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Modeling the Influence of Dynamic Zoning

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RESEARCHModeling the Influence of Dynamic Zoning of ForestHarvesting on Ecological Succession in a NorthernHardwoods LandscapePATRICK A. ZOLLNER*ERIC J. GUSTAFSONUSDA Forest ServiceNorth Central Research Station5985, Highway KRhinelander, Wisconsin 54501, USAHONG S. HEDepartment of ForestryUniversity of MissouriColumbia, Missouri 65211-7260, USAVOLKER C. RADELOFFDAVID J. MLADENOFFDepartment of Forest Ecology and ManagementUniversity of WisconsinMadison, Wisconsin 53706, USAABSTRACT / Dynamic zoning (systematic alteration in thespatial and temporal allocation of even-aged forest man-agement practices) has been proposed as a means tochange the spatial pattern of timber harvest across a land-scape to maximize forest interior habitat while holding timberharvest levels constant. Simulation studies have establishedthat dynamic zoning strategies produce larger tracts ofinterior, closed canopy forest, thus increasing the value ofthese landscapes for interior-dependent wildlife. We usedthe simulation model LANDIS to examine how the imple-mentation of a dynamic zoning strategy would change tra-jectories of ecological succession in the Great Divide RangerDistrict of the Chequamegon–Nicolet National Forest innorthern Wisconsin over 500 years. The components ofdynamic zoning strategies (number of zones in a scenarioand the length of the hiatus between successive entries intozones) and their interaction had highly significant impacts onpatterns of forest succession. Dynamic zoning scenarioswith more zones and shorter hiatus lengths increased theaverage amount of the forest dominated by early succes-sional aspen (Populus sp.). Dynamic zoning scenarios withtwo zones produced more late successional mature northernhardwoods than scenarios with four zones. Dynamic zoningscenarios with very short (30 years) or very long (120 years)hiatus lengths resulted in more late successional maturenorthern hardwoods than scenarios with intermediate hiatuslengths (60 and 90 years). However, none of the dynamicscenarios produced as much late successional maturenorthern hardwoods as the static alternative. Furthermore,the amounts of all habitat types in all dynamic zoning sce-narios fluctuated greatly in time and space relative to staticalternatives, which could negatively impact wildlife speciesthat require a stable amount of habitat above some minimumcritical threshold. Indeed, implementing dynamic zoningscenarios of different designs would have both positive andnegative effects on wildlife species and for other objectivesof forest management.Dynamic zoning strategies for timber harvestinghave been proposed as an alternative to traditionalstatic forest management practices that distribute even-aged forest management practices (such as clear-cut-ting) across an entire management area during eachtime period (Crow and Gustafson 1997). Dynamiczoning approaches change the spatial and temporalallocation of even-aged forest management practiceswhile holding the amount of timber being harvestedconstant or even increasing it (Gustafson and Crow1994). This change is accomplished by dividing amanagement area into spatial subsets or ‘‘zones’’(Figure 1) and focusing all of the even-aged manage-ment practices within a single zone for several decadesand then periodically shifting the focus through theremaining zones (Gustafson 1998). Thus, at any pointin time, the stands within one zone have a high prob-ability of even-age harvest, whereas stands in the otherzones will have a probability of zero. Dynamic zoningscenarios can be described by two key characteristics:(1) the number of zones used and (2) the length of theKEY WORDS: American marten; Dynamic zoning; Landscape pat-tern; LANDIS; Ruffed grouse; Simulation model;SuccessionPublished online May 17, 2005.*Author to whom correspondence should be addressed; email:[email protected] Management Vol. 35, No. 4, pp. 410–425 ª 2005 Springer Science+Business Media, Inc.DOI: 10.1007/s00267-003-0217-9hiatus between active harvest periods within a givenzone. These two factors interact to determine how thepattern of timber harvest changes in time and spaceand how successful a dynamic zoning strategy is atminimizing forest fragmentation while sustaining tim-ber harvest.The objective of dynamic zoning is to modify thelandscape pattern of forest openings to minimizelandscapewide fragmentation of closed-canopy forestconditions (Gustafson and Crow 1994), which can bedetrimental to the breeding success of some wildlifespecies (Thompson and others 1992; Manolis and oth-ers 2000; Flaspohler and others 2001). Previous simu-lation studies have demonstrated that dynamic zoningstrategies minimize forest fragmentation while main-taining timber harvest levels (Gustafson and Crow 1996;Gustafson 1998). This is an important result because itimplies that strategic allocation of timber harvests intime and space can address concerns about forestfragmentation without compromising timber manage-ment objectives. These previous investigations wereconducted using simulations that did not track forestsuccession, but only seral stage (forest age) (Gustafson1998). In this article, we hypothesize that implementa-tion of dynamic zoning strategies to change the spatialpattern of forest age structure will also alter succes-sional dynamics and forest composition. Differences inthe abundance of different tree species and the spatialarrangement of forest types could have a great influ-ence on ecological communities and forest manage-ment objectives (Mladenoff and Pastor 1993; Mladenoffand others 1994). For example, in northern Wisconsin,there are concerns about the influence of forest man-agement on the recruitment of white pine (Pinus stro-bus) relative to its historic occurrence (Landres andothers 1999). It is unclear how a dynamic zoning strat-egy would affect the occurrence of white pine or theresponse of other tree species of interest such as balsamfir (Abies balsamea), which is an important resource forlocal bough gatherers (Mickman 2002). Finally, theimplementation of a dynamic zoning strategy shouldalter the spatial and temporal patterns of forest covertypes on the landscape, which would affect the long-term supply of specific timber products.Figure 1. Maps of the dynamic zoning scenarios investigated. The numbers on the shaded zones in the figures indicate thedecades when 12,000 ha were harvested within that zone. Note that 12,000 ha are equivalent to approximately 16% of the area


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