Forest biogeochemistry interactions among greenhouse gases and N deposition

✍ Scribed by Lars-Owe Nilsson

• Publisher: Springer Netherlands
• Year: 1995
• Tongue: English
• Weight: 446 KB
• Volume: 85
• Category: Article
• ISSN: 0049-6979
• DOI: 10.1007/bf00477202

✦ Synopsis

Interactions between N deposition and the fluxes between atmosphere and forest ecosystems of the greenhouse gases CO2, CH 4 and N20 are examined. It is argued that forest productivity has increased due to increased N deposition since the industrial revolution in areas where N has been limiting to forest production. It is shown that most boreal and large parts of temperate forests growing on mineral soils are N limited still today. The increased above ground production due to improved N availability seems to result in an equal sized build-up of the C pool of at least boreal forest soils, in the first place in the humus layer. This is explained by an increased litter production of needles and roots arid a decreased decomposition rate in an N rich environment. N deposition thus contributes to reduce the atmospheric levels of CO 2. In areas where N is still limiting forest growth, a decreased N deposition, thus, logically, would result in decreased forest productivity and act as a source of increased CO 2 levels to the atmosphere. Increased N deposition results in decreased CH 4 oxidation of forest mineral soils and thus, acts to increase the greenhouse effect. However, this mechanism expressed as greenhouse contribution probably is small in relation to the reduction caused by increased CO 2 fixation. From most forest mineral soils there seem to be small rates of N20 formation independently of deposition rates.