Direct and Indirect Effects of Climate Change on Boreal Peatlands: A Mesocosm Approach

陆地生态系统可能会对 全球气候变化，虽然规模和方向 这些反馈在很大程度上是未知的。 北方湿地是 特别重要的是，由于其规模大，生产 厌氧“温室”气体，全球大量储存的 泥炭中的碳，以及潜在的反馈， 温度。 我们建议控制地下水位， 土壤温度在沼泽和沼泽围隔生态系统，以确定 气候变化和南方共同市场之间的直接和间接反馈 北方泥炭地 完整的泥炭块，伴随着 将使用灌木、苔藓和禾本科植被层。 还有， 模拟天然沼泽地的区域地下水流。 一系列的社区和生态系统的反应将是 测量，包括微量气体通量，营养矿化和 碳库和养分库的净变化 在土壤基质质量随时间的变化，孔隙水化学，植物 群落组成，植物养分吸收，植物和微生物 生物量和初级生产力。 %%% 我们的中心假设是：温度和通风状态 直接控制微量气体通量的速率和分配 和土壤养分的有效性，但这种气候 土壤链接受到土壤基质质量的限制。 土壤 养分的有效性反过来又控制着植物的动态， 土壤基质质量反馈。 之前的研究 研究人员已经表明，三个主要的控制因素 变量（基质质量、温度、通风状态） 以非线性、非直观的方式相互作用。 直接实验 将揭开北方气候的控制因素的层次结构 泥炭地，使我们能够作出强有力的预测， 未来的气候变化。

Terrestrial ecosystems may have significant feedbacks to global climate change, although the magnitude and direction of these feedbacks is largely unknown. Boreal wetlands are of particular importance due to their large extent, production of anaerobic "greenhouse" gases, globally significant stores of carbon in peat, and potential feedbacks with increased temperatures. We propose to manipulate water-table levels and soil temperatures in bog and fen mesocosms to determine the direct and indirect feedbacks between climate change and southern boreal peatlands. Intact blocks of peat, with the accompanying shrub, moss, and graminoid vegetation layers will be used. Also, the regional groundwater flow in natural fens will be simulated. A full array of community and ecosystem responses will be measured, including trace gas fluxes, nutrient mineralization and availability, net changes in carbon and nutrient pools, changes in soil substrate quality over time, pore water chemistry, plant community composition, plant nutrient uptake, plant and microbial biomass, and primary productivity. %%% Our central hypothesis is: Temperature and aeration status directly control the rates and partitioning of trace gas fluxes and soil nutrient availability in peatlands, but this climate - soil link is constrained by soil substrate quality. Soil nutrient availability in turn controls plant dynamics, which will feedback on soil substrate quality. The previous research of the investigators has shown that the three primary controlling variables (substrate quality, temperature, aeration status) interact in nonlinear, nonintuitive ways. Direct experimentation will unravel the hierarchy of controlling factors in boreal peatlands and allow us to make robust predictions of responses to future climate change.