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Impacts of Clearcut Logging on the Fish and Wildlife Resources of Southeast Alaska Editor: Marilyn J

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Impacts of Clearcut Logging on the Fish and Wildlife Resources of Southeast Alaska Editor: Marilyn J Impacts of Clearcut Logging on the Fish and Wildlife Resources of Southeast Alaska Editor: Marilyn J. Sigman Technical Report 85-3 Alaska Department of Fish and Game Habitat Division Juneau Novenkr 1985 TABLE OF CONEZNTS Prn 1 A-S A-S ...................... ~UCTION........................ GENERAL RFLATIONSHIP OF WILDLIFE TO THEIR HABITAT ..... DESCRIPTION OF OLD-GROGJTH FORESTS AND SJ3RAL STAGES FoLT-mmGCLEARCUTTING ................... Old-qrmth Forests .................. Early Successional Clearcuts ............. Pole Stands ...................... Effects of Precamnercial Thinning on Forest Succession Effects of Cannercia1 Thinning on Forest Succession . Other Natural Forest Types .............. Other Potential Habitat Managemnt Techniques ..... IMPACTS OF TIElBER HARVEST ON SPECIFIC WILDLIFE SPECIES ... Deer ......................... Mountain Goat ..................... Brawn/Grizzly Bear .................. Black Bear ...................... Wse........................... wolf ......................... Furbearers ....................... Marten ...................... Beaver ...................... Mink ....................... Land Otter .................... SrnallMamMls ..................... Birds ......................... Breeding Habitat Studies ............. Winter Habitat Studies .............. Bird Use of Snags and Tree Cavities ....... Bald Eagle .................... Osprey ...................... Marbled Murrelet ................. BlueGrouse ................... Vancouver Canada Goose .............. Birds-Final Considerations ............ CONCLUSIONS AND MANACZMENT IMPLICATIONS .......... LITERAmCITED...................... INTFODUCTION ...........................59 IMPOWANT AQUATIC HABITAT vPJUN3m FOR FISH PRODUCTION ......59 Streamflm and Hydrological Dynamics .............59 Water Quality .........................61 Tanperatwe .......................61 Dissolved Oxygen Concentrations .............62 S-nt Load ......................62 Nutrient Cycling .......................63 iii Physical Habitat Features ..................63 Stream banks ......................63 Riparian Vegetation ..................63 Barriers ........................64 SHOm-TERM EFFECTS ON FISH HABITAT ................64 Changes in Water Quality ...................65 Tenperatwe .......................65 Dissolved Oxygen Concentrations .............67 Sedhnt Load ......................67 Logging Slash and Debris Depositions ..........70 Changes in Physical Structure of the Habitat .........71 Juvenile Fish Habitat ..................71 ChannelMorpholcgy ...................73 IQNG-TERM EFFECTS ON FISH HABITAT .................74 Streamflm and Hydrological Dynamics ............74 Barriersto Fish Passage ...................75 Nutrient Cycling .......................75 Physical Habitat Structure-Recruitment of instreamwoody debris ...................76 BUFFERSTRIPS ..........................77 CONCLUSIONS AND MANAGEMEXT IMPLICATIONS .............79 LITERATURE CITED .........................83 The Impacts of Clearcut Logging on the Wildlife Resources of Southeast Alaska By: Marilyn J. Sigman Habitat Division Alaska Department of Fish and Gam Juneau ACKNOWLEDGEMENTS The author expresses her appreciation for the contributions and assistance provided by deparhnental staff in preparation of this report. Special thanks go to the following individuals for assistance: Bruce Dinneford, Joe Dcerr, RdFlynn, Chris Hundtermark, Jeffrey Hughes, Matthew Kirchhoff, Loyal Johnson, John Matthews, John Schcen, and Chris Smith. The preparation of this report has been made possible through allo- cation of a portion of a 5-year Regional Planning Capital Improvemnt Budget authorized the Alaska Depaxtxwnt of Fish and Gam for the period FY 82-86. INTRODUCTION Logging, as currently practiced and planned in southeast Alaska, has the potential to significantly and permanently alter large amunts of wildlife habitat. Wildlife species which are adapted to use existing habitat my decline and associated recreational and subsistence uses may be substantially reduced. Clearcut logging, with no post-logging treatment, is generally the prima.ry type of silvicultural system in southeast Alaska. The Forest Service is currently interpreting the Alaska National Interest Lands Conservation Act (ANID) as a mandate to offer for harvest 450 MMbf of timber yearly, which will result in the scheduling of an average of 158,000 acres cf old cjrclwth for timber harvest during this decade alone. Once cut, stands will be managed on a multiple-entry rotation schedule of 80-125 years. Thus, old-grcrwth stands on federal lands will be permanently converted to second-growth stands. While second-grcrwth trees will reach mturity prior to subsequent harvest, many of the forest stan6 characteristics which develop in older stands will not recur. The major long-term impacts cf this harvest schedule on wildlife species and numbers will. depend on hm the habitat characteristics will be altered through forest management relative to the species' habitat requirements. Significant timber harvest.^ are also occurring on state and privately-owned lands. Iluman activities associated with lqginf; can also have hot:h significant short-term and long-term effects on wildlife populat.ions . Roads will be built in roadless areas, camps and facilities will be established, and accessibility to wildlife populations will increase dramatically. Harvest rates and hmencounters with animals which are sensitive to hman disturbance, such as mountah- goat, brmn bear ar~clwolf, will increase. The habitat requirements of many wildlife species in southeast Alaska are not well knm. Hwever, evidence is mounting that a number of species present in southeast Alaska are dependent on old-growth, spruce-hemlock forest for their survival. Extensive research has been conducted on the Sitka black-tailed deer (Cdccoil e~is hemionus sitkensis) in southeast Alaska and other areas of its range. Certain types of old-grmth stands provide critical winter habitat for the animals during severe winters and largely determine carrying capacity. Research in southeast Alaska has also dccumnted the importance of old-grcwth forests to muntain goats (Oreamnus americanus) , black and brm bears (Ursus americanus and g. arctos, respectively), mse (Alces-- alces), several furbearer species, cavity-nesting forest birds, bald eagles (Haliaeetus leucocephalus) , Vancouver Canada geese (Branta canadensis fulva), and blue grouse (hdragapus obscurus). Concern is grcrwing over the rate at which old-grcmth- forest is being converted into second gr& and the likely impacts on wildlife populations. Wildlife habitat requirements can be generalized as fccd, water, cover, and special requirements such as those needed for breeding or denning areas, or migratory routes. Cover is essential for prey animals (e.g. deer), providing areas to hide frm predators (e.g. wolves) or for a mre sheltered environment from winds and deep snowfall. Fccd, breeding, and denning areas are extremely variable requirements, ranging from the needs of a tree cavit.y-nesting, insect-eating bird to that of a black bear that dens and gives birth in a hollow- tree, then forages throughout the forest fran spring through fall. To determine hm many anhls a specific land area can support requires the determination of habitat requirements for each species and the interactions of the different species. The number of aninmls of a single species that can be supported is ultbtely limited by whichever of its habitat requiremnts is in lowest supply, unless predation or disease has a severe impact on the population levels. This limiting factor will be different for different species. For example, deer ~mbersmy be limited by the amount of nutritious, abundant food present while wcdpecker nurrbers may be limited by the number of suitable nesting cavities present. Numbers of predators, such as wolves, my be indirectly limited by the same factors which limit the numbers of their prey species. The effects of a limiting factor can vary as well. Deer and wolves that cannot get enough fad die of starvation and/or fail to reproduce; woodpeckers fail to nest and reprduce or move to another area where they search for unoccupied nesting holes. Over time, animal populaticn nun-bers fluctuate as animals are born and die, but the armunt and quality of habitat ultimately determines the upper limit of animals that can be supported by a given area. As habitat is altered, this upper limit, or carrying capacity, is also altered. Although it is not always possible to determine the exact habitat requirements of all species, one general rule of ecolqy is that more species can be supported by a habitat with a diversity of conditions than one that is more homogeneous. Habitat diversity provides a variety of conditions which can meet the requirements of many wildlife species. One primary type of diversity is structural diversity. Layers of vegetation contribute to structural diversity. In the forest, trees provide vertical structural diversity. A stand of trees can significantly rrcdify the climate within the stand by intercepting snav and serving to break the force of winds. The trees provide a nurrkr of niches for animals that live or breed in tree cavities, feed on bark and leaves, den in dead, hollow logs, or use the tree foliage as cover for hiding from danger. Plants graving on the ground and litter fall from the trees add to diversity, providing mre abundant and varied winter foods for brmsing and grazing anbals than my be available in open areas
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