Pedosphere 29(4): 457--467, 2019
ISSN 1002-0160/CN 32-1315/P
©2019 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Depth Distributions of Belowground Production, Biomass and Decomposition in Restored Tallgrass Prairie
Adam C. VON HADEN1,2, Mathew E. DORNBUSH3
1Environmental Science and Policy Graduate Program, University of Wisconsin-Green Bay, Green Bay WI 54311(USA)
2Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison WI 53726(USA)
3Department of Natural and Applied Sciences, University of Wisconsin-Green Bay, Green Bay WI 54311(USA)
Corresponding Author:Adam C. VON HADEN
ABSTRACT
      Grasslands store large stocks of soil organic carbon (SOC) in the subsoil, but our knowledge of belowground processes becomes less robust with depth. Vertically explicit SOC models typically assume that the depth distribution of belowground production follows the depth distribution of belowground biomass, but this assumption has not been tested. In addition to the effects of soil temperature and moisture on decomposition, some vertically explicit SOC models implement an intrinsic decrease in belowground decomposition with depth, yet this effect has rarely been observed empirically. We simultaneously measured the depth distributions of belowground biomass, production, and litter decomposition to assess whether belowground biomass depth distributions were suitable predictors of belowground production and whether belowground decomposition decreased with soil profile depth. We found that live and total (live + dead) belowground biomass was distributed relatively more shallowly than total belowground production, and thus total belowground biomass was a biased predictor of the vertical distribution of belowground production. The depth distribution of live roots < 2 mm in diameter was found to be the best predictor of total belowground production depth distribution. Using an intact decay core method, we found that belowground litter decomposition decreased by 49% from 0-10 to 30-40 cm depth, and model-simulated effects of soil temperature and moisture accounted for only 9% of the observed decrease with depth. Vertically explicit SOC models can be improved with more accurate empirical belowground production depth distribution estimates, but depth-specific decomposition rates currently implemented in SOC models are necessary to explain observed decreases in belowground litter decay with depth.
Key Words:  carbon decomposition,litter decay,model simulation,roots,soil organic carbon,soil organic matter,temperate grassland,vertical rooting distributions
Citation: von Haden A C, Dornbush M E. 2019. Depth distributions of belowground production, biomass and decomposition in restored tallgrass prairie. Pedosphere. 29(4):457-467.
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