VARIATION IN FUEL LOADINGS WITHIN EXISTING PONDEROSA PINE AND MIXED CONIFER
FORESTS IN THE SOUTHERN COLORADO FRONT RANGE
M.A. Battaglia, W.D. Shepperd, and M.J. Platten Rocky Mountain
Research Station, Fort Collins, CO
Recent large fires in the Colorado Front Range and concern about
the volatility of forest conditions in this ecosystem have prompted
renewed interest in the need for treating these forests to reduce
fuels risk. With this interest comes the need to obtain quantitative
data on the fuels that exist under Front Range Forests and to understand
how ground fuels vary across differing site and stocking conditions
in Front Range landscapes. Here, we present data collected on the
16,700 ac Manitou Experimental Forest west of Colorado Springs,
CO. The forest contains a variety of stocking and physiographic
conditions in ponderosa pine and mixed conifer forest types typical
of the Southern Front Range.
Overstory Sampling – Plots were laid out along a grid of pre-selected
GPS coordinates in three distinctly different areas of the Experimental
Forest: Trout Creek (n = 313), Hotel Gulch (n = 117), and Rampart
Range (n = 49). At each plot, basal area of live and dead trees
were tallied by species using 20 BAF. Elevation, slope, and aspect
were recorded at Hotel Gulch and Rampart Range.
Fuels Sampling – A nested-plane fuels inventory transect
(Brown and others 1982) was oriented on a random bearing from the
center of each BAF plot. All fuels intersecting an imaginary vertical
plane along each transect were tallied or measured by diameter and
soundness class. All pieces in the 0 to ¼ and ¼ to
1 inch diameter classes were tallied in the first 6 ft. of the transect.
Fuels from 1 to 3 inches in diameter were tallied up to 10 ft. away
from plot center. Diameters of all sound and rotten fuels >3
inches intersecting the transect < 35 ft. from plot center were
measured and recorded. Data for each plot was summed to a ton/acre
basis by size and soundness class using an Excel spreadsheet program.
Trout Creek Timber Sale: This 2,700 acre area
is currently undergoing a restoration harvest to reduce overall
stocking and remove live fuels from the understory. This area contains
nearly pure ponderosa pine forests on nearly level terrain.
Hotel Gulch: This valley bisects the eastern portion
of the Forest from 7,800-9,400 ft elevation. Plots were sampled
on both north and south aspects and consisted of a mixture of ponderosa
pine, Douglas-fir, limber pine, aspen, and spruce.
Rampart Range: This high elevation (9,200 –
9,500 ft.) area contained mostly lodgepole pine, Douglas-fir, and
Mixed stands had the highest and most variable fuel loadings followed
by spruce and aspen (Fig. 1).
No clear relationships between aspect (Fig. 2), elevation (Fig.
3), or plot basal area (Fig. 4) were noted.
15% of all plots contained high (25 to 50 tons per acre) fuel loadings.
Most of these plots were found within the Hotel Gulch and Rampart
Range areas (Fig. 5).
Average fuel loadings were low in all three areas sampled (Fig.
Trout Creek had lower fuel loadings in all but the ¼ to 1
inch size class (Fig. 6).
The ¼ to 1 inch fuel class contributed the most to total
fuel loadings in the Trout Creek area (Fig. 7).
The 3+ inch fuel class contributed the most to total fuel loadings
in the Hotel Gulch and Rampart Range areas (Fig. 7).