biomass.forestguild.org - 1030 Fire Risk Reduction / Forest Restoration Treatment, AZ

Fire Risk Reduction / Forest Restoration Treatment

Flagstaff, AZ
Centennial Forest, Northern Arizona University
Submitted by Dr. Alex Finkral, Professor of Forest Management, Northern Arizona University

Project ID: 1030

1. Name - Fire Risk Reduction / Forest Restoration Treatment

Northern Arizona University’s School of Forestry manages nearly 50,000 acres as the Centennial Forest, much of which exists in the wildland-urban interface surrounding Flagstaff, Arizona. The Centennial Forest is part of a broader matrix of public and private land that is undergoing aggressive fire-risk-reduction thinning treatments, particularly on the southwestern corner of Flagstaff, in the direction from which the wind blows during the ‘fire season’.

This case study was conducted in a 230-acre stand dominated by ponderosa pine (Pinus ponderosa) with scattered Gambel oak (Quercus gambelii). The stand is comprised of two distinct cohorts. The vast majority of the trees initiated in a mass regeneration event in 1919. They comprise first cohort. The other cohort consists of older, larger trees that established prior to Euro-American settlement of the region. Soils are moderately deep, fine to clayey-skeletal, very cobbly loam on 0–15% slope. Annual precipitation is approximately 30 inches, with half coming as thunderstorms July through September and half as snow in the winter months. There were prior timber harvests on the site in 1914, 1951, 1956, and 1987, and pulpwood sales in 1965 and 1991. This stand abuts the Coconino National Forest and other Arizona State Land Department land.

The silvicultural goals for this stand were to reduce the risk of catastrophic crown fire by reducing the live and dead biomass (fuels) accumulations, and to restore the structure and function of the stand to a pre-fire-suppression state. The restoration treatment for the stand focused on retaining all live pre-settlement (at least 135 years of age) ponderosa pine trees, oak trees, and snags. All pre-settlement evidence (stumps, stumps holes, snags, logs) was identified, and three trees were retained within 60 feet of the pre-settlement evidence if possible. Post-settlement trees greater than 16-inch diameter at breast height (DBH) were left unless the trees were a safety hazard. Some areas, up to 2.5 acres, were excluded from treatment to protect structural diversity, nests, or unique features.

Of particular importance in treatments of this kind is slash treatment. Merchantable stems were removed log-length from the site on trailers, and all residual material – tops, branches, and sub-merchantable trees – were piled, both by bulldozer and by hand. All slash piles were burned approximately 16 months after the harvest at a time when there was snow on the ground.

The primary equipment used for the operation was a hydraulic shear feller buncher and a grapple skidder. Trees were skidded tree-length to landings, where they were processed with a stroke delimber and later loaded onto trailers with a truck-mounted knuckle boom loader. Some hand-felling was done, particularly on very small trees (less than 6 inches diameter), which were then hand-piled.

Because of a lack of strong timber market in this region, all merchantable stems were sold to a commercial firewood processor nearby. The low value of pine firewood offset harvesting costs somewhat, but overall the treatment cost $230 per acre to implement. The treatment was made possible by a State Fire Assistance Grant.

Links

Research on carbon impacts of thinning

	2	Land Ownership State
	3	Location Flagstaff, Arizona
	4	Forest Type Ponderosa pine
	Context
	5	Is this project a part of a landscape plan? Yes
	6	In a Wildland Urban Interface (WUI)? Yes
	7	Acreage treated 230 ac
	8	Type of contract Service contract
	9	Funding source State Fire Assistance Grant (National Fire Plan)
	10	Collaborators and partners AZ State Land Dept. (also coordinated with US Forest Service, AZ Game and Fish)
	11	Project start date Jul. 2006
	12	Project completion date Sep. 2006
	Treatment Goals
	13	Restoration, watershed or habitat improvement
	14	Reduce fuel load
	15
	16
	17	Forest Stand Improvement
	Treatment Specifics
	18	Primary treatment objective Fire risk reduction
	19	How does biomass removal fit with other objectives? Directly - fuels reduction
	20	Treatment description Restoration thinning aimed at smaller diameter classes
	21	Description of contractors Local logging operation
	22	Travel distance for contractors 15 miles
	23	Type of equipment used Shear fellerbuncher, chainsaws (some hand felling), skidder, stroke delimber/processor, bulldozer for slash piles
	24	Treatment of residual slash if any piled and burned
	25	Treatment cost per acre $230/ac
	26	Trucking costs
	Utilization
	27	Products from project Firewood
	28
	29	Date of Sale 2006
	30	Did biomass markets exist previous to project? Yes, firewood market existed
	31	Type of utilization Firewood
	32	How well did the woody biomass match the utilization options? Underutilized
	33	Distance to utilization 50 miles
	Treatment guidelines, targets, limitations
	34	Diameter limit 16 "
	35	Basal area reduction 40% reduction
	36	Crown coverage Patchy ("clumpy-groupy")
	37	Fuel loading 13 Mg/Ha surface fuels
	38	Retention guidelines Retain trees according to evidence of historic stand conditions
	39	Treatment of snags and downed logs Left where possible
	40	Soil impacts Compaction potential
	41	Other ecological impacts monitored Change in ecosystem carbon flux
	Pre Treatment
	42	Fuel load 13 Mg/Ha surface fuels
	43	Stem density (stems/ac) 230
	44	Basal area (ft2/ac) 94
	45	Canopy closure (%) Fairly continuous
	46	Height to live crown base 12.1 ft.
	47	Snags and downed woody material
	48	Size class distribution See figure
	49	Tree species composition 99% Ponderosa, <1% oak
	50	Presence/absence of invasive species None noted
	51	Soil and other ecological data Typic Eutroboralfs, moderately deep, fine to clayey-skeletal, very cobbly loam, 0-15% slope, benmorite parent material.
	Post Treatment
	52	Fuel load 13 Mg/Ha surface fuels
	53	Stem density (stems/ac) 66
	54	Basal area (ft2/ac) 60
	55	Canopy closure (%) More open, patchy canopy, clumped crowns
	56	Height to live crown base 21 ft.
	57	Snags and downed woody material
	58	Size class distribution See figure
	59	Tree species composition 99% Ponderosa, <1% oak
	60	Presence/absence of invasive species
	61	Soil and other ecological data

< Prev		Next >

[ Back ]