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Latent heat exchange in the boreal and arctic biomes
Author(s) -
Kasurinen Ville,
Alfredsen Knut,
Kolari Pasi,
Mammarella Ivan,
Alekseychik Pavel,
Rinne Janne,
Vesala Timo,
Bernier Pierre,
Boike Julia,
Langer Moritz,
Belelli Marchesini Luca,
Huissteden Ko,
Dolman Han,
Sachs Torsten,
Ohta Takeshi,
Varlagin Andrej,
Rocha Adrian,
Arain Altaf,
Oechel Walter,
Lund Magnus,
Grelle Achim,
Lindroth Anders,
Black Andy,
Aurela Mika,
Laurila Tuomas,
Lohila Annalea,
Berninger Frank
Publication year - 2014
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12640
Subject(s) - tundra , environmental science , vapour pressure deficit , eddy covariance , wetland , ecosystem , ecosystem respiration , atmospheric sciences , taiga , biome , latent heat , ecology , vegetation (pathology) , boreal , vegetation type , geography , grassland , transpiration , biology , geology , meteorology , botany , medicine , photosynthesis , pathology
In this study latent heat flux ( λE ) measurements made at 65 boreal and arctic eddy‐covariance ( EC ) sites were analyses by using the Penman–Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas‐fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The Penman–Monteith equation was calibrated with variable surface resistances against half‐hourly eddy‐covariance data and clear differences between ecosystem types were observed. Based on the modeled behavior of surface and aerodynamic resistances, surface resistance tightly control λE in most mature forests, while it had less importance in ecosystems having shorter vegetation like young or recently harvested forests, grasslands, wetlands and tundra. The parameters of the Penman–Monteith equation were clearly different for winter and summer conditions, indicating that phenological effects on surface resistance are important. We also compared the simulated λE of different ecosystem types under meteorological conditions at one site. Values of λE varied between 15% and 38% of the net radiation in the simulations with mean ecosystem parameters. In general, the simulations suggest that λE is higher from forested ecosystems than from grasslands, wetlands or tundra‐type ecosystems. Forests showed usually a tighter stomatal control of λE as indicated by a pronounced sensitivity of surface resistance to atmospheric vapor pressure deficit. Nevertheless, the surface resistance of forests was lower than for open vegetation types including wetlands. Tundra and wetlands had higher surface resistances, which were less sensitive to vapor pressure deficits. The results indicate that the variation in surface resistance within and between different vegetation types might play a significant role in energy exchange between terrestrial ecosystems and atmosphere. These results suggest the need to take into account vegetation type and phenology in energy exchange modeling.