不同生态恢复方式下生态系统服务与生物多样性恢复效果的整合分析

全球范围内关键生态系统服务的减少使人类社会面临巨大的威胁,生物多样性是生态系统提供各种产品和服务的基础。生态恢复工程对退化的生态系统服务和生物多样性进行修复,对于缓解人类环境压力具有非常重要的意义。长期的理论和实践工作形成了多种生态恢复措施:(1)单纯基于生态系统自我设计的自然恢复方式,(2)人为设计对环境条件进行干预,反馈影响生态系统的自我设计,(3)人为设计对目标种群和生态系统进行直接干预和重建。这3类恢复方式可以在不同程度上定向的影响生态系统的恢复进程,反映了人类对生态系统的低度、中度和高度介入。哪种恢复方式和介入程度能够实现更好的恢复效果,是生态恢复学中的一个关键问题,但到目前为止,虽广有争议,却无定量的分析和结论。针对这个空白,通过对ISI Web of Knowledge数据库中生态恢复相关文献的整合分析,基于数学统计的方法定量比较在不同条件下低度介入(自然恢复)、中度介入(环境干预)和高度介入(直接干预)3种恢复方式对生态系统服务与生物多样性的恢复效果。论文从4个方面展开研究:(1)低度、中度、高度介入生态恢复方式的划分,(2)比较3大类介入方式对生态系统服务和生物多样性恢复效果的差异,(3)不同气候条件、生态系统类型和恢复时间等背景因素的影响,(4)生物多样性恢复和生态系统服务恢复之间的关系。研究结果揭示了不同生态恢复方式的适用条件,以及对生物多样性和生态系统恢复相互关系的作用,对生态恢复实践中恢复方式的选择有指导作用。对未来的研究也有启示意义,如针对特定生态系统服务或具体研究问题进一步探索低度、中度和高度介入生态恢复方式的作用规律和机制;将地区的社会经济水平、生态系统的受损程度等因素纳入生态恢复方式的考察,以最优化生态恢复成本-效率等。

Effects of different ecological restoration approaches on ecosystem services and biodiversity: a meta-analysis

The global losses of biodiversity and critical ecosystem services are great threats to human society. Ecological restoration is an important way to regain the lost ecosystem services and biodiversity. In order to achieve successful results, various restoration approaches have been developed. While some approaches take advantage of the self-designing ability of natural restoration systems, others rely on man-made designs at various levels. Since different restoration approaches may have different effects, identifying the best approach becomes crucial for successful restoration implementation. In order to achieve this objective, we proposed herein a system to classify various restoration methods into three types of approaches, namely, high-, intermediate-and low-intensity intervention approaches based on the intensity or the degree of human intervention. We then conducted a meta-analysis by using data obtained from ISI Web of Knowledge to study the effects of different restoration approaches on ecosystem services and biodiversity. In addition, we examined restoration effects under different climate zones, ecosystem types, restoration ages, and ecosystem service types. Finally, the relationship between biodiversity and ecosystem services was studied. We used the median response ratio as an indicator of biodiversity and ecosystem service restoration effects. Since our data were not normally distributed, Wilcoxon and Kruskal-Wallis non-parametric analyses were applied to detect statistical differences. Spearman rank analysis was used to test the correlation between biodiversity and ecosystem services. In this study, a low-intensity intervention approach indicates that the restoration effects are entirely achieved by natural forces. Human contributions to ecosystem restoration occur only through behavioral changes, such as land abandonment and threat removal. The intermediate-intensity approach applies when people only alter the environment during restoration. There is no direct intervention exerted on restoration targets. Some examples of intermediate intensity approaches include fertilizer application, the establishment of green corridors to improve habitat connectivity, and the addition of large deadwood to streams in order to improve habitat heterogeneity. A high-intensity approach is defined by direct human control on restoration targets. This approach usually involves anthropogenic biological recovery of a degraded ecosystem. Tree planting and species introduction are good examples of high-intensity approaches. The meta-analysis indicated that the median increment of ecosystem services and biodiversity in restored ecosystems was 45% and 151%, respectively, when compared to that of degraded ecosystems. The median enhancement of ecosystem services and biodiversity was 31% and 25%, respectively, for the low-intensity approach, and 31% and 22%, respectively, for the intermediate-intensity approach. A positive correlation was observed between biodiversity and ecosystem services, especially in restored versus degraded ecosystems. Further detailed analysis revealed a significant variation with regard to the effects of restoration approaches dependent on restoration goals (biodiversity or ecosystem services), referring systems (degraded or reference), climatic conditions, and time elapsed since restoration. However, some prominent differences were still found in tropical and terrestrial ecosystems. In this context, the high-intensity approach generally generated the best restoration effects when compared to degraded ecosystems. However, this approach may be suboptimal if the goal of restoration is to recreate the original environmental state. Indeed, the high complexity of reference ecosystems may be more easily recreated via intermediate intensity approaches. Our study emphasizes the importance of considering socioeconomic factors during restoration planning and creating a standard evaluation system for restoration effects and sustainability based on indicators of ecosystem services.