全球生态系统服务的状况与趋势

The Condition and Trends of the World's Ecosystem Services

简要介绍了千年生态系统评估(MA)状况与趋势工作组的报告《生态系统与人类福祉:现状与趋势》中的第2部分,即“对生态系统服务的评估”。该部分主要对全球生态系统服务在20世纪末的总体状况,以及它们在20世纪后半叶的主要变化趋势进行了评估。评估结果表明,在MA明确评估的24项服务中,15项处于下降趋势,约占60%;4项处于上升趋势,约占18%;其余5项(约占22%)存在显著的空间或时间差异,即在有些地区(时段)处于上升趋势,而在另外一些地区(时段)处于下降趋势。这些变化主要表现在:①全球谷类作物和牲畜等方面的生态系统服务已经取得了显著的提高,但同时却对淡水资源和调控害虫等方面的服务造成了巨大的损害;②按照当前的捕捞速度,野生鱼类资源已经无法承受人类的持续捕捞;③许多地区的淡水资源已经不能满足人类和生态系统的需求,如果延续当前的水资源利用模式,供需之间的差距将会继续扩大;④在对污染物质进行无害化处理、保持养分平衡、调控自然灾害,以及控制害虫、疾病与入侵生物的爆发等方面,许多生态系统的调节服务已经呈现出明显的下降趋势;⑤作为生态系统提供供给服务、调节服务和文化服务的基础条件,全球生态系统的支持服务出现了复杂的变化趋势。

Based on four types of ecosystem services, including provisioning services, regulating services, cultural services, and supporting services, changes in global ecosystem services during the second half of the twentieth century were assessed in the report of MA＇s condition and trends working group. It indicated that approximately 60% （ 15 out of 24） of the ecosystem services evaluated in the MA are being degraded or used unsustainably, 18 % （4 out of 24） are being enhanced, and 22% （5 out of 24） are being used with mixed patterns. The most important changes of ecosystem services include ：①The supply of certain ecosystem services has increased at the expense of others. Significant gains in the provision of food and fiber have been achieved through habitat conversion, increased abstraction and degradation of inland waters, and reduced biodiversity; ② Fish cannot continue to be harvested from wild populations at the present rate. Deep -ocean and coastal fish stocks have changed substantially in most parts of the world and the harvests have begun to decline and will continue to do so ;③ The supply of fresh water to people is already inadequate to meet human and ecosystem needs in large areas of the world, and the gap between supply and demand will continue to widen if current patterns of water use will continue ; ④ Declining trends in the capacity of ecosystems to render pollutants harmless, keep nutrient levels in balance, give protection from natural disasters, and control the outbreaks of pests, diseases, and invasive organisms are apparent in many places; ⑤ Supporting services, which are necessary for the production of all other ecosystem services, have changed with mixed patterns.