Boreal birds reproductive activity and persitence in older forests

北方鸟类的繁殖活动和在古老森林中的持久性

• 批准号: 227576-2009
• 负责人: Drapeau, Pierre
• 金额: $ 2.11万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=524021
• 关键词: Boreal; birds; reproductive; activity; persitence

In the eastern Canadian boreal forest it is well documented that even-aged management is shifting the land base into a much younger mosaic of forest cover types, considerably reducing the mature to old-growth portion of the age-class distribution of natural forests. Provided the increasing context of human influence in this ecosystem, older forest cover types (> 100 years) are likely to become habitats of concern from a biological conservation standpoint. The persistence in time of a reduced proportion of the land base in older forests should also affect populations of species associated with these habitats or their attributes. Better knowledge of the response of older forest species is thus critical in the assessment of the sustainability of boreal forest bird communities. In the last decade several studies have documented the occupancy (presence-absence or relative abundance) patterns of boreal birds in older forests. Findings converge towards the fact that boreal birds' responses to habitat loss and fragmentation induced by timber harvesting were not as strong as those in temperate forest ecosystems, perhaps because land conversion is low and total forest cover does not change. Much less is known about the effects of loss of older forests on reproductive activity of forest birds. In this research program we measure and compare in dynamic natural and managed landscapes: (1) the reproductive activity of open-cup (ovenbird in boreal mixed-wood and golden-crowned kinglet in black spruce forests) and cavity excavators (woodpeckers) in forest remnants and undivided forest tracks (2) habitat quality of forest remnants and larger forest tracks as resource patches with regards to both foraging and nesting requirements of cavity excavators (3) the probability of persistence of these target species in reduced older forest habitat given their population size (density of territorial males) and reproductive performance (reproductive and nesting success).

在加拿大东部的北方针叶林，有充分的文件证明，即使是年龄管理也正在将土地基础转变为更年轻的森林覆盖类型，大大减少了天然林年龄级分布中成熟到老生长的部分。如果人类在这一生态系统中的影响越来越大，从生物保护的角度来看，较老的森林覆盖类型(100年)很可能成为令人担忧的栖息地。随着时间的推移，老森林中陆地基础比例的减少也应该影响到与这些生境或其属性有关的物种的数量。因此，更好地了解较老森林物种的反应对于评估北方森林鸟类群落的可持续性至关重要。在过去的十年里，几项研究记录了北方鸟类在较老的森林中的占据模式(存在-不存在或相对丰富)。研究结果一致表明，北方鸟类对采伐木材造成的栖息地丧失和碎片化的反应不如温带森林生态系统中的鸟类那么强烈，可能是因为土地转化率低，森林总覆盖率没有变化。关于老森林的丧失对森林鸟类繁殖活动的影响，人们所知的要少得多。在这项研究中，我们在动态的自然景观和管理景观中测量和比较了：(1)开杯鸟(北方混交林和黑云杉林中的金冠小王雀)和洞穴啄木鸟(啄木鸟)在森林残留物和未分割林迹中的繁殖活动(2)森林残留物和较大林迹作为资源斑块的栖息地质量，以及洞穴挖掘者对觅食和筑巢的要求(3)这些目标物种在减少的老森林栖息地中生存的可能性，因为它们的种群规模(区域雄性密度)和繁殖性能(繁殖和筑巢成功)。