Increased soil respiration in response to experimentally reduced snow cover and increased soil freezing in a temperate deciduous forest
Increased soil respiration in response to experimentally reduced snow cover and increased soil freezing in a temperate deciduous forest
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DOI：
10.1007/s10533-018-0497-z
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发表时间：
2018-09
期刊：
影响因子：
4
通讯作者：
A. Reinmann;P. Templer
中科院分区：
文献类型：
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作者：
A. Reinmann;P. Templer
季节性积雪地区的冬季积雪通过使土壤免受冰冻气温的影响，在缓和生态系统过程中发挥着重要作用。然而，气候模型预测，下个世纪中高纬度的积雪将会减少。我们在美国马萨诸塞州哈佛森林的温带落叶林中进行了一项除雪实验，以量化冬季积雪减少和土壤冻结增加对土壤总呼吸及其体积(即异养)和根际组分的影响。除雪使土壤冻结程度增加了三倍以上，导致年土壤总呼吸增加27.6%(p=0.058)。在我们的地块和多年的研究中，我们发现，土壤冻结的严重程度，而不仅仅是土壤冻结的存在，是土壤呼吸对冬季积雪减少的反应的主要驱动因素。总体土壤呼吸对土壤总呼吸的贡献最大，根-根际呼吸占总土壤呼吸的26.1±6.5%。除雪显著增加细根死亡率(p=0.03)，且与土壤霜冻深度和霜冻持续时间(p=0.068；=0.46)、土壤总呼吸速率(p=0.075；=0.27)、根-根际呼吸对土壤总呼吸的贡献(p=0.004；=0.58)呈正相关。我们的结论是，土壤呼吸对土壤冻结的响应是由植物介导的过程驱动的，即土壤霜冻诱导的根死亡通过分解根坏死体来刺激呼吸，额外的增强可能与启动土壤有机质分解和增加与生长相关的根呼吸速率有关。
Winter snowpack in seasonally snow-covered regions plays an important role in moderating ecosystem processes by insulating soil from freezing air temperatures. However, climate models project a decline in snowpack at mid and high latitudes over the next century. We conducted a snow removal experiment in a temperate deciduous forest at Harvard Forest in Massachusetts, USA to quantify the effects of a reduced winter snowpack and increased soil freezing on total soil respiration and its bulk (ie heterotrophic) and root-rhizosphere components. Snow removal increased soil freezing severity by more than three-fold, which resulted in a 27.6% increase in annual total soil respiration (p= 0.058). Across our plots and years of this study, we found that the severity, rather than simply the presence of soil freezing, was the primary driver of the soil respiration response to reduced winter snowpack. Bulk soil respiration made the largest contribution to total soil respiration with root-rhizosphere respiration contributing up to 26.1±6.5% of total soil respiration across plot types and years. Snow removal significantly increased fine root mortality (p= 0.03), which was positively correlated with soil frost depth and duration (p= 0.068,= 0.46), rates of total soil respiration (p= 0.075;= 0.27) and the contribution of root-rhizosphere respiration to total soil respiration (p= 0.004;= 0.58). We conclude that increased rates of soil respiration in response to soil freezing are driven by plant-mediated processes, whereby soil frost-induced root mortality stimulates respiration through decomposition of root necromass with additional enhancements possibly related to priming of soil organic matter decomposition and elevated rates of root respiration associated with growth.