pysiteindex

A Python package for exploring and using forest height growth and site index functions.

PySiteIndex CLI

PySiteIndex provides a basic command line interface to perform site index and height estimation for single trees.

Usage

$ pysi --help
Usage: pysi [OPTIONS] COMMAND [ARGS]...

Options:
  --help-curves  Return a list of supported site curve funtions.
  --help         Show this message and exit.

Commands:
  ht  Return the estimated height of a single tree for a given age and...
  si  Return the site index estimate for a single tree.

List Available Curves

$ pysi help-curves
Site Index Curves:
  bruce_1981: Douglas-fir, Bruce (1981)
  curtis_1974: Douglas-fir, Curtis, 1972
  farr_1984: Sitka spruce, Farr (1984), Res. Paper PNW-326
  fvs: Species site curves embedded in FVS variant libraries.
  harrington_1986: Red alder, Harrington (1986)
  king_1966: Douglas-fir, King (1966)
  wiley_1978: Western Hemlock, FIA PNW eq. 5a, Wiley (1978)

Estimate Site Index

$ pysi si --help
Usage: pysi si [OPTIONS]

  Return the site index estimate for a single tree.

Options:
  -c, --curve TEXT      Site curve name.  [required]
  -a, --age FLOAT       Tree age - BHA, TTA, etc. see curve description.
                        [required]
  -t, --height FLOAT    Tree height - See curve description.  [required]
  -v, --variant TEXT    FVS variant abbreviation when curve="fvs".
  -f, --forest INTEGER  FVS forest code when curve="fvs".
  -s, --species TEXT    FVS species code when curve="fvs".
  --help                Show this message and exit.

$ pysi si --curve=bruce_1981 --age=43 --height=107
118.28ft @bha=50

Estimate Height

$ pysi ht --help
Usage: pysi ht [OPTIONS]

  Return the estimated height of a single tree for a given age and site index.

Options:
  -c, --curve TEXT        Site curve name.  [required]
  -a, --age FLOAT         Tree age - BHA, TTA, etc. see curve description.
                          [required]
  -i, --site-index FLOAT  Site index - See curve description.  [required]
  -v, --variant TEXT      FVS variant abbreviation when curve="fvs".
  -f, --forest INTEGER    FVS forest code when curve="fvs".
  -s, --species TEXT      FVS species code when curve="fvs".
  --help                  Show this message and exit.

$ pysi ht --curve=bruce_1981 --age=97 --site-index=107
152.17ft @bha=97.0

FVS Site Curves

If the PyFVS package is available PySiteIndex can estimate site index and heights for any tree species from a variants of the Forest Vegetation Simulator (more can be added).

Sugar pine, Inland CA and S. Cascades variant

$ pysi si -c FVS -v CA -s SP -a 76 -t 124
87.21ft @bha=50

Pacific Yew, PN variant

$ pysi si -c FVS -v PN -s PY -a 43 -t 32
61.43ft @bha=100

PySiteIndex API

Basic usage

Estimate site index

from pysiteindex import si as pysi

sc = pysi.DF_Bruce_SiteCurve()

# Estimate site index from breast-height age and total height
si = sc.site_index(bha=75, ht=145)
print(si)
114.8828125

# Also accepts iterables and numpy arrays
si = sc.site_index(bha=[45,75], ht=[110,145])
print(si)
[117.8125    114.8828125]

Estimate height

ht = sc.height(bha=120, si=130)
print(ht)
205.97416666910453

Estimate breast height age

age = sc.age(ht=95, si=120)
print(age)
35.60888671875

Plot Site Index Curves

Standard Height Curves

import matplotlib.pyplot as plt
from pysiteindex import si as pysi

sc = pysi.DF_Bruce_SiteCurve()
fig,ax = plt.subplots()

ax = sc.plot_height_curves(min_bha=0, min_si=90, max_si=150, ax=ax)

Height Growth Curves

import matplotlib.pyplot as plt
from pysiteindex import si as pysi

sc = pysi.DF_Bruce_SiteCurve()
fig,ax = plt.subplots()

ax = sc.plot_height_growth(min_bha=0, min_si=90, max_si=150, ax=ax)

Site Index Curves

import matplotlib.pyplot as plt
from pysiteindex import si as pysi

sc = pysi.DF_Bruce_SiteCurve()
fig,ax = plt.subplots()

ax = sc.plot_site_index_curves(ax=ax)