Contrasting effects of reindeer grazing on CO2, CH4, and N2O fluxes originating from the northern boreal forest floor

• Published in: Land Degradation & Development
• Main Authors: Köster, Kajar, Köster, Egle, Berninger, Frank, Heinonsalo, Jussi, Pumpanen, Jukka
• Other Authors: Department of Forest Sciences, Forest Soil Science, Forest Ecology and Management, Viikki Plant Science Centre (ViPS), Ecosystem processes (INAR Forest Sciences), Helsinki Institute of Sustainability Science (HELSUS), Jussi Heinonsalo / Principal Investigator
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley and Sons Ltd 2020
• Subjects: boreal forests; greenhouse gases; lichens; mosses; reindeer grazing; NITROUS-OXIDE; PINE FOREST; CRYPTOGAMIC COVERS; SOIL; CARBON; EMISSIONS; TUNDRA; RESPIRATION; DYNAMICS; BIOMASS; Forestry; Environmental sciences; Arctic; Arctic lichen; Rangifer tarandus; Tundra
• Online Access: http://hdl.handle.net/10138/309202

Reindeer (Rangifer tarandus L.) is considered to be an important mammalian herbivore, strongly influencing Arctic lichen-dominated ecosystems. There is no wide knowledge about the effect of reindeer on greenhouse gas (GHG) fluxes in northern boreal forests. Ground vegetation plays an important role in absorbing nitrogen (N) and carbon dioxide (CO2) from the atmosphere. Lately, it has also been found to be a significant source of nitrous oxide (N2O) and a small source of methane (CH4). We investigated the influence of reindeer grazing on field layer GHG (CO2, CH4, and N2O) fluxes, ground vegetation coverage and biomass, and soil physical properties (temperature and moisture) in a northern boreal forest. At our study site, the reindeer-induced replacement of lichen by mosses had contrasting effects on the GHG fluxes originating from the field layer. Field layer CO2 efflux was significantly higher in grazed areas. The field layer was a CH4 sink in all areas, but grazed areas absorbed more CH4 compared to non-grazed areas. Although total N2O fluxes remained around 0 in grazed areas, a small N2O sink occurred in non-grazed areas with lower moss biomass. Our results indicated that grazing by reindeer in northern boreal forests affects GHG fluxes from the forest field layer both positively and negatively, and these emissions largely depend on grazing-induced changes in vegetation composition. Peer reviewed