Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil
Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil
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DOI：
10.1016/j.soilbio.2005.10.011
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发表时间：
2006-06-01
影响因子：
9.7
通讯作者：
Steudler, P
中科院分区：
文献类型：
--
作者：
Borken, W;Davidson, EA;Steudler, P
土壤湿度通过限制甲烷扩散到土壤中来强烈控制大气甲烷的吸收，导致在大多数非干旱条件下土壤湿度和甲烷吸收率之间呈负相关。然而，很少有人知道在严重干旱的温带森林水分胁迫对甲烷吸收的影响。我们模拟极端的夏季干旱排除168毫米（2001年）和344毫米（2002年）穿透雨使用三个半透明的屋顶在混合落叶林在哈佛森林，马萨诸塞州，美国。在2001年穿透雨排除的第一周和2002年治疗期间的大部分时间，治疗显着增加CH 4吸收。在自然夏末干旱期间，仅在对照和排除区中短暂发现夏季CH 4吸收率低，此时含水量低于0.15 g cm（-3）可能导致A层甲烷氧化菌的水分胁迫。由于这些土壤排水良好，排除处理湿润事件之间的A层含水量的影响不大，水应力的影响较小，更短的比甲烷扩散的整体处理效果。甲烷消耗率最高的是在A层，并表现出重量含水量和CH 4消耗之间的抛物线关系，在0.23 g H2O g（-1）土壤的最大速率。平均而言，约74%的大气CH 4消耗在顶部4-5厘米的矿质土壤。相比之下，很少或没有CH 4的消费发生在0地平线。积雪显著降低了吸收率从12月到3月。除雪增强CH 4吸收约700- 1000%，导致吸收率类似于生长季节期间测量的。土壤温度对CH 4吸收的影响很小，只要矿质土壤不冻结，表明甲烷氧化菌的强基板限制全年。我们的研究结果表明，雪期的延长可能会影响CH 4氧化的年速率，夏季干旱可能会增加土壤CH 4汇的温带森林土壤。(c)2005爱思唯尔有限公司保留所有权利。
Soil moisture strongly controls the uptake of atmospheric methane by limiting the diffusion of methane into the soil, resulting in a negative correlation between soil moisture and methane uptake rates under most non-drought conditions. However, little is known about the effect of water stress on methane uptake in temperate forests during severe droughts. We simulated extreme summer droughts by exclusion of 168 mm (2001) and 344 mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15 g cm(-3) may have caused water stress of methanotrophs in the A horizon. Because these soils are well drained, the exclusion treatment had little effect on A horizon water content between wetting events, and the effect of water stress was smaller and more brief than was the overall treatment effect on methane diffusion. Methane consumption rates were highest in the A horizon and showed a parabolic relationship between gravimetric water content and CH4 consumption, with maximum rate at 0.23 g H2O g(-1) soil. On average, about 74% of atmospheric CH4 was consumed in the top 4-5 cm of the mineral soil. By contrast, little or no CH4 consumption occurred in the 0 horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH4 uptake as long as the mineral soil was not frozen, indicating strong substrate limitation of methanotrophs throughout the year. Our results suggest that the extension of snow periods may affect the annual rate of CH4 oxidation and that summer droughts may increase the soil CH4 sink of temperate forest soils. (c) 2005 Elsevier Ltd. All rights reserved.