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Common structure in the heterogeneity of plant-matter decay.

Forney DC, Rothman DH - J R Soc Interface (2012)

Bottom Line: Changes in temperature and precipitation scale all rates similarly, whereas the initial substrate composition sets the time scale of faster rates.These findings probably result from the interplay of stochastic processes and biochemical kinetics, suggesting that the intrinsic variability of decomposers, substrate and environment results in a predictable distribution of rates.Within this framework, turnover times increase exponentially with the kinetic heterogeneity of rates, thereby providing a theoretical expression for the persistence of recalcitrant organic carbon in the natural environment.

View Article: PubMed Central - PubMed

Affiliation: Lorenz Center and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. dforney@mit.edu

ABSTRACT
Carbon removed from the atmosphere by photosynthesis is released back by respiration. Although some organic carbon is degraded quickly, older carbon persists; consequently carbon stocks are much larger than predicted by initial decomposition rates. This disparity can be traced to a wide range of first-order decay-rate constants, but the rate distributions and the mechanisms that determine them are unknown. Here, we pose and solve an inverse problem to find the rate distributions corresponding to the decomposition of plant matter throughout North America. We find that rate distributions are lognormal, with a mean and variance that depend on climatic conditions and substrate. Changes in temperature and precipitation scale all rates similarly, whereas the initial substrate composition sets the time scale of faster rates. These findings probably result from the interplay of stochastic processes and biochemical kinetics, suggesting that the intrinsic variability of decomposers, substrate and environment results in a predictable distribution of rates. Within this framework, turnover times increase exponentially with the kinetic heterogeneity of rates, thereby providing a theoretical expression for the persistence of recalcitrant organic carbon in the natural environment.

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Plots of the unaveraged lognormal parameters μ and σ versus experimental variables temperature and ℓ/N. All 191 datasets are shown in each figure. Colours indicate tissue types. Roots (blue), leaves (red), needles (green), wood (black) and wheat (cyan). (a) μ versus mean annual temperature. (b) μ versus ℓ/N. (c) σ versus mean annual temperature. (d) σ versus ℓ/N. Comparison with figure 2 of the main text shows similar trends.
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RSIF20120122F6: Plots of the unaveraged lognormal parameters μ and σ versus experimental variables temperature and ℓ/N. All 191 datasets are shown in each figure. Colours indicate tissue types. Roots (blue), leaves (red), needles (green), wood (black) and wheat (cyan). (a) μ versus mean annual temperature. (b) μ versus ℓ/N. (c) σ versus mean annual temperature. (d) σ versus ℓ/N. Comparison with figure 2 of the main text shows similar trends.

Mentions: We present here the unaveraged data shown in figures 2 and 3 of the main text. Figure 6 shows how the values of μ and σ for the 191 LIDET datasets vary with temperature and the lignin-to-nitrogen ratio ℓ/N. Figure 7a,b show the unaveraged variation of and τ with ℓ/N. Figure 7c shows the unaveraged plot of σ2 versus μ. While there is much scatter among the data, the general trends remain the same as in figures 2 and 3 of the main text.Figure 6.


Common structure in the heterogeneity of plant-matter decay.

Forney DC, Rothman DH - J R Soc Interface (2012)

Plots of the unaveraged lognormal parameters μ and σ versus experimental variables temperature and ℓ/N. All 191 datasets are shown in each figure. Colours indicate tissue types. Roots (blue), leaves (red), needles (green), wood (black) and wheat (cyan). (a) μ versus mean annual temperature. (b) μ versus ℓ/N. (c) σ versus mean annual temperature. (d) σ versus ℓ/N. Comparison with figure 2 of the main text shows similar trends.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3405759&req=5

RSIF20120122F6: Plots of the unaveraged lognormal parameters μ and σ versus experimental variables temperature and ℓ/N. All 191 datasets are shown in each figure. Colours indicate tissue types. Roots (blue), leaves (red), needles (green), wood (black) and wheat (cyan). (a) μ versus mean annual temperature. (b) μ versus ℓ/N. (c) σ versus mean annual temperature. (d) σ versus ℓ/N. Comparison with figure 2 of the main text shows similar trends.
Mentions: We present here the unaveraged data shown in figures 2 and 3 of the main text. Figure 6 shows how the values of μ and σ for the 191 LIDET datasets vary with temperature and the lignin-to-nitrogen ratio ℓ/N. Figure 7a,b show the unaveraged variation of and τ with ℓ/N. Figure 7c shows the unaveraged plot of σ2 versus μ. While there is much scatter among the data, the general trends remain the same as in figures 2 and 3 of the main text.Figure 6.

Bottom Line: Changes in temperature and precipitation scale all rates similarly, whereas the initial substrate composition sets the time scale of faster rates.These findings probably result from the interplay of stochastic processes and biochemical kinetics, suggesting that the intrinsic variability of decomposers, substrate and environment results in a predictable distribution of rates.Within this framework, turnover times increase exponentially with the kinetic heterogeneity of rates, thereby providing a theoretical expression for the persistence of recalcitrant organic carbon in the natural environment.

View Article: PubMed Central - PubMed

Affiliation: Lorenz Center and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. dforney@mit.edu

ABSTRACT
Carbon removed from the atmosphere by photosynthesis is released back by respiration. Although some organic carbon is degraded quickly, older carbon persists; consequently carbon stocks are much larger than predicted by initial decomposition rates. This disparity can be traced to a wide range of first-order decay-rate constants, but the rate distributions and the mechanisms that determine them are unknown. Here, we pose and solve an inverse problem to find the rate distributions corresponding to the decomposition of plant matter throughout North America. We find that rate distributions are lognormal, with a mean and variance that depend on climatic conditions and substrate. Changes in temperature and precipitation scale all rates similarly, whereas the initial substrate composition sets the time scale of faster rates. These findings probably result from the interplay of stochastic processes and biochemical kinetics, suggesting that the intrinsic variability of decomposers, substrate and environment results in a predictable distribution of rates. Within this framework, turnover times increase exponentially with the kinetic heterogeneity of rates, thereby providing a theoretical expression for the persistence of recalcitrant organic carbon in the natural environment.

Show MeSH