Evaluation Of The Forest Ecosystem Service Values And Landscape Ecological Risk Assessment In Qinling

Forest ecosystem provides mankind with both direct and indirect products and services which are called ecosystem services.Forest ecosystem services play an important role in water conservation,environment purification,biological species protection and conservation of the living environment.However,provided as social public products,the value of forest ecological service was not well recognized by human. Predatory exploitation has resulted in forest lost and environment deterioration,which in turn affects economic and social development.As the most important geography barrier and ecology corridor in China,there is a strong need to evaluate forest ecosystem services in Qinling.“Forest ecosystem services assessment standards”(LY/T1721-2008)issued by the State Forestry Administration has been a common method in ecosystem services evaluating.However,with much parameters,complicated calculation and lack of assessing standard,this method still have some limitations.With a special focus on spatial heterogeneity and the correlation between landscape patterns and ecological process deriving from landscape ecology,landscape ecological risk assessment(LERA) has currently been regarded as a hot topic in landscape ecology.LERA is used to describe and evaluate the possibility and degree of damage might be taken to the landscape structure and function by human activities and natural disasters on ecological system,which theory and methods has been used in resource management and environmental protection.But there is few research take the forest land as assessing target.The assessing model is the key problem of LERA.Landscape disturbance based on landscape metrics and vulnerability counted by weight setting of land-use type,was put forward to assess landscape ecological risk index.However,with much uncertainty of weight setting and simplification of assessing index,the assessing results is less convincing.In this study,the Landsat Thematic MapperTM images that cover the Qinling region were acquired for years of 1984,2000,2005 and 2014,and visually interpreted for landscape types.Based on the improvement of the evaluation method for per unit ecosystem service value,revised the average ecosystem service equivalent value into regions’ with the per unit grain productivity and biomass of the study area,and then grid revision was further applied based on the vegetation index.By using GIS and RS techniques,eleven ecosystem services provided by Qinling forest ecosystem was evaluated. The total ecosystem services value was assessed by Coefficient of Sensitive(CS).The landscape disturbance index was constructed based on the calculation of the landscape metrics by the moving window approach,and the remote sensing based ecological index(greenness,wetness,slope,aspect,and land use)was developed specially for monitoring and assessing landscape vulnerability status.Instead of a weighted additon of the five indicators,the principal component analysis(PCA) was utilized to compress the five indicators into one.Using ArcGIS and geostatistics,the landscape ecological risk map was obtained through spatial sampling and disjunctive Kriging interpolation.The ecological risk of studying area was classified into five levels(extremely low ecological risk,low ecological risk,moderate ecological risk,high ecological risk and extremely high ecological risk)by relative index method.The results are as follows:(1)Forest land was the dominated landscape type from 1984 to 2014,but the area increased slightly,and the fragmentation of forest land increased.Farmland take the second place,and the area has increased significantly from 1984 to 2000,decreased obviously from 2005 to 2014,At the same time,the area of built-up land increased year by year,and the fragmentation decreased and dominance increased yearly.(2)The total ecosystem services value of Qinling increased 167537.7 thousand billion,which was mainly supported by the forest land with a percentage of 93.76%.Among the ecological service,the biggest contribution of ecosystem service was adjustment service(62.67%-65.76%),especially the climate adjustment.(3)There was a signification spatial heterogeneity in the ecosystem service value and landscape types.The longer distance from the boundary of the study area,the bigger ecosystem value was.(4)The CS implied that the estimated of total ecosystem services value in the study area was inelastic and the results shown in this paper were believable.Since the forest ecosystem of Qinling is highly valuable,more effort should be made to protect ecosystem.(5)As a whole,the landscape ecological risk had been rising in the past 30 years.The area of extremely low risk and extremely high risk both decreased obviously and mainly distributed in farmland,but the area of moderate and high risk was expanding significantly and mainly located in the hilly and mountainous areas.To obtain the sustainable development of regional land resources,the usage of forest and water have to be optimized,and some measures for the high ecological risk management must be put forward.