Kutsch Werner

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  • Preprint
    Steeper declines in forest photosynthesis than respiration explain age-driven decreases in forest growth
    ( 2014-04) Tang, Jianwu ; Luyssaert, Sebastiaan ; Richardson, Andrew D. ; Kutsch, Werner ; Janssens, Ivan A.
    The traditional view of forest dynamics originated by Kira, Shidei, and Odum suggests a decline in net primary productivity (NPP) in ageing forests due to stabilized gross primary productivity (GPP) and continuously increased autotrophic respiration (Ra). The validity of these trends in GPP and Ra is, however, very difficult to test because of the lack of long-term ecosystem-scale field observations of both GPP and Ra. Ryan and colleagues have proposed an alternative hypothesis drawn from site-specific results that aboveground respiration and belowground allocation decreased in ageing forests. Here we analyzed data from a recently assembled global database of carbon fluxes and show that the classical view of the mechanisms underlying the age-driven decline in forest NPP is incorrect and thus support Ryan’s alternative hypothesis. Our results substantiate the age-driven decline in NPP, but in contrast to the traditional view, both GPP and Ra decline in ageing boreal and temperate forests. We find that the decline in NPP in ageing forests is primarily driven by GPP, which decreases more rapidly with increasing age than Ra does, but the ratio of NPP/GPP remains approximately constant within a biome. Our analytical models describing forest succession suggest that dynamic forest ecosystem models that follow the traditional paradigm need to be revisited.
  • Article
    Building a global ecosystem research infrastructure to address global grand challenges for macrosystem ecology
    (American Geophysical Union, 2022-04-25) Loescher, Henry W. ; Vargas, Rodrigo ; Mirtl, Michael ; Morris, Beryl ; Pauw, Johan C. ; Yu, Xiubo ; Kutsch, Werner ; Mabee, Paula M. ; Tang, Jianwu ; Ruddell, Benjamin L. ; Pulsifer, Peter L. ; Bäck, Jaana K. ; Zacharias, Steffen ; Grant, Mark ; Feig, Gregor ; Zhang, Leiming ; Waldmann, Christoph ; Genazzio, Melissa A.
    The development of several large-, “continental”-scale ecosystem research infrastructures over recent decades has provided a unique opportunity in the history of ecological science. The Global Ecosystem Research Infrastructure (GERI) is an integrated network of analogous, but independent, site-based ecosystem research infrastructures (ERI) dedicated to better understand the function and change of indicator ecosystems across global biomes. Bringing together these ERIs, harmonizing their respective data and reducing uncertainties enables broader cross-continental ecological research. It will also enhance the research community capabilities to address current and anticipate future global scale ecological challenges. Moreover, increasing the international capabilities of these ERIs goes beyond their original design intent, and is an unexpected added value of these large national investments. Here, we identify specific global grand challenge areas and research trends to advance the ecological frontiers across continents that can be addressed through the federation of these cross-continental-scale ERIs.