Effects of Thinning Young Forests on Chanterelle Mushroom Production
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forest ecology Effects of Thinning Young Forests on Chanterelle Mushroom Production David Pilz, Randy Molina, and Jim Mayo Chanterelle productivity responses were investigated in a replicated, landscape-scale thinning experi- management for nontimber forest products, ment in 50-year-old Douglas-fir stands in the Cascade Range of Oregon. Chanterelle numbers and Jones et al. (2002) provide an overview of weight were significantly decreased by thinning the first year after logging, more so in heavily thinned nontimber forest product issues in the stands than lightly thinned stands for chanterelle numbers. Nearly all evidence of differences in United States, Kerns et al. (2003) provide a chanterelle productivity among thinning treatment means disappeared within 6 years. Management review of research on compatible manage- implications and mitigation measures are discussed. ment of timber and commercially harvested ABSTRACT understory species, Pilz and Molina (2002) Keywords: chanterelle productivity, Cantharellus, young stand thinning, nontimber forest products discuss issues regarding the management and monitoring of edible forest mushrooms, and Alexander et al. (2002) describe com- parisons of the value of timber and mush- dible chanterelle mushrooms that successional habitat. The commercial har- rooms comanaged in the same forest. grow wild in the moist coniferous vest of forest products (timber and nontim- Chanterelles and other renowned edi- E forests west of the Cascade Range in ber) is one of the many uses that managers of ble forest mushroom species in the Pacific Oregon and Washington are avidly sought national forests are expected to provide for Northwest also are integral functional com- each summer and autumn by mushroom the public in perpetuity. Before the 1980s, ponents of forest ecosystems. Chanterelles, hunters. The Pacific golden chanterelle chanterelles were predominantly harvested boletes (Boletus species), American mat- (Cantharellus formosus, Redhead et al. 1997; for personal use but now have become im- sutake (Tricholoma magnivelare [Peck] Red- formerly known as Cantharellus cibarius Fr.) portant nontimber forest products. head), truffles (Tuber gibbosum Harkn. and and the white chanterelle (C. subalbidus Schlosser and Blatner (1995) report that 1.1 Leucangium carthusianum [Tul. & C. Tul.] A.H.S. & Morse) are the two most com- million pounds of chanterelles were com- Paol.), and hedgehogs (Hydnum repandum monly collected chanterelle species in the mercially harvested in Oregon, Washington, L. ex Fr.), among others, are ectomycorrhi- Pacific Northwest (Pilz et al. 2003). Both and Idaho in 1992. Mushroom buyers paid zal fungi; i.e., they grow symbiotically in as- fruit in young dense Douglas-fir (Pseudo- harvesters $3.6 million for the crop; the sociation with the roots of particular host tsuga menziesii [Mirbel] Franco) and western chanterelles were then marketed locally, na- tree species (Molina et al. 1993, Hosford et hemlock (Tsuga heterophylla [Raf.] Sarg.) tionally, and internationally. Pacific North- al. 1997, Cairney and Chambers 1999, Pilz stands that are common throughout the re- west chanterelles continue to contribute to a et al. 2003). Both Douglas-fir and western gion as a result of logging native forests dur- global trade in wild edible mushrooms that hemlock are ectomycorrhizal with chan- ing the latter half of the 20th century. is large and multifaceted (Boa 2004). Al- terelles; hence, we hypothesize that their re- Many of these young stands are now though timber production has long been in- moval during stand thinning is likely to re- slated for thinning to produce wood fiber, tegral to forest management, foresters are duce, at least temporarily, the food supply enhance the growth and health of residual grappling with how to fit forest products that is available for the fruiting of chan- trees, and meet other management goals. such as chanterelles into their management terelles. Similar effects might be expected On national forestlands, these other goals plans because so little is known about how with other edible ectomycorrhizal species of include multiple use, increasing the biolog- various management practices and silvicul- fungi, although the influence of thinning ical diversity of plantations and in some tural regimes affect their persistence and likely differs by species (Kropp and Albee cases accelerating the development of late- productivity. For context regarding forest 1996). We anticipate, however, that as the Journal of Forestry • January/February 2006 9 Table 1. Thinning treatments, plot descriptions, and timeline. a Strip plot length Plot area Years sampled and thinning status Timber sale (replicate) Thinning treatment (chains) (ft2) 1994 1995 1996 1997 1999 2001 Flat Thin Control 7 7,579 OOOOOO Flat Thin Light 7 7,579 O OXXX Flat Thin Heavy 7 7,579 O OXXX Mill Thin Control 20 21,654 OOOOOO Mill Thin Light 19 20,571 O XXXX Mill Thin Heavy 20 21,654 O XXXX Tap Thin Control 9 9,744 OOOOOO Tap Thin Light 16b 17,323 O XXXX Tap Thin Heavy 9 9,744 O XXXX Walk Thin Control 7 7,579 OOOOOO Walk Thin Light 7 7,579 O XXXX Walk Thin Heavy 7 7,579 O XXXX aO, not thinned when sampled; X, thinned; blank, not sampled that year because of logging activity hazards. The Flat Thin timber sale replicate was thinned a year later than the other three replicates. bOne of the five plots is 17 chains long for a plot area of 18,406 ft2. leave trees resume vigorous growth and re- may be obtained by contacting the Cascade maintain standard plot lengths for all the occupy the site, chanterelle fruiting should Center for Ecosystem Management (2003). treatment stands within a replicate timber rebound, perhaps to levels higher than be- Study Design. Each thinning treat- sale. Practical considerations during plot es- fore thinning because the remaining trees ment was applied to a forest stand of 50– tablishment resulted in several instances will be growing more vigorously. In this 100 ac and with trees around 50 years old. where plots differed in length. study, we investigate stand-level chanterelle Treatments consisted of a nonthinned con- Leave tree densities differed somewhat productivity responses during 4 of 6 years trol (Ϸ250 trees per ac [tpa]), a light thin within the thinned stands, and some areas after the thinning of 50-year-old Douglas-fir (Ϸ100–120 residual tpa), a heavy thin (such as protection buffers along streams forests. (Ϸ50 residual tpa), and a light thin with and roads) were not thinned even in the light 20% of the area in gaps (1⁄2-ac clearings). and heavy thin treatments. Postthinning Young Stand Thinning and The four stand treatments were replicated in forest floor conditions that might inhibit Diversity Study each of four timber sales (located from 2 to chanterelle fruiting or make the mushrooms Study Context. Landscape-scale stud- 20 miles apart) in forests that were climati- hard to find (soil disturbance, soil compac- ies of forest thinning are expensive; there- cally, physiographically, edaphically, and tion, deep slash, or burned slash piles) also fore, this study was a part of a larger inte- ecologically similar. For the chanterelle por- were distributed irregularly within our grated study entitled the Young Stand tion of the study we chose to sample only the stands. Our strip plots were established be- Thinning and Diversity Study (YSTDS). control, light, and heavy thinning treat- fore thinning and traversed these smaller- The YSTDS is a cooperative venture be- ments, not the light thin with gaps. Logging scale conditions without prior knowledge of tween the Cascade Center for Ecosystem methods included harvester-forwarder, trac- their location. The plots also were estab- Management in Blue River, Oregon; Ore- tor, and skyline, but the logging systems lished before we knew where, or even if, gon State University in Corvallis, Oregon; were not replicated (Kellogg et al. 1998). chanterelles fruited in each stand. As a result, the Pacific Northwest Research Station, Chanterelle Sampling. Prethinning we obtained unbiased stand-scale estimates USDA Forest Service; and the McKenzie chanterelle productivity was sampled in au- of thinning effects. and Middle Fork Ranger Districts of the tumn 1994. Earlier that summer, crews who Table 1 gives replicate timber sale Willamette National Forest in the central were sampling understory vegetation had es- names, thinning treatments, plot lengths in Cascade Range of Oregon. The overall goal tablished parallel transects through each chains, plot area in square feet, the year each of the YSTDS was to investigate the envi- stand along cardinal compass directions. stand was sampled, and whether the stand ronmental effects of several thinning re- These transects were marked at each chain (1 had been thinned yet. All chanterelles found gimes, including a heavy thin that might be chain ϭ 66 ft ϭ 20.12 m). We chose to during a sampling visit were collected, used to speed the development of late-suc- sample chanterelles along these transects to counted, and weighed by plot. Subsamples cessional stand characteristics such as large- save the expense of establishing new plot lo- from each plot were dried to determine diameter trees, a multiple-layered canopy, cations. We established five strip plots in moisture content for dry weight analyses. An tree species diversity, and snags for wildlife each stand to obtain estimates of variation effort was made to collect all chanterelles habitat. The YSTDS objectives included in- among plots within each stand. The strip that grew during the fruiting season. Crews vestigating the effect of young stand thinning plots (elongated rectangles) that we delin- began sampling when autumn rains elicited on ecosystem variables such as understory veg- eated were 16.4 ft (5 m) wide. We deter- the first flush of chanterelles (typically, mid- etation, woody debris, tree regeneration, song- mined the side boundaries by measuring 8.2 September) and continued until snow made bird and small mammal populations, and ft (2.5 m) on either side of the central sampling impractical (typically, early to chanterelle production, as well as analyzing the transect.