Compensating Growth of Grazed Plants and Its Relevance to the Use of Rangelands.

There are several well-known mechanisms by which grazing can reduce the subsequent growth rate of plants, and several other well-documented mechanisms by which grazing can enhance plant growth rate. The net effect of single or repeated grazing events on the cumulative growth of plants may thus be zero, negative, or positive, depending on availability of leaf area, meristems, stored nutrients, and soil resources, and on the frequency and intensity of defoliation. Plants are preadapted to compensate, up to a certain point, for losses due to grazing, by virtue of their modular structure and development. Reports of "overcompensation" to grazing, as one extreme of a wide range of responses observed in natural grasslands, need not be treated with special skepticism; neither are they a solid base for a general theory of evolved grass-grazer mutualism. The question of compensatory growth is of relevance to management of Western rangelands for livestock production, but of relatively little relevance to conservation goals. No region-wide answers can be expected. Any drastic change in grazing intensity in either direction requires evaluation by community-specific and long-term research. © 1993 by the Ecological Society of America.