Jim C Y
Department of Geography, The University of Hong Kong, Pokfulam Road, Hong Kong.
Environ Monit Assess. 2006 May;116(1-3):53-80. doi: 10.1007/s10661-006-7245-x.
Urban trees serve important environmental, social and economic functions, but similar to other natural endowments they are not customarily depicted in monetary terms. The needs to augment protection, funding and community support for urban greening call for proper valuation. Heritage trees (HTs), the cream of urban-tree stock, deserve special attention. Existing assessment methods do not give justice to outstanding trees in compact cities deficient in high-caliber greenery, and to their social-cultural-historical importance. They artificially separate evaluation from valuation, which should be a natural progression from the former. Review of tree valuation methods suggested the formula approach to be more suitable than contingent valuation and hedonic pricing, and provided hints on their strengths and weaknesses. This study develops an alternative formulaic expert method (FEM) that integrates evaluation and valuation, maximizes objectivity, broadly encompasses the key tree, tree-environment and tree-human traits, and accords realistic monetary value to HTs. Six primary criteria (dimension, species, tree, condition, location, and outstanding consideration) branched into 45 secondary criteria, each allocated numerical marks. Each primary criterion was standardized to carry equal weight, and a tree's maximum aggregate score is capped at 100. A Monetary Assignment Factor (MAF) to consign dollar value to each score unit was derived from three-year average per m(2) sale price of medium-sized residential flats. The applicability of FEM was tested on selected HTs in compact Hong Kong. The aggregate score of a tree multiplied by MAF yielded monetary value, which was on average 66 times higher than the result from the commonly-adopted Council of Tree and Landscape Appraisers method. The computed tree values could be publicized together with multiple tree benefits to raise understanding and awareness and rally support to protect HTs. The property-linked FEM could be flexibly applied to other cities, especially to assess HTs in compact developing cities.
城市树木具有重要的环境、社会和经济功能，但与其他自然资源一样，它们通常不以货币形式体现。加强城市绿化保护、资金投入和社区支持的需求促使人们进行合理估值。古树名木作为城市树木的精华，值得特别关注。现有的评估方法未能公正对待绿化资源匮乏的紧凑型城市中的杰出树木及其社会文化历史重要性。这些方法人为地将评估与估值分开，而估值应是评估的自然延伸。对树木估值方法的综述表明，公式法比条件估值法和享乐定价法更合适，并指出了它们的优缺点。本研究开发了一种替代性的公式化专家方法（FEM），该方法将评估与估值相结合，最大限度地提高了客观性，广泛涵盖了关键的树木、树木与环境以及树木与人的特征，并赋予古树名木现实的货币价值。六个主要标准（尺寸、树种、树木、状况、位置和特殊考量）细分为45个次要标准，每个标准都赋予数值分数。每个主要标准都进行了标准化处理，以使其具有同等权重，一棵树的最高总分上限为100分。通过中型住宅单位每平方米三年平均售价得出货币赋值因子（MAF），用于为每个分数单位赋予美元价值。在香港紧凑型城市中选取的古树名木上测试了FEM的适用性。一棵树的总分乘以MAF得出货币价值，该价值平均比常用的树木与景观评估师协会方法的结果高出66倍。计算得出的树木价值可以与树木的多种益处一起公布，以提高人们的理解和认识，并争取对保护古树名木的支持。与房地产挂钩的FEM可以灵活应用于其他城市，特别是用于评估紧凑型发展中城市中的古树名木。
