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

由于人类活动，全世界的森林正在发生重大变化。在加拿大东部的北方森林，过去35年来木材采伐的北方扩展已经将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移到现在以年轻森林为主的矩阵。这代表了生物体的一个重大变化，这些生物体在整个全新世进化并经历了封闭的树冠和基石结构（如腐烂和死亡的树木）的高可用性。这种减少比例的古老森林特别影响物种是专门在封闭的树冠（开杯巢）和腐烂和死亡的树木（腔巢）。 通常在鸟类取样站附近（半径500米至2公里）评估鸟类对古老森林覆盖丧失和破碎的景观敏感性。这种方法提供了深入了解物种在当地规模的反应。然而，它们在推断这种模式如何在整个森林镶嵌图的区域人口一级转化方面受到限制。要做到这一点，需要对生物群落进行大规模的鸟类调查。鸟类繁殖地图集（BBA）项目，最近纳入了细粒度尺度调查（点计数），现在提供了这样的机会，调查鸟类种群的栖息地变化在大的地理区域。 这项建议措施在魁北克省的商业北方森林的规模的影响，从一个老的到年轻的森林马赛克的森林年龄结构的变化对鸟类群落的反应。我们将联合收割机（区域，BBA数据）和密集（当地、实地研究）对开杯和洞巢采取的方法，以：1）评估古老森林的丧失和破碎对敏感鸟类种群的区域规模影响; 2）确定采伐景观的再生动态如何使古老森林鸟类群落恢复活力; 3）测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社区的反应，从当地到区域的影响，古老的森林损失和碎片，拟议的研究计划将有助于突破性的进展，我们的理解木材采伐制度对北方生物多样性的累积影响，在人类改造的景观。除了传统的分类学多样性，使用基于特征的方法（开杯和腔巢）将提供一个原始的视角来确定关键的栖息地驱动程序，北方鸟类群落的功能多样性。从保护规划的角度来看，拟议的研究将产生创新的科学为基础的准则，制定政策，在加拿大北方森林，更好地满足长期的挑战，保持生物多样性和可持续森林管理在一个迅速变化的世界。

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.