Author
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Belesky, David |
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Submitted to: Southern Pasture and Forage Crop Improvement Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 4/15/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Plant communities can respond to topographic, environmental, biotic, and management factors at the community, species, and individual plant level. Each level of response, in turn, can modify the other so that a flexible and dynamic community exists over time. Short-term experiments may not accurately predict the long-term response of a pasture, especially in complex hill-land environments, that often times are marginal in capacity to sustain productive plant communities. The interaction of topography and local climate can result in a very complex plant community that varies with elevation, exposure, and use. Plant communities can respond to these factors by shifting in terms of species, lines within species, and reallocation of resources with individual plants. The responses of plant communities in well-managed environments are relatively well documented, while marginal resource environments are not. This review examines the principles of interplant competition and factors controlling plant response to microclimate and management in hill-lands of the Eastern US. This review will help define the resources and outline the challenges facing pasture managers in the Region. Technical Abstract: Naturalized and intensively managed pasture can be considered at three levels of organization: the sward, the species comprising the sward, and the individual. The equilibrium of the community can be influenced by environmental, biotic, and management factors. Some factors may be simple such as clipping or applying lime or complex such as microbial associations and interplant responses at a given site. At the sward level, changes can occur as seasonal or long-term shifts in species, which influence production patterns and canopy morphology. Species respond to management or microsite within the sward in terms of ecotypes or lines. At the individual plant level, changes can occur in size and resource allocation, with variation in initiation, expression, and size of vegetative propagules, and root:shoot size and architecture relationships. Plasticity appears to be related to competition for resource-rich zones in the canopy in productive environments, while in marginally productive habitats, adaptation to localized stresses occur. Management and environmental impacts may be realized at the individual plant level, where morphological adjustments occur because of localized conditions within the sward. Many of the considerations presented here are not readily apparent in, nor applicable to, monoculture canopies; however, complex plant communities found in many hill-land pastures are dynamic systems responding to a range of modifiers. Morphological shifts among species within a canopy, within species, and in individuals within a species will be considered as a function of response to factors influenced by topography, nutrients, and management. |
