Assessing Landscape Constraints on Species Abundance: Does the Neighborhood Limit Species Response to Local Habitat Conservation Programs?

Landscapes in agricultural systems continue to undergo significant change, and the loss of biodiversity is an ever-increasing threat. Although habitat restoration is beneficial, management actions do not always result in the desired outcome. Managers must understand why management actions fail; yet, past studies have focused on assessing habitat attributes at a single spatial scale, and often fail to consider the importance of ecological mechanisms that act across spatial scales. We located survey sites across southern Nebraska, USA and conducted point counts to estimate Ring-necked Pheasant abundance, an economically important species to the region, while simultaneously quantifying landscape effects using a geographic information system. To identify suitable areas for allocating limited management resources, we assessed land cover relationships to our counts using a Bayesian binomial-Poisson hierarchical model to construct predictive Species Distribution Models of relative abundance. Our results indicated that landscape scale land cover variables severely constrained or, alternatively, facilitated the positive effects of local land management for Ring-necked Pheasants.

农业系统中的景观仍在经历显著变化，生物多样性丧失的威胁与日俱增。尽管栖息地修复具有益处，但管理举措往往难以达成预期效果。管理者亟需厘清管理举措失效的根源，但既往研究多聚焦于单一空间尺度下的栖息地属性评估，往往未考虑跨空间尺度运作的生态机制的重要性。我们在美国内布拉斯加州南部布设了调查样点，采用点计数法评估该区域具有重要经济价值的物种——环颈雉（Ring-necked Pheasant）的种群丰度，同时借助地理信息系统（geographic information system）量化景观效应。为筛选出可分配有限管理资源的适宜区域，我们采用贝叶斯二项-泊松层级模型，结合调查计数数据评估土地覆被与种群丰度的关联关系，进而构建相对丰度的预测性物种分布模型（Species Distribution Models）。研究结果表明，景观尺度的土地覆被变量会显著限制或促进本地土地管理对环颈雉的积极效应。