Evaluation Indices of Ecosystem Service of Urban Green Space in Chang―Zhu―Tan Ur

Abstract. The Evaluation Indices of ecosystem service of urban green space is the evaluating standard of ecological environment quality ， and also the important datum for construct the low-carbon and ecologic city of Chang-Zhu-Tan Urban Agglomeration. Through confirmed the evaluation factors of Ecosystem service on the basis of further study about the per capita area and the specific ecosystem services of urban green space， and then according to the scientific principle， using Delphi and SSMII to calculate the results of weight value， present situation value and target value and set up the evaluation index system of urban ecosystem service of urban green space of Chang-Zhu-Tan Urban Agglomeration. Thus it can give reference to develop the Two-oriented Society of Chang-Zhu-Tan Urban Agglomeration.

Keywords： evaluation index， ecosystem service， urban green space， Chang-Zhu-Tan Urban Agglomeration.

Knowing as the “lung of the city”， a combination of urban green space which is consist of Arbor trees， shrub， flower， grass is recognized as the Green carrier of the urban landscape and the sign of modern city civilization and social development（Xin Y，2009）. As the balance lever of city environment and climate adjustment concerning improving the air quality.，it can help to reduce the affect of urban heat island effect， drop dawn the temperature and increas the humidification， to make the nitrogen be fixation and release the oxygen etc. With the accelerating development of Two-oriented Society of Chang-Zhu-Tan Urban Agglomeration（Wu J-Y，2008）， the environmental problems like dust pollution， harmful gas pollution， greenhouse effect， sewage discharge are given increasingly close attention. Meanwhile， the theme of two-oriented society construction is building environmental-friendly and energy-saving city， and more and wide requires to ecology service of urban green space. Therefore， it’s very necessary to study the evaluation indices of ecosystem service of urban green space.

1. Ecosystem service of green space and the evaluation indices of ecosystem service

The name “green space” is taken from a document of middle-late 1800’s， its English name is “open space”， that is， wide and opening space which respectively means “the space open to the air” and “the space open to the public”. And its Chinese definition is about all kinds of ecosystem， wild area and public green land to emphasize the ecology and human activity of space. Besides， the ecosystem of green space is mainly constructed with point and line to plane system. The evaluation indices of ecosystem service is the judging standard for ecological environment quality and the important datum to construct the low-carbon and ecologic city. To set up a series of scientific evaluation indices of a developing city is not only very important to improve the urban ecologic environment but the inhabitant’s live quality.

1.1. Ecosystem service of green space

Ecosystem service of green space is about the support and integration process of human survival， development and environment quality that green ecosystem and its constituent species provided or brought about， including regulating climate， sterilization， absorption in toxic and harmful gas， detaining dust， maintenance of carbon oxygen balance， soil and water conservation and cleaning the water of city.

1.2. Evaluation indices of ecosystem service

According to the different ecology service ecosystem service of green space， the evaluation indices of ecosystem service formed a series of index system to measure the quality of urban ecosystem through scientific calculation and derivation. It is the vital and core basis for urban green space planning as well as the assessment of building ecology and low-carbon cities. That is to say， if one city need assessing the construction of green space and quality of planning accurately， it will largely depend on the strength and width amplitude of urban ecosystem. What’s more， the evaluation indices of ecology service would be the foundation.

2. The general situation of Chang-Zhu-Tan Urban Agglomeration

Chang-Zhu-Tan Urban Agglomeration is located in the northeast of Hunan， it consists of three main city Changsha，Zhuzhou and Xiangtan which is distributed in shape of delta， the three cities just 40 km away from each other .The area belongs to humid subtropical monsoon climate and the geographic location is between26°18′19″～ 28°41′22″ degrees north latitude and between 111°58′38″～ 114°13′20″ degrees east longitude. Its average temperature of a year is 16.5 ℃， the absolute maximum temperature of 39 7 ℃ while the absolute minimum temperature is -13.4℃. The average annual rainfall reaches 1350mm and the annual average relative humidity is 81%， its sunshine hours is more than 1700h and the Frost-free period is about 268d. The average greening rate is 45.67 and the average greening rate in downtown is up to 11%， the green plants mainly in the humid subtropical climate evergreen broad-leaved and coniferous， the ecosystem almost coming into shape.

3. Green space status quo of Chang-Zhu-Tan Urban Agglomeration

The method which using the per capita public green area， rate of urban green space， urban green coverage， the average ratio of green space and other indicators to evaluate the Chang-Zhu-Tan Urban Agglomeration green construction is obviously insufficient in quantity.According to statistics， the green coverage in Chang-Zhu-Tan Urban Agglomeration reached to 43%， but the urban green coverage is less than 20% and the per capita public green area decreased 1 compared to the standard data. This does not fully take the floating population and urban population growth rate into account construction. Built-up area ratio of green space is less 5.6% than the standard 30%， the urban green coverage rate is less 8.2% than the standard 35% and the production of green area is less 1.47% than the standard total area 2%. There are many problems such as the public green space distribution is uneven， weak capacity for environmental protection and there is a big gap between the current situation and ecological energy requirements of the development of urban green space of Two-oriented Society.

4. Construction of indexes of ecological functions of Chang-Zhu-Tan Urban Agglomeration

4.1. Research Methods

On the basis of the Per capita area and the further analysis and explore action， using Delphi and SSMII to get the result of Weight value， present situation value and target value， and build up the evaluation index system of urban ecosystem service of green space.

4.2. Determine the principle（LIU Y-G ， ZHANG H-Z，2003） of evaluation indices

4.2.1 Scientific Principles

Evaluation indexes must objectively reflect the functional characteristics of Chang-Zhu-Tan Urban Agglomeration green ecological environment and the development with clear calculation methods and standards.

4.2.2 Systematic Principle

Evaluation indexes requires a comprehensive， systematically reflect function of Chang-Zhu-Tan Urban Agglomeration urban forest ecology and environment in various aspects， to fully reflect the relationship between the ecological， economic， social system structure， function and efficiency（JIN You-hua，）. What’s more， those indicators must complement each other， fully embodies the integration and coordination of urban ecosystem functions.

4.2.3 Maneuverability Principle

Determined indexes must be testability and easily to be measured.

4.2.4 Relative independence Principle

Every index should be independent of each other， there is no mutually inclusive and cross-relations， and similar with others.

4.2.5 Pertinence Principle

Each index should be choose based on the importance pertinently. Make sure the indicators are concise， critical and useful.

4.3. The construction of evaluation factors of ecological services

Using Delphi to build the factors according to the existing characteristics of green area and the current ecological functions.

Inviting 5 experts to survey the effect of all factors related literature， the weight value， present situation value and target value， confirm the study factors of the urban green space according to the four principle and give the analysis on the fixed amount. If above 1/3 experts think the factor is less important ，it will be sifted out， and towards factors with small weight value， it will be merged into the similar item .Thus after 5 rounds calculation， we’ve got the most effective 14 factors of the urban green space（fig1）.

Fig 1 The evluation factors of the green space of Chang-Zhu-Tan Urban Agglomeration

4.4. Weight， present situation and target values of urban ecosystem service of green space of Chang-Zhu-Tan Urban Agglomeration

4.5. Target， evaluation and analysis of the urban green space ecological service in Chang-Zhu-Tan Urban Agglomeration

The evaluation of the urban green space ecological function is part of the evaluation index system of forest benefits as complex soft system. （WU Ji-you ，2007）Thus， it is not objective to apply any single evaluation software according to the construction and development requirements of the Two-oriented Society. Accordingly， it’s necessary to introduce SSMII by scientifically integrating the four methods SSM， SIM， Qualitative Research and SE， which are usually adopted in the evaluation of forest benefits. Firstly， on the basis of weight value and present situation value of the existing green space ecological functions in Chang-Zhu-Tan Urban Agglomeration， fifty types of urban green landscape vegetation can be selected containing arbor，shrub， grass scientifically collocated according to the weight of 4：3：3.Then， the experiment of three indicators， six functions and fourteen factors will be done according to the natural characteristics of the vegetation above-mentioned. Lastly.

5. Conclusion

The selection of the evaluation factors of green space ecological function in Chang-Zhu-Tan Urban Agglomeration is based on the amount of existing urban green space there as the base. Under the construction and development outline of Chang-Zhu-Tan Urban Agglomeration， the evaluation weight value， index value and target value of urban green space ecological functions in Two-oriented Society can be determined by adopting SSMII and Delphi and accessing related literature. Furthermore， the index value can be determined by the calculation method of urban forest evaluation index system in order to provide parameters and indices for the planning and construction of urban ecological functions in future Two-oriented Society.

6. Acknowledgements

This work supported by Hunan social science funds of 2010（NO.2010YBB186），and Hunan educational science funds of 2010（NO.10C0203）.

Reference

[1] Xin-Yi， Urban ecological problem and compensation in the urbanization process〔J〕，City Problem，2009，129 （8），65-70.

[2] Wu Ji-You， Ecological Function s of Urban Forest Plants-A Case Study of the Changsha-Zhuzhou-Xiangtan City Group〔J〕， Journal of Central South University of Forestry & Technology，2008，4 （24），101-105