The Methods And Results Comparative Analysis Of Urban Ecological System Service Value In Lanzhou City

Ecosystem plays an important role in the life and development of human being. Itprovides a variety of human resources needed in production and living and absorbsthe wastes generated by human activities， ecosystem services are of great value， toevaluate the ecosystem services is meaning. In order to explore the evaluation methodof the urban ecosystem service value， this paper combines the evaluations of thevalue of the ecological system and the human subjective value， and the exploratorycorrections have been conducted based on the willingness to pay and the scarcity ofecosystem services. It choosed Lanzhou city as study area， the service values of theecosystem of the Lanzhou city from2005to2010were calculated through using theoriginal method and the modified method respectively， the dynamic changes andcauses of the values of the ecosystem services were comparatively analyzed based onthe said two methods. The main results were as follows：(1)During the period of2005-2010， the land use structure of Lanzhou citychanged obviously， the area of farmland， orchard， grassland， water and unusedland decreased years by years， the range： farmland>unused land>grassland>orchard>water.Water reduced fastest at a annual rate of0.58%. The area of buildingland (land for settlements and mining)，transport land and woodland increased，landfor settlements and mining increased most， the change rate was up to1.06%，followed by forestry and transport.(2)The value assessment results of regional ecosystem service had largedifferences， with the two different methods before and after correction， but the totalecosystem service value of Lanzhou city in2005-2010rose， the change trend ofsingle ecosystem value existed obvious differences， the change trends of farmland，water and unused land ecosystem kept consistent， both were reduced trend. Theservice value of woodland ecosystem also kept consistent change trends， but thesecond result was larger than the first one. The change trends of orchard and grasslandecosystem kept inconsistent， the value in6years decreased based on Costanzaassessment method， and it increased based on the revised method.(3)The revised assessment method is more dynamic which is based on thewillingness to pay and the scarcity of ecosystem services. Ecosystem service value changes with subjective preferences. The rise and fall of the total ecosystem servicevalues can not reflect whether the regional land use is reasonable or not， and thedevelopment direction of the ecological system. The effect factors of value arevarious， including the subjective factors and objective factors， the objective factorsinclude changes in land area， the subjective factors include willingness to pay，resource supply， demand change and so on.(4)The ecosystem services value of Lanzhou city within6years rose from8.834billion yuan to10.459billion yuan， increased1.625billion yuan， the totalincreasing value was due to the grassland ecosystem and woodland ecosystems.Because the willingness to pay in six years changed a little， the effect to the valuewas not obvious. The increment of ecosystem scarcity was the main reason that leadsto the rise of the total service value of the ecosystem of Lanzhou city， whichreflected the unreasonable land utilization and the degenerative change in theecological system of Lanzhou city. The farmland and grassland faced great threat.(5)Based on above study， this paper proposed suggestions for ecologicalprotection for Lanzhou city， that is： Attaching great importance to the protection ofcultivated land and grassland resources in the city， It was the precondition of theregional sustainable development. Woodland should be enlarged continuously.Controlling the expansion of land use in the urbanization process， optimizing theland utilization structure， ensuring the quantity of the reserve land resources and soon are the premises of sustainable development in Lanzhou city.