Bryophytes in fir waves: Forest canopy indicator species and functional diversity decline in canopy gaps
Bryophytes in fir waves: Forest canopy indicator species and functional diversity decline in canopy gaps
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DOI：
10.1111/jvs.12718
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发表时间：
2019-03
影响因子：
2.8
通讯作者：
Monica B. Berdugo;M. Dovciak
中科院分区：
文献类型：
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作者：
Monica B. Berdugo;M. Dovciak
协编：Tohru Nakashizuka 摘要目的：苔藓植物可以覆盖四分之三的地表，发挥关键的生态功能，并增加温带中温带高海拔针叶林的生物多样性。正如间隙和间隙大小划分假设（GPH、GSPH）所示，森林间隙影响物种共存（和生态系统功能）。在这里，我们在高海拔森林苔藓植物群落及其功能属性的背景下测试这些假设。研究地点：美国纽约州怀特菲斯山的云杉-冷杉森林。方法：我们对 20 个间隙（冷杉波）的三种冠层开放环境（间隙、间隙边缘、森林冠层）中的冠层开放度、小气候、森林地表基质、维管植被覆盖和苔藓层（覆盖、常见物种和功能属性）进行了表征（n = 60）；功能属性基于 16 个形态、繁殖和生态苔藓植物功能性状 (PFT)。我们使用指示物种分析、排序和回归测试了与苔藓植物群落指标（覆盖度、组成）、性状和性状功能敏感性（功能分散度；FDis）相关的 GPH 和 GSPH。结果：冠层开放度驱动了地面温度、基质丰度和异质性（β多样性）以及林下维管束植被覆盖的梯度。 GPH 与 (a) 森林冠层指示物种（Dicranum fuscescens、Hypnum imponens 和 Tetraphis pellucida）的丰度模式和 (b) 基于三个 PFT（生长形式、肥力和酸度）的 FDis 一致，两者均随冠层覆盖而增加。我们没有在其余物种或性状中找到对 GPH 的支持，也没有发现对一般 GSPH 的支持；间隙宽度（12-44 m）与环境或苔藓植物群落梯度无关。结论：观察到，在整个冠层环境中，大多数苔藓植物指标缺乏变化，这表明苔藓植物层对高海拔森林中的自然冠层间隙具有高度抵抗力。然而，森林冠层指示物种的反应表明，气候变化或害虫可能会增加冠层死亡率，可能会导致某些森林冠层物种的减少，从而导致苔藓植物群落功能多样性的下降。
Co-ordinating Editor: Tohru Nakashizuka Abstract Aims: Bryophytes can cover three quarters of the ground surface, play key ecological functions, and increase biodiversity in mesic highelevation conifer forests of the temperate zone. Forest gaps affect species coexistence (and ecosystem functions) as suggested by the gap and gapsize partitioning hypotheses (GPH, GSPH). Here we test these hypotheses in the context of highelevation forest bryophyte communities and their functional attributes. Study Site: Spruce–fir forests on Whiteface Mountain, NY, USA. Methods: We characterized canopy openness, microclimate, forest floor substrates, vascular vegetation cover, and moss layer (cover, common species, and functional attributes) in three canopy openness environments (gap, gap edge, forest canopy) across 20 gaps (fir waves) (n = 60); the functional attributes were based on 16 morphologic, reproductive, and ecological bryophyte plant functional traits (PFTs). We tested GPH and GSPH relative to bryophyte community metrics (cover, composition), traits, and trait functional sensitivity (functional dispersion; FDis) using indicator species analysis, ordination, and regression. Results: Canopy openness drove gradients in groundlevel temperature, substrate abundance and heterogeneity (beta diversity), and understory vascular vegetation cover. The GPH was consistent with (a) the abundance patterns of forest canopy indicator species (Dicranum fuscescens, Hypnum imponens, and Tetraphis pellucida), and (b) FDis based on three PFTs (growth form, fertility, and acidity), both increasing with canopy cover. We did not find support for GPH in the remaining species or traits, or for GSPH in general; gap width (12–44 m) was not related to environmental or bryophyte community gradients. Conclusions: The observed lack of variation in most bryophyte metrics across canopy environments suggests high resistance of the bryophyte layer to natural canopy gaps in highelevation forests. However, responses of forest canopy indicator species suggest that canopy mortality, potentially increased by changing climate or insect pests, may cause declines in some forest canopy species and consequently in the functional diversity of bryophyte communities.