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dc.contributor.authorSweeney, Beth A.
dc.date.accessioned2020-10-27T18:16:24Z
dc.date.available2020-10-27T18:16:24Z
dc.date.issued1996-08
dc.identifier.urihttp://digital.library.wisc.edu/1793/80671
dc.description.abstractThe study measured landscape level diversity of the herbaceous understory of mature, upland forests in north central Wisconsin across a moisture-nutrient gradient. Sites were located in Region Three of the Kotar et al. (1988) habitat typing system, which includes Vilas, Oneida, Florence, and Forest Counties. Eight habitat types were used to segregate the landscape along a moisture-nutrient gradient. There were 40 sites, with five replicate stands for each habitat type, except TMC which had four sites and A ViO which had six. All sites were reproductively mature, had closed canopies, were undisturbed for at least 20 years, and were at least 8 ha in size. Ocular estimation of percent cover of groundlayer species was performed in randomly located one meter square plots along two or three randomly placed 25 meter transects during June and August of 1995. Shrub cover was estimated by line intercept. Sampling intensity was determined from data collected in 1994. Data were analyzed at the gamma (landscape), beta (among site), and alpha (within site) levels; early and late summer data were treated separately. Gamma diversity was quantified using a new method, affinity analysis, which generates a list of modal and outlier sites and calculates mosaic diversity, a measure of landscape complexity. Modal communities are rich in species common to the region, while outlier communities are rich in rare species, or are species poor (Scheiner, 1992). The diversity indices used in the analysis were also compared for their efficacy. Generally, communities in the middle of the moisture-nutrient gradient were modal, while those at the mesic end of the gradient were outlier. Hemlock (Tsuga canadensis) dominated communities were exclusively outlier. Mosaic diversity values, with jackknifed standard errors, were 2.88± 0.04 for early summer, 2.95±0.03 for late summer, and 3.95±0.07 for all data combined. A paired t-test detected a significant difference between early and late summer values (p</=0.01). Whittaker's Index (beta diversity) revealed varying rates of species turnover along both the moisture and nutrient gradients. Species densities (richness) were relatively constant. Rank abundance plots (evenness) indicated that communities were composed mainly of species represented by a few individuals. A one-way analysis of variance of Shannon-Weaver values uncovered no significant differences among site types (p>/= 0.05). Regional diversity mainly resulted from high beta values (mesic sites). The sources of high beta values were the moisture and nutrient gradients because they contributed significantly and approximately equally to differences in composition among stands. The mechanisms creating differences in composition along the moisture-nutrient gradient probably were niche partitioning, disturbance and succession, site history, and differences in life history strategies. The influence of these factors on composition probably varied in importance along the moisture and nutrient gradients. Overall, this landscape was about as diverse as other temperate mixed forest ecosystems (Scheiner and Rey Benayas, 1994). Affinity analysis is unique because it is the first known diversity index to quantify landscape level diversity. A recommended combination of indices is a landscape level one, such as affinity analysis, along with species density (if sample sizes are unequal) and evenness. These indices together provide the researcher with a working knowledge of the landscape and key factors influencing it.en_US
dc.description.sponsorshipMcIntire-Stennis Fund and the University of Wisconsin Stevens Point Student Research Funden_US
dc.language.isoen_USen_US
dc.publisherUniversity of Wisconsin-Stevens Point, College of Natural Resourcesen_US
dc.titleA Landscape-Level Measure of Herbaceous Diversity in Upland Forests of North Central Wisconsin Across a Site Quality Gradienten_US
dc.typeThesisen_US


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