basal_area: Basal area of tree trunks in TERN AusPlots

Description

Calculates basal area (or number of basal wedge hits) for each plot, using the raw basal wedge data returned from get_ausplots.

Usage

basal_area(veg.basal, by.spp=FALSE, by.hits=FALSE, 
species_name=c("SN","HD","GS"))

Arguments

veg.basal

Raw basal wedge data generated from get_ausplots.

by.spp

Set to TRUE to get values per individual species in plots rather than combined values per plot.

by.hits

Set to TRUE to return the number of individual basal wedge hits rather than basal area per se.

species_name

If by.spp=TRUE, set to "SN" to use "standardised_names" (the default), "HD" to use "herbarium_determination", and "GS" to use "genus_species". See details for explanation of each setting.

Value

Returns a dataframe with rows for plots (or species by plots) and basal area (m2/ha) or hit scores.

Details

Basal area is the cross-sectional area of tree trunks per unit area, and is measured at each plot using a basal wedge sweep. Measurement is by species at nine points. Basal area is averaged, while raw tree stem counts are also recorded.

species_name provides multiple options for calculating basal area if by.spp=TRUE. For example, if species_name="HD", the function will use the "herbarium_determination" provided by state herbaria to identify unique species. "herbarium_determination" are made to the lowest possible taxonomic rank, which may be the family, genus, species, subspecies or variety. It includes incomplete identifications, dead or generic vegetation identifications (e.g. "Dead Tree/Shrub", "Annual Grass"), and "No ID" labels. If species_name="SN", the default, the function will use the the "standardised_name" to identify unique species. Values are based on the veg.PI$herbarium_determination but have been edited to match the most commonly used or widely accepted scientific name according to "World Flora Online" (http://www.worldfloraonline.org/). "standardised_name" determinations are made to the lowest possible taxonomic rank, which may be the genus, species, subspecies or variety, but not family. It excludes generic vegetation identifications (e.g. "Dead Tree/Shrub", "Annual Grass") and "No ID" labels. If species_name="GS", only the standardised genus species rank ("genus_species" in the veg.basal input table) is used to identify species. species_name="GS" maximises consistency in species comparisons between plots, but reduces the taxonomic detail and excludes records where only the genus was identified.

Examples

Run this code

# NOT RUN {
#get basal wedge data for selected plots:
my.data <- get_ausplots(my.Plot_IDs=c("SATFLB0004", "QDAMGD0022", "NTASTU0002"),
	veg.vouchers=FALSE, site_info=FALSE, veg.PI=FALSE, basal.wedge=TRUE)

#calculate basal area:
basal_area(my.data$veg.basal)
# }