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Understanding disturbance regimes from patterns in biomass and primary productivity
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  • Siyuan Wang,
  • Hui Yang,
  • Sujan Koirala,
  • Matthias Forkel,
  • Markus Reichstein,
  • Nuno Carvalhais
Siyuan Wang
Max-Planck Institute for Biogeochemistry, Max-Planck Institute for Biogeochemistry

Corresponding Author:[email protected]

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Hui Yang
Max-Planck Institute for Biogeochemistry, Max-Planck Institute for Biogeochemistry
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Sujan Koirala
Max-Planck Institute for Biogeochemistry, Max-Planck Institute for Biogeochemistry
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Matthias Forkel
TU Dresden, TU Dresden
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Markus Reichstein
Max-Planck Institute for Biogeochemistry, Max-Planck Institute for Biogeochemistry
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Nuno Carvalhais
Max-Planck Institute for Biogeochemistry, Max-Planck Institute for Biogeochemistry
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Abstract

Natural and anthropogenic disturbances act as important drivers of tree mortality, shaping the structure, composition and biomass distribution of forests. Disturbance regimes may emerge from different characteristics of disturbance events over time and space. We design a model- based experiment to investigate the links between disturbance regimes at the landscape scale and spatial features of biomass patterns. The effects on biomass of a wide range of disturbance regimes are simulated by varying three different parameters, i.e. μ (probability scale), α (clustering degree), and β (intensity slope) that shape the extent, frequency, and intensity of disturbance events, respectively. A simple dynamic carbon cycle model is used to simulate 200 years of plant biomass dynamics in response to circa +2000 different disturbance regimes, depending on the different combinations of μ, α, and β. Each parameter combination yields a spatially explicit estimate of plant biomass for which sixteen synthesis statistics are estimated on the spatial distributions of biomass, including information-based and texture features. Based on a multi-output regression approach we link these synthesis statistics with additional gross primary production (GPP) constraints to retrieve the three disturbance parameters. In doing so we evaluate the confidence in inferring disturbance regimes from spatial distributions of biomass. Our results show that all three parameters can be confidently retrieved. The Nash-Sutcliffe efficiency for the prediction of the μ, α, and β is 97.3%, 96.6%, and 97.9%, respectively. A feature importance analysis reveals that the distribution statistics dominate the prediction of μ and β, while features quantifying texture have a stronger connection with α. Overall, this study clarifies the association between biomass patterns emerging from different underlying disturbance regimes, while overcoming the previously found equifinality between mortality rates and total biomass. Given the links between decadal vegetation dynamics and the uncertainties in the role of terrestrial ecosystems in the global biogeochemical cycles, a better understanding and the quantification of disturbance regimes would improve our current understanding of controls and feedback at the biosphere-atmosphere interface in the current Earth system models.
27 Oct 2023Submitted to ESS Open Archive
27 Oct 2023Published in ESS Open Archive