214: Estimation of the turnover time from a soil radiocarbon...
In SoilR: Models of Soil Organic Matter Decomposition

Description Usage Arguments Details Value Author(s) Examples

This function finds the best possible value of turnover time from a soil radiocarbon sample assuming a one pool model and annual litter inputs.

1 2	turnoverFit(obsC14, obsyr, In, C0 = 0, yr0 = 1900, Zone = "NHZone2", plot = TRUE, by = 0.5)

`obsC14`	a scalar with the observed radiocarbon value in Delta14C of the soil sample.
`obsyr`	a scalar with the year in which the soil sample was taken.
`In`	a scalar or data.frame with the annual amount of litter inputs to the soil.
`C0`	a scalar with the initial amount of carbon stored at the begning of the simulation.
`yr0`	The year at which simulations will start.
`Zone`	the hemispheric zone of atmospheric radiocarbon. Possible values are NHZone1: northern hemisphere zone 1, NHZone2: northern hemisphere zone 2, NHZone3: northern hemisphere zone 3, SHZone12: southern hemisphere zones 1 and 2, SHZone3: southern hemisphere zone 3. See `Hua2013` for additional information.
`plot`	logical. Should the function produce a plot?
`by`	numeric. The increment of the sequence of years used in the simulations.

This algorithm takes the observed values and a given amount of litter inputs, runs OnepModel14, calculates the squared difference between predictions and observations, and uses optimize to find the minimum difference. If the turnover time is relatively short (< 50 yrs), it is safe to assume C0=0 because the soil will reach steady state within the simulation time. However, for longer turnover times it is recommended to use a value of C0 close to the steady state value.

A scalar with the value of the turnover time that minimizes the difference between the prediction of a one pool model and the observed radiocarbon value.

Carlos A. Sierra, Markus Mueller

# To calculate the turnover time for a sample from a temperate forest soil
# remove uncomment the following lines!

#turnoverFit(obsC14=115.22, obsyr=2004.5, C0=2800, yr0=1900,
#                          In=473, Zone="NHZone2")

SoilR documentation built on May 4, 2017, 9:08 p.m.