Forest disturbances and climate constrain carbon allocation dynamics in trees

Area of Science:

• Forest Ecology
• Carbon Cycle Science
• Climate Change Impacts

Background:

• Forest disturbances (drought, fire, logging) disrupt carbon dynamics and the terrestrial carbon sink.
• Forest mortality post-disturbance introduces uncertainties in understanding forest dynamics and carbon sequestration.
• Accurate assessment of forest carbon dynamics is crucial for climate change mitigation strategies.

Purpose of the Study:

• To estimate time series of annual woody biomass growth (ABI) using combined plot data.
• To benchmark a vegetation model for analyzing forest productivity and carbon allocation dynamics.
• To investigate the influence of environmental variability and disturbances on forest carbon partitioning.

Main Methods:

• Combined data from permanent resampling plots and dendroecological plots to estimate ABI time series.
• Developed and utilized a vegetation model with explicit source/sink limitations for carbon allocation.
• Analyzed biases in tree-ring reconstructed ABI in relation to time and disturbance intensity.

Main Results:

• Bias in ABI reconstruction increased with time and disturbance intensity, exceeding 100% in heavily disturbed stands.
• Stand leaf area remained reduced for decades after heavy thinning compared to control plots.
• Disturbances, species traits, and climate variability significantly affected tree carbon allocation patterns.

Conclusions:

• Higher disturbance intensity leads to greater modifications in carbon allocation, increasing errors in biomass dynamics reconstruction.
• Legacy effects of disturbances reduce model performance and limit the use of ABI as a proxy for net primary productivity.
• Vegetation models require refinement in trait-based carbon allocation dynamics to accurately reflect environmental variability and disturbance impacts.