Snag Management - PDF document

Problems In Snag Management Implementation A Case Study1 2 Edward W. Styskel Abstract.--Providing suitable snags over time for de­pendent wildlife within intensively managed forests is an extremely complex task. Problems encountered in achieving this goal include: (1) moderate responsiveness by account­able personnel; (2) determining and following snag status; (3) minimizing timber yield reductions; (4) imprecise "longevity" data for standing 20, 40, and 50 years, respectively. Furthermore, rotation ages for these stands will be relatively short, at approximately 80, 135, and 120 years. Snag management goals for the Forest have been established based on .the concept of "maxi­ mum potential population" offered by Thomas, et al. (1979). Obstacles in Symposium, Flagstaff, Ariz., June 7-9, 1983.2 Edward W. Styske1 is Forest Wildlife Biologist, Deschutes National Forest, Bend, Oreg. 24 efforts concentrated on protecting existing snags. Then, additional attention was given to reserving some live trees for future snag replacements. Now, systematic calculation of the number and size of live trees for snag replacements over a managed forest stand rotation is undertaken, based upon growth pre­dictions and estimated snag standing longevity. the--ratter is a performance appraisal element upon which the agency measures their managerial ability, and the former is not. Until such time as performance appraisals relate equally to all phases of National Forest manage­ment (i.e. meeting all targets of the Forest Plan, instead of singling out specific ones such as timber volume), the barrier is still potentially there. Project workers who perform the details of project layout, whether it inhibitory of evenly distributed live tree (3) diminish the influence of or diseased live replacements on seedling crop trees; (4) lessen blowdown loss experienced by single trees exposed after forest canopy removal; (5) shrink wildlife tree losses associated with other forest activities; and (6) provide habitat values for other wildlife. Monitoring over time will determine the validity of these assumptions. Snag Standing Longevity Knowledge of the standing "life expectancy" of snags is critically significant in deter­mining how many tree replacements must be reserved over a managed forest rotation to meet established goals. Few studies have been specifically designed to collect the kind of data a biologist might desire. Interpolation from research conducted with other objectives in mind is often necessary, and the more localized the better. Factors including soil type, site produc­tivity, climate, heartwood/sapwood ratio, the incidence of insects or disease, and others have been identified by Keen (1955) as influencing the rate of snag fall. To refine the longevity estimates used on the Forest, these factors will be measured in snag longevity monitoring efforts beginning this year. Wildlife Tree Protection Physical protection of reserved snags and live replacements is the final obstacle. Wind­throw, and land management activities such as logging, forest fuel treatment, timber stand improvement, prescribed burning, and public firewood cutting, are all known sources of attrition. It has been established that snag attrition occurs from windthrow, and is influenced by bole diameter--large diameter snags remaining upright longer than smaller ones (Dahms 1949, Lyon 1977). Determination of this loss is paramount to calculating snag and live replacement needs for areas where snag retention is planned. For example, some areas of the Forest have exhibited reductions in evenly distributed reserved snags of 25 percent for 20-inch or greater dbh snags, and 75 percent for less than 20-inch dbh snags, immediately after canopy removal by clear-cut or shelterwood. Snag hazards to worker safety and fire protection in woods operations have prompted State Laws and Administrative Rules which require snag felling for reasonable hazard control. The consequences of these requirements can be moderated with careful attention to project design and wildlife tree position. For example, wildlife trees would not be positioned where obvious hazard to log landings or proposed road locations would jeopardize their retention. While the felling of hazardous snags in timber harvest is a step backwards in terms of 26 snag management goals, this loss, and that from other causes, can often be mitigated with timber sale generated funds to artificially create or manipulate snags. Such plans are underway on the Forest to accelerate snag formation by various techniques, including fire-scarring by piling and burning logging debris at the base of live snag replacements, and topping with explosives (Bull, et al. 1981) or cutting. The latter technique was successfully contracted this spring on snags and livg replacements at a cost of $45 per tree. Ponderosa pine with dimensions of 18 to 26 inches dbh averaging about 80 feet tall were sawn off at a height of approximately 30 to 50 feet. The live replacements were topped to retain just enough live foliage for the tree to stay alive, the assumption being that a dimin­ished live crown would be more windfirm and less influential on understory retardation and the spread of dwarf mistletoe. Logging (or thinning) debris disposal and vegetative manipulation accomplished by pre­scribed burning may consume snags and down logs without pre-planned safe-guards. Loss of snags or live replacements due to post-sale activities has occurred because attention to snags often does not carry through to these stages of 'timber management. The land manager must learn to think about snags in all types of management activity before this short-circuit can be remedied. Uncontrolled public firewood cutting can have significant consequences upon the retention of snags for wildlife, especially where rela­tively flat and open terrain or extensive road systems allow easy vehicular access. Land managers can control this activity, though, to lessen the influence on wildlife trees. First, a permit system, the provisions of which are legally enforceable and require public user contact with the manager, is requisite. Protection of wildlife trees must be considered in specifying the requirements of the permit. For example, specifications on permissible tree species or diameter, areas open to cutting, or snags with evidence of wildlife use or pro tec­ tive signing may be necessary. Public education of the potential for cohflict between firewood cutting and main­taining snag habitat for wildlife can occur at the time of permit acquisition, and with Public Service Announcements during the woodcutting season. Violation of permit provisions on the Deschutes National Forest is punishable through criminal citation and fine. In addition, miti­gative damages can be assessed against violators for the cost of replacing the felled snag. When 6 Corn, Deschutes Don. 1983. Personal conversation. National Forest, Sisters, Oreg.