Factors controlling atmospheric methane consumption by temperate forest soils

Over the past 6 years (1988–1993), we have examined the effects of soil temperature, soil moisture, site fertility, and nitrogen fertilization on the consumption of atmospheric CH 4 by temperate forest soils located at the Harvard Forest in Petersham, Massachusetts. We found that soil temperature is an important controller of CH 4 consumption at temperatures between −5° and 10°C but had no effect on CH 4 consumption at temperatures between 10° and 20°C. Soil moisture exerts strong control on CH 4 consumption over a range of 60 to 100% water‐filled pore space (% WFPS). As moisture increased from 60 to 100% WFPS, CH 4 consumption decreased from 0.1 to 0 mg CH 4 ‐C m −2 h −1 because of gas transport limitations. At 20 to 60% WFPS, site fertility was a strong controller of CH 4 consumption. High‐fertility sites had 2 to 3 times greater CH 4 consumption rates than low‐fertility sites. Nitrogen‐fertilized soils (50 and 150 kg NH 4 NO 3 ‐N ha −1 yr −1 ) had annually averaged CH 4 consumption rates that were 15 to 64% lower than annually averaged CH 4 consumption by control soils. The decrease in CH 4 consumption was related to both the years of application and quantity of nitrogen fertilizer added to these soils.