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Root Development of Native Plants Under Three Grazing Intensities
Author(s) -
Schuster Joseph L.
Publication year - 1964
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1937107
Subject(s) - grazing , ecology , biology , agronomy , environmental science , botany
The purpose of this study was to determine the effects of various intensities of grazing upon roots and root systems of plants native to the ponderosa pine zone of the Colorado Front Range. It was designed to ascertain the root characteristics of certain species of the plant community and any changes in root distribution induced by 17 years of moderate and heavy grazing by cattle. The cumulative effects of such grazing are also illustrated. Most studies concerning the effects of plant defoliation show that any cropping (clipping or grazing) reduces plant growth, especially root growth. The initial root and rhizome response to defoliation is the cessation of elongation (Parker and Sampson 1931, Crider 1955). Subsequent reactions to continued defoliation are reduction in root numbers and branching (Jacques 1937, Albertson, Riegel, and Launchbaugh 1953), root diameter (Biswell and Weaver 1933), and depth of soil penetration (Ruby and Young 1953, Cook, Stoddart, and Kinsinger 1958). The amount of reduction is directly related to the severity and frequency of defoliation (Graber 1931, Albertson et al. 1953, Thaine 1954). In general the degree of defoliation is more detrimental to root growth than frequency of defoliation. Crider (1955) showed that apical growth of grass roots stopped within 24 hr after the removal of 40% or more of the foliage in one operation. The time required for roots to resume growth varied directly with the degree of foliage removal. The consequences of overgrazing are apparently carried over from season to season. WVeaver