Ecological Scale and Forest Development: Squirrels, Dietary Fungi, and Vascular Plants in Managed and Unmanaged Forests
Andrew B. Carey, Janet Kershner, Brian Biswell, Laura Domínguez de Toledo
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Abstract: Understandingecological processes and their spatial scales is key to managing ecosystems for
biodiversity, especially for species associated with late-seral forest. We focused on 2 species of squirrel (Sci-
uridae: northern flying squirrel, Glaucomys sabrinus, and Townsend's chipmunk,Tamias townsendii) in a
cross-sectional survey of managed and naturalstandsin southwestern Oregon during 1985-89.
We measured vegetation and abundances of squirrelsat >2,000 pointsin 19 stands in 3 seral stages.We described the diets of the squirrels in the stands. We analyzed data at point, stand, and stage scales to identify key processes contributing to biodiversity and scales at which emergent properties (synergistic effects) appeared.
(vegetation cover by layer,foliage-heightdiversity,fallen trees, snags, conifers,and deciduous trees), 33 species variables (variables occurring at <5% of grid points were excluded), and a combined data set in a series of factor analyses. Four factorsfromanalysisofvegetation structureand MGV were used to define a habitat "hypervolume"(Hutchinson 1958, Whittakeret al. 1973) of the data set. Factor analysis of species variables and combined species-structuredata sets added littlebeyond detrended
confounded because stands may produce confounded and misleading differin (1) the proportionof variationin results.Because trappingto describe pop- habitat elements that theycontain relative ulations necessitates grids of traps, some to the variationacross the landscape and lack of independence among trap stations (2) within-standrelativeabundance of varis inevitable.All the vagaries of mark-and- ious habitat elements. Each stand comrecapture processes (e.g., trap-happiness prises a unique subset
patternsand habitatuse in the southern Washington Cascades. M.S. Thesis, Univ. Washington,Seattle. 72pp. MARRA, J. L., AND R. L. EDMONDS. 1994. Coarse woody debris and forestfloor respirationin an old-growth coniferous forest on the Olympic Peninsula, Washington,USA. Can. J. For. Res. 24:1811-1817. MASER, C., Z. MASER,J. W. WITT, AND G. HUNT. 1986. The northernflyingsquirrel:a mycophagist in southwesternOregon. Can. J. Zool. 64:20862089. , J. M. TRAPPE, AND R. A. NUSSBAUM. 1978. Fungal-small
cross-sectionalsurveyof managed and naturalstands in southwesternOregon during1985-89. We measured vegetationand abundances of squirrelsat >2,000 points in 19 stands in 3 seral stages. We described the diets of the squirrels in the stands. We analyzed data at point, stand, and stage scales to identifykey processes contributingto biodiversityand scales at which emergentproperties(synergisticeffects)appeared. Four factors(crown-classdifferentiation, and understory decadence, canopystratification,
squirrels.Correlationsbetween squirrelsand habitatvariableswithin stands were low. Linear regressionsexplained <20% of the within-standvariance in squirrel captures, but logisticregressionscorrectlyclassified74 and 88% of the points accordingto usage (used, not used) by flying squirrels and chipmunks,respectively.Compared to available habitat space, the realized habitat of flying squirrelshad high decadence and complex canopies. The realized habitatof chipmunkshad complexcanopies and large,