphere is the worst.During the changes from 1992 to 2020,the overall protection effect of international protected areas was better than that of national protected areas,UNESCObiosphere protection achieved remarkable results,and internationally important wetlands were less effective. |
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