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Carbon allocated underground through belowground net primary production represents the main input to soil organic carbon. This is of significant importance, because soil organic carbon is the third-largest carbon stock after oceanic and geological pools. However, drivers and controls of belowground productivity and the fraction of total carbon fixation allocated belowground remain uncertain. Here we estimate global belowground net primary productivity as the difference between satellite-based total net primary productivity and field observations of aboveground net primary production and assess climatic controls among biomes. On average, belowground carbon productivity is estimated as 24.7 Pg y−1, accounting for 46% of total terrestrial carbon fixation. Across biomes, belowground productivity increases with mean annual precipitation, although the rate of increase diminishes with increasing precipitation. The fraction of total net productivity allocated belowground exceeds 50% in a large fraction of terrestrial ecosystems and decreases from arid to humid ecosystems. This work adds to our understanding of the belowground carbon productivity response to climate change and provides a comprehensive global quantification of root/belowground productivity that will aid the budgeting and modeling of the global carbon cycle.
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Bioavailability of Macro and Micronutrients Across Global Topsoils: Main Drivers and Global Change Impacts
Abstract Understanding the chemical composition of our planet's crust was one of the biggest questions of the 20th century. More than 100 years later, we are still far from understanding the global patterns in the bioavailability and spatial coupling of elements in topsoils worldwide, despite their importance for the productivity and functioning of terrestrial ecosystems. Here, we measured the bioavailability and coupling of thirteen macro‐ and micronutrients and phytotoxic elements in topsoils (3–8 cm) from a range of terrestrial ecosystems across all continents (∼10,000 observations) and in response to global change manipulations (∼5,000 observations). For this, we incubated between 1 and 4 pairs of anionic and cationic exchange membranes per site for a mean period of 53 days. The most bioavailable elements (Ca, Mg, and K) were also amongst the most abundant in the crust. Patterns of bioavailability were biome‐dependent and controlled by soil properties such as pH, organic matter content and texture, plant cover, and climate. However, global change simulations resulted in important alterations in the bioavailability of elements. Elements were highly coupled, and coupling was predictable by the atomic properties of elements, particularly mass, mass to charge ratio, and second ionization energy. Deviations from the predictable coupling‐atomic mass relationship were attributed to global change and agriculture. Our work illustrates the tight links between the bioavailability and coupling of topsoil elements and environmental context, human activities, and atomic properties of elements, thus deeply enhancing our integrated understanding of the biogeochemical connections that underlie the productivity and functioning of terrestrial ecosystems in a changing world.
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- PAR ID:
- 10475902
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- Global Biogeochemical Cycles
- Volume:
- 37
- Issue:
- 6
- ISSN:
- 0886-6236
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2022GB007680
