convertIncrement: Convert size increment according to time elapsed between censuses.

Description

Adjusts the intervals of census data that is not annual to report output on population dynamics on an annual basis.

Usage

convertIncrement(dataf, nYrs = 1)

Arguments

dataf

a dataframe with columns `size' `sizeNext', `exactDate', `exactDateNext'.

nYrs

the number of years between sequential measurements (i.e. if census interval is 5, nYrs = 5, if census interval is 3 times a year, nYrs = 0.333).

Value

Returns the adjusted increments.

Details

In some data sets the time interval between census measurements can be different than one year. In some species demographic information is recorded several times within a year, while in others, particularly in "slow-living" species (e.g. trees) the census frequency is greater than one year and/or vary across intervals. This function takes a data frame dataf and uses columns with the term extractData to adjust the size increment to the number of years given in nyears. It defaults to annual.

References

Sampling three times/year (nYrs = 0.333): Smith, Caswell & Mettler-Cherry. Stochastic flood and precipitation regimes and the population dynamics of a threatened floodplain plant. Ecological Applications 15, p1036-1052.

Sampling every five years (nYrs = 5): van Mantgem & Stepheson. 2005. The accuracy of matrix population model projections for coniferous trees in the Sierra Nevada, California. Journal of Ecology 93, p737-747.