Fire has been a part of natural ecosystems for many millennia. The species of those ecosystems have evolved through a series of “coarse filters,” one of which is resistance or resilience to disturbance by fire. Plant adaptations to fire include the ability to sprout, seed bank adaptations in the soil or canopy, high dispersal ability for seeds, and thick bark. These adaptations are often to a particular fire regime, or combination of fire frequency, intensity, extent, and season. Fire can be used by managers to achieve species to ecosystem-level conservation biology objectives. Examples using prescribed fire include the grasslands of the Puget Trough of Washington State, maintenance of oak woodlands, and perpetuation of ponderosa pine/mixed-conifer forests.

Degradation of Great Plains rangelands can be linked to past management practices that reduced native species diversity and accelerated establishment and expansion of exotic weeds and less desirable native species. Leafy spurge is an exotic perennial weed that infests more than 1 million ha in the northern Great Plains and reduces rangeland carrying capacity by competing with desirable forages and causing infested areas to be undesirable to cattle and wildlife. Research was conducted to determine the feasibility of using herbicides to suppress leafy spurge and other resident vegetation, which facilitated planting and establishment of native tallgrasses. Four experiments were conducted where 0.28, 0.56, and 0.84 kg ai/ha imazapyr and 0.1 kg ai/ha sulfometuron were applied alone and in combination and 0.84 kg ai/ha glyphosate was applied to leafy spurge-infested range sites in fall 1991 near Ainsworth, NE, and in fall 1991, 1992, and 1993 near Ansley, NE. Research areas were burned about 200 d after herbicide application to reduce plant residue. Monoculture stands of big bluestem and switchgrass were then no-till planted in each experiment and indiangrass was no-till planted in experiments initiated at Ansley in 1992 and 1993. Yields of the planted grasses, leafy spurge, and other vegetation were measured in August at each location starting the year after planting. Imazapyr was an essential component of treatments applied before planting to facilitate establishment of highly productive stands of the tallgrasses. Generally, yields were maximized by fall treatments of 0.28 kg/ha imazapyr + 0.1 kg/ha sulfometuron for big bluestem, 0.84 kg/ha imazapyr for indiangrass, and 0.84 kg/ha imazapyr + 0.1 kg/ha sulfometuron for switchgrass. Yields of the planted grasses were frequently four times greater where these herbicides were applied compared to where glyphosate or no herbicide were applied. Leafy spurge yields were usually reduced in areas where tallgrass yields were greatest. The sequential combination of suppressing vegetation with fall-applied herbicides, burning standing dead plant residue, then no-till planting desirable native tallgrasses in the spring increased productivity of these leafy spurge-infested range sites.

Integrated weed management strategies (IWM) are being advocated and employed to control invasive plants species. In this study, we compared three management strategies (biological control alone [BC], BC with fire [BC + F], and BC with mowing [BC + M]) to determine if physical controls reduce seed production by Scotch broom and interfere with the action of the biological control agent—the Scotch broom seed weevil. We measured seed production and seed predation by the weevil at both pod and plant scale, and seed bank density over two field seasons. We found no difference in the number of seeds per pod among management strategies. However, combining management strategies (BC + M and BC + F) resulted in significant reductions in pods per plant, mature seeds per plant, and seed bank density relative to biological control alone. We did not find differences among management strategies in number of weevils per pod or proportion of seeds predated by the weevil at either pod or whole-plant scale. However, combining management strategies (BC + M and BC + F) resulted in a significant reduction in healthy mature seeds per plant relative to biological control alone. Although both integrated strategies outperformed biological control alone in reducing seed production and the seed bank, with no statistical difference between them, we propose that short-rotation prescribed fire could prove to be a more effective strategy for long-term management of Scotch broom due to its potential for slightly greater depletion of the seed bank.

Yellow starthistle (Centaurea solstitialis) is among the most invasive plant species in the western United States. The long-term management of yellow starthistle should include an integrated approach that incorporates establishment of competitive vegetation. In this study, conducted in two locations at Fort Hunter Liggett in Monterey County, California, we evaluated the combination of prescribed burning, the herbicide aminopyralid, and reseeding of native broadleaf and grass species on both yellow starthistle control and native plant restoration. Both study sites were burned in late October 2009. Over the following season, aminopyralid was applied at three timings and native plant species were seeded at three timings, using both a drill-seeder and broadcast spreader. Evaluations over the next 3 yr showed that aminopyralid provided complete to nearly complete control of yellow starthistle when applied between January and March, and this level of control was maintained for two seasons. Native plants failed to establish when broadcast seeded, regardless of the timing. December and January drill seeding timings were the most successful in establishing native species. There was a strong herbicide and drill seed timing interaction effect on native grass cover at both study sites. Over the course of the study the native perennial grass Stipa cernua was the most successful seeded species to establish, but establishment was slow and required 3 yr. Our results indicate that a January or March aminopyralid treatment integrated with a native perennial grass drill seeding program in January offers the greatest probability of both successful yellow starthistle control and perennial grass establishment.

Medusahead is an introduced, winter-annual grass covering millions of hectares of the semiarid West. It forms exclusive stands and has a dense thatch cover that resists the establishment of desirable species. Prescribed fire can remove medusahead litter and improve plant establishment. Medusahead control is fundamental to establishing desirable species that will, in turn, resist further invasion. Imazapic is an effective herbicide for control of medusahead, but more information is needed on its effects on desirable species. Our objectives were to test how imazapic application rate and timing affected medusahead, seeded desirable species, and other nontarget vegetation on burned and unburned rangeland in southeast Oregon. We burned existing medusahead infestations at two different sites in June 2003. Following the burn, imazapic was applied at rates of 0, 35, 70, 105, 140, 175, and 210 g ai/ha between July and October of 2003 in a randomized strip-plot design. In November 2003, monocultures of seven desirable species were drill-seeded across the imazapic treated areas. Data on cover and density of medusahead and seeded species were collected in 2004 and 2005. Cover data of nontarget species were collected in the summer of 2005. Medusahead cover was highest in control plots and lowest in plots that received the highest herbicide application rates. Medusahead cover was lower in burned plots. The effect of imazapic on nontarget vegetation was less clear. Seeded species established in the study plots, but their response to herbicide rate showed few consistent patterns; some of the seeded species showed little response to herbicide, whereas others appeared to establish best at different herbicide rates, depending on site and whether the plots were burned or unburned. Site and burn treatment also affected how imazapic rate or application month influenced cover of perennial or annual grasses or forbs.

Introduced accidentally from South America, deeproot sedge is rapidly expanding in a variety of habitats throughout the southeastern United States. Of particular concern is its rapid expansion, naturalization, and formation of monocultures in Texas coastal prairie, one of the most imperiled temperate ecoregions in North America. The objective of this research was to examine how deeproot sedge responds to prescribed fire, to the herbicide imazapic, and to treatment combinations of both. Combinations of prescribed fire and imazapic treatments and imazapic-only treatments effectively reduced deeproot sedge cover and frequency. However, plots exposed to dormant season fires (with no imazapic) had greater deeproot sedge cover after burn treatments were applied, indicating that coastal prairie management using only dormant season prescribed fire will not work toward reduction or management of this exotic invasive species. Although deeproot sedge cover was often reduced in fire–imazapic treatment combinations, it was still present in treatment plots. Moreover, desirable functional plant groups (i.e., native bunchgrasses) did not respond positively to the fire–imazapic treatments, but in some instances, woody plant coverage increased. Repeated, long-term approaches using integrated and coordinated efforts with multiple treatment options will be necessary to restore community structure to desired compositional levels. Such integrated approaches should be effective in reducing deeproot sedge frequency, cover, and extent to more manageable levels throughout its introduced geographic range.

Brachypodium sylvaticum, a shade-tolerant, forest dwelling, and aggressive invasive grass native to Eurasia, is a noxious weed in California, Oregon, and Washington. This species could cause ecosystem collapse by altering forest fire regimes. To examine interactions with fire, we divided two Willamette National Forest sites into eight units and randomly selected half for treatment with prescribed fire in spring 2011. We assessed the effect of B. sylvaticum on fire (severity and intensity) as well as the effect of fire on B. sylvaticum (cover, seedling emergence, and dispersal). We found that B. sylvaticum cover decreased fire severity but had no effect on intensity. Furthermore, fire severity influenced B. sylvaticum cover; in areas receiving low-severity fire, the grass increased from 21 ± 15.05 to 34 ± 15.81%, but in areas of high-severity fire, cover remained consistently around 0% (0 ± 0% cover in yr 1 to 0.2 5± 0.25% in yr 3). In the field, prescribed fire decreased seedling emergence by 32% compared to controls, but not in an associated greenhouse experiment. However, in the greenhouse, severely burned plots had zero emergence, compared to 0.29 ± 0.14 seedlings low-severity m−2 plot. Fire severity also influenced dispersal in the field; we monitored plots with < 0.5% cover B. sylvaticum initially; when these plots experienced low severity fire, they had greater B. sylvaticum cover (increasing 1,200%), suggesting increased dispersal with less severe fires. High-severity dispersal plots did not experience increased cover. High severity fires have the potential to control the grass, but low-severity fires will likely increase its cover.

Green spaces such as golf courses that intermingle within or exist on fringes of urban landscapes can provide opportunities for increasing the ecological value of urban areas. To that end, more naturalistic and less input-intensive “links”-style golf courses have recently gained favor over input-intensive parkland courses. The Osgood Public Golf Course in Fargo, ND is a links-style golf course set adjacent to suburban housing developments. This course incorporated large areas of prairie plantings, or “constructed grasslands,” which over time became dominated by fescue species and infested with Canada thistle. Our objective was to explore the efficacy of using prescribed fire combined with aminopyralid herbicide to control Canada thistle and promote a more diverse mix of warm-season C4 and cool-season C3 grasses. Aminopyralid was applied during fall 2010 and prescribed fire was applied during spring 2011. We found that aminopyralid provided excellent control of Canada thistle 1 and 2 yr post-treatment. Open niches created from Canada thistle control were readily filled by C3 grasses, primarily fescue species, which were the dominant species on the constructed grasslands prior to treatment. Fire intensity was variable within and across plots and was associated with reductions of litter and C3 grasses, but was not associated with increases of C4 grasses within the time frame of this study. Our results demonstrate the effectiveness of aminopyralid for Canada thistle control in constructed grasslands. Prescribed fire maintained C3 grass dominance while removing litter, but C4 grass response was variable and appeared dependent on pretreatment C4 species abundance. Reduction of litter in constructed grasslands dominated by fescue could potentially lead to microsite conditions that would favor C4 and other C3 species, especially if short-term management promoted additional facilitation efforts, such as repeat spring fire treatments and seeding.

Restoring range sites dominated by western juniper is central to maintaining healthy functioning shrub–steppe ecosystems. On sites without adequate species composition to respond favorably to juniper controlled by fire, revegetation is necessary. We tested the following two hypotheses related to restoration after juniper control: (1) higher seeding rates would translate into higher density of seeded species, and (2) a rich seeding mixture would provide higher density and biomass than monocultures. Western juniper control was done by cutting 25% of the trees in 2002, allowing cut trees to dry for one year, followed by a broadcast fire applied in October 2003 which killed the remaining live juniper trees. Seeding treatments were applied in 2003 and included seeding six native species in monocultures, seeding a mixture of all six species at four rates (16.8, 22.4, 28.0, or 33.6 kg ha−1 of pure live seeds), and a nonseeded control. Treatments were applied on a Sagebrush/bunchgrass and Snowberry/fescue site. We found that bluebunch wheatgrass, Idaho fescue, big bluegrass, and western yarrow density ranged from 450 to 700 plants m−2, which was over six-fold that of the control in 2004 at both sites. Only arrowleaf balsamroot did not establish successfully. The density of big bluegrass nearly doubled from 2004 to 2005. The highest plant density resulted from the highest seeding rate. The highest biomass production was combination seeding at 22.4 kg ha−1 on the Sagebrush/bunchgrass site and 33.6 kg ha−1 on the Snowberry/fescue site. Seeding a combination of species resulted in a moderate to high density of plants and optimized plant diversity and richness over seeding monocultures.

Medusahead is an aggressive, nonnative, winter annual grass that infests rangelands in the western United States. Its ability to rapidly spread, outcompete native vegetation, and destroy forage potential is a primary concern for landowners and land managers exposed to this weed. Prescribed burns were conducted at a low- and high-litter site in northern Utah prior to conducting experiments to evaluate the effects of fall and spring applications of sulfometuron at 39 or 79 g ai/ha and imazapic at 70 or 140 g ai/ha on medusahead and associated perennial grasses, annual and perennial forbs, and bare ground cover. Large differences in pretreatment medusahead litter between the sites resulted in less surface area burning at the low-litter site (∼10%) compared to the high-litter site (∼80%). Higher herbicide rates significantly increased medusahead control and bare ground cover; however, this rate affect largely depended on site, season, and herbicide. The low- and high-litter sites did not differ significantly in perennial grass cover 2 yr after burning. Annual forb cover was greater, but perennial forb cover was lower at the low-litter site compared to the high-litter site. Several treatment combinations were identified as having the potential to maintain greater than 50% medusahead control in the second year after herbicide applications. These results collectively demonstrate that potential exists to successfully control medusahead and produce a window of opportunity to reintroduce a greater abundance of perennial species back into the plant community via seeding.

Early succession plant communities consisting of a diverse mixture of grasses, forbs, and scattered shrubs are required by a variety of wildlife species. Early seral stages follow some form of disturbance but can become dominated by shrubs and trees rather quickly, especially in areas with abundant rainfall and relatively long growing seasons, such as the southeastern United States. In the absence of natural disturbance regimes, the quality and maintenance of these plant communities for wildlife is largely dependent upon management. Prescribed fire, disking, herbicide applications, and mowing are practices commonly used to maintain early succession plant communities for various wildlife species throughout this region. Prescribed fire consumes vegetative debris, provides open structure at ground level, and facilitates travel and foraging for wildlife throughout the field. Burning during the dormant season may promote cool-season grasses if they are present in the field. Burning in late March or early April generally promotes warm-season grasses and forbs. Late growing-season fire (September) will reduce woody encroachment and may encourage additional forb cover. Disking promotes vegetation decomposition, provides open structure at ground level, and generally promotes annual plant species. Disking in the fall and winter stimulates more forb growth than disking in the spring, which will stimulate undesirable nonnative warm-season grasses if present in the seedbank. Selective herbicides can influence plant composition and can be used to encourage grasses where forbs dominate, to promote forbs where grasses dominate, and to reduce woody cover. Mowing during midsummer encourages additional grasses in fields dominated by forbs but is not recommended for field maintenance because mowing produces thatch, which limits the ability of several wildlife species to travel and forage through the field, suppresses the seedbank, and destroys nests and young wildlife. Several practices can be used in combination to meet specific objectives. Succession should be set back every 2 to 4 yr, depending on plant response and focal wildlife species. It is important to intersperse disturbance in space and time, so that a variety of cover types are always available, even to those animals with small home ranges.