Package 'LAD'

Calculate summary statistics from measured leaf inclination angles

Description

The function derives summary statistics from measured leaf inclination angles:.

• Mean (MTA), standard deviation (SD) and frequency (NR) observations.

• The two (mu, nu) Beta parameters derived from the formula provided by Goel and Strebel (1984) doi:10.2134/agronj1984.00021962007600050021x.

• The distribution type, comparing the distribution against the six theoretical LAD distributions provided by de Wit (1965).

Arguments

data	Dataframe. The dataframe containing leaf inclination angle measurements.
angles	Numeric. The column containing leaf inclination angle measurements (in degrees).
type	Character. If set to "summary", it gives summary distributions. If set to "extended", it calculates LAD probability density (pdf) and G-function (G) for view or inclination angles (theta). Default set to "summary".
...	The column(s) indicating the grouping variables to be considered for calculating summary statistics.

Value

A dataframe with the grouping variable(s), and:

• summary statistics (MTA, SD, N, mu, nu, distribution) in case of type="summary";

• LAD (pdf) and G-function (G) in case of type="extended".

Examples

head(Chianucci)

calcLAD(Chianucci,Angle_degree,type='summary',Genus,Species)
calcLAD(Chianucci,Angle_degree,type='extended',Genus,Species)

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Chianucci dataset

Description

The dataset provide measured leaf inclination angles from 138 temperate and boreal woody species.

Usage

Chianucci

Format

Chianucci

A data frame with 23,882 rows and 9 columns:

N

row ID record

ICP_Code

ICP species code, when available

Family, Genus, Species

Family, Genus, Species taxonomy information

Author_citation

Species author name

Canopy_sector

The portion of the canopy where the leaves have been measured

Angle_degree

Measured leaf inclination angles (degree)

Date

Date of sampling (dd-mm-yy)

...

Source

doi:10.1007/s13595-018-0730-x

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Fit Leaf Angle Distribution (LAD) from two-parameters (mu, nu) Beta distribution

Description

The function derives both the Leaf Angle Distribution (LAD) and the G-function from two-parameters (mu, nu) Beta distribution.

• The LAD function is fitted through a Beta distribution as recommended by Goel and Strebel (1984).

• The G-function is derived from LAD using the formula provided by Ross (1981) and reported as Equations 2-3 by Chianucci et al. (2018).

• The fitted LAD is also compared with six theoretical LAD distributions provided by de Wit (1965).

• The distribution type is then classified using a leaf inclination index Ross (1975) and reported as Equation 8 by Chianucci et al. (2018).

Arguments

mu	Numeric. The mu parameter of the Beta distribution.
nu	Numeric. The nu parameter of the Beta distribution.
plot	Logical. If set to TRUE, it plots the measured and theoretical LAD and G distributions. Default set to FALSE.

Value

A list of two elements:

• dataset: a dataframe with three columns indicating the measured LAD (pdf), the G-function (G), for view or inclination angle (theta).

• distribution: a vector containing the matched distribution type.

Examples

fitLAD(0.9,0.9) # uniform LAD distribution
fitLAD(2.8,1.18)# planophile LAD distribution
fitLAD(1.1,1.7, plot=TRUE)# spherical LAD distribution

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