生态地理区域界线划分的指标体系

生态地理区域界线由一系列反映生态地理区域特征的指标为依据 ,通过其空间差异落实到具体的空间位置上。客观地认识和划定生态地理区域界线是揭示生态环境时空有序性的重要途径 ,是地域系统研究的基础。生态地理区域界线是两个相邻的、彼此不同的生态地理区质上转变的线或带 ,反映同一等级内划分出来的内部相对一致性与外部的差异性。界线代表有一定宽度的带 ,而且可能随着时间而迁移变化 ,等级越低界线越明显 ,等级越高界线越宽。在生态地理区域划分中 ,先选择人力不能大规模改变的几个主要因素 :温度指标 ,主要指标是日平均气温≥ 1 0℃的天数和积温 ,最冷月平均气温 ,最暖月平均气温等 ;水分指标 ,干湿指数 ,目前比较普遍采用的是年干燥度 ,它可以近似地表征某一地方的干湿程度 ;年降水量的资料通常比较可靠 ,但潜在蒸发的计算需要改进和提高。生态地理区域较高级单位的划分依据侧重考虑生物气候的差异 ,先注意水平地带性 ,由于气候台站的有限性 ,所划分出的界线往往用植被界线去修正 ;而垂直地带性则将潜在植被与气候联系起来 ,按照降水量、潜在蒸发率和生物温度来进行划分。如何处理级别与依据和指标之间的关系是另一个重要问题 ,在这个问题的处理上 ,国内外很不统一。

An Index System for Boundaries of Eco-geographical Regions of China

Boundary of eco geographical regions is based on a set of index that indicates the regional features. It is located on special location by spatial differences in environmental features. Impersonally recognizing and delineating the boundary is an important way to open out spatial order of the environment. This boundary is a line or belt as border for two joined regions with different features. It shows relative coherence in environmental features within a region and otherness to the other region. The boundary is a belt with wideness that can be changed as course of time. Higher-class regions have wider boundary and lower class regions have clearer boundary. In delineation of eco geographical regions, several factors that can hardly be controlled by human are selected as main indexes. Days and cumulated temperature of daily temperature ≥10℃, average temperatures of the coldest and hottest months are used as indexes of temperature state. Dryness is the most common factor as token of dry humid degree of a region. Annual precipitation is more reliable but calculation of latency evaporation should be improved. Division of higher class of eco geographical regions focuses on biological and climatic differences, first of all on horizontal zonality. Because of limitation of number of climatic stations, the boundary is always modified with vegetation. Vertical zonation links latency vegetation with climate, which is divided according to precipitation, potential evaporation and bio temperature relationship. How to deal with relation between classes and indexes of eco geographical regions is another important point. Some studies tried to combine indexes of natural factors with social economic factors. Some considered the index system should cover environmental, resources, economic, social and population factors. Some proposed taking temperature, water moisture factors for the higher classes and introducing resources and social-economic factors for the lower classes. However, the former has not given detailed index and the latter took different indexes for different regions, which should have more work to realize the combination.