Monitoring mid‐grass prairie in southwestern South Dakota and northwestern Nebraska, USA

Abstract

AbstractIt is expensive and difficult to make precise measurements of standing herbage and to monitor changes in rangeland pastures. This study used a modified Robel pole with 1.27‐cm alternating white and gray bands to estimate standing herbage on adjacent Buffalo Gap and Oglala National Grasslands in western South Dakota and northwestern Nebraska. We determined the relationship between visual obstruction readings (Robel pole) with clipped standing herbage and developed resource guidelines for monitoring standing herbage. Clipped standing herbage ranged from 72 to 4953 kg dry matter (DM) ha−1 with a mean of 1784 kg DM ha−1. Visual obstruction bands (band = 1.27 cm) averaged 6.9 bands and ranged from 0.1 to 22.9. Visual obstruction reliably predicted standing herbage (R 2 = 0.80, P = 0.001, SE = 485 kg DM ha−1, n = 182 transects). Cluster analyses grouped visual obstruction readings (bands) and standing herbage into three resource categories; short, intermediate and tall. Band 6 corresponds to residual standing herbage of 1626 kg DM ha−1 and is recommended as a monitoring guideline for minimum residual herbage. Monitoring of residual standing herbage is accurate, precise and easy to apply. The monitoring protocol and guidelines developed based on bands and/or standing herbage provide information for managers to determine compliance with desired plans to maintain diversity for plants, wildlife and livestock use that sustain grassland communities.