Journal Article

Understanding Disturbance Regimes From Patterns in Modeled Forest Biomass

Koirala, Sujan, Carvalhais, Nuno, Forkel, Matthias, Wang, Siyuan, Reichstein, Markus, Yang, Hui

2024

Overview

Natural and anthropogenic disturbances are important drivers of tree mortality, shaping the structure, composition, and biomass distribution of forest ecosystems. Differences in disturbance regimes, characterized by the frequency, extent, and intensity of disturbance events, result in structurally different landscapes. In this study, we design a model‐based experiment to investigate the links between disturbance regimes and spatial biomass patterns. First, the effects of disturbance events on biomass patterns are simulated using a simple dynamic carbon cycle model based on different disturbance regime attributes, which are characterized via three parameters: μ (probability scale), α (clustering degree), and β (intensity slope). 856,800 dynamically stable biomass patterns were then simulated using combined disturbance regime, primary productivity, and background mortality. As independent variables, we use biomass synthesis statistics from simulated biomass patterns to retrieve three disturbance regime parameters. Results show confident inversion of all three “true” disturbance parameters, with Nash‐Sutcliffe efficiency of 94.8% for μ, 94.9% for α, and 97.1% for β. Biomass histogram statistics primarily dominate the prediction of μ and β, while texture features have a more substantial influence on α. Overall, these results demonstrate the association between biomass patterns and disturbance regimes. Given the increasing availability of Earth observation of biomass, our findings open a new avenue to understand better and parameterize disturbance regimes and their links with vegetation dynamics under climate change. Ultimately, at a large scale, this approach would improve our current understanding of controls and feedback at the biosphere‐atmosphere interface in the present Earth system models. Plain Language Summary Forest dynamics are shaped by different disturbances, which are challenging to monitor and predict. Identifying individual disturbance occurrences and their impact on forest carbon stocks (biomass) is complex. However, our study deciphers the characteristics of disturbance occurrence, that is, disturbance regime, from biomass pattern. We characterized this regime across three dimensions: extent (μ), frequency (α), and intensity (β). Through a 200‐year landscape experiment, we explored the synthetic dynamically stable biomass under different disturbance regimes. Statistical features from biomass simulations revealed distinct spatial patterns, forming a connection between these patterns and the disturbance regime parameters via machine learning. Notably, specific biomass pattern statistics influence distinct disturbance regime parameters: μ and β are linked to histogram stats, while α is tied to texture statistics. This approach establishes a framework to diagnose disturbance regimes from biomass patterns, offering a way to incorporate these regimes into Earth system models. Key Points We investigate the link between disturbance regimes and spatial patterns of aboveground biomass emerging from diverse primary productivity The proposed framework allows for inferring disturbance probability, size and intensity from spatial features in aboveground biomass Disturbance regimes from high‐res Earth observations can enhance carbon cycle dynamics prediction from interannual to longer time scales

• Publisher: John Wiley & Sons, Inc,American Geophysical Union (AGU)
• Subject: Anthropogenic factors / Biomass / Biosphere / Carbon / Carbon cycle / carbon cycle dynamics / Climate and vegetation / Climate change / disturbance regime / Disturbances / Ecosystem disturbance / Forest biomass / Forest ecosystems / forest mortality / gap dynamics / Mortality / Parameters / Pioneers / Primary production / Productivity / Respiration / Vegetation