Determining Reference Conditions
for Southwestern Ponderosa Pine
Forests
GOALS FOR LECTURE
1. You will be able to define ecological restoration.
2. You will be able to define reference conditions
and how reference conditions are determined.
3. You will be able to discuss reference conditions
in the context of southwestern ponderosa pine
forests.
WHAT IS ECOLOGICAL
RESTORATION???
What is Ecological Restoration?
The Society of Ecological Restoration (SER)
defines ecological restoration in its mission
statement as “the process of assisting the
recovery and management of ecological
integrity. Ecological integrity includes a critical
range of variability in biodiversity, ecological
processes and structures, regional and
historical context, and sustainable cultural
practices” (Society for Ecological Restoration
1996).
Ecological Restoration
Need to identify ecological restoration goal,
identify the restoration potential of a site,
how to conduct the restoration, and how to
evaluate the success of restoration.
* REFERENCE CONDITIONS
Reference Conditions
The range of historical or natural variability in
ecological structures and processes that
reflect evolutionary history, disturbance
regimes, and abiotic and biotic conditions
(Covington et al. 1997).
HOW DO YOU
DETERMINE REFERENCE
CONDITIONS???
PONDEROSA PINE
•Ponderosa pine (Pinus
ponderosa) trees grow in every
state found west of the Great
Plains
•In Colorado, ponderosa pine
trees are commonly found on
mesas to the montane from
5,000-9000 ft
•In the San Juan Mountains,
pure stands of ponderosa pine
can be found on sandstone
substrates from 6,500-8,000 ft
Drawing by Robert Petty in “Graced by Pines” 1994
PONDEROSA PINE
PONDEROSA PINE
HISTORICAL DATA
WRITTEN RECORDS
Lt. Edward Beale, 1857 (northern Arizona) “A vast forest of
gigantic pines, intersected frequently with open glades,
sprinkled all over with mountains, meadows, and wide
savannas, and covered with the richest grasses, was
traversed by our party for many days.”
C. DuBois, 1903 (San Juan Mountains) “Throughout the
[“bull” or ponderosa pine] type there is good cattle range,
consisting of blue-stem grass beneath the trees and bunch
grass in the parks. The underbrush is very heavy, chiefly
oak brush, choke-cherry, scarlett thorn, and wild rose.
Reproduction of bull pine is poor.”
PHOTOGRAPHS
Courtesy of Cline Library Special Collections, Northern Arizona University
1911
1928
1985
RESEARCH
Woolsey 1910 Forest Stand Inventory
DBH CLASS
DBH RANGE
1985/87
1962
1910
6
4.6-7.5
68.0
45.0
6.3
9
7.6-10.5
36.1
21.8
3.2
12
10.6-13.5
18.1
11.1
2.5
15
13.6-16.5
8.8
6.6
2.2
18
16.6-19.5
4.5
4.0
2.0
21
19.6-22.5
2.3
*
1.8
24
22.6-25.5
1.3
*
1.4
27
25.6-28.5
0.6
*
0.7
30
28.6+
0.4
0.6
0.8
140.0
93.6
20.8
TOTAL
CONTEMPORARY
DATA
FIRE SCARS
EURO-AMERICAN SETTLEMENT
GRAZING
LOGGING
FIRE
SUPPRESSION
LOS ALAMOS
OTHER CONTEMPORARY DATA
*SPECIES COMPOSITION AND STRUCTURE
*SOIL SEED BANK
*BIOTIC AND ABIOTIC SOIL CHARACTERISTICS
*DEAD/DOWN WOODY MATERIALS
*TRADITIONAL ECOLOGICAL KNOWLEDGE
REFERENCE CONDITIONS
SOUTHWESTERN PONDEROSA PINE
Fire- Key disturbance that regulates ponderosa pine
forests
*Low intensity fires (2-20 year interval)
*Large diameter trees interspersed with grassy meadows
*Diverse, productive herbaceous understory
WHO USES THIS INFORMATION?
Governmental Agencies-National Park Service, Forest
Service, BLM
State and Local Government- e.g., Montezuma County
(Ponderosa Pines Project), Boulder Mountain Parks
Conservation Organizations-The Nature Conservancy,
Grand Canyon Forest Trust
General Public-e.g., where to build a house (fire-prone
environment, floodplain, etc.), where to recreate,
forming opinions on public land management actions
GOALS FOR LECTURE
1. You will be able to define ecological restoration.
2. You will be able to define reference conditions
and how reference conditions are determined.
3. You will be able to discuss reference conditions
in the context of southwestern ponderosa pine
forests.
QUESTIONS??
Tree Canopy Data for
the Gus Pearson
Natural Area, Arizona
for 1876 and 1990
Components of Ecological Restoration
Four Main Components:
1) Cultural
* Native Americans played an important role in
the evolutionary history of many ecosystems
through their interactions with the natural world.
* Native Americans used fire as a tool for hunting,
promoting/discouraging specific plant species
which differs from lightning fires in seasonality,
frequency, and intensity.
Components of Ecological Restoration
Four Main Components:
2) Economical
* How much will the restoration project cost to
plan, implement, and monitor?
* What are the economical benefits from
restoration (immediate and long-term)?
Components of Ecological Restoration
Four Main Components:
3) Social
* Need to look at restoration as an outcome of
complex interactions between nature and society
and divergent social and political views within
society.
* Need to develop common ground among all
participants when identifying and planning
restoration projects.
Components of Ecological Restoration
Four Main Components:
4) Ecological
* Need to identify ecological restoration goal,
identify the restoration potential of a site, how to
conduct the restoration, and how to evaluate the
success of restoration.
* Need to identify a spatial and temporal context
for ecological restoration.
* REFERENCE CONDITIONS