![Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil [An article from: Soil Biology and Biochemistry]](https://www.ebooknetworking.net/books/B00/0RR/bigB000RR8HMY.jpg)
Effect of summer throughfall exclusion, summer drought, and winter snow cover on methane fluxes in a temperate forest soil [An article from: Soil Biology and Biochemistry]
Description
This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
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 168mm (2001) and 344mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH"4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH"4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15g 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 CH"4 consumption, with maximum rate at 0.23g H"2Og^-^1 soil. On average, about 74% of atmospheric CH"4 was consumed in the top 4-5cm of the mineral soil. By contrast, little or no CH"4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH"4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH"4 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 CH"4 oxidation and that summer droughts may increase the soil CH"4 sink of temperate forest soils.
Description:
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 168mm (2001) and 344mm (2002) throughfall using three translucent roofs in a mixed deciduous forest at the Harvard Forest, Massachusetts, USA. The treatment significantly increased CH"4 uptake during the first weeks of throughfall exclusion in 2001 and during most of the 2002 treatment period. Low summertime CH"4 uptake rates were found only briefly in both control and exclusion plots during a natural late summer drought, when water contents below 0.15g 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 CH"4 consumption, with maximum rate at 0.23g H"2Og^-^1 soil. On average, about 74% of atmospheric CH"4 was consumed in the top 4-5cm of the mineral soil. By contrast, little or no CH"4 consumption occurred in the O horizon. Snow cover significantly reduced the uptake rate from December to March. Removal of snow enhanced CH"4 uptake by about 700-1000%, resulting in uptake rates similar to those measured during the growing season. Soil temperatures had little effect on CH"4 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 CH"4 oxidation and that summer droughts may increase the soil CH"4 sink of temperate forest soils.
