place under the snow. Any plants crushed to the ground 

 with bracken fronds might perish as a direct or indirect 

 result of bracken decomposition, including succulent con- 

 ifers and shrubs regenerating on pocket gopher mounds. 



This possibility is speculative (and needs to be tested) 

 but seems plausible because the few species associated 

 with bracken fern in these glades are herbaceous (annual, 

 biennial, or perennial plants that die back to the ground at 

 the end of the growing season). Bracken appears to have 

 dominated these glades for hundreds of years, and there is 

 little evidence of succession to woody species. We have 

 observed that shrub and conifer seed are cast into the 

 glade. Some species of seed may be kDled during strati- 

 fication or the germination energy reduced below the level 

 needed for sur\aval. If seed does germinate, it can die as a 

 result of absorbing phytotoxins. Seedlings surviving all of 

 the above would then be subjected to smothering by 

 bracken fronds and decomposition under the snow. These 

 competitive mechanisms severely limit the establishment 

 of woody species in bracken-dominated areas of northern 

 Idaho. 



RECOMMENDATIONS 



The exploratory studies reported in this paper were 

 designed to increase our understanding of bracken fern. 

 Based on these results and the hterature review, a Hst of 

 recommendations was compiled. Additional research is 

 needed to find answers to specific reforestation questions. 

 For now, it should be remembered that bracken is a prob- 

 lem weed throughout the world, no economical solutions 

 for its control have been found, and prevention of prob- 

 lems with bracken is the preferred alternative. These 

 recommendations apply to reforestation efforts in areas 

 where bracken has successfully invaded previously 

 harvested stands and where bracken is present in and 

 around stands scheduled for harvesting. 



1. Recognize that allelopathy can be a major considera- 

 tion when developing a silvicultural prescription. Ignoring 

 this constraint negates investments of time and money in 

 reforestation efforts. However, allelopathy is not a magical 

 answer to reforestation failures. 



2. Plan to regenerate stands quickly following harvest. 

 We have found bracken rhizomes in dense forest stands 

 adjacent to bracken glades and bracken-dominated cutover 

 stands. Rhizome expansion coupled with colonization by 

 spores can quickly increase bracken dominance. 



3. Keep site preparation to a minimtmti. Hot burns or 

 excessive scarification encourage invasion of bracken fern 

 via spores. See Stickney (1986) for examples of bracken in- 

 vasion following a severe fire in northern Idaho. Repeated 

 burns unduly favor bracken because fires do not kill the 

 rhizomes, which readily resprout. 



4. Do not rely on natural regeneration. Plant trees as 

 soon after harvest as possible and protect them from 

 pocket gophers and grazing animals. Prompt planting will 

 help ensure that trees are estabhshed before gopher 

 populations and bracken cover build up. Planted trees 

 should survive well if protected, but growth rates will be 

 reduced where bracken cover is thick. 



5. Exclude natural bracken glades within the stand from 

 land to be reforested. Few, if any, trees have grown on 

 these sites in the past. Including these areas gives a false 

 picture of seedling density and percentage of stocked 

 plots. Naturally occurring bracken glades are hundreds of 

 years old and appear to be the climax vegetation. These 

 glades are worthy of consideration as a distinct habitat 

 type. 



REFERENCES 



Acsai, J.; Largent, D. L. 1983. Ectomycorrhizae of 

 selected conifers growing in sites which support dense 

 growth of bracken fern. Mycotaxon. 16: 509-518. 



Advincula, B. A.; Woo, J. Y.; Partridge, A. D. 1983. A 

 method for germination of western white pine seeds. 

 Unpublished paper presented at: Western Forestry and 

 Conservation Association Conference; 1983 December 

 12-14; Portland, OR. 4 p. 



Bohm, B. A.; Tryon, R. M. 1967. PhenoHc compounds in 

 ferns. I. A survey of some ferns for cinnamic acid and 

 benzoic acid derivatives. Canadian Journal of Botany. 

 45: 585-593. 



Boyd, R. J.; Znerold, R. M. [In preparation]. The effects of 

 bracken fern control with asulam on the subsequent per- 

 formance of planted conifers in northern Idaho. Moscow, 

 ID: U.S. Department of Agriculture, Forest Service, 

 Intermountain Research Station. 



Braid, K. W. 1959. Bracken: a review of the literature. 

 Publication 3. England: Commonwealth Bureau of 

 Pastures and Field Crops. 69 p. Mimeo. 



Brown, R. T. 1967. Influence of naturally occurring com- 

 pounds on germination and growth of jack pine. 

 Ecology. 48: 542-546. 



Cody, W. J.; Crompton, C. W. 1975. The biology of 

 Canadian weeds. 15. Pteridium aquilinum (L.) Kuhn. 

 Canadian Journal of Plant Science. 55: 1059-1072. 



Conway, E. 1952. Bracken - the problem plant, a review 

 of recent conclusions about its spread and dominance. 

 Scottish Agriculture. 31: 181-184. 



Cooper-Driver, G. 1976. Chemotaxonomy and phyto- 

 chemical ecology of bracken. Linnean Society Botanical 

 Journal. 73: 35-46. 



Cooper, S. V.; Neiman, K. E.; Steele, R.; Roberts, D. W. 

 1987. Forest habitat types of northern Idaho: a second 

 approximation. Gen. Tech. Rep. INT-236. Ogden, UT: 

 U.S. Department of Agriculture, Forest Service, Inter- 

 mountain Research Station. 135 p. 



DeBell, D. S. 1970. Phytotoxins, new problems in 

 forestry? Journal of Forestry. 68: 335-337. 



del Moral, R.; Gates, R. G. 1971. Allelopathic potential of 

 the dominant vegetation of western Washington. 

 Ecology. 52: 1030-1037. 



Dimock, E. J., II. 1964. Supplemental treatments to aid 

 planted Douglas-fir in dense bracken fern. Res. Note 

 PNW-11. Portland, OR: U.S. Department of Agriculture, 

 Forest Service, Pacific Northwest Forest and Range Ex- 

 periment Station. 10 p. 



Evans, I. A. 1976. Relationship between bracken and 

 cancer. Linnean Society Botanical Journal. 73: 105-112. 



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