The terrestrial silica pump

PLoS One. 2012;7(12):e52932. doi: 10.1371/journal.pone.0052932. Epub 2012 Dec 31.


Silicon (Si) cycling controls atmospheric CO(2) concentrations and thus, the global climate, through three well-recognized means: chemical weathering of mineral silicates, occlusion of carbon (C) to soil phytoliths, and the oceanic biological Si pump. In the latter, oceanic diatoms directly sequester 25.8 Gton C yr(-1), accounting for 43% of the total oceanic net primary production (NPP). However, another important link between C and Si cycling remains largely ignored, specifically the role of Si in terrestrial NPP. Here we show that 55% of terrestrial NPP (33 Gton C yr(-1)) is due to active Si-accumulating vegetation, on par with the amount of C sequestered annually via marine diatoms. Our results suggest that similar to oceanic diatoms, the biological Si cycle of land plants also controls atmospheric CO(2) levels. In addition, we provide the first estimates of Si fixed in terrestrial vegetation by major global biome type, highlighting the ecosystems of most dynamic Si fixation. Projected global land use change will convert forests to agricultural lands, increasing the fixation of Si by land plants, and the magnitude of the terrestrial Si pump.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carbon
  • Carbon Cycle
  • Climate*
  • Ecosystem*
  • Silicon Dioxide*
  • Silicon*
  • Soil*


  • Soil
  • Carbon
  • Silicon Dioxide
  • Silicon

Grant support

This research was partially developed under STAR Fellowship Assistance Agreement no. FP917238 awarded by the U.S. Environmental Protection Agency (EPA) to J.C. Carey. It has not been formally reviewed by EPA. The views expressed in this paper are solely those of J.C. Carey and R.W. Fulweiler, and EPA does not endorse any products or commercial services mentioned in this publication. In addition, this research was conducted under an award from the Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean Service, National Oceanic and Atmospheric Administration to J.C. Carey. The authors would also like to thank the Department of Earth Sciences at Boston University for partial funding support of J.C Carey. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.