Representing connectivity: quantifying effective habitat availability based on area and connectivity for conservation status assessment and recovery
Representing connectivity: quantifying effective habitat availability based on area and connectivity for conservation status assessment and recovery
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代表连通性：根据面积和连通性量化有效栖息地的可用性，以进行保护状态评估和恢复
作者：
M. Neel;Hayley R. Tumas;Brittany W. Marsden
我们应用一套全面的图论指标来说明如何将景观连通性有效地纳入保护状态评估和设定保护目标。这些指标使保护从业者能够评估和量化代表性、弹性和冗余方面的连通性，并且尽管对物种特异性生物学和扩散过程的了解不完整，但仍可以应用该方法。我们通过评估在当前条件下对三种濒危植物物种（Erigeron parishii、Acanthoscyphus parishii var. Goodmaniana 和 Eriogonum ovalifolium var. vineum）实施两项保护计划所导致的分布和连通性变化（相对于当前条件下的连通性）来展示图表指标的实用性。尽管在研究景观中各物种的分布范围和占据斑块的具体位置方面各不相同，但现有网络中的潜在连通性的空间尺度对于灯盏花和灯盏花来说惊人地相似，但对于棘龙属却有所不同。具体来说，前两个物种的斑块分布更规则，而棘龙斑块的子集则聚集成更孤立的成分。基于美国鱼类和野生动物管理局关键栖息地指定的保护区不会对维持连通性做出很大贡献；它们包括每个物种现有分布的 83-91% 和超过 92% 的空中范围。所有物种的有效连通性保持在整个网络的 10% 以内。林务局栖息地管理策略排除了每个物种多达 40% 的占用栖息地，导致每个物种分布范围的缩小和中心部分的出现次数减少。总体有效网络连接减少至整个网络的 62-74%。由于排除了外围斑块，每个 CHMS 网络首次完全连接的距离相对于灯盏花和棘蚴属的完整网络有所减少，但对于灯盏花来说略有增加。由于存在非冗余连接，网络对连接丢失敏感的距离主要受到棘蚴的影响。最令人担忧的是，由于缺乏冗余而产生高风险的距离范围远大于整个网络。通过这个使用一整套成熟的图论指标评估连通性的深入示例，我们建立了一种方法，并提供了对连通性细微变化的样本解释，保护管理者可以将其纳入规划中。
We apply a comprehensive suite of graph theoretic metrics to illustrate how landscape connectivity can be effectively incorporated into conservation status assessments and in setting conservation objectives. These metrics allow conservation practitioners to evaluate and quantify connectivity in terms of representation, resiliency, and redundancy and the approach can be applied in spite of incomplete knowledge of species-specific biology and dispersal processes. We demonstrate utility of the graph metrics by evaluating changes in distribution and connectivity that would result from implementing two conservation plans for three endangered plant species (Erigeron parishii, Acanthoscyphus parishii var. goodmaniana, and Eriogonum ovalifolium var. vineum) relative to connectivity under current conditions. Although distributions of the species differ from one another in terms of extent and specific location of occupied patches within the study landscape, the spatial scale of potential connectivity in existing networks were strikingly similar for Erigeron and Eriogonum, but differed for Acanthoscyphus. Specifically, patches of the first two species were more regularly distributed whereas subsets of patches of Acanthoscyphus were clustered into more isolated components. Reserves based on US Fish and Wildlife Service critical habitat designation would not greatly contribute to maintain connectivity; they include 83–91% of the extant occurrences and >92% of the aerial extent of each species. Effective connectivity remains within 10% of that in the whole network for all species. A Forest Service habitat management strategy excluded up to 40% of the occupied habitat of each species resulting in both range reductions and loss of occurrences from the central portions of each species’ distribution. Overall effective network connectivity was reduced to 62–74% of the full networks. The distance at which each CHMS network first became fully connected was reduced relative to the full network in Erigeron and Acanthoscyphus due to exclusion of peripheral patches, but was slightly increased for Eriogonum. Distances at which networks were sensitive to loss of connectivity due to presence non-redundant connections were affected mostly for Acanthoscyphos. Of most concern was that the range of distances at which lack of redundancy yielded high risk was much greater than in the full network. Through this in-depth example evaluating connectivity using a comprehensive suite of developed graph theoretic metrics, we establish an approach as well as provide sample interpretations of subtle variations in connectivity that conservation managers can incorporate into planning.