A Characterization of Timber Salvage Operations on Public Forests in Minnesota and Wisconsin

Transcription

1 A Characterization of Timber Salvage Operations on Public Forests in Minnesota and Wisconsin Matthew Russell1, Michael Kilgore2, Charles Blinn3 Abstract Despite the common management practice and benefits of salvage logging in recently disturbed forests, little is known about the contribution salvage logging operations make to wood markets. This study reports the contribution of salvage wood to the total volume of wood sold on state and county lands in Minnesota and Wisconsin. From 2010 through 2014, salvage wood made up 10% of the volume offered from a total of 7.5 million cords sold by these ownerships, a percentage similar to the total amount of forest area on state and county land that was disturbed by insects, disease, weather damage, or some other agent over the same time period. State and county salvage sales offered more volume per sale and were larger in size compared to non-salvage sales, but only if a widespread forest disturbance was observed (e.g., a catastrophic windstorm that resulted in blowdown). This analysis demonstrates that public timber sale records can be used to examine a range of ecological and economic impacts associated with forest disturbances. Keywords: forest disturbance, timber sale, salvage logging, forest health Background Forest disturbances are relatively discrete events that can change resources, substrate availability, and/or the forested environment (Helms 1998). Salvage logging is used by forest managers as a tool to reduce fuel loads, mitigate wildfire risk, and/or recover economic losses associated with forest disturbances (Lindenmayer et al. 2008). An extended delay in salvaging timber (e.g., waiting to harvest following a forest disturbance) can result in substantial economic losses as timber decays (Prestemon et al. 2006) as well as the potential loss of ecological benefits (Figure 1). Public forests play an important role in contributing to the forest products industry in Minnesota and Wisconsin. In 2012, 867,000 cord equivalents were harvested on state-owned lands in Minnesota, the highest volume of timber from any ownership group within the state (Minnesota Department of Natural Resources 2015b). Similarly for Wisconsin, timber sales on state and county lands represented 1.25 million cord equivalents in 2012 (Teague Pritchard, personal communication). Harvesting wood following a large forest disturbance can be used as a tool to sustain the development of a healthy and productive forest. Despite the beneficial ecological and economic effects salvage operations have in promoting forest recovery following widespread 1 Assistant Professor/Extension Specialist, University of Minnesota, Department of Forest Resources,1530 Cleveland Ave. N. St. Paul, MN, 55108, russellm@umn.edu 2 Professor and Interim Head, University of Minnesota, Department of Forest Resources,1530 Cleveland Ave. N. St. Paul, MN, 55108, mkilgore@umn.edu 3 Professor/Extension Specialist, University of Minnesota, Department of Forest Resources,1530 Cleveland Ave. N. St. Paul, MN, 55108, cblinn@umn.edu

2 disturbances common to the US Lake States (e.g., windstorms, insect defoliations, wildfire), an assessment of the extent of timber salvage operations conducted by public land management agencies remains largely unknown. The objective of this study is to characterize salvage logging operations on state- and countymanaged forestland in Minnesota and Wisconsin. Specific study objectives are to: (1) describe and characterize these salvage logging operations and (2) quantify and compare total statewide wood volume represented by non-salvage and salvage timber sales. Figure 1. Stand damage from the 2011 St. Croix Valley windstorm outside of Hinckley, MN (photo: Matt Russell). Methods Timber sale records for tracts sold between 1 July 2009 and 30 June 2014 were obtained from the Minnesota and Wisconsin Department of Natural Resources (DNR). For Minnesota, timber sales records were available for state-owned lands, which represents approximately 3.8 million forested acres (Miles and VanderSchaaf 2012). For Wisconsin, timber sale records on both stateand county-owned forests were available and represent approximately 3.5 million acres of forest lands (Perry et al. 2008). Timber sale types were defined as either non-salvage (a normal commercial harvest or thinning operation) or salvage (timber was sold with reduced value as a result of a forest disturbance that damaged stumpage). Wood products from these timber sales

3 included those sold in board feet (i.e., logs/sawtimber) and cords (i.e., bolts, mixed products, cordwood, fuelwood, and fine woody material). Appraised volumes identified in each timber sale were used through this analysis. Products sold as logs and sawtimber were converted to cord equivalents using the Scribner Decimal C log rule and assuming 2.44 and 2.20 cords per 1,000 board feet for softwoods and hardwoods, respectively (Wisconsin Department of Natural Resources 2014). Products that were sold by the ton (i.e., for biomass) were discarded in this analysis. Mean total volume sold, acreage, and number of species for non-salvage and salvage sales were summarized for each state. Ordinary least squares regression was used to estimate the price sold for non-salvage and salvage sales for individual species group and product class (i.e., sawtimber and cordwood). Regression analysis was conducted separately for the primary cordwood (aspenbirch, mixed conifer, mixed hardwood, and spruce-fir) and sawtimber species groups (maple, oak, and pine). In each case, the dependent variable was the price sold per cord or MBF of wood and the independent variable was the total amount of wood offered in the timber sale. Results A total of 426 salvage sales occurred in Minnesota from 2011 through 2014, comprising 11% of all timber sales in the state. Similarly for Wisconsin, 268 salvage sales during this same time period, comprising 8% of all timber sales. Salvage sales offered fewer species per sale on average, while total sale size (average acreage) was larger in Wisconsin (Table 1). For all timber sales, an individual species was commonly recorded in multiple product classes (e.g., cordwood and sawtimber). Total volume harvested from salvage sales was 757,000 cords in these two states across the five year period, representing 10% of the total 7.5 million cords sold in both salvage and non-salvage sales. Table 1. Mean and standard deviation (SD) of timber sale characteristics by timber sale type on state and/or county forestland in Minnesota and Wisconsin, 2010 through State Sale type n Total volume sold (cord equivalents) Sale size (acres) Number of species Mean SD Mean SD Mean SD Minnesota Non-salvage Salvage Wisconsin Non-salvage Salvage For the same amount of volume offered, non-salvage timber sales generated a significantly higher per unit price sold compared to salvage sales, depending on the species group and product of interest (Figures 2 and 3). As an example, for aspen-birch species in Minnesota, a non-salvage sale that offered 2,000 cords yielded a 105% increase in the price sold per cord ($29.70) compared to that offered in a salvage sale ($14.45). Aspen-birch (p < 0.001) and spruce-fir cordwood (p = 0.046) offered in salvage sales were the only two species to show significant positive slopes when examining price sold per cord (Tables 2 and 3).

4 Figure 2. Mean selling price for the primary cordwood species from salvage and non-salvage timber sales on state and/or county lands in Minnesota and Wisconsin, 2010 through Shaded regions indicate 95% confidence limits. For parameter estimates, see Table 2. Table 2. Linear regression parameters (standard errors in parentheses) for the mean selling price for the primary cordwood species from salvage and non-salvage timber sales on state and/or county lands in Minnesota and Wisconsin, 2010 through State Sale type Aspen-birch Mixed conifer Mixed hardwood Spruce-fir Intercept Slope Intercept Slope Intercept Slope Intercept Slope (0.2) (0.0002) (0.2) (0.0002) (0.1) (0.0004) (0.2) (0.0004) MN Salvage (0.6) (0.0004) (0.9) (0.002) (0.5) (0.001) (0.6) (0.002) (0.2) (0.0003) (3.0) (0.006) (0.5) (0.0007) (0.3) (0.0004) WI Salvage (1.0) (0.001) (9.2) (0.02) (2.0) (0.004) (1.1) (0.002)

5 Figure 3. Mean selling price for the primary sawtimber species from salvage and non-salvage timber sales on state and/or county lands in Minnesota and Wisconsin, 2010 through Shaded regions indicate 95% confidence limits. For parameter estimates, see Table 3. Table 3. Linear regression parameters (standard errors in parentheses) for the mean selling price for the primary sawtimber species from salvage and non-salvage timber sales on state and/or county lands in Minnesota and Wisconsin, 2010 through State Sale Type Maple Oak Pine Intercept Slope Intercept Slope Intercept Slope (21.4) (0.4) (11.9) (0.09) (3.7) (0.01) MN Salvage - - (68.5) (0.5) (10.8) (0.07) (5.1) (0.04) (4.4) (0.04) (8.1) (0.07) WI Salvage (22.2) (0.16) (15.1) (0.2) (43.0) (0.5) Discussion Salvage sales from state-owned forests in Minnesota and state- and county-owned forests in Wisconsin produced nearly 800,000 cords of wood from 2010 to 2014, representing 8 to 11% of the total number of timber sales from these ownerships. Major forest disturbance events occurring during the study period included the St. Croix Valley windstorm, which brought 80 to

6 100 mile-per-hour winds across central Minnesota and northwestern Wisconsin in July Outbreaks of eastern larch beetle (Dendroctonus simplex), a native insect that has contributed to over 200,000 acres of mortality to tamarack trees since the early 2000s (Minnesota Department of Natural Resources 2015a), likely contributed to relatively high salvage wood volumes sold across northwestern Minnesota during this period. For many salvage sales, species were recorded as mixed hardwoods or mixed conifers, which could explain the lower number of species offered in salvage sales. These broad species groupings could be a strategy to reduce time in the field conducting timber salvage appraisals or which would subsequently condense administrative costs. Similarly, broad species groupings may result from not having up-to-date inventory data prior to a disturbance. The difference in the number of species offered between timber sale types may arise because detailed forest inventory information and timber appraisals are not typically available if managers seek to implement a salvage operation, but are if a final harvest or thinning operation is planned (two activities associated with non-salvage timber sales). Salvage sales offered by state agencies tended to include higher volume and were larger in size compared to non-salvage sales, but only if a widespread forest disturbance was observed (e.g., a catastrophic windstorm that resulted in blowdown). To better relate the economic attributes of timber sale records with their associated ecological impacts, public agencies could seek to (1) more fully document forest disturbance type (e.g., beetle damage, windstorm damage) as a part of salvage sale descriptions; and (2) better describe pre-disturbance stand conditions (e.g., stand age, size-class distribution) to characterize forest attributes that contribute to susceptible forests to a variety of disturbances. Timber sale records may be one of the few data sources available to understand the economic and ecological impacts of forest disturbances and their role in forest products industries. Literature Cited Helms, J.A The dictionary of forestry. Society of American Foresters, Bethesda, MD. 210 pp. Lindenmayer, D., P.J. Burton, and J.F. Franklin Salvage logging and its ecological consequences. Island Press, Washington, D.C. Miles, P.D., and C.L. VanderSchaaf Minnesota s forest resources, Res. Note NRS Newtown Square, PA: USDA, For. Ser., Northern Research Station. 4 p. Minnesota Department of Natural Resources. 2015a Minnesota forest health annual report. Division of Forestry, Minnesota Department of Natural Resources, St. Paul, MN. 86 pp. Minnesota Department of Natural Resources. 2015b. Minnesota's forest resources, Minnesota Department of Natural Resources, Division of Forestry, Resource Assessment, Grand Rapids, MN. 74 pp. Perry, C.H., V.A. Everson, I.K. Brown, J. Cummings-Carlson, S.E. Dahir, E.A. Jepsen, J. Kovach, M.D. Labissoniere, T.R. Mace, E.A. Padley, R.B. Rideout, B.J. Butler, S.J. Crocker,

7 G.C. Liknes, R.S. Morin, M.D. Nelson, B.T. Wilson, and C.W. Woodall Wisconsin s forests, USDA For. Serv. Resour. Bull. NRS-23. Newtown Square, PA. 104 pp. Prestemon, J.P., D.N. Wear, F.J. Stewart, and T.P. Holmes Wildfire, timber salvage, and the economics of expediency. Forest Policy and Economics 8(3): Wisconsin Department of Natural Resources Timber sale handbook Wisconsin Department of Natural Resources, Madison, WI. 199 pp.