A Nutritional quality of aspen suckers under simulated browsing on Cedar Mountain of Southern Utah, Western United States of America

Abstract

The objective of the study was to determine how time and intensity, of clipping (simulated browsing) on suckers of Populus tremuloides Michx affected the nutritional quality of the clipped material on Cedar Mountain, Southern Utah, Western United States of America. Three randomly selected stands measuring 70 m x 70 m were clear-felled in mid-July, 2005, and fenced. Simulated browsing treatments of 0%, 20%, 40%, and 60% removal of current year’s growth on aspen suckers were randomly applied in the early, mid-, and late summers of 2006 and 2007 on permanently demarcated quadrats. The leaf and clipped materials were evaluated for crude protein (CP) content and in vitro true digestibility (IVTD). Data for crude protein and IVTD were analyzed as a three-way factorial in a split-split plot design using the MIXED procedure of Statistical Analysis System. Percentage of both CP .and IVTD decreased with intensity of clipping and advancing season, but these differences were small for IVTD. In mid- summer, leaves (18.6i0.98), intensity 20% (19.2±0.98) and 40% (18.1i0.98) -were not significantly different (p>0.05) but %CP for leaves and intensity 20% had significantly (p<0.05) higher CP percentage than intensity 60% (16.2i0.98) in 2006. IVTD percentage for intensity 20% (77.8±0.95) and 40% (76.4±0.95) did not differ significantly in mid-summer but intensity 60% (75.2i0.95) was significantly lower than for intensity 20% in 2007. Relatively high levels of CP and IVTD suggest that carefully managed browsing of aspen suckers can add appreciably to the nutritional budgets of ungulates for at least two years post-treatment.