Study On The Potential Ecological Carrying Capacity

As a quantitative basis for sustainable development,ecological carrying capacity(ECC)aim at protection of the environment,the bearing capacity is an important criterion for sustainable development.There is of prime guiding significance in sustainable development of performance of potential ecological carrying capacity(PECC)do to the ecosystem,the results lay a favourable basis for perfection and development of sustainable theory and provide new clues and directions for quantitative study on ECC,to explore the effectual measures,relieve pressure and enhance capacity.Based on the EF-NPP,this paper calculates the PECC of 31provinces in China(excluding Hong Kong,Macao and Taiwan)by simulating"potential NDVI(PNDVI)"and potential NPP(PNPP)and improving the ecological footprint model.The spatial patterns of“PNDVI”,PNPP and PECC are analysed,and the impact of human activities on ecosystems is explored,potential carrying space and ecological pressure were revealed.The following conclusions are drawn through the study:(1)The spatial distribution of"PNDVI"and its comparison with 2015 NDVI:the lower occurred at desert,Gobi and other arid areas,and the higher are mostly distributed in low and middle plain.In particular,the spatial pattern can be divided into relative higher and lower parts,in demarcation line with of 400mm rainfall.Controlled by the fine climate,the vegetation restoration in the low,middle mountain plains and the areas along the northwest high mountains are probably at higher chance,but natural deserts are not.The irrecoverable areas(difference rate<30.00%)are highly consistent with the irrigated land on the edge of desert and hard-to-use land.The impregnable areas(-9.99%<difference rate<10.00%)are more distributed in the southeast,less in the northeast and irregular patches in the west.The define restorable areas(difference rate>30%)occurred at the areas with serious ecological damage(western margin o f Inner Mongolia Plateau,Kunlun Mountains,Tianshan Mountains,the Junggar Basin).(2)The distribution of PNPP and its comparison with 2015 NPP:The PNPP,as a whole,is a pattern of eastern coastal areas and the south are higher than the northwest.The higher values are distributed in areas with abundant precipitation,high temperature and slightly low evapotranspiration,and,the Gobi and sandy land show the lower value,but a small amount of PNPP can still be developed in some regions.Existing circumstances of 2015 NPP can be divided into three parts by difference rates of 2015 NPP based on PNPP:High potential region in the west,low potential region in the north and non-potential region in the south.(3)Spatial distribution of ECC:The spatial difference of ECC is closely related to the local environment,land resources and population.Per capita PECC presents the northwest is higher than the southeast with huge spatial differences,among them,the highest(20.771 hm~2/person in Tibet)is 278.09 times that of the lowest(0.047hm~2/person in Shanghai).Per capita PECC of the 7 provinces(Heilongjiang,Inner Mongolia,Xinjiang,Qinghai,Tibet,Yunnan and Gansu)were all above 1 hm~2/person,and they are distributed in the shape of“Y”around the northeast-southwest-northwest of China.Beijing,Tianjin and Shanghai are the lowest with below 0.1 hm~2/person.The comparison of PECC and 2015 ECC:to the conversion coefficient,there is a big gap between the potential equilibrium coefficients and 2015 equilibrium coefficients in different biological resource lands.Excepting for waters and woodlands,the types of potential land biological productivity are higher than 2015.Furthermore,the better the ecological environment,the higher the yield coefficients in different periods,and the greater the difference between different types.The yield coefficients of low-productivity land are the highest,and the differences among provinces and regions are the greatest.The water and grassland in most provinces show a trend that the yield coefficients in 2015 is higher than the potential,but the cultivated land and woodland are different in various periods.Viewed from the feedback of human activities on ecology,it is found that the human activity has great interfere to the ECC of 5 provinces(Tianjin,Shanxi,Qinghai,Xinjiang and Tibet),which means the negative effects of human and ecological restoration pressure are most severe.The PECC of Jiangsu,Hubei,Jiangxi and Guangdong are comparable to that of 2015,which proves that human disturbance and destruction or positive promotion are inapparent.Fortunately,there are 9 provinces(Guangxi,Zhejiang,Fujian,Sichuan,Yunnan,Chongqing,Guizhou,Hunan and Hainan)with the lowest excavation space and ecological restoration pressure,so we can guess that human disturbance and damage to the natural environment may be negligible,and even human was played a positive role in promoting to a certain extent.