ABSTRACT
Regional ecological quality is largely affected by human activities, which restricts the sustainable development of regional economy. Taking the China-Laos railway economic belt as an example, we investigated the effects of human activities on ecological quality. The remote sensing images of 1999, 2009 and 2019 were selected to calculate remote sensing ecological index (RSEI). Spatial autocorrelation statistics and local G statistics were used to explore the spatial-temporal variations of ecological quality in the study area. Combined with the population density in the same period, a geographically weighted regression model was constructed to quantitatively analyze the ecological effects of different human activity intensities in the study area. The results showed that the ecological quality in the study area presented a trend of increasing firstly and then decreasing later from 1999 to 2019, and that the mean value of RSEI varied from 0.645 (1999) to 0.738 (2009) and then decreasing to 0.721 in 2019. Specially, the ecological quality fluctuated more apparently in the midlands. The results of fitting population density and ecological quality based on geographical weighted regression model (GWR) were significantly better than that of least square method. R2 of different periods based on GWR was higher than 0.7 and the fitting effect was stable. The fitting degree of GWR in 2019 was the best (R2 was 0.785), and R2 in 1999 and 2009 were 0.726 and 0.754, respectively. The ecological quality along the China-Laos railway south area (such as Vientiane) was more sensitive to human activities, with most of these places belonged to moderately sensitive regions. For the highly, moderately and lowly ecological sensitive regions, every 10, 100, 1000-fold increases in population density would lead to a decrease of 0.2, 0.4 and 0.6 to the mean value of RSEI in turn. The development of economic belt would increase population density. During the planning and layout of economic belt, human activities should be controlled to avoid the deterioration of ecological quality in the potential and current sensitive regions.
Subject(s)
Ecosystem , Environmental Monitoring , China , Human Activities , Humans , LaosABSTRACT
The Wuyi Mountain National Nature Reserve (WYS), established in 1979, is the largest and most intact subtropical forest ecosystem in southeastern China. No study has assessed the vegetation coverage change along with its ecological effect after the protection of the reserve for almost 40 years. In this study, the NDVI data of Landsat Image was corrected using the NDVI data of MODIS, the fractional vegetation cover (FVC) and the remote sensing based ecological index (RSEI) were calculated to assess the change of FVC and ecological quality in WYS with five Landsat images representing a period from 1979 to 2017. The results showed that after protection for nearly 40 years the FVC of the reserve had been significantly increased from 73.6% in 1979 to 89.5% in 2017, which consequently improved ecological quality from 0.801 in 1988 to 0.823 in 2017. In 2017, the area with the good and excellent ecological quality grades accounted for 98.7% of the total. Spatially, the ecologically-improved areas mainly distributed in the northeast core area and the center of the southwest core area. The ecologically-declined areas mostly occurred along roadsides and peaks. Vertically, the highest FVC and ecological quality areas distributed in the elevations between 1300-1900 m. In general, the improvement of FVC and ecological quality in the Wuyi Mountain National Nature Reserve was due largely to the effective policies and the successful protection by local government and people, except for some special year that may be affected mainly by climate conditions.
Subject(s)
Ecosystem , Remote Sensing Technology , China , Climate , Environmental MonitoringABSTRACT
Using Landsat 5/TM and Landsat 8/OLI images in 2000 and 2017, based on remote sensing ecological index (RSEI) model, combined with meteorological observation data and socio-economic data in Nanjing from 2000 to 2017, we analyzed and evaluated the ecological environment changes and the characteristic ecological areas in Nanjing. The results showed that the average RSEI of Nanjing decreased from 0.626 to 0.618 during 2000-2017. The RSEI values could be divided into five grades: bad, poor, fair, good and excellent. The proportion of area above good grade decreased from 61.0% to 57.1%, while that below poor grade increased slightly. Compared with 2000, the proportion of areas with improved ecological environment quality was 34.5%, 34.7% area had deteriorated, and 30.8% area remained unchanged in 2017. Among them, the ecological quality of main urban area had significantly improved, and the area with improved ecological quality exceeded that of deterioration. The ecological quality of new urban area and suburbs had deteriorated. The area with poor ecological environment exceeded the area of improvement. Among the three ecological protection areas, the ecological quality of Zijin Mountain was significantly better than that of Laoshan Mountain and Jiangxinzhou. The urbanization rate was negatively correlated with RSEI, with a correlation coefficient of -0.91. The urbanization process would have negative impacts on the ecological environment in general. However, strict protection and management measures could maintain the good ecological environment even improve it.
Subject(s)
Ecosystem , Urbanization , China , Environmental Monitoring , Remote Sensing TechnologyABSTRACT
The urban spatial expansion has led to the considerable substitution of natural vegetation-dominated land surfaces by impervious surfaces, especially in large cities, with great impacts on urban ecological quality. Two most heavily populated cities, Shanghai of China and New York of USA, were chosen as the study cases. Based on Landsat images obtained in 1989, 2002, 2015 in Shanghai and in 1991, 2001, 2015 in New York, normalized difference impervious surface index (NDISI) was used to extract impervious surface (IS) information. The remote sensing based ecolo-gical index (RSEI) was then applied to evaluate the changes of urban ecological quality caused by the increased impervious surface. Furthermore, landscape pattern indices were used to analyze the differences of spatial structure of impervious surface between Shanghai and New York and their influences on urban ecological quality. The results showed a significant difference in urban expansion rate and pattern between Shanghai and New York from the early 1990s to 2015. The IS expansion area in Shanghai was 17.4 times as much as that in New York. The annual IS increase rate of Shanghai was 62.2 times as much as that of New York. Shanghai had experienced an expansion from urban center to the surrounding countryside in a concentric ring pattern, whereas New York showed no much expansion but had IS increase mainly within the inner city through space filling pattern. These differences in IS change rate and spatial distribution pattern had resulted in the difference in urban ecological quality of the two cities. The mean RSEI in Shanghai dropped from 0.717 in 1989 to 0.453 in 2015, with a decrease of 36.8%. In contrast, the RSEI of New York had a decline of 6.9% from 0.552 in 1991 to 0.514 in 2015. The poor ecological condition urban area tended to have large IS patches that were well connected and aggregated.
Subject(s)
Ecology , Environmental Monitoring , China , Cities , New YorkABSTRACT
Since China's reform and opening-up, the rapid growth of China's economy has greatly accelerated the expansion of built-up land, which has affected regional ecological environment to a great extent. Taking Jinjiang County of Fujian Province, one of the fastest economic-developing counties in the coastal areas of southeastern China, as a case study area, this paper focused on analyzing the rapid built-up land expansion process of the county and its impact on county's ecological quality using remote sensing techniques. Based on two Landsat images of 1996 and 2015 of Jinjiang, the built-up land of the county was extracted using the index-based built-up index (IBI) and its change was analyzed. In the meantime, the ecological status of Jinjiang was evaluated with a recently-proposed remote sensing based ecological index (RSEI) and the relationship between the built-up land dynamics and the ecological status changes of the county was quantitatively examined. The results showed that during the period from 1996 to 2015, the area of built-up land of Jinjiang had a net increase of 68.54 km2, a growth of 45%, and the expansion intensity was 0.55. The expansion of the built-up lands has caused overall degradation of the county's ecological quality. The mean value of RSEI of the county had declined from 0.532 in 1996 to 0.460 in 2015, a drop of13.5%. The area proportion of high ecological-quality grades also significantly fell from 39% in 1996 to 21% in 2015. The built-up land expansion intensity was negatively correlated with the ecological quality change.
Subject(s)
Conservation of Natural Resources , Ecosystem , China , EcologyABSTRACT
Based on the data of remote sensing images from Landsat in 1995 and 2015, this paper used the principal component analysis (PCA) method to determine the weights of four ecological indexes (greenness, dryness, wetness and heat), and then selected a evaluation model of remote sensing based ecological index (RSEI) to monitor and analyze the ecological environment quality of Weinan City from 1995 to 2015. The results showed that the mean values of RSEI in Weinan City increased from 0.489 to 0.556 during 1995-2015, which indicated the ecological environment qua-lity had been improved. The improved area of ecological quality was mainly distributed in the central area of Weinan City and its proportion was 49.6%. While the proportion of ecological environment degradation was 15.4%, and such areas were mainly distributed in some mine areas of Hancheng City and the southern Weinan (Weinan Section in North Qinling Mountains). The quality of ecolo-gical environment was greatly influenced by the urban planning and construction in the study area. Generally, the ecological condition of Weinan City had been improved, which benefited from the attention and investment of government.