IV: IV

In NCRN/NPSForVeg: Data anaylsis and graphing for NPS forest vegetation monitoring.

IV

Description

Calculates "importance values" from forest data

Usage

IV(object, group, years = NA, output = "dataframe", ...)

Arguments

object	Either an object of class NPSForVeg or a list of such objects
group	A required character string indicating which group of plants should be selected. Options are: "trees", "saplings", "seedlings", "shseedlings"(indicated shrub seedlings), or "herbs'. Currently not implemented for "vines" or "shrubs".
years	years Defaults to NA. A numeric vector indicating which years should be included. This is passed on to getPlants.
output	Either "dataframe" or "list". Determines the output type When object is a list. "Dataframe",the default, indicates the output from all of NSPForVeg objects should be a data.frame combining allo data as if all objects were a single park. "List" will return a list where each element of the list is a data.frame from a single NSPForVeg object, and each element is named based on that object's ParkCode slot.
...	Other arguments passed to SiteXSpec. If not used by that function the arguments will be passed to getPlants.

Details

This function is used to calculate forestry importance values in conjcution with calcIV. One or more objects of class NPSForVeg are used. The arguments to the funciton are passed on to SiteXSpec and from there to getPlants, so any argument which is accepted by either of these fucntions (eg. size.min or crown) is valid. getPlants is used to acquire the relevent data. SiteXSpec is then used to create three site X spcies matrices - one which measures abundance per plot, one which is a measure of size per plot and one which is a presence/absence matrix. For trees, saplings and seedlings abundance is mearsured as the number of stems per plot, whereas for herb abundace is the number of quadrats a speices is found in. Size is measured as basal area for trees and saplings, height for seedlings and percent cover for herbs. Once the matrices are created they are passed to calcIV which calcuates the IV values.

Value

A data.frame with the IV values for each species. Values are returned for the three separate components of IV (Density, Size and Distribution), as well as the Total. The values for each of the tree components will sum to one, so the the total will sum to three.

NCRN/NPSForVeg documentation built on June 7, 2024, 1:01 p.m.