Relationship between ecosystem productivity and photosynthetically active radiation for northern peatlands

摘要: We analyzed the relationship between net ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density or PPFD), using published unpublished data that have been collected during midgrowing season for balance studies at seven peatlands in North America Europe. NEE measurements included both eddy-correlation tower clear, static chamber methods, which gave very similar results. Data were by site, as aggregated sets peatland type (bog, poor fen, rich all fens) a single set peatlands. In cases, fit with rectangular hyperbola (NEE = α PPFD Pmax/(α + Pmax) R) better described NEE-PPFD than did linear β R). Poor fens generally had relationships, while bogs lower respiration rates (R −2.0μmol m−2s−1 −2.7 μmol moderate high light levels (Pmax 5.2 10.8 fens). As class, northern much smaller −2.4 m−2s−1) (α 0.020 Pmax 9.2μmol upland ecosystems (closed canopy forest, grassland, cropland) summarized Ruimy et al. [1995]. Despite this low productivity, soil pools are 5–50 times larger because slow decomposition caused litter quality anaerobic, cold soils.