Global patterns and climatic controls of belowground net carbon fixation
Laureano A Gherardi1,2, Osvaldo E Sala3,2,4
1Global Drylands Center, Arizona State University, Tempe, AZ 85287-4501; Lau@ASU.edu.
Summary
Belowground net primary production is a major soil carbon input, accounting for 46% of global carbon fixation. This belowground carbon productivity is influenced by precipitation, with more carbon allocated underground in arid regions.
Area of Science:
- Ecology
- Biogeochemistry
- Earth System Science
Background:
- Soil organic carbon is the third-largest global carbon pool, crucial for climate regulation.
- Belowground net primary production (BNPP) is the primary input to soil organic carbon, yet its global controls are poorly understood.
- Understanding BNPP is vital for accurate global carbon cycle modeling.
Purpose of the Study:
- To estimate global BNPP and its contribution to total terrestrial carbon fixation.
- To assess the influence of climate, specifically precipitation, on BNPP across different biomes.
- To improve the understanding of belowground carbon dynamics in response to climate change.
Main Methods:
- Estimated BNPP by subtracting aboveground net primary production (ANPP) from satellite-derived total net primary production (NPP).
- Utilized field observations for ANPP and satellite data for total NPP.
- Analyzed climatic controls on BNPP across various terrestrial biomes.
Main Results:
- Global BNPP was estimated at 24.7 petagrams per year (Pg y-1), representing 46% of total terrestrial carbon fixation.
- BNPP increased with mean annual precipitation, but at a decreasing rate.
- The proportion of NPP allocated belowground exceeded 50% in many ecosystems and decreased from arid to humid regions.
Conclusions:
- This study provides a comprehensive global quantification of belowground productivity.
- Findings enhance understanding of how BNPP responds to climate change, particularly precipitation.
- Results will aid in refining global carbon cycle budgets and climate models.
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