silv_density_sdi: Calculates the Stand Density Index

In silviculture: Utility Functions for Forest Inventory and Silviculture

Calculates the Stand Density Index

Description

The Stand Density Index (SDI) is relationship between the average tree size and density of trees per hectare.

Usage

silv_density_sdi(ntrees, dg, classify = FALSE, max_sdi = NULL)

Arguments

ntrees	A numeric vector representing the number of trees per hectare
dg	A numeric vector of quadratic mean diameters
classify	whether to classify the values using USDA thresholds
max_sdi	used when classify = TRUE. The maximum SDi, which depends on the species, stand type, and site

Details

The SDI has different interpretation depending on the species, location, and also the management type (even-aged, uneven-aged...). The value of maximum SDI must be determined from the literature and used carefully. The option classify = TRUE will use this value to classify the SDI in low density (<24%), moderate density (24-35%), high density (34-55%), and extremely high density (>55%).

Value

A numeric vector

Examples

## calculate SDI for a Pinus sulvestris stand (max 990)
silv_density_sdi(ntrees = 800, dg = 23.4, max_sdi = 990)

## check base classification (other can be used)
silv_density_sdi(ntrees = 800, dg = 23.4, classify = TRUE, max_sdi = 990)

silviculture documentation built on Nov. 5, 2025, 7:13 p.m.