Pinyon-juniper (Pinus spp.-Juniperus spp.) encroachment and decliningmule deer (Odocoileus hemionus) populations in western Colorado have necessitated management for increased forage. Pinyon-juniper removal is one such technique; however, it is unclear which method of tree removal most effectively promotes forage species. We conducted an experiment to quantify understory responses to mechanical pinyon-juniper removal and seed additions in a blocked design using three different methods: anchor-chaining, rollerchopping, and mastication. Blocks contained each mechanical and seeding treatment along with an untreated control. Seven blocks across two sites, North Magnolia (NM, 4 blocks) and South Magnolia (SM, 3 blocks), were treated during the fall of 2011. Half of each plot was seeded before or during mechanical treatment with a mix of grasses, shrubs, and forbs. After two growing seasons, biomass of perennial grasses was 90-160 kg · ha-1 in mechanically treated plots compared with 10 kg · ha-1 in untreated controls. There were no differences, however, between mechanical treatments for any perennial plant species. Response of annual plant species depended on mechanical treatment type and site. Rollerchopping had higher exotic annual grass cover than mastication or control at NM and higher exotic annual forb cover than chaining or control at SM. Rollerchopping was the only treatment to have higher native annual forb cover than control in the absence of seeding. Seeding increased native annual forb biomass in mastication compared with control. Seeding also increased shrub density at SM, which had fewer shrubs pretreatment relative to NM. Results suggest any type of mechanical removal of pinyon-juniper can increase understory plant biomass and cover. Seeding in conjunction with mechanical treatments, particularly mastication, can initially increase annual forb biomass and shrub density. Finally, different understory responses between sites suggests that pretreatment conditions are important for determining outcomes of pinyon-juniper removal treatments. © 2016 The Authors. Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license.

The productivity and stability of cattle production on rangelands depends on the maintenance of a dense and productive perennial grass-dominated resource base, which is contingent on appropriate grazing and recovery periods. We investigated the effect of simulated trampling, dung inputs, frequency of defoliation in the previous growing season (grazing history), and timing of recovery periods on various grassland functional responses in two experiments in western and northwestern Botswana. A field-based clipping experiment at the individual tuft scale demonstrated that perennial grasses are most productive when rested for a full growing season, but that productivity of the highly palatable soft leaved Brachiaria nigropedata Ficalho & Hiern. decreases exponentially with increasing clipping frequency in the previous season (a lagged effect of grazing history). This species was also more productive in the next season when rested during the early than late growing season. The less palatable needle-leaved Stipagrostis uniplumis Licht. ex Roem. & Schult. was less resistant to defoliation than B. nigropedata and decreased equally at each clipping frequency regardless of season. A second field-based experiment at the plot scale demonstrated that a full-season recovery period increased tuft densities while its combination with dung increased cover. The effects of hoof trampling on sandy nutrient-poor grasslands appear to be less significant compared with grasslands on fertile soils. Thus, optimal livestock management strategies should aim to promote season-long grazing of both palatable and unpalatable species to disadvantage the less grazing-tolerant unpalatable species and full growing season recovery periods to ensure optimal recovery and future productivity. © 2016 The Society for Range Management. Published by Elsevier Inc. All rights reserved.

Objectives of postfire seeding in the Great Basin include reestablishment of perennial cover, suppression of exotic annual weeds, and restoration of diverse plant communities. Nonconventional seeding techniques may be required when seeding mixes of grasses, forbs, and shrubs containing seeds of different sizes. We conducted an operational-scale experiment to test the effectiveness of two rangeland drills (conventional and minimum-till) for seeding native plant mixes following wildfire in Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) communities. Both drills were configured to place small and large seeds in alternate rows. We hypothesized that the minimum-till drill's advanced featureswould improve establishment compared with the conventional drill. We also hypothesized that theminimum-till drill would cause less damage to residual perennials, whereas the conventional drill would have a greater impact on annual weeds. The experiment was replicated at three burned sites and monitored for 2 yr at each site. Seeded plant establishment was lowest at a low-precipitation site that became dominated by exotic annuals. Another site had high perennial grass establishment, which effectively suppressed exotic annuals, while a third site attained high diversity of seeded species and life forms but became invaded by exotic annuals in plant interspaces. Small-seeded species generally established better with the minimum-till drill equipped with imprinter wheels than the conventional drill with drag-chains. However, large-seeded species frequently established better with the conventional drill despite its lack of depth bands and press wheels. Soil disturbance associated with the conventional drill had a negative effect on residual perennials and exotic annuals at some sites. Results indicate that different drill features are advantageous in different ways, but that either of the tested drills, if properly used, can be effective for seeding native plant mixes provided site conditions are otherwise favorable for seedling establishment. © Published by Elsevier Inc. on behalf of The Society for Range Management.

Understanding the influence of grazing management and environmental drivers on net ecosystem exchange of CO2 (NEE) is essential for optimizing carbon (C) uptake in rangelands. Herein, using 15 treatment-years (two 3-yr experiments, one with three grazing treatments, the other two) and Bowen ratio flux towers, we evaluated the influence of grazing intensity, soil water content (SWC), and plant cover (Normalized Difference Vegetation Index, or NDVI) on NEE in Colorado shortgrass steppe. Among several soil water and plant cover traits evaluated over 6-yr, early season (April, DOY 91-120) SWC and early season (DOY 130) NDVI weremost highly correlated with NEE (-0.96 and-0.98, respectively) during the second quarter (April to June) of the year and also over the entire growing season (April to September;-0.97 and-0.96). Due to the strong effect of early-season SWC, an average of 166 gm-2 CO2 were lost in 2 yr with dry spring weather, compared with an average annual uptake of 218 g m-2 CO2 in 4 yr with more abundant early-season precipitation and plant cover. Grazing effects on NEE were also apparent. In one experiment, moderate grazing resulted in annual CO2 uptake of 267 g m-2 CO2 over 3 yr compared with essentially zero NEE in heavily grazed pasture. However, that treatment difference in annual NEEwas only half that experienced between dry and wet years. Similar trends were observed in a second experiment, although results were insignificant. Results suggest that the recommended moderate grazing intensity for the Colorado shortgrass steppe is near optimal for CO2 uptake under season-long continuous grazing, with annual climatic variability sometimes being more influential. To enhance C sequestration in the western Great Plains of North America, grazing management strategies should emphasize flexible and adaptive practices that consider early-season SWC and promote vegetation cover during the key early spring growth period. © Published by Elsevier Inc. on behalf of The Society for Range Management.

The impact on palatable shrubs when herbivores have access to high-quality food is unclear. We determined if providing high-quality food and increasing white-tailed deer (Odocoileus virginianus) density reduced growth and altered nutritional quality of two palatable shrub species. We maintained target densities of 13, 31, or 50 deer km-2 in six 81-ha-1 enclosures on each of two ranches. We provided nutritious, dry feed ad libitum in one of each pair of enclosures with similar densities on each ranch. We measured height and width of Texas kidneywood (Eysenhardtia texana Scheele) and spiny hackberry (Celtis ehrenbergiana [Klotzsch] Liebm), measured hackberry thorns, and estimated crude protein. Plants were protected from browsing with wire exclosures in 2005; a similar-sized unprotected plant was paired with each protected plant. We estimated density of shrub species using twenty 3 × 50mbelt transects/enclosure June 2005, 2007-2012. Growth of protected and unprotected kidneywood was similar (P ≥ 0.88) at 13 deer km-2, but growth was reduced (P ≤ 0.05) by higher deer densities. Protection from browsing and increasing deer density did not influence (P ≥ 0.25) size of spiny hackberry. Browsed kidneywood plants had a 34% lower crude protein (P ≤ 0.01) compared with protected plants when deer did not have access to feed. Spiny hackberry protein was greater (P ≤ 0.05) in unprotected plants compared with protected plants at 50 deer km-2. Response of Texas kidneywood density at > 1.5-mtall to deer density depended on year (P=0.04), with no effect of deer density (P ≥ 0.10) on spiny hackberry density. Density of both shrubs was similar (P > 0.14) with and without supplement. Access to feed does not alter effects of browsing on these sympatric shrubs; however, responses to increasing herbivore density contrast. Texas kidneywood is less tolerant of herbivory than spiny hackberry. © 2016 The Society for Range Management. Published by Elsevier Inc. All rights reserved.