The valuable role that healthy riparian ecosystems play in regional diversity of plant and wildlife communities is just beginning to be recognized. Resource managers need to know how degraded riparian areas respond to changes in management, such as reduction and elimination of grazing. Differences in vegetation structure were examined in a montane riparian zone in northcentral Colorado after 30 years of cattle exclusion and continued, but reduced, grazing pressure. In order to assess the changes in the riparian community, canopy coverage, density, and standing crop of important riparian species were measured in 1985 and 1986. Total vascular vegetation, shrub, and graminoid canopy cover was greater (P?0.05) in the exclosures as compared to grazed areas, while forb canopy cover was similar (P>0.05) between treatments. Exclosures had nearly 2 times the litter cover, while grazed areas had 4 times more bare ground. Willow canopy coverage was 8 1/2 times greater in protected areas than in grazed areas. Kentucky bluegrass (Poa pratensis L.) cover was 4 times greater in grazed areas than exclosures, while the cover of fowl bluegrass (Poa palustris L.) was 6 times greater in the protected sites. Canopy cover of other important riparian species, such as tufted hairgrass (Deschampsia caespitosa (L.) Beauv.), Nebraska sedge (Carex nebraskensis Dewey), and beaked sedge (C. rostrata Stokes), was similar (F>0.05) between treatments. Mean peak standing crop over the 2 years of the study ws 2,410 kg/ha in the exclosures and 1,217 kg/ha in caged plots within grazed areas. Cattle utilized approximately 65% of the current year's growth of vegetation during the 1985 and 1986 grazing seasons.

Stubble height, a measure of the herbaceous vegetation remaining after grazing, has been widely used in recent years to gage the impacts of grazing use in riparian areas. Stubble height is a short-term management guide that should only be applied to help attain long-term ecological objectives; it should not be thought of as a long-term management objective.Maintaining a minimum stubble height helps preserve forage plant vigor, retain sufficient forage to reduce cattle browsing of willows (Salix spp.), stabilize sediments, indirectly limit streambank trampling, maintain cattle gains, and provide an easily communicated management criterion. Based on limited specific research of riparian system response and on knowledge of the characteristics of how cattle graze, a 10-cm residual stubble height is recommended by the authors as a starting point for improved riparian grazing management. Monitoring should then be conducted to determine if an adjustment is needed. In some situations, 7 cm or even less stubble height may provide for adequate riparian ecosystem function, particularly when streambanks are dry and stable or possibly at high elevations where vegetation is naturally of low stature. In other situations, 15-20 cm of stubble height may be required to reduce browsing of willows or limit trampling impact to vulnerable streambanks. The recommended criterion would apply to streamside and nearby meadow sites with hydrophilic or potentially hydrophilic vegetation, but not directly to dry meadows or even to all wet meadows. Stubble height may have little application where the streambanks are stabilized by coarse substrates, or the channels are deeply incised.The effects of residual stubble height in riparian functions have received limited direct experimental examination. Consequently, much of the information in this review was derived from studies indirectly related to the questions raised and, to some extent, from observations of experienced professionals. The authors have identified areas of scientific investigation needed to improve our understanding of the effects of stubble height on riparian function and grazing management.Key Words: Grazing, livestock management, streambanks, trampling, utilization, willowIn the early settlement history of the western United States management of riparian grazing lands was pretty straightforward-no irrigation or stock water to worry about-just turn the livestock out in the spring and take them home in the fall. We now know that proper management of these highly diverse ecosystems is not that easy. These land-water ecotones are among the most ecologically productive and diverse of all terrestrial habitats, and the influence of moving water within stream ripari- ResumenLa altura del rastrojo, una medida de la vegetación herb·cea remanente después de que ha sido sujeta apacentamiento, ha sido ampliamente utilizada en años recientes para medir el impacto del apacentamiento en las áeas ribereñas. La altura del rastrojo es una guáa de manejo a corto plazo que debe ser aplica...

A 2-year rainfall simulation study was conducted to evaluate the effectiveness of riparian vegetation to reduce sediient movement. Three vegetation height treatments [clipped to the soil surface, 10 cm height, and undisturbed (unclipped)] were evaluated in 2 montane riparian vegetation communities in northern Colorado. One community was a tufted hairgrass (Deschampsio caespitosa (L.) Beauv.), cinquefoil (Potenti& gracilis Dougl. ex Hook), Kentucky bluegrass (Poa pratensis L.), and sedge (Curex

A laboratory rainfall simulation was conducted to compare the influence of three lengths of vegetation buffer strips and two vegetation heights on sediment filtration. The purpose of the experiment was to help evaluate stubble height grazing guidelines. Rainfall (50 mm h−1) was sprayed simultaneously over six trays (0.3 × 1.0 m). Concurrently, sediment laden (150 g tray−1) overland flow (50 mm h−1) was introduced to the upslope end of the trays. Two trays contained 12.5 cm, two trays contained 25.0 cm, and two trays contained 50.0 cm of Kentucky bluegrass (Poa pratensis L.) buffer strips during each simulation run. Paired buffer length trays either were clipped to the soil surface or grass was 10 cm tall. A significant interaction existed between vegetation buffer length and vegetation height. The clipped to the soil surface vegetation height was more effective as a sediment filter with the 12.5 cm buffer length than was the 10.0 cm height. Conversely, the 10.0 cm vegetation height was more efficient as a sediment filter with a 50 cm buffer length than was the clipped to the soil surface vegetation. No differences in sediment filtration efficiency existed between vegetation heights at the 25 cm buffer length. Additionally, 50 mm h−1 of rainfall was applied and 50 mm h−1 overland flow was added to six trays containing bare soil (no vegetation). Three the bare soil trays received sediment laden (150 g tray−1) overland flow and three trays received sediment free overland flow. All trays with the three vegetation buffer lengths had less sediment yield than did the bare soil trays. Results from this study suggest that vegetation height alone is not a suitable guideline for estimating sediment filtration and that length of vegetation buffer was more important than vegetation height in filtering sediment.

Willows (Salix spp.) are an integral component in the restoration of wetland plant communities that have been impacted by the fluvial deposition of mine tailings. A greenhouse study was conducted to compare growth and metal uptake of Geyer (S.