Monitoring roots of grazed rangeland vegetation with the root periscope/mini-rhizotron technique

Abstract

The root periscope/mini-rhizotron technique has been used most commonly to monitor root growth of field crops in a nondestructive manner. This study introduces a successful application of the technique for monitoring root growth of grazed rangeland vegetation. The relative, root growth response of orchardgrass (Dactylis glomerata L. 'Potomac') to defoliation by cattle was monitored on a conifer plantation in southwest Oregon. Despite stocking densities of about 2.7-4.4 animal unit/ha and 19 days of grazing during 1988, trampling and breakage of mini-rhizotrons on the cattle-grazed area was minimal. Defoliation by cattle had a negative impact on the relative number of roots for grazed orchardgrass in June and July (P < 0.05). Cautions and limitations for the use of the technique on rangelands are presented. The root periscope/mini-rhizotron appears to be a suitable, nondestructive, and affordable (1,000-1,200 per root periscope; 8.50 per mini-rhizotron) technique for monitoring root growth of rangeland vegetation defoliated by livestock and/or native ungulates.