• Clipping and Japanese brome reduce western wheatgrass standing crop

      Haferkamp, M. R.; Heitschmidt, R. K.; Karl, M. G. (Society for Range Management, 1998-11-01)
      Japanese brome (Bromus japonicus Thunb.) and downy brome (Bromus tectorum L.), introduced annuals, have invaded many northern mixed-prairie plant communities. This study determined the effect of removing Japanese brome and clipping western wheatgrass [Pascopyrum smithii Rydb. (Love)] on aboveground forage production of a western wheatgrass dominated northern mixed-prairie community. During early spring 1993, a wet year, and 1995, a drier year, western wheatgrass tillers were clipped to ground level in May or June and Japanese brome seedlings were left undisturbed or removed in circular, 1-m2 plots on a clay-pan field site. Western wheatgrass standing crop and tiller densities were estimated by clipping and counting in May and June, and these plus community standing crops were estimated in all plots after Japanese brome matured in mid July. Year effects were significant for standing crop and tiller density due to annual variation in amount and distribution of fall, spring, and early summer precipitation. Conditions were most favorable for tiller initiation of western wheatgrass and germination of annual brome seed in fall 1994 and for herbage production in 1993. Clipping western wheatgrass tillers reduced accumulated standing crop 230 to 350 kg ha-1 and reduced tiller weight by 17 to 58%. Standing crop of western wheatgrass was increased 102 kg ha-1 with removal of Japanese brome, while total standing crop was reduced 284 kg ha-1 with brome removal. Increased standing crop of western wheatgrass appeared to result from increased tiller density rather than increased tiller weight. Removal of Japanese brome from northern mixed prairie plant communities may increase production of associated perennial grasses, but managers should also expect a short-term decrease in total standing crop.
    • Effect of ground squirrel burrows on plant productivity in a cool desert environment

      Laundre, J. W. (Society for Range Management, 1998-11-01)
      Previous work demonstrated that burrows of Townsend's ground squirrels (Spermophilus townsendii Merriam) in cool deserts increased the amount of spring recharge of soil moisture compared to areas without burrows. The objective of this study was to test the hypothesis that this additional soil moisture would enhance plant productivity. I compared productivity of western wheatgrass (Agropyron smithii Rydb.) and big sagebrush (Artemisia tridentata Nutt.) plants adjacent to burrows to plants in areas lacking burrows. Grass productivity was estimated within an experimental grid containing cells of either 0, 2, 4, or 6 artificial burrows and was based on measures of annual above ground biomass production and number of seed heads produced. For sagebrush, productivity was estimated from bushes without burrows (controls) and ones having a natural burrow near their base. Sagebrush productivity was based on average length of new annual terminal growth of vegetative stems. The mean annual estimates of grass biomass (50.0 g m-2 year-1, SE = 11.8) was significantly higher in test grid cells with the highest number of artificial burrows than controls (42.6 g m-2 year-1, SE = 11.4). The mean of annual estimates of sagebrush stem growth for bushes adjacent to burrows was a significant 0.6 cm (SE = 0.11) longer than bushes without burrows. I conclude that the added moisture from spring recharge at ground squirrel burrows can increase plant productivity in a cool desert environment.