Brian A. Mealor

Potential selection in native grass populations by exotic invasion.

Ecological impacts of invasive plant species are well documented, but the genetic response of native species to invasive dominance has been often overlooked. Invasive plants can drastically alter site conditions where they reach dominance, potentially exerting novel selective pressures on persistent native plant populations. Do native plant populations in old exotic invasions show evidence of selection when compared to conspecific populations in adjacent, noninvaded areas? We employ amplified fragment length polymorphism (AFLP) analysis to screen a large number of loci from two native grass species (Hesperostipa comata (Trin. & Rupr.) Barkworth and Sporobolus airoides Torr.) that occur in old infestations of the invasive forb Acroptilon repens. We then compare observed locus by locus FST values with distributions of FST estimated from simulation models under expectation of neutrality. We also compare the proportion of loci possibly linked to selection and those not linked to selection which exhibit parallel trends in divergence between two community types (invaded, noninvaded). Few loci (H. comata, 2.6%; S. airoides, 8.7%) in the two native grasses may be linked to genes under the influence of selection. Also, loci linked to selection showed a greater portion of parallel trends in divergence than neutral loci. Genetic similarities between community types were less than genetic similarity within community types suggesting differentiation in response to community alteration. These results indicate that a small portion of scored AFLP loci may be linked to genes undergoing selection tied to community dominance by an invasive species. We propose that native plants in communities dominated by exotic invasives may be undergoing natural selection.

Land Uses, Fire, and Invasion: Exotic Annual Bromus and Human Dimensions

Human land uses are the primary cause of the introduction and spread of exotic annual Bromus species. Initial introductions were likely linked to contaminated seeds used by homesteading farmers in the late 1880s and early 1900s. Transportation routes aided their spread. Unrestricted livestock grazing from the 1800s through the mid-1900s reduced native plant competitors leaving large areas vulnerable to Bromus dominance. Ecosystems with cooler and moister soils tend to have greater potential to recover from disturbances (resilience) and to be more resistant to Bromus invasion and dominance. Warmer and drier ecosystems are less resistant to Bromus and are threatened by altered fire regimes which can lead to Bromus dominance, impacts to wildlife, and alternative stable states. Native Americans used fire for manipulating plant communities and may have contributed to the early dominance of Bromus in portions of California. Fire as a tool is now limited to site preparation for revegetation in most ecosystems where Bromus is a significant problem. Once Bromus dominates, breaking annual grass/fire cycles requires restoring fire-tolerant perennial grasses and forbs, which can compete with Bromus and resist its dominance. Current weed management policies often lack regulations to prevent further expansion of Bromus. Research is needed on how and where livestock grazing might help increase perennial grass and forb cover and density to create ecosystems that are more resistant to Bromus. Also, studies are needed to ascertain the role, if any, of oil and gas development in contributing to the spread of Bromus.

Native Grasses Collected from Invasions Demonstrate Invasion Resistance

Native grasses can persist in areas dominated by invasive species, yet resistance to invasion by the selected remaining natives is largely unknown. We examine native grass lineages differing in history of survival within invasions, when transplanted into association with 2 invasive perennials. Invaded plants were collected from Russian knapweed (Rhaponticum repens) invasions, and non-invaded plants were collected outside invasions. We assess growth and reproduction of alkali sacaton (Sporobolus airoides) in the presence of Russian knapweed (the original invader) and Canada thistle (Cirsium arvense), an invasive species to which the grasses lacked exposure. On 2 field sites (Crowheart, WY and Cheyenne, WY) and in an environmentally controlled lab at the University of Wyoming, we monitored plant growth (longest leaf, basal circumference, and tiller production) of grass lineages from the 2 histories with and without the presence of the invaders. We monitored invasive species recruitment, grass seedling germination, and grass seedling establishment to determine grass fecundity and resistance to invasive encroachment. At Crowheart, when competing with Russian knapweed, invaded plants were larger than non-invaded plants, irrespective of sampling date. At Cheyenne, invaded plants competing with Canada thistle grew larger than non-invaded grasses irrespective of sampling date. In the controlled growth chamber, growth of the 2 histories differed on few dates, yet non-invaded lineages had greater leaf growth, and seedling germination was greater for invaded grasses. Lines of native grasses collected from within historic invasions display competitive growth traits in field transplants that may be useful for reclamation.

Downy Brome Control and Impacts on Perennial Grass Abundance: A Systematic Review Spanning 64 Years ☆

ABSTRACT Given the high cost of restoration and the underlying assumption that reducing annual grass abundance is a necessary precursor to rangeland restoration in the Intermountain West, United States, we sought to identify limitations and strengths of annual grass control methods and refine future management strategies. We systematically reviewed all published journal articles spanning a 64-yr period (1948–2012; n = 119) reporting data on research efforts to either directly or indirectly reduce the abundance of the most common invasive annual grass, downy brome (Bromus tectorum L.). The seven most common control methods studied were herbicide, burning, revegetation, woody removal, defoliation or grazing, soil disturbance, and soil amendment. In addition, the majority of control methods were 1) applied at scales of 10–100 m2, 2) sampled within small plots (i.e., 0.1–1.0 m2), 3) implemented only once, and 4)monitored at time scales that rarely exceeded 5 yr. We also performed summary analyses to assess how these control methods affect downy brome and perennial grass abundance (i.e., cover, density, biomass). We found conflicting evidence regarding the assumption that reducing downy brome abundance is necessary to enhance the growth and establishment of perennial grasses. All methods, with the exception of woody plant removal, significantly reduced downy brome in the short term, but downy brome abundance generally increased over time and only herbicide and revegetation remained reduced in the long term. Only burning, herbicide, and soil disturbance led to long-term increases in perennial grass abundance. We suggest that future research should prioritize a broader array of ecological processes to improve control efficacy and promote the reestablishment of desirable rangeland plant communities.

Response of Delphinium occidentale and Associated Vegetation to Aminocyclopyrachlor

ABSTRACT Duncecap larkspur (Delphinium occidentale [Wats.] Wats.) is an important perennial weed on high-elevation rangelands because of significant cattle losses due to toxic alkaloids in the plant. Aminocyclopyrachlor was evaluated at six rates between 17.5 and 315 g ai · ha-1 for larkspur control alone, and in combination with chlorsulfuron or metsulfuron, at a high-elevation location inWyoming. Aminocyclopyrachlor-containing treatments were compared with 1120 g ai · ha-1 picloram and 63 g ai · ha-1 metsulfuron-methyl. Herbicides were applied to two sites in a randomized complete block design with four replicates each on June 18, 2010 at the first site and June 28, 2011 at the second site. Larkspur mortality, plant species richness, vegetation cover, and grass biomass datawere collected 1 yr after treatment. Cover datawere used to calculate vegetation diversity and to assess changes in species composition associated with herbicide application. A four-parameter log-logistic model was used to evaluate larkspur mortality, species richness, and vegetation cover in response to aminocyclopyrachlor rate. Ninety-percent larkspur reduction was obtained with aminocyclopyrachlor applied alone at rates of 168–303 g ha-1, depending on site. Mixture of aminocyclopyrachlor plus chlorsulfuron at a 2.5:1 ratio required 102–127 g ha-1 of aminocyclopyrachlor to reduce larkspur 90%. Aminocyclopyrachlor plus metsulfuron was the most effective herbicide combination for larkspur control of those we evaluated, requiring 47+15 g ha-1, respectively, to reduce larkspur 90%. Species richness and diversitywere reduced by herbicide rates required to effectively control larkspur. Graminoid biomass was not significantly impacted by herbicide or rate. Aminocyclopyrachlor may be a useful tool for duncecap larkspur control. Addition of chlorsulfuron ormetsulfuron to aminocyclopyrachlor increased larkspur control but had a greater impact on associated nontarget vegetation.

Inter- and Intraspecific Variation in Native Restoration Plants for Herbicide Tolerance

Choosing appropriate plant materials for restoration projects can affect establishment and persistence of desirable species. In situations where herbicides are used to manage invasive weeds, plant materials able to tolerate herbicides at early growth stages could increase probability of successful restoration of vegetation. However, little is documented regarding relative herbicide tolerance of native species commonly used in restoration and information regarding intraspecific variation for such characteristics is missing. We conducted a greenhouse study in 2010 and repeated in 2011 to investigate seedling response of 17 desirable species (27 germplasm), Russian thistle, and downy brome to aminocyclopyrachlor, a relatively new herbicide with potential applications in reclamation and restoration. We applied aminocyclopyrachlor at six rates between 10 and 320 g ha−1 30 days after planting. Grasses were in the three to five leaf stage and forbs and shrubs were less than five cm tall at the time of herbicide application. We used a log-logistic model to estimate dry weight reduction in response to aminocyclopyrachlor rate. Russian thistle biomass was reduced 95% at 120 g ha−1. At that same aminocyclopyrachlor rate, grass biomass was reduced 0 to 48% and flax and sagebrush species were reduced ≥ 77%. We document variation among and within species for relative tolerance to this herbicide. If aminocyclopyrachlor were used in a restoration project for postemergence control of Russian thistle, most grasses in this experiment would experience negligible biomass reduction whereas the selected sagebrush and flax species were highly susceptible at this early growth stage even at low aminocyclopyrachlor rates.

2008 Rangeland Cup

First Place: Utah State University Team Members (left to right): Casey Addy, Ashley Hansen, and Katie Santini Team Advisor (right): Chris Call The Rangeland Cup team problem solving competition is an activity to promote critical thinking and cooperative, collaborative work on current topics and/or topics of historical importance to rangeland ecology and management. As we progress in our careers, much of our work is performed as part of a group. This competition is intended to build skills in interpersonal communication and group problem solving, both of which are highly desired qualities in the workplace. At the 2008 Annual SRM meeting in Louisville, Kentucky, eight institutions entered teams into the Rangeland Cup competition. All posters were well-prepared and presented. Each team presented their solution to the following challenge:

The Rangeland Cup

The Rangeland Cup team competition is an activity to promote critical thinking and cooperative, collaborative work on current topics or topics of historical importance to rangeland ecology and management. In today’s world, much of our work is performed as part of a group. This competition, which is held at the SRM Annual Meeting, is intended to build skills in interpersonal communication and group problem-solving, both of which are highly desired qualities for rangeland professionals. The fi rst competition took place earlier this year at the 60th Annual Meeting in Reno/Sparks, NV. The task of managing rangelands, though complex in the past, has been compounded by new challenges of the 21st century. As a result, the profession and the Society for Range Management are in a constant state of fl ux. Debates over name changes, policy statements, membership goals, and the purpose of the Society suggest that a clear vision for the future is needed. Who better to provide this vision than future professionals in the fi eld? The topic for the 2007 Rangeland Cup competition at the SRM Annual Meeting was as follows: “Apply the state and transition theoretical framework to describe SRM’s current and potential future ‘identities’ as an organization. Include stable states and transitions between those states, identify forces that drive the SRM over particular thres holds into each state, and describe feedback mechanisms that are needed to maintain each state or to revert the SRM to an alternative state.” Nine teams participated from 6 different institutions. Eight individuals graciously volunteered to judge the competition. The competition generated a great amount of interest and interaction between the students and professionals within the organization. The top 3 posters were 1) “The ‘Adaptive Phases’ of SRM and the Range Profession” from Utah State University, 2) “Society for Range Management: Drivers of Sustainability” from the University of Wyoming, and 3) “Application of State and Transition Model to SRM” from Chadron State College. To showcase these innovative young professionals’ work, posters from the competition are presented on the following pages.