This study optimized an existing conservation network system using SCP and gap analysis while evaluating the effectiveness of the new system. The process of establishing high-value conservation networks took into account biodiversity features of different levels and dimensions in the Sanjiang Plain. The process also accounted for the irreplaceability of catchments, since these planning units fall under the framework of SCP. In the horizontal dimension, we had two conservation level objectives, one for the ecosystem level and one for the species level. Eight types of marsh wetland systems, all lake ecosystems, and high conservation value river wetland systems were selected as ecosystem level conservation surrogates. Thirteen endangered birds and four endangered mammals were selected as species level conservation surrogates. In the vertical dimension, we chose 3 effective underground water distribution areas. Ecosystem conservation targets were set based on ecological function value, rarity and threat trends. Species conservation targets were set based on level of endangerment, scope for survival, and population growth/decline trends. Protection targets were set for water resources according to their runoff modulus and recharge modulus. SCP utilizes the key concept of irreplaceability, which is a measure, varying from zero to one, indicating the importance of an area (planning unit) for the achievement of regional conservation targets. A map of irreplaceability values is therefore a base map of conservation planning. Finally, we combined irreplaceability values with vulnerability factors (factors threatening the ecology of the region) to design different planning options.
Results were as follows:(1) High conservation value areas accounted for about 16% of the whole region and were generally distributed along river and lake ecosystems. Specifically, at headwater intersections, such as the intersection of the Heilongjiang and Wusulijiang, the junction of the Tongjiang and Fuyuan, the marsh wetlands between Fujin and Baoqing, the waterfront in Hulin, and the middle part of Luobei, the northeast Hegang, northeast of Yilan, and the south Muling.(2) Lake ecosystems and target species were well-protected in existing conservation areas. They accounted for 83.90% and 81.25% of the whole conservation network respectively. After the prioritization, these percentages increased only slightly to 86.65% and 100%.(3) Marsh, riverine and wetland ecosystem protection by the existing conservation network was less effective. Prioritization would afford an increase in marsh wetlands (from 22.88% to more than 50%), riverine wetlands (from 16.20% to 33.92%), and underground water resources (from just 2.01% to 12.05%).(4) Vulnerability analysis showed high vulnerability areas on the Sanjiang Plain were mainly distributed in Jiamusi, south of Hegang, north of Shuangyashan and Jixi, the middle of Huanan and Luobei, and the intersection of the Fujin and Suibin.
The work detailed above indicates that future conservation planning must continue to preserve well-protected ecosystems and species and emphasizes the need for protection and management of marsh, riverine and wetland ecosystems, especially underground water resources. Quantification of resource irreplaceability and vulnerability were evaluated as a supplement to this future conservation planning. The authors combined irreplaceability and vulnerability indexes to propose three scenarios (the ecological value prioritized scenario, the rescue prioritized scenario and the economic avoidance prioritized scenario), and provide recommendations for decision-makers under each scenario in terms of ecological threats.
This irreplaceability-based biodiversity conservation planning method integrates protected objects, conservation targets and contributions into one framework and expresses the information in a quantified form. Quantifications enables conservation planning and prioritizing work to be more scientific and better visualized, providing a feasible and effective framework for natural reserve network establishment and prioritization.