RESUMO
Regional habitat quality is an important indicator of ecosystem health. Understanding land use change and habitat quality will help protect biodiversity and build an ecological security pattern. We used the InVEST model to quantitatively evaluate the habitat quality of the Xinjiang Corps and Non-corps Region based on land use data of 1990, 2000, 2010 and 2018, and further analyzed the similarities and differences of the spatiotemporal distribution. The results showed that from 1990 to 2018, Xinjiang's land use types were generally stable, characterized mainly by the expansion of cultivated land and construction land, and the decrease of grassland and unused land. The main changes were shown as the mutual conversion of grassland and cultivated land, and the conversion of cultivated land to construction land. The cultivated land and construction land of the Corps increased by 8.3% and 0.7%, while the grassland and forest land decreased by 6.7% and 0.3%, respectively. The change in the Non-corps region was relatively small, with a 1.5% reduction of grassland, a 1.2 % increases of cultivated land, and a 0.2% increase of construction land. From 1990 to 2018, the degree of habitat degradation in Xinjiang first decreased and then increased, with the quality of habitats decreasing gradually. The low-quality habitat areas were distributed in cities and towns, which gradually expand. The high-value areas of the Corps were distributed on the edge of the basin, and the patches tend to be fragmented. The high-value areas of the Non-corps Region were located in the mountains, with little change. The habitat quality level of Corps was higher than that of the Non-corps Region, with fast decline. Higher or lower habitat quality grades were easily transferred to medium ones. Compared with the Non-corps region, the transfer rate of the Corps was higher and the habitat damage was more severe. Economic development resulted in rapid expansion of low-level regions, which seriously threatened the quality of regional habitats. The prediction of land use showed that the area of cultivated and construction land in the Crops and the Non-corps Region would gradually increase in 2018-2035, and forest land and grassland would gradually decrease, which may lead to a gradual decline in habitat quality.
Assuntos
Conservação dos Recursos Naturais , Ecossistema , Biodiversidade , China , Cidades , FlorestasRESUMO
In recent years, haze pollution in China is becoming increasingly serious, especially in the Beijing-Tianjin-Hebei region. In order to identify the temporal and spatial distributional characteristics of PM2.5 aerosol mass concentration in the region, this study selected the inland plain of the Beijing-Tianjin-Hebei region as the research area, and used MODIS AOD as the main predictor in a mixed effects model to establish the daily relationship of AOD-PM2.5 in the study area, from 2013 to 2014. The model was validated by a ten-fold cross validation method. The results showed that the correlation between AOD-PM2.5 can be improved by daily calibration of the mixed effects model (R2=0.78); the cross-validated R2 was 0.70, and RMSE and RPE were 20.80 µg·m-3 and 28.76%, respectively. Considering the importance of unbiased PM2.5 predictions, the correction factors calculated from the surface PM2.5 measurements were applied to correct the biases in the predicted annual average PM2.5 concentrations introduced by non-stochastic missing AOD measurements. The results showed that the annual average concentration of PM2.5 in the study area was higher than 75 µg·m-3, and the spatial distribution of PM2.5 concentration was higher in the southern and western regions, and lower in the northern and eastern regions. These results suggest that the mixed effects model can be used to monitor ground PM2.5, and also provide a scientific basis for the control of atmospheric particulate pollution in the region.