Janssens I.A

Publications (2)10.5 Total impact

• Source

  Available from: Daniel Epron

  Article: Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes

  Bahn M, Reichstein M, Davidson E.A, Grunzweig J, Jung M, Carbone M.S, Epron D, Misson L, Nouvellon Y, Roupsard O, Savage K, Trumbore S.E, Gimeno C, Yuste J.C, Tang J, Vargas R, Janssens I.A
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  ABSTRACT: Soil respiration (SR) constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. However, there still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 80 site-years for 57 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SRMAT), irrespective of the type of ecosystem and biome. This is theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q(10)). We further show that for seasonally dry sites where annual precipitation (P) is lower than potential evapotranspiration (PET), annual SR can be predicted from wet season SRMAT corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SRMAT for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle.
  Biogeosciences 07/2010; 7(7):2147-2157. · 3.86 Impact Factor
• Source

  Available from: Rodrigo Vargas

  Article: Ecosystem CO2 fluxes of arbuscular and ectomycorrhizal dominated vegetation types are differentially influenced by precipitation and temperature

  Vargas R, Baldocchi D.D, Querejeta J.I, Curtis P.S, Hasselquist N.J, Janssens I.A, Allen M.F, Montagnani L
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  ABSTRACT: P> Here, we explore how interannual variations in environmental factors (i.e. temperature, precipitation and light) influence CO2 fluxes (gross primary production and ecosystem respiration) in terrestrial ecosystems classified by vegetation type and the mycorrhizal type of dominant plants (arbuscular mycorrhizal (AM) or ectomycorrhizal (EM)). We combined 236 site-year measurements of terrestrial ecosystem CO2 fluxes and environmental factors from 50 eddy-covariance flux tower sites with information about climate, vegetation type and dominant plant species. Across large geographical distances, interannual variations in ecosystem CO2 fluxes for EM-dominated sites were primarily controlled by interannual variations in mean annual temperature. By contrast, interannual variations in ecosystem CO2 fluxes at AM-dominated sites were primarily controlled by interannual variations in precipitation. This study represents the first large-scale assessment of terrestrial CO2 fluxes in multiple vegetation types classified according to dominant mycorrhizal association. Our results support and complement the hypothesis that bioclimatic conditions influence the distribution of AM and EM systems across large geographical distances, which leads to important differences in the major climatic factors controlling ecosystem CO2 fluxes.
  New Phytologist 01/2010; 185(1):226-236. · 6.64 Impact Factor