COMPENSATING GROWTH OF GRAZED PLANTS AND ITS RELEVANCE TO THE USE OF RANGELANDS

There are several well-known mechanisms by which grazing can reduce th e subsequent growth rate of plants, and several other well-documented mechanisms by which grazing can enhance plant growth rate. The net eff ect of single or repeated grazing events on the cumulative growth of p lants may thus be zero, negative, or positive, depending on availabili ty of leaf area, meristems, stored nutrients, and soil resources, and on the frequency and intensity of defoliation. Plants are preadapted t o compensate, up to a certain point, for losses due to grazing, by vir tue of their modular structure and development. Reports of ''overcompe nsation'' to grazing, as one extreme of a wide range of responses obse rved in natural grasslands, need not be treated with special skepticis m; 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 answ ers can be expected. Any drastic change in grazing intensity in either direction requires evaluation by community-specific and long-term res earch.