Scaling habitat loss and fragmentation of old forests on bird communities in boreal landscapes

北方景观中鸟类群落的栖息地丧失和老森林破碎化

• 批准号: RGPIN-2019-07075
• 负责人: Drapeau, Pierre
• 金额: $ 2.91万
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688021
• 关键词: Scaling; habitat; loss; fragmentation; old

Forests worldwide are undergoing major changes as a result of human activity. In the eastern boreal forest of Canada, the northern expansion of timber harvesting in the last 35 years has shifted the age-class distribution from a matrix formerly dominated by mature and old forest cover types to a matrix that is now dominated by young forests. This represents a major change for organisms that evolved and experienced high availability of closed canopy and keystone structures such as decaying and dead trees throughout the Holocene. This reduced proportion of old forests specifically affects species that are specialised on closed canopy (open-cup nesters) and on decaying and dead trees (cavity nesters). ***Landscape-scale sensitivity of birds to loss and fragmentation of old forest cover has usually been assessed in the neighbourhood of bird sampling stations (500 m to 2-km radius). Such approaches provide insightful knowledge on species responses at local scales. They are, however, limited for extrapolating how such patterns translate at the level of regional populations, across the entire forest mosaic. To do so large-scale bird surveys over biomes are required. Breeding Bird Atlas (BBA) projects, which have recently incorporated fine-grain scale surveys (point counts), now provide such opportunities for investigating bird populations' responses to habitat changes over large geographic regions. ***This proposal measures at the scale of Québec's commercial boreal forest the effects of shifting the forest age structure from an old to a young forest mosaic on the response of bird communities. We combine extensive (regional, BBA data) and intensive (local, field studies) approaches on open-cup and cavity nesters to: 1) assess the regional-scale effects of loss and fragmentation of old forests on populations of sensitive birds; 2) determine how the dynamics of regeneration in harvested landscapes enables the resilience of old forest bird communities; 3) measure how local habitat quality and connectivity of old forests are drivers in bird species nesting and foraging ecology. By scaling-up the response of bird populations and communities to old forest loss and fragmentation from local to regional effects, the proposed research program will contribute to groundbreaking advances in our understanding of the cumulative effects of timber-harvesting regimes on boreal biodiversity in human-modified landscapes. The use of a trait-based approach (open-cup and cavity nesters) in addition to traditional taxonomic diversity will provide an original perspective to pinpoint critical habitat drivers to which the functional diversity of boreal bird communities responds. From a conservation planning perspective, the proposed research will produce innovative science-based guidelines for developing policies in the Canadian boreal forest that better meet the long-term challenges of maintaining biodiversity and sustainable forest management in a rapidly changing world. *****

由于人类活动，全世界的森林正在发生重大变化。在加拿大东部北方森林中，过去 35 年木材采伐向北扩展，使年龄级分布从以前以成熟和古老森林覆盖类型为主的矩阵转变为现在以幼龄森林为主的矩阵。对于在整个全新世进化并经历了封闭树冠和基石结构（例如腐烂和枯死的树木）的高可用性的生物体来说，这代表着一个重大变化。古老森林比例的减少特别影响到专门栖息在封闭树冠（开杯筑巢者）和腐烂和死亡树木（洞穴筑巢者）的物种。 ***通常在鸟类采样站附近（500 m 至 2 km 半径）评估鸟类对旧森林覆盖丧失和破碎的景观尺度敏感性。这些方法提供了有关当地尺度物种反应的深入知识。然而，它们在推断这些模式如何在整个森林马赛克的区域人口层面上转化方面受到限制。为此，需要对生物群落进行大规模鸟类调查。鸟类繁殖地图集 (BBA) 项目最近纳入了细粒度调查（点数），现在为调查鸟类种群对大地理区域栖息地变化的反应提供了这样的机会。 ***该提案在魁北克商业北方森林的规模上衡量了森林年龄结构从古老森林镶嵌转变为年轻森林镶嵌对鸟类群落反应的影响。我们将针对开杯和空洞筑巢鸟的广泛（区域、BBA 数据）和密集（当地、实地研究）方法结合起来：1）评估老森林的丧失和破碎对敏感鸟类种群的区域规模影响； 2）确定收获景观的再生动态如何使古老的森林鸟类群落具有恢复能力； 3) 衡量当地栖息地质量和古老森林的连通性如何驱动鸟类筑巢和觅食生态。通过扩大鸟类种群和群落对旧森林丧失和破碎化（从地方到区域的影响）的反应，拟议的研究计划将有助于我们在理解木材采伐制度对人类改造景观中北方生物多样性的累积影响方面取得突破性进展。除了传统的分类多样性之外，使用基于性状的方法（开杯和空洞筑巢者）将为查明北方鸟类群落功能多样性所响应的关键栖息地驱动因素提供一个原创视角。从保护规划的角度来看，拟议的研究将为加拿大北方森林制定政策提供基于科学的创新指南，以更好地应对在快速变化的世界中维持生物多样性和可持续森林管理的长期挑战。 *****