NO AND N2O FLUXES FROM A BELGIAN FOREST AFFECTED BY ELEVATED NITROGEN DEPOSITION

Nitrous oxide (N2O) and nitric oxide (NO) are important atmospheric trace gases, and soils (including forest soils) are a substantial source of both gases. In forests subjected to elevated N deposition these emissions are considered as indirect emissions from agricultural N sources (mainly NH3) or c...

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Autores principales: Boeckx,Pascal, Vervaet,Hilde, Cleemput,Oswald van
Lenguaje:English
Publicado: Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción 2005
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Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432005000200003
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Sumario:Nitrous oxide (N2O) and nitric oxide (NO) are important atmospheric trace gases, and soils (including forest soils) are a substantial source of both gases. In forests subjected to elevated N deposition these emissions are considered as indirect emissions from agricultural N sources (mainly NH3) or combustion (e.g. NOx from traffic). However, knowledge about N2O and NO exchange between forests and the atmosphere is scarce. The aim of this study was to determine N2O and NO emission rates from a deciduous forest in Belgium, receiving a high N-deposition (ca. 40 kg N ha-1 yr-1). In April 2000, the NO emission from the forested location was 17.3 (± 1.2) and 17.05 (± 0.7) ng NO-N m-2 s-1, respectively, for the soil including the organic layer and the mineral soil only. In June 2000, the NO flux from the same location was 94.3 (± 14.1) and 53.8 (± 10.3) ng NO-N m-2 s-1, respectively, for the soil with organic layer and the mineral soil only. In April 2000, the NO emission from a clear-cut location in the same forest for the soil with organic layer was 30.5 (±1.52) ng NO-N m-2 s-1, whereas the flux from the mineral soil was 42.3 (± 1.33) ng NO-N m-2 s-1. In June 2000, however, the mineral soil emitted a significantly higher amount of NO than the clear-cut soil with organic layer (145.8 ± 7.2 ng NO-N m-2 s-1 versus 22.6 ± 3.1 ng NO-N m-2 s-1). The soil at the forested location acted as a net sink for N2O, with a mean annual flux of -0.63 ± 0.57 ng N2O-N m-2 s-1. In contrast the soil at the clear-cut site acted as a net N2O source, with a mean annual flux of 1.55 ± 0.90 ng N2O-N m-2 s-1. From these measurements it could be concluded that the forested soil was a significant secondary NO source and a N2O source or sink. However, more research is needed to investigate how N deposition, climate and forest management can affect N trace gas exchange in forest soils