ppine: Tree Growth Data for Ponderosa Pine

In systemfit: Estimating Systems of Simultaneous Equations

Tree Growth Data for Ponderosa Pine

Description

A subset of tree growth observations from a Ponderosa pine growth database.

The ppine data frame has 166 rows and 8 columns.

Usage

data(ppine)

Format

This data frame contains the following columns:

elev

Altitude of the plot, in feet above mean sea level.

smi

Summer moisture index is the ratio of growing season heating degree days to growing season precipitation.

dbh

Diameter of the tree at breast height (4.5 feet).

tht

Total stem height for the tree.

cr

Crown ratio code. The scale is from 1 to 9 where a crown class of one represents a crown ratio between 0 and 15 percent. A crown ratio code of 2 represents a crown ratio value between 16 and 25%,...,8=76-85%, 9 >=85%.

ba

Plot basal area at the beginning of the growth period.

dg

Five-year diameter increment.

hg

Five-year height increment.

Details

The exogenous variables are elev, smi, dbh, tht, cr, and ba; the endogenous variables dg and hg. There are no lagged variables in the dataset and the observations are for a single remeasurement.

The data was provided by the USDA Forest Service Intermountain Research Station.

Source

William R. Wykoff [e-mail] Rocky Mountain Research Station, 1221 South Main Street, Moscow, ID 83843

Examples

data(ppine)

systemfit documentation built on March 31, 2023, 3:07 p.m.