Protected area systems that are ecologically representative and effectively managed are essential tools for the conservation and sustainable use of biodiversity worldwide. However, global protected area coverage and management effectiveness is highly insufficient, even in areas of global biodiversity significance. Under the Convention on Biological Diversity (CBD), governments committed to improve management effectiveness and expand the global coverage of protected areas from 13% to 17% of land area by 2020, targeting especially areas of particular importance for biodiversity. It is important for the feasibility of conservation to identify spatial priorities that are cost-effective, that is to meet intended biodiversity targets while minimizing, as far as possible, conservation costs.
To date, global-scale analyses of cost-effective priorities either accounted for management costs of protected areas associated with required staff and infrastructure, or for opportunity costs associated with forgone agricultural production. Management costs are the main costs paid by conservation organizations, while a large part of agricultural opportunity costs is paid by local land users. Therefore, the choice of the cost type has important normative implications on whose costs have standing in the prioritization process. Furthermore, different methods were proposed to approximate agricultural opportunity costs, and the choice of the agricultural opportunity cost indicator itself may influence prioritization results. However, the sensitivity of priority areas for global biodiversity conservation towards these normative and methodological degrees of freedom remains unclear.
The general aim of this thesis is to increase the transparency of cost-effective prioritization at the global-scale, and to investigate the robustness of its results by reassessing priorities for differing types and indicators of conservation costs.
Chapter I of this thesis provides an overview on the thesis background, motivation and aim. In chapter II, it is investigated how focusing on management costs or on agricultural opportunity costs differently affects the selection of cost-effective priority areas for global biodiversity conservation. The results of this analysis demonstrate that prioritization needs to include both management and opportunity costs because focusing on either cost type alone results in undue cost burdens to conservation organizations or to local land users, which compromises the success of conservation. Further, it is concluded that remapping priority areas based on several alternative cost scenarios can not only ensure overall cost-effective selection of sites, but also ensure that trade-offs between costs to different stakeholder groups are transparently identified, which could lead to overall more equitable and economically feasible outcomes. Finally, it was also found that two commonly used prioritization approaches, minimum set and maximum coverage, differ markedly in their degree of sensitivity towards diverging cost data. In chapter III, it is investigated how commonly used indicators to approximate agricultural opportunity costs differently influence the selection of priority areas. It was discovered that the different indicators of agricultural opportunity costs are only weakly to moderately correlated spatially. Most importantly, it was found that that cost-effective selection of global priority areas according to one cost indicator shifted priorities to areas with high costs according to any of the other indicators. These results show that outcomes from current state-of-the-art approaches for minimizing agricultural opportunity costs of global biodiversity priority areas are inconclusive because cost-effectiveness varies widely depending on which cost indicator is considered, while at the same time it is uncertain how well each cost indicator reflects the actual agricultural opportunity costs of conservation. In chapter IV, it is reviewed that previous global prioritization analyses commonly relied on economic returns from past agricultural lands (mid 1990s) to account for agricultural opportunity costs of conservation. However, opportunity costs do not only include the benefits currently obtained from a site but also those that could have been obtained in the future. While the extension path of agricultural land cannot be exactly predicted, the scenario analyses presented in this chapter clearly illustrate that cost-effectiveness of global prioritization may be improved substantially by more fully using available knowledge on possible pathways of agricultural expansion during the 21th century.