Nitric oxide emissions from forest soils

Abstract

Nitric oxide (NO) fluxes to the atmosphere were determined from different soil types in coniferous forest and deciduous forest in the Netherlands. Dynamic chambers were used to determine the emission every week throughout a year. Forest type and soil texture are important parameters leading to large differences in fluxes between sites. High fluxes of up to 178 ng m −2 s −1 were observed in summer in a Douglas fir forest on a sandy soil. In a nearby beech forest, on the same soil, fluxes of up to 63 ng m −2 s −1 were observed. Emissions from clayey soils in a beech forest were much lower, ranging from 0 to 14 ng m −2 s −1 . Besides the important effect of the forest community type and the soil texture on the NO flux, a strong positive correlation with soil temperature was observed (accounting for up to 70% of the variance). Soil moisture could explain up to 60% of the variance of the NO flux. It seems that an optimum range of intermediate moisture content exists, ranging from 30 to 45% dry weight or from 55 to 85% water‐filled pore space, approximately, where high temperatures lead to high emissions.