Climate Change, Northern Birds of Conservation Concern and Matching the Hotspots of Habitat Suitability with the Reserve Network

National reserve networks are one of the most important means of species conservation, but their efficiency may be diminished due to the projected climatic changes. Using bioclimatic envelope models and spatial data on habitats and conservation areas, we studied how efficient the reserve network will be in preserving 100 forest, mire, marshland, and alpine bird species of conservation concern in Finland in 2051–2080 under three different climate scenarios. The occurrences of the studied bird species were related to the amount of habitat preferred by each species in the different boreal zones. We employed a novel integrated habitat suitability index that takes into account both the species’ probability of occurrence from the bioclimatic models and the availability of suitable habitat. Using this suitability index, the distribution of the topmost 5% suitability squares (“hotspots”) in the four bird species groups in the period 1971–2000 and under the three scenarios were compared with the location of reserves with the highest amounts of the four habitats to study the efficiency of the network. In species of mires, marshlands, and Arctic mountains, a high proportion of protected habitat was included in the 5% hotspots in the scenarios in 2051–2080, showing that protected areas cover a high proportion of occurrences of bird species. In contrast, in forests in the southern and middle boreal zones, only a small proportion of the protected habitat was included in the 5% hotspots, indicating that the efficiency of the protected area network will be insufficient for forest birds in the future. In the northern boreal zone, the efficiency of the reserve network in forests was highly dependent on the strength of climate change varying between the scenarios. Overall, there is no single solution to preserving biodiversity in a changing climate, but several future pathways should be considered.国家保护地网络是物种保护的关键途径之一，但受未来预估气候变化的影响，其保护效率或有所降低。本研究借助生物气候包络模型（bioclimatic envelope models）以及生境与保护地空间数据，针对芬兰境内100种具有保护优先级的森林、藓沼、沼泽及高山鸟类，探究了2051–2080年三种不同气候情景下，保护地网络对这些物种的保护效能。研究中将目标鸟类的出现记录与各寒温带针叶林带内物种偏好生境的面积相关联。我们构建了一种全新的综合生境适宜性指数（integrated habitat suitability index），该指数同时纳入了基于生物气候模型得到的物种出现概率，以及适宜生境的可获得性两项指标。基于该适宜性指数，我们分别对比了1971–2000年基准期以及三种气候情景下，四类鸟类类群中适宜性得分前5%的网格单元（即热点区域（hotspots））的分布，与四类生境占比最高的保护地的空间位置，以此评估保护地网络的保护效率。针对藓沼、沼泽及北极山地鸟类，2051–2080年三种气候情景下，5%热点区域内的受保护生境占比均较高，表明现有保护地可覆盖多数该类鸟类的潜在分布区域。与之相对，南部及中部寒温带针叶林带的森林鸟类，其5%热点区域内的受保护生境占比仅为少量，这意味着未来保护地网络对森林鸟类的保护效能将不足。而在北部寒温带针叶林带，森林鸟类保护地网络的保护效能则高度依赖不同情景下气候变化的强度。总体而言，气候变化背景下的生物多样性保护并无普适性方案，需综合考量多种未来发展路径。