Understanding the Effects of Forest Management on Avian Species Author(s): John M. Marzluff, Martin G. Raphael, Rex Sallabanks Source: Wildlife Society Bulletin, Vol. 28, No. 4 (Winter, 2000), pp. 1132-1143 Published by: Allen Press Stable URL: http://www.jstor.org/stable/3783874 Accessed: 20/03/2009 21:21 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=acg. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that promotes the discovery and use of these resources. For more information about JSTOR, please contact [email protected]. Allen Press is collaborating with JSTOR to digitize, preserve and extend access to Wildlife Society Bulletin. http://www.jstor.org 1132 SPECIALCOVERAGE Understandingthe effects of forest managementon avian species by John M. Marzluff,Martin G. Raphael, and Rex Sallabanks Abstract We reiterate the general problems of small scale and lack of rigorous experimental design that reduce the ability of wildlife studies to offer concrete recommendations for forest management. We emphasize the need to increase our understanding of mechanisms during the translation of forest structure, composition, and function into avian population abundance, distribution, and viability. Mechanistic understanding increases the manager's likelihood of correctly predicting prescription outcomes and gives him increased flexibility to balance competing demands of resource produc- tion and wildlife conservation. Until detailed mechanistic relationships are deter- mined, we will have to manage forests with incomplete knowledge. Managersand researchers should embrace these uncertainties and form partnerships to adaptively manage forests. This relationship will likely increase the scale and relevance of re- search but may carry costs of reduced statistical rigor (poor replication, low power) and suboptimal short-term management. The costs of large-scale research and man- agement are great, but partitioning large projects into small, connected ones, forming funding and research cooperatives, and developing new funding sources will help offset the costs. Researchers and managers should clearly articulate priorities. We urge scientific societies to cooperate to develop conservation priorities, encourage data collection to support prioritization, and assess progress toward meeting conser- vation goals. The Wildlife Society is in a unique position to take the lead in such an effort and objectively guide wildlife conservation's future direction. Key Words adaptive management, birds, conservation priorities, edge effects, experimental design, forestry,habitat, nest predation, policy, population viability,silviculture | ostei ogical studiesin general,and studiesof conserva- cal practicalitythan out of relevanceto pressingenviron- tin blogy or wildlife ecology in particular,suffer from 2 mentalproblems (May 1994). Second,studies often lack majorproblemsthat limit theirapplication. First, they are rigorousexperimental design and seek correlativerather necs,ly conductedat limitedspatial and temporal thancausal relationships (Raphael and Maurer 1990, scales (Weatherhead1986, Kareivaand Anderson 1989, Irwinand Wigley 1993, Marzluffand Sallabanks 1998). Tilman1989). Scale is selectedmore often out of logisti- Investigationsof the effects of forestmanagement on birds Addressfor John M. Marzluff:College of ForestResources, University of Washington,Seattle, WA 98195, USA;e-mail: [email protected]. Addressfor MartinG. Raphael:United States Department of Agriculture,Forest Service, Pacific Northwest Research Station, Olympia, WA 98512, USA. Addressfor Rex Sallabanks:Sustainable Ecosystems Institute, 1543 N. MansfieldPlace, Eagle,ID 83616, USA. Wildlife Society Bulletin 2000, 28(4):1132-1143 Peer refereed Forest management effects on birds * Marzluff et al. 1133 are no exception. Herethe typicalstudy correlates avian and generalknowledge to causal,strong inferences and abundancewith timbermanagement using 1 to 3 replicates specificknowledge, hallmarks of a maturescience studiedover 1 to 2 years(Sallabanks et al. 2000). (Romesburg1981). Increasedpredictive ability allows Some ongoingstudies of forestryand birds are correct- managersto more accuratelyanticipate the outcomesof ing past limitationsby expandingtheir scale of investiga- theirprescriptions and thereforemore effectively balance tion (Hansenand Urban 1992, Forsmanet al. 1996, the competingdemands of diverseresource users. Thompsonet al. 2000), using soundexperimental design Managerswho understandmechanistic relationships can (Schmiegelowet al. 1997), andrelating forest manage- move from conservativeactions that invite legal chal- mentto aviandemography (Manolis et al. 2000, Yahner lenge becausethey stop resourceextraction or provide 2000). Such studieswill greatly increaseour understanding of how We believe. that increasing the efficacy and accuracy forestryaffects birds, especially if they of wildlife mechanistic under- successfullyidentify the mechanisms management through thatrelate silviculture to population standing o f ecological relationships will increase processes. We arguethat understanding societal support for our profession. mechanismsis essentialin applied ii ii ii. ij~ i i i i i lliiiiiJk l researchbecause it increasesthe man- ager'slikelihood of correctlypredicting prescription out- little for wildlife, to balancedactions. Balancedactions comes andincreases the manager'sflexibility in balancing providea rationalrelationship between economic and competingdemands. Our first objective in this paperis to wildlife benefitsand thus can betterwithstand legal chal- illustratethe powerof mechanisticunderstanding in gener- lenges. For example,understanding that mortality from al by demonstratingits applicationto the managementof shootinghas a greaterimpact on deserttortoise forestsfor wildlife andwood products. (Gopherusagassizii) population viability than mortality Showingthe value of mechanisticunderstanding to the from commonraven (Corvus corax) predation (Doak et manageris simple comparedto accomplishingsuch al. 1994) allows managersto effectivelyaddress factors research. Long-term,large-scale experimental or obser- thatmost affectpopulation declines. vationalresearch is required.Recognizing that we may Foreststructure and composition are affectedby timber be askingthe researchand managementcommunities to harvestand, in turn,affect avian community composition do the impossible,we 1) discuss the abilityof adaptive and demography.The typical,exemplary study may managementto revealmechanistic understandings, 2) relatestructure or compositionto populationviability in a suggesthow researcherscan obtainand sustainfunding well-designed,large-scale experiment. However, such a for long-termstudies, and 3) call for coordinatedprioriti- studywould not illuminatemechanisms unless it included zationof researchneeds. We believe thatincreasing the detailedassessments of how structureand composition efficacy and accuracyof wildlife managementthrough affectedrelevant factors that directly affect populations, mechanisticunderstanding of ecologicalrelationships such as food, predators,disease, and nest sites (Figure1). will increasesocietal supportfor our profession. Such Thus,mechanistic understanding requires a 2-step supportcould establisha positivefeedback loop that increasesfunding, which increasesecological under- Food and Competitors standing managementaccuracy, furthering public Forest Predators support,attracting funding, and so on. Parasites structure Disease _ Population and Microclimate Mechanisms ~- Perch sites viability that link forest composition> Nest sites (abundance, management to avian population Roost sites survival, Escape cover reproduction, viability Foraging space recruitment) Foraging substrate Mechanisticrelationships are those thatdetermine why a factor(e.g., timberharvest) causes a response K in nest mechanisticrela- I (e.g., change success). Deriving 1. of or that leads to the maturationof Figure Examples mechanisms, limitingfactors, connectfor- tionships wildlife biology as a est structureand compositionwith avianpopulation viability. The typ- science and facilitateseffective management through an ical studydirectly relates forest properties to avian populations(lower arrow). a mechanistic determineshow increasein predictive andMaurer However, study forestproperties ability(Raphael 1990). affect the limitingfactors and determinesthe relativeimportance of This allows us to move from correlative,weak inferences those factorsto avianpopulation dynamics (upper arrows). 1134 Wildlife Society Bulletin 2000, 28(4):1132-1143 research strategy that first determines whether changing