On multi-use public lands in the Western US, it is a challenge to balance the many demands on riparian ecosystems. For example, riparian systems are expected to provide sustainable forage for livestock, while also providing habitat for wildlife and maintaining water quality. Historically, livestock grazing has at times negatively impacted the quality of riparian habitat in arid Western ecosystems. However, an increased interest in managing multiple ecosystem functions by private ranchers and public land managers can inspire better management practices, leading to increased ecosystem services in riparian areas. It is possible that riparian ecosystem improvements can be achieved through manipulation of grazing duration and timing, which can target riparian plant phenology to allow for plant regrowth. To examine how grazing may be used to manage for multiple ecosystem services, we studied the effects of two grazing strategies: continuous turnout and 4-pasture rotation. As an indicator for riparian health, we determined stubble height (cm) and % bare-ground using point-intercept methods along three streams in each grazing system. We surveyed treatments once per month from May to August 2016.
Results/Conclusions
Each grazing strategy yielded contrasting patterns of average stubble height and % bare-ground. In the continuous turnout system, cattle were constantly present from May 15th – September 15th. Here, stubble height exhibited an initial growth period followed by a steady decline. Additionally, the % bare-ground in these areas steadily increased throughout the study. This suggests constant grazing pressure both prohibited vegetation recovery and led to increased disturbance of streambank vegetation. In the 4-pasture system, cattle grazed for a shorter duration--May 15th-July 1st. We observed initial vegetation growth, then a mid-summer decline, followed by a significant bounce-back of vegetation height. This suggests once cattle were removed, the vegetation recovered. The % bare-ground in this system initially increased, but when cattle were removed it steadily declined, again indicating plant regrowth post-grazing. Overall, our results suggest that controlling the duration and timing of grazing along streams is an important tool in managing riparian health. Implementing grazing strategies that allow vegetation to recover later in the grazing season can lead to increased levels of valued ecosystem services, including: habitat for target native species and streambank stability. Such management also benefits the maintenance of livestock grazing, which is currently an important use of public rangelands.