Calculate Nurse Tree Association Energy — calc_nurse_tree

Calculates deviation from target nurse tree associations. In pinyon-juniper ecosystems, pinyon pines (PIED) often establish near junipers (JUMO/JUSO) which act as "nurse trees" providing shade and protection. This function quantifies how well the current tree pattern matches this association.

Usage

calc_nurse_tree_energy(trees, nurse_distance = 3)

Arguments

trees: Data.table with columns: x, y, Species
nurse_distance: Numeric. Target mean distance from PIED to nearest juniper (m). Default 3.0m based on field observations.

Value

Numeric. Energy value representing squared deviation from target distance. Lower values indicate better match to target association pattern.

Details

For each PIED tree, calculates distance to nearest JUMO or JUSO tree. Returns squared deviation of mean distance from target. Returns 0 if either species is absent.

Examples

# \donttest{
trees <- data.table::data.table(x = runif(100, 0, 100), y = runif(100, 0, 100),
                    Species = sample(c("PIED", "JUSO"), 100, replace = TRUE))
calc_nurse_tree_energy(trees, nurse_distance = 3.0)
#> [1] 24.43518
# }