In a recent Journal of Range Management article, Singer et al. (1994) reported that evidence from his study indicates that suppressed willows (Salix spp.) on Yellowstone National Park's northern winter range have lower tannin levels than intermediate-height and tall willows. This article agrees with these findings; however, they contend that there is no evidence from the study supporting the inferences that lower tannins were the primary cause attracting heavier browsing, and that hedged plants produced less tannins because they occurred on suboptimal sites for willow growth. The suppression of willow stature on the northern range is an inverse function of elevation as are the numbers of wintering elk. Wagner et al., in this review, suggest further that the lower tannin concentrations in suppressed plants are more likely the result of stress induced by heavier browsing, an inference supported by the differences in tannin concentrations in plants inside and outside exclosures. Singer et al. (1994) measured production, forage quality, moisture stress, and tannin content of growth shoots in relation to ungulate browsing, browsing-induced architectural variation, and altitude. It is Wagner et al.'s view that the evidence presented does not support a number of the major inferences drawn. The prevailing evidence remains that the progressive decline of woody vegetation on the northern range, especially willow, has been induced by a wintering elk herd, that has greatly increased since establishment of YNP.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.