Norby Richard J, Childs Joanne, Hanson Paul J, Warren Jeffrey M
Environmental Sciences Division and Climate Change Science Institute Oak Ridge National Laboratory Oak Ridge TN USA.
Ecol Evol. 2019 Oct 30;9(22):12571-12585. doi: 10.1002/ece3.5722. eCollection 2019 Nov.
mosses are keystone components of peatland ecosystems. They facilitate the accumulation of carbon in peat deposits, but climate change is predicted to expose peatland ecosystem to sustained and unprecedented warming leading to a significant release of carbon to the atmosphere. responses to climate change, and their interaction with other components of the ecosystem, will determine the future trajectory of carbon fluxes in peatlands. We measured the growth and productivity of in an ombrotrophic bog in northern Minnesota, where ten 12.8-m-diameter plots were exposed to a range of whole-ecosystem (air and soil) warming treatments (+0 to +9°C) in ambient or elevated (+500 ppm) CO. The experiment is unique in its spatial and temporal scale, a focus on response surface analysis encompassing the range of elevated temperature predicted to occur this century, and consideration of an effect of co-occurring CO altering the temperature response surface. In the second year of warming, dry matter increment of increased with modest warming to a maximum at 5°C above ambient and decreased with additional warming. cover declined from close to 100% of the ground area to <50% in the warmest enclosures. After three years of warming, annual productivity declined linearly with increasing temperature (13-29 g C/m per °C warming) due to widespread desiccation and loss of . Productivity was less in elevated CO enclosures, which we attribute to increased shading by shrubs. desiccation and growth responses were associated with the effects of warming on hydrology. The rapid decline of the community with sustained warming, which appears to be irreversible, can be expected to have many follow-on consequences to the structure and function of this and similar ecosystems, with significant feedbacks to the global carbon cycle and climate change.
苔藓是泥炭地生态系统的关键组成部分。它们促进了泥炭沉积物中碳的积累，但气候变化预计会使泥炭地生态系统面临持续且前所未有的变暖，导致大量碳释放到大气中。对气候变化的响应及其与生态系统其他组成部分的相互作用，将决定泥炭地碳通量的未来轨迹。我们在明尼苏达州北部的一个雨养泥炭沼泽中测量了苔藓的生长和生产力，在那里，十个直径12.8米的地块在环境CO或升高（+500 ppm）的CO条件下接受了一系列全生态系统（空气和土壤）变暖处理（+0至+9°C）。该实验在空间和时间尺度上独具特色，专注于响应面分析，涵盖了预计本世纪会出现的升温范围，并考虑了同时存在的CO改变温度响应面的影响。在变暖的第二年，苔藓的干物质增量随着适度变暖而增加，在比环境温度高5°C时达到最大值，之后随着进一步变暖而减少。苔藓覆盖度从接近地面面积的100%下降到最温暖围栏中的<50%。经过三年的变暖，由于广泛干涸和苔藓损失，苔藓的年生产力随温度升高呈线性下降（每升温1°C，生产力下降13 - 29克碳/平方米）。在CO浓度升高的围栏中生产力较低，我们将其归因于灌木遮荫增加。苔藓的干涸和生长响应与变暖对水文的影响有关。随着持续变暖，苔藓群落迅速衰退，这似乎是不可逆的，预计会对该生态系统及类似生态系统的结构和功能产生许多后续影响，并对全球碳循环和气候变化产生重大反馈。
