Soil properties and species diversity of grazed crested wheatgrass and native rangelands

Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is an introduced gras s used extensively for rangeland revegetation in the semiarid and arid regi ons of western North America. The long-term effects of crested wheatgrass o n soil properties and plant community were evaluated on 5 grazed sites in t he southern interior of British Columbia, Canada, Each site included plant communities of native bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Scribn, & Smith) and 14- to 60-year-old stands of crested wheatgrass, Soil samples and plant data were collected in June 1997, Species numbers were s imilar for native and crested wheatgrass rangelands, while the diversity in dex of crested wheatgrass rangeland was lower due to lower evenness. Creste d wheatgrass and native grasses were observed to produce similar amounts of root biomass, Most soil properties were similar under the 2 rangelands. On e of the exceptions was soil carbon at 0-7.5 and 7.5-15 cm depths, which wa s higher on crested wheatgrass than native rangeland. Soil nitrogen at 15-3 0 cm depth was also higher on crested wheatgrass rangeland, Greater soil pe netration resistance was observed at 7.5 and 9 cm depths on crested wheatgr ass than native rangeland, Higher soil compaction was caused by grazing of crested wheatgrass earlier in the season when soils are wetter relative to the native rangeland, The results of this study indicate that seeding of cr ested wheatgrass combined with the long-term grazing by cattle did not resu lt in the degradation of soil properties, but plant diversity was reduced r elative to grazed native, bluebunch wheatgrass rangeland.