Bird Communities Reveal the Ecological Value of Exotic Norway Spruce Plantations in Massachusetts, USA

Abstract from study: "The establishment of monoculture plantations of exotic tree species is a common practice for supplementing native timber stocks. Since native wildlife species may lack co-evolved traits needed to successfully exploit exotic tree species, exotic plantations are expected to provide inferior habitat for native biodiversity. However, some studies report that plantations may increase net biodiversity at the landscape scale by introducing novel habitats or supplementing existing natural forests. We used point counts to sample birds in 2016 and 2017 in mature Norway spruce (Picea abies) plantations in western Massachusetts, as well as representative native forest types, to evaluate bird use of these plantations relative to native forest types. Our findings showed that overall species richness for spruce plantations was similar to that of native forest habitats, and that several native conifer-dependent species (red-breasted nuthatch (Sitta canadensis), golden-crowned kinglet (Regulus satrapa), blackburnian warbler (Setophaga fusca), and brown creeper (Certhia americana) were significantly more abundant in spruce plantations relative to native deciduous, hemlock, and mixed stands. Bird species reported to associate with eastern hemlock (Tsuga canadensis), such as blue-headed vireo (Vireo solitarious) and black-throated green warbler (Setophaga virens), were observed using spruce plantations at similar levels as eastern hemlock stands. These results demonstrate that Norway spruce plantations can provide suitable habitat for native species associated with conifers, which is significant given projected continued decline of eastern hemlock in response to the hemlock wooly adelgid (Adelges tsugae). Although large-scale conversion of native forest to plantations would likely lead to a loss in biodiversity, land managers could be justified in allowing small-scale plantations to persist without suffering negative impacts to native biodiversity".

This data set represents observations (visual and aural) from avian point count surveys conducted over the course of two breeding seasons (May- June 2016 and 2017) at two sites in Massachusetts, U.S.A as well as associated vegetation surveys.

本研究摘要：外来树种单一人工林的营造是补充本土木材储备的常见手段。由于本土野生动物类群可能缺乏成功利用外来树种所需的协同演化性状，外来人工林被认为可为本土生物多样性提供较劣的栖息生境。然而，部分研究指出，人工林可通过引入新生境或补充现有天然林，在景观尺度上提升净生物多样性。2016至2017年，我们采用定点计数法（point counts），对美国马萨诸塞州西部的成熟挪威云杉（Picea abies）人工林及典型本土林分开展鸟类取样调查，以评估鸟类对云杉人工林与本土林分的利用差异。研究结果显示，云杉人工林的整体物种丰富度与本土林生生境相当，且多种本土针叶林专性物种（红胸鳾（Sitta canadensis）、金冠戴菊（Regulus satrapa）、黑顶林莺（Setophaga fusca）以及褐旋木雀（Certhia americana））在云杉人工林中的种群丰度显著高于本土落叶林、铁杉林及混交林分。据报道与东部铁杉（Tsuga canadensis）伴生的鸟类类群，如蓝头莺雀（Vireo solitarius）与黑喉绿林莺（Setophaga virens），在云杉人工林中的利用程度与东部铁杉林分相当。本研究结果表明，挪威云杉人工林可为与针叶林伴生的本土物种提供适宜栖息生境，鉴于铁杉球蚜（Adelges tsugae）侵染将导致东部铁杉持续衰退的预测趋势，这一发现具有重要现实意义。尽管将本土森林大规模转化为人工林可能导致生物多样性丧失，但土地管理者可允许小型人工林存续，且不会对本土生物多样性造成负面影响。本数据集包含2016年与2017年两个繁殖季（2016年5-6月、2017年5-6月），在美国马萨诸塞州两个调查站点开展的鸟类定点计数调查（avian point count surveys，涵盖目视与鸣听两类观测）结果，以及配套的植被调查数据。