生态补偿机制中若干关键科学问题——以甘南藏族自治州草地生态系统为例

以甘南州草地生态系统水源涵养服务为例,构建以机会成本、交易成本和实施成本为参数的参与成本模型确定生态补偿标准。基于生态补偿资金效率的考虑,构建以土地所有者提供的生态系统服务、土地所有者的参与成本和生态系统服务受损风险为参数的空间选择模型,以乡镇为研究单元,对生态补偿区域进行选择,采用聚类分析将全州划为5大等级补偿区:优先补偿区、次级优先补偿区、次级补偿区、临界补偿区和潜在补偿区或可能补偿区,并对各类补偿区的特征进行了分析。构建生态补偿额基尼系数与生态补偿资金效率评价模型,分别评价了补偿额在受偿群体和补偿区域中分配的公平性、合理性与不同等级补偿区的补偿效率。结果表明:①以草地生态系统服务功能的价值(4776.4元/hm²·a)和机会成本(621.3元/m²·a)作为补偿标准的上下限,结合参与成本确定甘南州草地生态系统补偿标准为1999.8元/hm²·a;②草地生态系统的补偿优先度与生态重要性、生态脆弱性呈现出吻合趋同的状态,即草地生态系统优先补偿区既是高效补偿区,又是重要生态区和生态脆弱区;③受偿者(草地生态系统水源涵养服务供给者)得到的补偿额有明显不均衡状态,而在补偿区域(草地生态系统)上的分配却处于绝对平均范围内;④草地生态系统补偿区的优先等级次序与补偿效率吻合,即草地生态系统的优先补偿区的补偿效率最高,每元获取的草地生态系统水源涵养服务为38.18,是临界补偿区的14.68倍;次级优先补偿区的效率仅次于优先补偿区,每元补偿的生态系统服务为21.02。

Discussion on Several Key Scientific Issues of Eco-compensation Mechanism in Gannan Tibetan Autonomous Prefecture

The participation costs model, including the opportunity costs, transaction costs and implementation costs is constructed to determine the ecological compensation standards in Gannan Tibetan Autonomous Prefecture. Based on the efficiency of ecological compensation funds, we construct an applied site selection tool, which takes into account three variables that vary in space: environmental services provided, risks of losing those services, and participation costs, with town as a basic unit, to determine and choose the scope of ecological compensation. On the basis of the model, this study classifies Gannan into five compensation zones by cluster analysis: priority compensation zones, sub-priority compensation zones, secondary compensation zones, critical compensation zones and potential compensation zones, and analyzes the characteristics of the above five types of compensation zones. Besides, Gini coefficient for ecological compensation payments is designed according to the conception of Gini coefficient and used to evaluate the faimess levels of payments distribution in the communities receiving payments and compensation zones. The evaluation model of compensation funds efficiency is built to assess the efficiency of five compensation areas at limits of compensation criterion, combined with the participation costs of farmers and (2) The five types of compensation zones coincide with the order of efficient compensation as well as the order of the ecological importance. The main priority compensation zones of grassland ecosystem cover larger pasture, the grassland sizes of towns compensated are larger, but few participants are involved, however secondary compensation zones cover nearly half of the grassland ecosystem, towns and the population. In terms of spatial distribution, the main priority compensation zones are mainly in pastoral areas, while non-priority zones are mainly in the farming-pastoral areas, agricultural areas and forest areas. (3) There are great differences in the distribution of compensation payments among participants (suppliers of grassland ecosystem services), however the payments are evenly distributed in compensation zones of grassland ecosystem. (4) The order of compensation efficiency of grassland ecosystem is consistent with priorities of compensation areas. The priority compensation zones is most efficient, and their payments are more than 14 times (38.18) those of the environmental benefits for each yuan in the critical zones, followed by the sub-priority zones, being 21.02 for each yuan.