Variability of ecosystem carbon source from microbial respiration is controlled by rainfall dynamics.

Area of Science:

• Ecology
• Biogeochemistry
• Climate Science

Background:

• Soil heterotrophic respiration (Rh) is a critical yet unpredictable component of the terrestrial carbon cycle.
• Understanding Rh variability is essential for accurate climate change projections and ecosystem carbon balance assessments.

Purpose of the Study:

• To analyze ecosystem-scale soil respiration dynamics using the global FLUXNET 2015 database.
• To identify key predictors of soil respiration variability and develop a predictive model.

Main Methods:

• Utilized the FLUXNET 2015 global database.
• Employed a probabilistic model of microbial growth to analyze respiration dynamics.
• Applied statistical analysis to identify drivers of temporal variability in Rh.

Main Results:

• Soil respiration variability consistently follows a Gamma distribution, irrespective of biome, soil type, or microbial physiology.
• Rainfall characteristics and vegetation productivity were identified as the sole determinants of the distribution's shape and scale parameters.
• The model accurately estimated mean Rh and its variance, validated against an independent global dataset.

Conclusions:

• Future alterations in rainfall patterns and net primary productivity will significantly impact Rh dynamics and the global carbon budget.
• Increasing wetness may lead to faster Rh increases than net primary productivity, potentially decreasing terrestrial carbon storage.
• The findings provide a robust framework for predicting soil respiration and its role in climate regulation.