Academic journal article The American Midland Naturalist

Composition and Diversity of Ground-Layer Vegetation in Silvicultural Openings of Southern Indiana Forests

Academic journal article The American Midland Naturalist

Composition and Diversity of Ground-Layer Vegetation in Silvicultural Openings of Southern Indiana Forests

Article excerpt

ABSTRACT.-Between 1993 and 1995 we sampled ground-layer vegetation on 150 plots in Facus-Acer saccharum/Arisaema Mesic Slope and Quercus alba-Acer saccharum/Parthenocissus Dry-Mesic Slope forests to determine how the understory of these forests responded to forest management. Four different stand types, clear-cuts (2-12 ha), group-selection openings (0.11.6 ha), single-tree selection openings (0.005-0.013 ha) and uncut 80-100 y-old reference stands were sampled. There was little relationship between the percent cover of most ecological species groups and opening age or size on either mesic or dry-mesic slopes. While clear-cuts and group-selection openings had significantly greater cover of several ecological species groups (used to classify mesic and dry-mesic slopes) than reference stands, single-tree selection openings did not differ significantly from reference stands in the cover of any ecological species group. Pearson correlation analysis indicated that more ground-layer species were significantly correlated with opening size than opening age, suggesting that the size of the initial opening has more influence on species composition than opening age. Overall, forest management has not constituted a severe enough disturbance to shift ground-layer species composition away from that associated with the sampled ecological landtype phases (mesic and dry-mesic slopes). Aspect was the dominant factor determining species distribution in Canonical Correspondence Analysis ordinations of ground-layer vegetation in both openings and reference stands.

INTRODUCTION

In the past, studies of vegetation response to forest management in the Central Hardwood Region of the United States have focused on the regeneration of commercially valuable woody plant species, mostly members of the genus Quercus (Gammon et al., 1960; Roach and Gingrich, 1968; Sander, 1972). Consequently, evaluation of forest management has been based mostly on whether a technique regenerates desirable economic species, with little attention to the effects of forest management on herbaceous and noncommercial woody species. During the past 2 decades, however, foresters and ecologists have begun to recognize the importance of other aspects of successful forest management, including biological diversity. The Society of American Foresters (1991) has recommended that "Professional foresters should manage forest lands to conserve, maintain, or enhance the biological diversity of the region." However, agreement on how to implement an effective strategy for ecosystem management has been difficult to achieve.

Christensen et al. (1996) acknowledged that "Ecosystem management seeks to maintain biological diversity as a critical component in strengthening ecosystems against disturbance" and that "management approaches must be viewed as hypotheses to be tested by research and monitoring programs." An important next step towards improved management for species diversity is to evaluate how specific management strategies affect species composition and diversity patterns over time (Roberts and Gilliam, 1995) . Any evaluation of management strategies must consider the composition and species diversity of ground-layer vegetation.

To understand how plant communities react to disturbance, one must also consider the synergistic influence of topographic and soil characteristics. In recent years multifactor ecological classification systems (ECS) have been developed for several forest regions in the eastern United States (Spies and Barnes, 1985; Hix, 1988; Van Kley et al., 1994). Since the multifactor approach integrates both environmental and vegetation data into the development of classification units, it is useful in classifying historically disturbed forest landscapes, such as those in eastern North America (Barnes et aL, 1982). Multifactor ecological classification also allows researchers to stratify a landscape into replicate units that help separate the influences of the physical environment on species distribution from those of management. …

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