Water Yield And Carbon Storage Ecosystem Services Evaluation Of Xijiang River Basin In Guangxi Based On InVEST Model

The Xijiang River basin,with the lower reaches located at the Pearl River delta,is one of the most important impetus of Chinese economic development with high innovation capability,comprehensive strength and dense population.The ecological environment of Xijiang River basin has important implications for not onlythe regional economy and social development,but also the ecological security maintenance and constructions of the Pearl River Delta.The development plan of Pearl River-Xijiang River(2014)proposed to establish the ecological civilization pilot projects,to explore the ecological environment management and mechanism for regional ecological compensation.The rejuvenation program of the old revolutionary base areas along the Zuo River and You River clearly put forward the requirement of establishing ecological compensation system,and carrying out the ecosysterm service evaluation of Xijiang River basin.Therefore,taken Xijiang River basin as a case study,we assessed the spatial patterns and evolvement features of water yielding capacity and carbon storage services in Xijiang River quantitatively by applying the In VEST model.The results could provide the basis both for the establishment of ecological compensation system and the scientific effective management of ecological system,and it has great significance to protect the ecological security of research area and Pearl River Delta.The In Vest model was applied to evaluate the ecosystem service function in this paper.The author settles a full set of method about data collection,model calculation and result analysis.On the base of data processing and parameter localization,the author applies several data,such as meteorological station data,soil data,altitude data,remote-sensing image data and soil carbon density,to make simulation assessment for the two ecological functions,water yield and carbon storage in 2000,2005,2010 and 2015 respectively.Besides,this paper utilizes the average values of the assessment results about water yield and carbon storage in these years,to class the important area,and to make comprehensive regionalization about water yield and carbon storage by use overlay analysis,and then to confirm the protected section where needs to be developed prior to other areas.This article enriches the service function research of Xijiang River basin ecological system,in the meantime,it provides reference for relevant studies.The following conclusions:(1)In 2000,2005,2010 and 2015,the average water yield is 857.82 mm.The water production is higher in the northeast,southwest of Guangxi Xijiang River Basin.The water production is lower in the west and northwest of it.In 2000,2005,2010 and 2015,the total water yield of the Xijiang River Basin in Guangxi appeared an increasing trend,and the 99.9252% area showed an increasing trend,the 0.0748% area showed a downward trend.In 2000,2005,2010 and 2015,the average water yield of the study area was 692.49 mm,702.76 mm,859.10 mm and 1163.17 mm.The water yield was extremely significant positively correlated(P<0.05)with precipitation but negatively correlated with annual average temperature.The year of 2000,2005,2010 and 2015,the increased water yield in the study area is mainly caused by the increase of precipitation.(2)In 2000、2005、2010 and 2015,the space change is small in Guangxi Xijiang River carbon storage.The total carbon storage is between 0-244.286Mg/ha,the year of 2005,2010 and 2015,the average carbon storage in the study area was 186.99 Mg/ha.the average total carbon storage is 3794(10~6 Mg)of these years.The average carbon storage is 187.11 Mg/ha in 2000.The total carbon storage is 3796.45(10~6 Mg);The average carbon storage is 187 Mg/ha,the total carbon storage is 3794.06(10~6 Mg);The average carbon storage is 186.98 Mg/ha,the total carbon storage is 3793.83(10~6 Mg);The average carbon storage is 186.87 Mg/ha,the total carbon storage is 3791.52(10~6 Mg);With the increase of altitude,the vegetation carbon density gradually showed an increasing trend.The total carbon density increased first and then decreased.With the increase of slope,the plant carbon density and the total carbon density gradually increased,the maximum reached 25 degrees-30 degrees,and then gradually decreased.(3)In 2000-2015,the carbon storage of the Xijiang River Basin in Guangxi showed a downward trend.The total carbon density of ecosystem is decreased,from 187.11Mg/ha in 2000 to 186.87 Mg/ha in 2015.The total carbon storage of ecosystem decreased from 3796.5(106Mg)in 2000 to(106Mg)in 2015,decreased by 0.13%,and the carbon storage of Guangxi Xijiang River Basin decreased little.The reason is that the rapid development of social economy,the accelerated development of urbanization during the period of 2000-2015 in Guangxi.From 2000 to 2015,the weak carbon sequestration capacity building land area has increased,the cumulative is 83648.34 hectares.The carbon sequestration ability of the forest area has decreased 31948.9 hectares.It caused the ecosystem carbon storage in Guangxi Xijiang River Basin.(4)According to the comprehensive regionalization of the water yield function and the carbon storage function of the Xijiang River,we divided it into the carbon sequestration advantage area,the water enrichment area,the compound carbon sequestration advantage area and the water enrichment area.The area of water enrichment in Xijiang River Basin of Guangxi is 53.3 thousand km2,which is accounted 26.24% in the total area.It mainly distributed in the study area in the northeast(Longsheng,Sanjiang,Xingan,Lingchuan,Guilin resources,city area,Gongcheng,Yangshuo,northern of Yongfu,Eastern of Rongshui Rong’an),southwest(Shangsi),Mengshan,and less distribution area of Hezhou and Fuchuan.The area of carbon sequestration advantage in Xijiang River Basin of Guangxi province is 43 thousand km2,it accounts 21.15% of the total area.the distribution is dispersed,it mainly distributed in the East(Cangwu,Hezhou,Zhaoping,Mengshan,Jinxiu),northwest(Douan,Dahua,Western of Huanjiang)and southwest of the study area.The area of complex carbon sequestration advantage and water enrichment in Xijiang River Basin of Guangxi province is 9.4 thousand km2,which accounts 4.62% in the total area.The distribution is dispersed.It mainly distributes in Shangsi,Mengshan and Guilin.(5)This paper adopted the data from the Xijiang River in Guangxi hydropower station,National Forest Park and Nature protection area to verify the delineation of the water enriched region,rationality of solid advantage area and put forward the method of testing the indirect inspection of ecosystem services results.The results show that the water enriched region in the paper is basically correct,which fits the actual situation of Guangxi Xijiang River Basin.