Ecosystem Services and Opportunity Costs Shift Spatial Priorities for Conserving Forest Biodiversity

Inclusion of spatially explicit information on ecosystem services in conservation planning is a fairly new practice. This study analyses how the incorporation of ecosystem services as conservation features can affect conservation of forest biodiversity and how different opportunity cost constraints can change spatial priorities for conservation. We created spatially explicit cost-effective conservation scenarios for 59 forest biodiversity features and five ecosystem services in the county of Telemark (Norway) with the help of the heuristic optimisation planning software, Marxan with Zones. We combined a mix of conservation instruments where forestry is either completely (non-use zone) or partially restricted (partial use zone). Opportunity costs were measured in terms of foregone timber harvest, an important provisioning service in Telemark. Including a number of ecosystem services shifted priority conservation sites compared to a case where only biodiversity was considered, and increased the area of both the partial (+36.2%) and the non-use zone (+3.2%). Furthermore, opportunity costs increased (+6.6%), which suggests that ecosystem services may not be a side-benefit of biodiversity conservation in this area. Opportunity cost levels were systematically changed to analyse their effect on spatial conservation priorities. Conservation of biodiversity and ecosystem services trades off against timber harvest. Currently designated nature reserves and landscape protection areas achieve a very low proportion (9.1%) of the conservation targets we set in our scenario, which illustrates the high importance given to timber production at present. A trade-off curve indicated that large marginal increases in conservation target achievement are possible when the budget for conservation is increased. Forty percent of the maximum hypothetical opportunity costs would yield an average conservation target achievement of 79%.

在保护规划中纳入生态系统服务（ecosystem services）的空间显性（spatially explicit）信息，是一项相对新兴的实践。本研究探讨了将生态系统服务作为保护要素纳入规划后，对森林生物多样性保护的影响，以及不同机会成本（opportunity cost）约束如何改变保护的空间优先级。本研究借助启发式优化规划软件Marxan with Zones，为挪威泰勒马克郡（Telemark）的59个森林生物多样性要素与5项生态系统服务，构建了空间显性的成本效益保护情景。研究组合了多种保护工具，将林区划分为完全禁伐的非使用区（non-use zone）与有限制利用的部分使用区（partial use zone）两类区域。机会成本以放弃的木材采伐量进行核算——木材采伐是泰勒马克郡重要的供给型（provisioning service）生态系统服务。相较于仅考虑生物多样性的情景，纳入多项生态系统服务会改变优先保护位点，并使部分使用区面积增加36.2%、非使用区面积增加3.2%。与此同时，机会成本上升6.6%，这表明在该区域，生态系统服务或许并非生物多样性保护的附带收益。本研究通过系统性调整机会成本水平，分析其对空间保护优先级的影响。生物多样性与生态系统服务的保护，与木材采伐存在权衡（trade-off）关系。当前已划定的自然保护区与景观保护区域，仅实现了本研究情景中设定保护目标的9.1%，这表明当下木材生产被赋予了极高的优先地位。权衡曲线显示，若增加保护预算，保护目标达成率可实现大幅边际提升。当机会成本达到最大假想值的40%时，保护目标的平均达成率可达79%。