slope {BAT}

Slope of accumulation curves.

Description

This is similar to the first derivative of the curves at each of its points.

Usage

slope(accum)

Arguments

accum

A matrix resulting from the alpha.accum or beta.accum functions (sampling units x diversity values).

Details

Slope is the expected gain in diversity when sampling a new individual. The slope of an accumulation curve, of either observed or estimated diversity, allows verifying if the asymptote has been reached (Cardoso et al. 2011). This is an indication of either the completeness of the inventory (low final slopes of the observed curve indicate high completeness) or reliability of the estimators (stability of the slope around a value of 0 along the curve indicates reliability).

Value

A matrix of sampling units x slope values.

References

Cardoso, P., Pekar, S., Jocque, R. & Coddington, J.A. (2011) Global patterns of guild composition and functional diversity of spiders. PLoS One, 6, e21710.

Examples

comm1 <- matrix(c(2,2,0,0,0,1,1,0,0,0,0,2,2,0,0,0,0,0,2,2), nrow = 4, ncol = 5, byrow = TRUE)
comm2 <- matrix(c(1,1,0,0,0,0,2,1,0,0,0,0,2,1,0,0,0,0,2,1), nrow = 4, ncol = 5, byrow = TRUE)
tree <- hclust(dist(c(1:5), method="euclidean"), method="average")
acc.alpha = alpha.accum(comm1)
slope(acc.alpha)
acc.beta = beta.accum(comm1, comm2, tree)
slope(acc.beta)