Principle – Ecological Integrity

Criterion- Regrouped to Q: Ecosystem Function is Maintained

Indicator – Coarse woody debris and snags should be retained at functional levels

Box B: Definition:

There is considerable research to show the importance of both standing snags (standing dead trees and suitable live cavity trees) and down coarse woody debris for maintenance of biodiversity (see reviews by Harmon et al., 1986, Freedman et al. 1995). Such material is important for nesting sites, denning sites, feeding areas, and thermal and drought refuges, and habitat, among other values. Coarse woody debris and snags are an indicator of ecosystem structure that are required by a range of forest dwelling organisms. Intensive forest management that creates short rotational forests may not be compatible with the immediate needs of most species of wildlife which require tree cavities or downed coarse woody debris at some point during the year.

Box D: Applicability to Different Landowners. Explain any differences:

This would apply to all landowners with aims to conserve native biodiversity. Management of coarse woody debris and snags occurs at the stand level. It is easy to do and often part of forest practice codes.

Box E: Overlap:

CIFOR 4.1.5 Soil carbon pools.

CIFOR 4.1.6 Soil carbon pool decay rates.

CIFOR 2.4.6 The status of decomposition and nutrient shows no significant change.

Notes: Coarse woody debris and snags are habitat features that occur at the site level. They are managed at the tenure level. Individual animals (i.e. Pileated woodpecker) use distributions of snags across a home range that may be up to 30 mi. ² and are thus more relevant to the forest management unit scale.

Notes: This indicator can be either diagnostic or predictive, depending on how it is used. Because snags and coarse woody debris are limiting features for many species, their density has both assessment and predictive value for the density of many species.

Notes: The presence of snags and coarse woody debris is a structural measure at a site level.

Box I: Underlying Concepts:

There is considerable research to show the importance of both standing and down coarse woody debris (CWD) for maintenance of biodiversity (see reviews by Harmon et al., 1986, Freedman et al. 1995). Such material is important for denning sites, decomposition, feeding areas, and thermal and drought refuges, among other values. These habitat features are especially important to certain species of birds, and are used for nesting in excavated and/or natural cavities, as foraging substrate, and as perches for hunting, resting, feeding, and singing. Scott et al. (1980) estimated that 30-45% of the breeding bird species of conifer and aspen forests of the northwestern United States are cavity nesters, requiring snags as a necessary habitat feature. These species include primary excavators such as woodpeckers, secondary cavity users, and species that use natural cavities. Clearly, management of coarse woody debris, including snags, can be an important variable that influences the effects of forest harvesting on birds.

Coarse woody debris can provide protection from erosion, store large amounts of water, and act as a nitrogen fixation site. Coarse woody debris on the forest floor is an important habitat components for salamanders, insects, plants, mammals and micro-organisms (Freedman et al., 1996). As a continual input to soils, coarse woody debris enhances soil physical properties. In aquatic system, coarse woody debris from forests is also important substrate and shelter and can influence hillslope and stream geomorphology. In general, there are substantial differences in the amounts and distributions of woody biomass between naturally-disturbed forests and those that develop as the result of a silvicultural system (Harmon et al., 1990).

Box J: Relevance to Sustainable/Unsustainable Management:

Implicit in the ecological integrity component of sustainability is the maintenance of ecosystem structure. Coarse woody debris and snags are limiting structural components to many forest species. Coarse woody debris is also critical to the maintenance of soil condition and thus the growth of trees and other valued ecosystem components.

Box K: Measurement Methods:

Measurements of coarse woody debris and snags are commonly employed and straightforward. Snags are recorded in densities per unit area. Coarse woody debris is divided into size classes and recorded as mass per unit area. This involves sub-sampling and air drying before weighing.

Box L: Data Required:

Box M: Data Used for the North American Test:

The land managers in the study area were asked for available standards and practices relative to coarse woody debris and snags.

Box N: Example Results:

For the Payette National Forest, snag density recommendations are provided by forest type and size class for 3 different fire intensity classes. The recommendations range from a total of 1.6 snags/acre in open canopy ponderosa pine (unburned and low fire intensity) to 13.5 snags/acre in spruce/fir (high fire intensity) (Evans and Martens, 1995). For the Boise National Forest there are standards in the forest plan to maintain 180 snags/100 acres (1.8 snags/acre) in Ponderosa pine and Douglas fir with a minimum diameter of 12 in. DBH. Eleven of the snags must be larger that 20 inches. For Lodgepole pine and Subalpine fire, there are standards to create or maintain 144 snags/100 acres (1.4 snags/acre) with a DBH of 10 inches and at least 47 snags larger than 12 in. DBH. Monitoring of targets for snags is done as part of post harvest evaluation.

On Idaho State lands, management standards state "in general leave at least 3 snags per acre." Along with the standard are suggestions for snag selection, leaving snags in burned areas and considerations of snag recruitment.

Boise Cascade lands do not have fixed rules for leaving snags, but refers decisions to the operational level. In general, snags are left wherever possible (Brad Holt, pers. Com., Boise Cascade).

Coarse woody debris standards for the Boise National Forest are not currently part of the forest plan. However coarse woody debris considerations are written as part of individual harvest prescriptions (timber sales). In general, prescriptions follow Graham et al. (1994) with some local adjustments for aspect and sites with frequent fire return intervals (Lynnette Morelan, pers. Com., Boise National Forest). Prescriptions including leaving minimum number of pieces of coarse woody debris in several size classed per acre.

Coarse woody debris guidelines for Idaho State lands suggest leaving logs some over 6 inches in diameter for wildlife purposes, with no numerical targets. There is no system to formally record compliance with the standard.

Boise Cascade does not have management targets for coarse woody debris.

On the National Forest lands, post harvest inventories record whether snag and coarse woody debris guidelines are met. We did not have time to look at compliance levels from these inventories, but were told it was virtually 100%.

Standards for the management of snags are available in many North American jurisdictions. In old-growth, Douglas- fir-dominated forests of eastern Oregon, woodpeckers require the following snag characteristics as a component of their habitat: Pileated Woodpecker (Dryocopus pileatus), 0.32 snags/ha, larger than 64-cm diameter for use as a nest tree; Common Flicker (Colaptes auratus), 0.93 snags/ha, >43 cm; Hairy Woodpecker (Picoides villosus), 4.5 snags/ha, >38 cm; and Black-backed Three-toed Woodpecker (Picoides arcticus), 1.5 snags/ha (Thomas et al., 1979; Maser et al., 1988). For the same region, Bull et al. (1980) recommended that at least 4 snags/ha be left on a harvested site, to ensure maintenance of at least 70% of the potential woodpecker population. In the Acadian Forest, recommendations are to leave a minimum of 12-15 snags (defined as standing dead trees, preferably 20 cm or greater dbh) per hectare for feeding plus 10-12 live, or partially dead, mature Aspen or Beech. Subsequent interventions should strive to maintain those numbers and ratio (Woodley et al. 1996).

There are a smaller number of standards for coarse woody debris, but they do exist. The USDA Forest Service suggested standards for the forests of the US Rocky Mountains (Graham et al., 1994). Recommendations were given by habitat type and ranged form 2.5 tons/acre in grand fir/mountain maple to 33 tons per acre in Western hemlock. These recommendations were based on relationships between ectomycorrhizal activity and soil organic matter activity provided by Harvey et al., 1987. In the Acadian Forest, the Greater Fundy research group recommend that there should be a minimum of 200 pieces/ha of coarse woody debris (average piece diameter greater than or equal to 10 cm), and a minimum total of 10 m³/ha throughout the rotation of the stand. These values were based on average values for the unharvested for the area.

Most species of wildlife dependent on tree cavities have different food, cover, and spatial requirements, thus the utility of snag trees varies by species. For example in Pileated woodpeckers, there are great differences between trees used for nesting and trees used for feeding. It is estimated that a Hairy Woodpecker, for example, requires 160 snags per 40 ha of habitat, a Pileated Woodpecker 14 snags per 40 ha (most are for feeding, a few may be used for roosting). However, the territory of a Pileated Woodpecker may be 12 times that of a Hairy Woodpecker. Thus, the Pileated has access to a greater area and thus a greater variety of snags (Woodley et. al, 1996).

Box O: Assessing the Practicality:

Data on snags and coarse woody debris is relatively easy to obtain. However there is a high degree of variability in the amount of snags and coarse woody debris in a forest. The creation and accumulation of these ecosystem elements depends on forest type, time since disturbance, insect and disease activity, weather events, fire return intervals, decay rates and past timber harvest activities.

Snag and coarse woody information is relatively easy to collect. As a measure it is now regularly assessed by the National Forest and standards exist for State lands.

Box P: Assessing the Information Value:

The role of snags seems to be accepted by the public and land managers, as evidenced by the fact that snag guidelines have been around for decades. The role of coarse woody debris is less well known or understood. The understanding of the value of these components can be improved by information programs. Of particular focus is the role of continual inputs of organic matter into the soil to maintain soil heath and thus tree growth. There are a number of established targets available for both snags and coarse woody debris. The relationship of existing and projected conditions relative to these targets will have good information value.

Box Q: Overall assessment:

Accepted. Snags and coarse woody debris are key structural elements of the forest ecosystem. Because they have the potential to be dramatically altered by management, they must be planned for and monitored. This should be regrouped under Criteria Q, Ecosystem Function is maintained as it refers more to maintaince of function.

Currently, many guidelines exist for the management of snags and coarse woody debris. There is ongoing formal monitoring in the National Forest lands of the study area. There are no specific problems with developing monitoring protocols, and from this test site, no difficulty with setting standards.

Box R: Did you rewrite or revise to a new indicator. If so what?

No. Regrouped under Ctiterion Q, ecosystem functions is maintained.

Box S: References :

• Bull, E.L., A.D. Twombly, and T.M. Quigley. 1980. Perpetuating snags in managed mixed conifer forests of the Blue Mountains, Oregon. pp. 325-336 in: Management of Western Forests and Grasslands for Non-game Birds. USDA For. Serv., Gen. Tech. Rep. INT-86, Intermountain Forest and Range Experiment Station, Ogden, UT.
• Bull, E.L., S.R. Peterson, and J.W. Thomas. 1986. Resource Partitioning Among Woodpeckers in Northeastern Oregon. USDA For. Serv., Res. Note PNW-444, Pacific Northwest Research Station, Portland, OR.
• Conner, R.N. and D.C. Rudolph. 1989. Red-cockaded Woodpecker Colony Status and Trends on the Angelina, Davy Crockett, and Sabine National Forests. Res. Pap. SO-250, Southern Forest Experiment Station, New Orleans, LA
• Davis, J.W., G.A. Gregory, and R.A. Ockenfels (eds.). 1983. Snag Habitat Management. USDA For. Serv., Tech. Rep. RM-99, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.
• Evans, Diane and Dean Martens. 1995. Snag and Coarse Woody debris Guidelines for Timber Harvest Projects. Payette National Forest Internal Report. 24pp.
• Freedman, B., V. Zelazny, D. Beaudette, T. Fleming, S. Flemming, G. Forbes, J.S. Gerrow, G. Johnson, and S. Woodley. 1996. Biodiversity Implications Of Changes In The Quantity Of Dead Organic Matter In Managed Forest. Environmental Reviews. 7:33-77.
• Graham, Russel T., Alan E. Harvey, Martin F. Jurgensen, Thersa B. Jain, Jonalea R. Tonn and Deborah S. Page-Dumroese. 1994. Managing Coarse Woody Debris in Forests of the Rocky Mountains. Gen. Tech. Rep. INT-RP-477, UT: U.S.D.A. Forest Service, Intermountain Research Station. 13 p.
• Harmon, M.E., J.F. Franklin and F.J Swanson. 1986. Ecology of Coarse Woody Debris in Temperate Ecosystems. Advances in Ecological Research. Vol. 15. New York, Academic Press: 133-302.
• Harmon, M.E., W.K. Ferrell, and J.F. Franklin. 1990. Effects of carbon storage conversion of old-growth forests to young forests. Science, 247: 699-702.
• Harvey, A.E., E.A. Jurgenson, and M.J. Larsen. 1981. Organic reserves: importance to ectomycorrhizae in forest soils in western Montana. Forest Science 27:422-445.
• Hooper, R.G., A.F. Robinson, and J.A. Jackson. 1980. The Red- cockaded Woodpecker: Notes on Life History and Management. USDA For. Serv., Gen. Rep. SA-GR-9, Southeastern Forest Experiment Station, Asheville, NC.
• Lundquist, R.W. and J.M. Mariani. 1991. Nesting habitat and abundance of snag-dependent birds in the southern Washington Cascade Range. pp. 220-240 in: Wildlife and Vegetation of Unmanaged Douglas-fir Forests. USDA For. Serv., Gen. Tech. Rep. PNW-285, Pacific Northwest Forest and Range Experiment Station, Portland, OR.
• Maser, C., S.P. Cline, K. Cromack, J.M. Trappe, and E. Hansen. 1988. What we know about large trees that fall to the forest floor. pp. 25-45 in: From the Forest to the Sea: A Story of Fallen Trees. USDA For. Serv., Gen. Tech. Rep. PNW-GTR-229, Pacific Northwest Forest and Range Experiment Station, Portland, OR.
• Scott, V.E., J.A. Whelan, and P.L. Svoboda. 1980. Cavity- nesting birds and forest management. pp. 311-324 in: Management of Western Forests and Grasslands for Non-game Birds. USDA For. Serv., Gen. Tech. Rep. INT-86, Intermountain Forest and Range Experiment Station, Ogden, UT.
• Thomas, J.W., R.G. Anderson, C. Maser, and E.L. Bull. 1979. Snags. USDA For. Serv., Agric. Handb. 553, Washington, D.C.
• Woodley, Stephen and Graham Forbes (eds.) 1996. Forest management guidelines for protecting native biodiversity in the Fundy Model Forest. Publication of the Fundy Model Forest, Sussex, New Brunswick. 40 pp. http://www.unb.ca/forestry/centers/cwru/toc.htm