Structure and functions of bryophyte communities in temperate and boreal ecosystems

在北方针叶林中，森林地面苔藓植物（苔藓、苔类植物和角苔类植物）执行关键的生态系统过程和维持生态系统恢复力的植物-土壤反馈。这是否适用于由阔叶落叶、混交林和针叶林组成的寒温带过渡带尚不清楚。我们对苔藓植物的功能特征，即定义其在生态系统中作用的物种特征的了解仍然很少，特别是沿着冠层或气候驱动的梯度。破译冠层组成、气候和物种相互作用对苔藓植物的影响对于保护和可持续森林管理至关重要，特别是在像阿卡迪亚森林这样的地区。我的长期目标是全面了解温带和北方生态系统中苔藓植物群落的结构和功能，特别是在过渡地带，如阿卡迪亚森林。我最近在北方和亚北极生态系统的研究表明，森林的冠层组成和年龄、自然和人为干扰、叶片微生物群落和气候之间的相互作用对苔藓植物群落的组成和与碳氮循环和维管植物补充相关的生态系统功能有重要影响。我的短期目标是通过利用植物学、生物地球化学和分子工具，结合野外观测和实验工作，了解不同空间尺度下寒带-温带过渡带苔藓植物群落组成和功能的影响机制。通过本研究，我们将：(1)研究阿卡迪亚森林苔藓植物的功能特征和生态系统功能；(2)研究苔藓植物及其微生物组如何相互作用并影响固氮；(3)测试苔藓植物对新环境条件的适应潜力和表型可塑性。我们的工作将沿着北方森林南部边缘的三个自然梯度进行：沿海到内陆的水分可用性梯度，落叶到针叶林的梯度，以及温度的纬度梯度。过渡带对环境变化特别敏感，物种范围可能在北方森林的南缘发生变化，以应对气候变化。我们将提供关键的野外和实验为基础的生态，结构和功能的林下苔藓植物群落在寒带-温带过渡带的证据。阿卡迪亚森林已被世界自然基金会指定为极度濒危的生态系统。我们的研究将提高我们对森林在应对气候变化和日益增加的人为压力方面的恢复力的理解，因为在未来50年里，新不伦瑞克省大约50%的森林将得到积极的管理。

In boreal coniferous forests, forest-floor bryophytes (mosses, liverworts, and hornworts) carry out key ecosystem processes and plant-soil feedbacks that maintain ecosystem resilience. Whether this holds true at the boreal-temperate ecotone that comprises a mosaic of broadleaf deciduous, mixed wood, and coniferous forests remains unclear. Our knowledge of the functional traits of bryophytes, i.e. the characteristics of species that define their roles in ecosystems, is still scant, especially along canopy or climate driven gradients. Deciphering the effects of canopy composition, climate, and species interactions on bryophytes is critical for conservation and sustainable forest management, especially in areas like the Acadian forest. My long-term objective is to provide a comprehensive understanding of the structures and functions of bryophyte communities in temperate and boreal ecosystems, particularly in transition zones, such as the Acadian forest. My recent research in boreal and subarctic ecosystems has shown that interactions between canopy composition and age of forests, natural and anthropic disturbances, leaf microbial communities, and climate have major impacts on bryophyte community assembly and ecosystem functions related to carbon and nitrogen (N) cycling and vascular plant recruitment. My short-term objective is to understand the mechanisms affecting the composition and functions of bryophyte communities at the boreal-temperate ecotone at different spatial scales by combining field-based observational and experimental work using botanical, biogeochemical, and molecular tools. With the proposed research we will: (1) characterize bryophyte functional traits and ecosystem function in Acadian forests, (2) determine how bryophytes and their microbiome interact and affect N-fixation, and (3) test the adaptation potential and phenotypic plasticity of bryophytes to novel environmental conditions at the boreal-temperate ecotone. Our work will be conducted along three natural gradients at the southern edge of the boreal forest: coastal to inland gradient in moisture availability, deciduous to coniferous gradient, and a latitudinal gradient in temperature. Ecotones are particularly sensitive to environmental change and species range shifts are likely at the southern edge of the boreal forest in response to climate change. We will provide key field- and experimental-based evidence on the ecology, structure, and functions of understory bryophyte communities in the boreal-temperate ecotone. Acadian forests have been designated as a critically endangered ecosystem by the World Wildlife Fund. Our research will improve our understanding of forest resilience in response to climate change and to increasing anthropogenic pressures, as about 50% of forests in New Brunswick will be actively managed in the next 50 years.