城市河流生态系统服务的CVM估值及其偏差分析

Study on the ecosystem services value of urban river using contingent valuation method and bias analysis of the results

城市河流具有特殊的景观生态学意义,并能提供重要的生态系统服务,其价值逐渐受到社会各界的广泛关注。以全国河道治理的样板工程——上海浦东张家浜综合整治为例,采用条件价值评估法(CVM),共回收507份有效二分式CVM调查问卷,研究了城市河流生态系统服务改善的支付意愿及其总经济价值,同时也重点对二分式CVM研究中的相关问题如问卷设计、偏差分析和CVM可靠性与有效性的计量经济学验证过程等进行了适量探讨。二分式CVM研究表明(1)张家浜生态系统服务改善的平均支付意愿为1289.08元/(a·户),张家浜作为一条城市河流在未来3a内每年为浦东新区提供的生态系统服务价值为RMB6.34亿元。这与国际上的研究结论在数量级上是接近的,但与国内研究结果相比明显较高,应与研究区域的经济水平差异有关。(2)二分式CVM问卷投标数额的设计较好地界定了支付意愿的范围和分布形态,支付意愿平均值具有较高的统计效率,问卷的设计调查过程较好地控制了CVM研究中一些常见的偏差。(3)收入、学历、捐款经历、环境态度等社会经济信息变量对支付意愿具有显著的影响水平,符合经济学理论,CVM的可靠性得到较好的验证。(4)58.10%的非张家浜沿线居民对张家浜生态系统服务的改善和保护具有正支付意愿,城市河流的非使用价值(存在价值)得到了良好体现,显示了条件价值评估法在估算生态系统服务非使用价值的有效性。

Rivers in urban area are characterized themselves by special landscape ecological function, and can provide with important ecosystem services. For this reason, this paper discusses mainly the nature and value of the services, and in order to probe into this, a case study on the comprehensive management project of Zhangjiabang Creek, Shanghai using Contingent valuation method (CVM) is conducted, where 640 Dichotomous Choice questionnaires have been sent out with 507 fed back. In the case study, the values of Willingness to Pay (WTP) and the total economic value of the ecosystem services of the urban river Zhangjiabang Creek have been surveyed. Meanwhile, relative problems of the Contingent valuation method such as design and survey techniques of the questionnaires, bias analysis, reliability and validity test of the results have also been approached. It shows that: (1)The mean value of WTP to the ecosystem services of the urban river Zhangjiabang Creek is RMB $107.42 per household per month (RMB $1289.08 per household annually), and the total economic value of the ecosystem services is RMB $0.634 billion every year in the forthcoming 3 years. Due to disparities of the economic level, comparatively, the results are close to the findings of overseas cases in the order of magnitude while obviously higher than that of the domestic. (2)The bid vector designed in the Dichotomous Choice CVM study has well defined the range and distribution of the respondents' WTP, which makes the statistical efficiency of the mean value of the WTP relatively higher than expected. While some biases, such as starting-point, hypothetical, strategic, payment vehicle, information and yea-saying bias are basically under control in the design and survey procedure of this study. (3)Socio-economic variables of the respondents such as income, education degree, donation experience and environmental attitude significantly influence the values of the WTP of the respondents and this is consistent with the economic theory and verifies the reliability of the CVM. However, as far as we can see in this paper, ages of the respondents have no clear relation with their WTP. (4)About 58.10 per cent of the respondents who do not live near Zhangjiabang Creek have positive WTP to the ecosystem services of the urban river Zhangjiabang Creek, and 86.17 per cent of the respondents think that the river is very important to them in life, this testifies the existence value of the urban river, with the validity of the CVM justified in the non-use value evaluation process of ecosystem services.