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Forb Response to Herbicides in a Degraded Tallgrass Prairie
Abstract
Herbicides are useful tools to manage undesirable plants on grasslands. However, the negative response of desirable plants is a common concern when herbicides are used to manipulate grassland plant composition. Our objective was to determine the response of the forb community in a tallgrass prairie following herbicide application to manage Rhus glabra L. (smooth sumac). Two experiments (replicated in space and time) were conducted to evaluate forb response to selected herbicides, application rates, and broadcast spray and hand-held wick application techniques. In Experiment 1, the shrub Amorpha canescens Pursh (leadplant) had the greatest frequency where 2,4-D was selectively applied with a wick and Ambrosia psilostachya DC. (western ragweed) and Solidago missouriensis Nutt. (Missouri goldenrod) were greatest where glyphosate was applied with a wick, whereas Aster ericoides L. (heath aster) frequency was greatest where no herbicide was applied. In Experiment 2, Helianthus annus L. (annual sunflower) frequency was greatest where picloram was broadcast applied. Species richness varied by treatment in Experiment 1 with the greatest species richness in the areas where picloram + 2,4-D and glyphosate were applied with a wick. In Experiment 2, species richness did not differ among treatments. We determined that wick-applied herbicides were less detrimental to the forb community than broadcast spraying when managing R. glabra in a tallgrass prairie.
... Few studies have been conducted to evaluate the selective removal of tall goldenrod from grass pastures and hayfields with herbicides. Tunnell et al. (14) found that applications of 2,4-D ester at 1.9 lb/acre, 2,4-D amine plus picloram at 0.18 plus 0.75 lb/acre, triclopyr at 1.96 lb/acre, and picloram at 0.5 lb/acre provided from 79 to 94% reduction in Missouri goldenrod ground cover two growing seasons after the herbicide treatment. Since this research was conducted, a variety of new pasture herbicides that are labeled for the control of weeds like tall goldenrod have entered into the marketplace. ...
... Although no treatment completely eradicated tall goldenrod, all of the remaining herbicide treatments reduced tall goldenrod density by 94 to 99% 1YAT (Table 1). Similar to the results of Tunnell et al. (14), picloram plus 2,4-D amine provided good control (90% or greater) of tall goldenrod 1YAT, as did any treatment containing metsulfuron. ...
The addition of several new herbicides labeled for use in pastures or hayfields has led many growers to question their options for weed management. In addition, little is known about the effects of common pasture weeds on total biomass yield or nutritive value in a pasture or hayfield setting. Therefore, field experiments were conducted to evaluate the effect of selected herbicide treatments on tall goldenrod [(Solidago canadensis subsp. altissima (L.)] control and total forage biomass and nutritive values in mixed tall fescue [Lolium arundinacea (Schreb.) S.J. Darbyshire] and legume hayfields. Aminopyralid and aminopyralid plus 2,4-D amine was least effective in controlling tall goldenrod one year after treatment (YAT). Total biomass yields were generally lower in herbicide-treated compared to untreated plots, likely due to the reduction in tall goldenrod and legume density with these treatments. Herbicide-treated biomass yields decreased by an average of 12% 1YAT compared to the untreated control. Nutritive value was also greater in biomass harvested from untreated compared to herbicide-treated forage 1YAT. Results from this study indicate that a variety of herbicide treatments will control tall goldenrod, but that tall goldenrod infestations will not likely decrease the overall yield or nutritive value of the harvested biomass in mixed tall fescue and legume hayfields.
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... However, for successful restoration, seeding may need to be accompanied by effective weed control (Blumenthal et al. 2003;Huddleston and Young 2005;Rice and Toney 1998). Whether herbicides are applied once or repeatedly, there is need to ensure the proper timing and use of low, efficacious rates to minimize effects on nontarget species (Ewing 2002;Tunnell et al. 2006). ...
... In predominately annual plant communities, techniques that enhance resource capture by native plants may be emphasized, whereas in predominately perennial plant communities, techniques that reduce negative effects on native plants may be a priority (Carpinelli et al. 2004). Additionally, Tunnell et al. (2006) point out that plant communities differ in response to restoration treatments along a secondary successional gradient and suggest that measurements based on indicators of successional status can inform treatment selection. ...
Prairies are imperiled habitats, with remnants being generally small and often existing in isolation. Invasive plants have the potential to invade not just the edge of small remnants but also the interior because smaller remnants experience greater edge effects than do large, contiguous prairies. Additionally, invasive plants limit recruitment of native plants, which can arrest secondary succession. We proposed to assess techniques for restoration that included removing annual grasses and supplementing native species recruitment with seeding of native grass and forb species. We also assessed the effect of specific factors affecting recruitment: soil moisture and seed predation. Treatments included broadcast, spot, or no application of the herbicides imazapic and glyphosate and with or without seeding plus mulch. With treatments nested within each of three plant communities, ranging from annual- to perennial-dominated communities, in four blocks per community, plant characteristics (percentage of cover and plant density), soil moisture availability, and seed-predation losses were measured along a plant community gradient within one season at two locations. A combination of broadcast herbicide application and seeding with mulching was found to be more effective in reducing annual grasses and enhancing the establishment of native grass species in predominately annual and mixed communities (annuals and perennials). Spot herbicide application was effective in predominately perennial communities, whereas only seeding native species did not improve recruitment. Although seed predation reduced seedling recruitment, mulch provided seed protection and enhanced soil moisture retention. Plant community response to imposed treatments differed among communities, suggesting that a decision support tool would facilitate management decisions tailored for each plant community. The decision tool would be useful to ensure that appropriate treatments are applied and that specific factors affecting recruitment, such as seed predation and soil moisture, are addressed. Nomenclature: Glyphosate; imazapic. Interpretive Summary: Restoration of grasslands in the Pacific Northwest from annual, nonindigenous plant–dominated communities to native, perennial plant–dominated communities is impeded by loss of viable native perennial seed reserves and by competition from the nonindigenous annuals. Addressing those challenges within the framework of a decision mechanism that considers initial plant community composition would allow restoration strategies tailored to emphasize techniques appropriate to the challenges faced. Our study assessed techniques for restoration within Palouse Prairie that included removing annual grasses by broadcast and spot-herbicide applications and supplementing native species recruitment with seeding of native grass and forb species across a plant community gradient. We also assessed seed predation and soil moisture as specific factors affecting plant recruitment. The results showed that response to treatment differed for annual and perennial grasses and forbs among the plant communities. High seed predation, ranging from 40 and 85% was observed. Although seed predation was associated with the observed low recruitment of native perennial grasses, mulch seemed to provide seed protection and enhanced soil moisture retention. The results enabled us to develop a decision mechanism that suggests (1) predominately perennial plant communities do not benefit from added seed, but spot herbicide treatment can reduce annual grass cover; (2) broadcast herbicide applications are required in mixed plant communities, even when foliar cover of perennial grasses approaches 20%; and (3) predominately annual plant communities should be seeded along with the use of a broadcast herbicide application. Decision mechanisms focused on foliar cover and density of dominant plant species can inform restoration efforts within the Palouse Prairie and are likely useful within other Pacific Northwest grasslands as well.
... Decades of reliance on herbicides to combat sericea lespedeza have not resulted in satisfactory control (Wong et al., 2012). In addition, herbicides can be lethal to ecologically important, non-target, native plant species and may cause further degradation of native habitat (Tunnell et al., 2006). This unintended loss in rangeland biodiversity can be difficult to reverse (Marshall, 2001). ...
Mature ewes were used in a 4-yr study to evaluate effects of intensive late-season sheep grazing on vigor of sericea lespedeza in native tallgrass prairie. Pastures (n = 8; 31 ± 3.6 ha) infested with sericea lespedeza (initial basal frequency = 1.4%) were assigned randomly to 1 of 2 treatments: early-season beef steer grazing (1.1 ha / steer; initial BW = 258 ± 34 kg) from 15 April to 15 July followed by no grazing for the rest of the year (control; STR) or steer grazing from 15 April to 15 July followed by intensive grazing by mature ewes (0.2 ha / ewe; SHP) from 1 August to 1 October. Ewes (initial BW = 65 ± 3.1 kg) were assigned randomly to graze 4 of 8 pastures; remaining pastures were not grazed from 1 August to 1 October. Vegetation responses to treatment were measured along 4 permanent 100-m transects in each pasture. Herbivory on sericea lespedeza was monitored weekly in each pasture from 21 July to 7 October. Herbivory on sericea lespedeza in SHP and STR after steer grazing and before sheep grazing was not different (P = 0.51). In contrast, sericea lespedeza herbivory following sheep grazing was greater (P < 0.01) in SHP than in STR. Herbivory of individual sericea plants was greater (P < 0.01) in SHP than in STR by the end of week 1 of the sheep-grazing period (10.6 vs. 0.5%); moreover, herbivory on sericea lespedeza steadily increased (P ≤ 0.01) such that 92.1% of sericea lespedeza plants were grazed in SHP compared to 1.4% in STR by week 8 of the sheep-grazing period. Whole-plant DM weight of sericea lespedeza at dormancy was less (P < 0.01) in SHP than in STR. Additionally, annual seed production by sericea lespedeza was less (P < 0.01) in SHP than in STR (114 vs. 864 seeds / plant). Pasture forage biomass was not different (P = 0.76) between SHP and STR after the steer-grazing period. Conversely, STR had more (P < 0.01) residual forage biomass than SHP at the end of the sheep-grazing period. Growth performance of beef steers grazing from 15 April to 15 July annually was not different (P ≥ 0.59) between treatments. Our results were interpreted to suggest that intensive late-season grazing by sheep decreased vigor of sericea lespedeza. Late-season sheep grazing decreased forage biomass by 904 kg DM / ha compared with late-season rest; however, residual biomass was adequate to prevent soil-moisture loss and erosion during the dormant season.
... In contrast, controlling sericea lespedeza with herbicides may result in collateral damage to sensitive nontarget forbs, such as wildflowers (Blocksome, 2006;Cummings et al., 2017;Gatson, 2018). Utilization of herbicides in native grasslands for the control of other invasive or undesirable species, including broom snakeweed (Gutierrezia sarothrae; McDaniel et al., 2000), leafy spurge (Euphorbia esula; Rinella et al., 2009), and smooth sumac (Rhus glabra; Tunnell et al., 2006), likewise reduced the frequency of native forbs. Native forbs are an essential food source for native invertebrates, which are in turn food sources for grassland-nesting birds (Beran et al., 1999;Ogden et al., 2019). ...
The predominant grazing-management practice of the Kansas Flint Hills involves annual prescribed burning in March or April with postfire grazing by yearling beef cattle at a high stocking density from April to August. There has been a dramatic increase in sericea lespedeza (Lespedeza cuneata [Dumont] G. Don) coincident with this temporally focused use of prescribed fire in the Flint Hills region. The species is an aggressive invader and a statewide noxious weed in Kansas. Control has generally been attempted using repeated herbicide applications. This approach has not limited proliferation of sericea lespedeza and resulted in collateral damage to nontarget flora and fauna. Alternative timing of prescribed fire has not been evaluated for its control. Our objectives for this 4-yr experiment were to (1) document the effects of prescribed burning during early April, early August, or early September on vigor of sericea lespedeza, standing forage biomass, and basal cover of native graminoids, forbs, and shrubs and (2) measure responses to fire regimes by grassland bird and butterfly communities. Whole-plant dry mass, basal cover, and seed production of sericea lespedeza were markedly less (P < 0.01) in areas treated with prescribed fire in August or September compared with April. Forage biomass did not differ (P ≥ 0.43) among treatments when measured during July; moreover, frequencies of bare soil, litter, and total basal plant cover were not different (P ≥ 0.29) among treatments. Combined basal covers of C4 grasses, C3 grasses, annual grasses, forbs, and shrubs also did not differ (P ≥ 0.11) between treatments. Densities of grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), and eastern meadowlark (Sturnella magna) were not negatively affected (P > 0.10) by midsummer or late-summer fires relative to early-spring fires. There were no differences (P > 0.10) in densities of grassland-specialist butterfly species across fire regimes. Under the conditions of our experiment, prescribed burning during summer produced no detrimental effects on forage production, desirable nontarget plant species, grassland birds, or butterfly communities but had strong suppressive effects on sericea lespedeza. Additional research is warranted to investigate how to best incorporate late-summer prescribed fire into common grazing-management practices in the Kansas Flint Hills.
... Many of the species present are agricultural weeds and often require treatment with mowing and herbicides to comply with local and regional weed laws. These practices can lead to a loss of forb cover over time (Fuhlendorf et al. 2002;Tunnell et al. 2006), which causes a concomitant loss of structural diversity and potential food resources (Fuhlendorf et al. 2002). The lack of alfalfa in Site 14 can be attributed to spraying of herbicide(s). ...
Vegetative characteristics and grassland passerine use of conservation plantings were studied in eastern South Dakota Game Production Areas, June 2007-2008. Fourteen fields, from 1 to 8 years old at the onset of the study, were surveyed in each year to describe vegetative characteristics and to correlate grassland pas-serine use. Sites had been planted to a mixture of 5 native warm-season grasses, 3 cool-season grasses, and alfalfa. Grassland passerines were sampled along fixed width transects during June 2007-2008. Vegetation was sampled at 7 points along each of 3 parallel transects within the bird sampling transects. Younger plantings had lower height and percent canopy cover of dead vegetation, greater litter depth, higher coverage of alfalfa and unplanted forbs, and more bare ground than older plantings. Nonmetric multi-dimensional scaling based upon vegetative characteristics showed that sites tended to become more similar with age. A total of fifteen bird species were identified along transects in each year. Six species showed a relationship between abundance and the measured vegeta-tion structure and composition variables. Although research showed that grass-land passerines use these plantings, more research is needed to determine nest success of passerines to determine the true conservation value of these plantings and associated management practices.
... 2-3 m below the farmlands and within a range of nitrate and phosphate runoff, a significant expansion of ruderal plants, such as Artemisia vulgaris and Urtica dioica was found. These habitats are also under the influence of herbicides, which negatively affect the species composition of grasslands (Rice and Stritzke, 1989;Tunnell et al., 2006). Herbicides most likely led to the prevalence of species relatively resistant to herbicides, such as Calamagrostis epigejos and Elymus repens. ...
The aim of the investigation was to study the flora of grasslands within the Zachodniowołyńska Dolina Bugu Special Area of Conservation and to identify the types of habitats with the highest concentration of grassland species. In the years 2011-2012, floristic analyses covered the slopes of the valley of the Bug river, balks and places of shallow bedrock deposition, roadsides, as well as railway and earthwork sites. One hundred and fifty eight plant species belonging to 37 families were found. Though considered extinct in Polish flora, Dianthus collinussubsp. glabriusculuswas discovered.
Close to half of the recorded species (47%) were grassland taxa and 15% rare and/or protected plants, which make the studied area particularly valuable for the conservation of biodiversity. The fewest grassland plants occurred on habitats that are under the influence of agriculture, where the dominance of nitrophilous and herbicide resistant plant species was observed.
... We studied the effects and mechanisms of grazing, nutrient supply, and mowing. We did not examine the effects of herbicides and tillage because these practices are rarely employed in permanent grasslands and poorly documented in the literature (Rahman et al. 1993; Rice and Stritzke 1989; Sheley 2007; Tunnell et al. 2006), making it difficult to formulate generalizations (Kleijn and Snoeijing 1997). All factors and underlying processes described in this literature review are summarized inTable 1. ...
Research has delivered convincing findings on the effect of biodiversity on ecosystem functioning and humankind. Indeed, ecosystems
provide provisioning, regulating, supporting, and cultural services. The global value of annual ecosystem services of grasslands
and rangelands is about US$ 232 ha−1 year−1. Nevertheless, the precise evaluation of biodiversity benefits remains challenging. This issue is due to valuation methods,
subjective assumptions, and complexity of drivers of plant community dynamics. Here, we review the primary factors that influence
plant diversity of permanent grasslands, and we describe underlying processes. These factors must indeed be identified to
focus policies meant to preserve and restore plant diversity and to advise farmers about efficient decision rules. We show
that plant dynamics of permanent grasslands cannot be explained simply by agricultural management rules, e.g., grazing, fertilization,
and mowing, implemented at the field scale. The configuration of the surrounding landscape, e.g., landscape heterogeneity,
habitat fragmentation, and connectivity, acts as a species filter that defines the regional species pool and controls seed
flow. The regional species pool often contains higher species richness in a heterogeneous landscape, because of a higher diversity
of suitable habitats. This regional pool could be a major species sources for permanent grasslands according to the seed flow.
We discuss the need to consider all of these factors to understand plant species composition of permanent grasslands and the
necessity to study plant communities using both taxonomic and functional approaches. In order to report this integrative approach,
we propose a conceptual model based on three ecological challenges—dispersal, establishment, and persistence—that are considered
to act as filters on plant diversity, and a graphical representation of the complexity of such studies due to the interaction
effects between plant dispersal abilities, forage productivity, disturbances induced by farming practices, and landscape heterogeneity
on plant diversity. Last, we discuss the ability of farmers to manage each factor and the necessity of such study in the improvement
of the current agro-environment schemes efficiency for farmland biodiversity restoration or preservation.
... In many U.S. ecosystems, the application of selective herbicides has become the primary approach to reducing the spread of invasive exotics (Fuhlendorf et al. 2001). In prairies, this can be partially accomplished by application of graminoid-specific herbicides (graminicides; Tunnell et al. 2006). However, the long-term effects of herbicide application and invasive species control on plant communities are not well-documented (Browne et al. 2009). ...
We evaluate prairie plant community variation in a matrix of restoration treatments in the south Puget Lowland, WA. Native and exotic plant community diversity and composition were measured across areas that differed in burning history and grass-specific herbicide application, having received one to several treatments since 2002. All plots were also variable in historical proximity to a key invasive exotic species (Cytisus scoparius - Scotch broom), a nitrogen-fixing shrub. Three trends were readily apparent from our data: 1) total plant species richness was higher following a prescribed fire. This trend was associated with increases in both native and exotic plants; 2) areas treated with a grass-specific herbicide generally had lower exotic and higher native cover; and 3) using a combination of GIS modeling and community analysis, we found that historical proximity to C. scoparius across all treatment areas was associated with suppressed native species richness. In fact, the magnitude of the effect of historical proximity to C. scoparius was as large as the differences among fire treatment areas. These data suggest that restoration treatments such as fire and herbicide application affect species richness and diversity in prairies, but the changes were neither rapid nor large. Further, exotic species legacies may interact with treatment effects to variably alter restoration outcomes.
... None of the fire or herbicide treatments caused a strong increase in the amount of exotic species seen in other studies (Holmes et al. 2000;Mau-Crimmins 2007;Mason and French 2007;Ogden and Rejmanek 2005). The results are encouraging because retreatment of the site with broadspectrum herbicides can result in depletion of native forb species (Fuhlendorf et al. 2002;Tunnell et al. 2006), further complicating restoration. Disturbance, such as overgrazing, could release the Kentucky bluegrass and exotic forb seeds in the seedbank or shift composition to that of an earlier successional flora (Kinucan and Smeins 1992;Perez et al. 1998). ...
Smooth brome and Kentucky bluegrass are introduced cool-season perennial grasses known to invade grasslands throughout North America. During the fall of 2005 and spring of 2006, we implemented a restoration study at six native prairie sites in eastern South Dakota that have been invaded by smooth brome and Kentucky bluegrass. Treatments included five herbicide combinations, a fall prescribed burn, and an untreated control to determine the potential of each for renovation of invaded native grasslands. Herbicide treatments tested were sulfosulfuron, imazapyr, imazapic + sulfosulfuron, and imazapyr + imazapic, and were applied in late September 2005 and mid-May 2006. Untreated control plots averaged 64% (± 3.1) smooth brome cover and 38% (± 5.5) Kentucky bluegrass cover after the third growing season. Smooth brome cover in herbicide treated plots ranged from 6 to 23% and Kentucky bluegrass cover ranged from 15 to 35% after the third growing season. Smooth brome cover was 20% (± 2.9) and Kentucky bluegrass cover was 19% (± 4.0) in burned plots after the third growing season. Spring and fall treatments had similar native plant cover after three growing seasons. Spring and fall application of 0.33 kg ai ha -1 imazapyr and 0.10 kg ai ha-1 imazapic + 0.16 kg ai ha-1 imazapyr had ≤ 10% smooth brome cover and increased native species cover after three growing seasons. Herbicides were effective at reducing cover of smooth brome and Kentucky bluegrass, and can be incorporated with other management strategies to restore prairie remnants.
Synthetic‐auxin herbicides are often used to control woody plants and aid in grassland restoration. Seed‐based restoration is common alongside herbicide applications and there may be unintended effects of these herbicides on dryland plants at the seed and seedling stages. Additionally, abiotic conditions at the time of herbicide application may influence herbicide–soil–plant interactions. We conducted a greenhouse study to examine the effects of a common shrub‐control herbicide mix and its interaction with soil type and a post‐herbicide water pulse on common desert plant seeds and seedlings. In this greenhouse study, we found that a subset of species responded negatively to soil residual herbicide activity of a mixture of aminopyralid, clopyralid, and triclopyr at the seed and seedling stages. Species sensitive to soil herbicide residues were primarily shrub and forb species that are often the target species of herbicide applications for woody plant control, such as honey mesquite ( Prosopis glandulosa ) and creosote bush ( Larrea tridentata ). However, two shrub species (four‐wing saltbush [ Atriplex canescens ], soaptree yucca [ Yucca elata ]) and one perennial grass species (Arizona cottontop [ Digitaria californica ]), which are used in dryland restoration projects, were found to be particularly sensitive to soil residual herbicide activity. Thus, if using these herbicides to control woody plants and restore herbaceous vegetation via active seeding or relying on the in situ seed bank, considerations should be given to what species are used in the seed mix, what species are already present in the soil seed bank, and other details of the circumstances of herbicide application.
Herbicides are the most widely used class of pesticides in the world, applied to eliminate target plants that compete with crops or to kill crop plants to facilitate harvesting. Impacts of herbicide use is not limited to plants but has various consequences for other non-target organisms including humans, overall biodiversity and ecosystem functions. This article provides a scientific overview of current knowledge of herbicide nontarget effects and identifies gaps in herbicide risk assessment. We conclude that current Environmental Risk Assessment (ERA) schemes for herbicides do not readily consider impacts on ecosystem functions and biodiversity, although protecting biodiversity is one of the biggest global challenges. We identified a lack in interdisciplinary approaches considering real-world ecological interactions taking place within agricultural fields and at the landscape level in order to better understand non-target effects of herbicides.
Background/Question/Methods
In this study we used a matrix of restoration management practices in a glacial outwash prairie south of the Puget Sound in Washington to evaluate treatments of fire and herbicide as well as the legacy effects of the N-fixing non-native species Cytisus scoparius on prairie plant communities. We measured plant community diversity and abundance across five data sets spanning three years for both spring and fall seasons. We compared native and non-native plant communities, community structure, composition, and diversity among 1) different aged burn treatments (2002, 2006, no burn) and pre/post burn treatments, 2) graminoid specific herbicide treatments over 1 and 4 years, and 3) we evaluated legacy effects of C. scoparious using historic aerial photos showing distribution and subsequent removal across all fire and herbicide treatments.
Results/Conclusions
There are three major findings of this work: 1) Species richness was highest in the most recently burned site (2006; P < 0.05) compared to an older burn (2002) and control treatment (P < 0.05). These findings are also supported by data on 20 1m2 vegetation plots that were monitored pre, and post-burn in 2006/2007. However, both datasets suggest burn treatments increase richness through an increase in the diversity and abundance of non-native plants; 2) graminoid-specific herbicide showed promise as a restoration mechanism with significant reductions in invasive grass cover over 1-year and 4-years of consecutive treatment (P < 0.05); and 3) using a combination of GIS modeling, non-metric multidimensional scaling ordination, and multiple response permutation analyses, we found relationships that suggest historical proximity to C. scoparious is a strong predictor of community differences through promotion of invasive plant abundance for all treatments (P < 0.05). This work suggests that while plant communities respond to fire and herbicide as restoration tools, fire may promote invasive species dominance over native species. Further, key soil-modifying invasive species can have legacy effects that transcend the effects of even high-intensity restoration activities. Since these legacy effects and fire may both increase invasive success, targeted invasive species management in areas previously occupied by an N-fixing shrub may increase efficacy of restoration treatments over broad-landscape-level application of tools like fire and herbicide.
Natural grasslands are one of the most threatened ecosystems in North America. Conservation efforts are often hampered by exotic plant invasions in existing remnant natural grasslands. Tall fescue [Schedonorus phoenix (Scop.) Holub.] is an introduced cool-season (C3) forage/turf grass which readily invades natural grasslands in Kentucky and neighboring states. Our study objectives were to (1) compare the efficacy and application timing effect of clethodim to that of imazapic to selectively remove tall fescue from natural grasslands and (2) evaluate the response of the nontarget grassland plant community (i.e., native grass and forb canopy cover) following herbicide treatments. Clethodim and imazapic treatments consisted of early (April 4, 2001) and late (April 20, 2001) applications, and these were applied at 0.23 and 0.21 kg ai ha−1, respectively. Both herbicides reduced tall fescue cover (P ≤ 0.05); herbicide application timing had no effect on herbicide efficacy to control tall fescue. Native grass cover was higher (P ≤ 0.05) in all herbicide-treated plots compared to the untreated controls, except for the late clethodim-treated plots. All herbicide treatments increased forb abundance compared to controls. Spring applications of clethodim were equally effective to those of imazapic at controlling tall fescue in natural grasslands. Imazapic released native grasses better than clethodim, whereas clethodim was better at increasing forb abundance. Furthermore, early clethodim treatments had fewer nontarget effects on native C4 grasses compared to late clethodim treatments. Overall, clethodim shows promise as a beneficial management tool for tall fescue control in C4-dominated natural grasslands. Nomenclature: Clethodim; imazapic; tall fescue, Schedonorus phoenix (Scop.) Holub
Prescribed fire has become a common tool of natural area managers for removal of non-indigenous invasive species and maintenance of barrens plant communities. Certain non-native species, such as tall fescue (Festuca arundinacea), tolerate fire and may require additional removal treatments. We studied changes in soil N and C dynamics after prescribed fire and herbicide application in remnant barrens in west central Kentucky. The effects of a single spring burn post-emergence herbicide, combined fire and herbicide treatments, and an unburned no-herbicide control were compared on five replicate blocks. In fire-plus-herbicide plots, fescue averaged 8% at the end of the growing season compared with 46% fescue cover in control plots. The extent of bare soil increased from near 0 in control to 11% in burned plots and 25% in fire-plus-herbicide plots. Over the course of the growing season, fire had little effect on soil N pools or processes. Fire caused a decline in soil CO2 flux in parallel to decreased soil moisture. When applied alone, herbicide increased plant-available soil N slightly but had no effect on soil respiration, moisture, or temperature. Fire-plus-herbicide significantly increased plant-available soil N and net N transformation rates; soil respiration declined by 33%. Removal of non-native plants modified the chemical, physical, and biological soil conditions that control availability of plant nutrients and influence plant species performance and community composition.
Abstract Research on fire in tallgrass prairie focuses almost exclusively on dormant season fires, primarily in winter and spring. Relatively little is known,about the response of tallgrass prairie vegetation to growing-season fiies or follow-up management.,We evaluated vegetation response of grazed, high-seral tallgrass prairies to her- bicides after late-summer burning. Dry matter yields of little blue- stemscopuriutn (Michx.) Nash], other perennial grasses, total perennial grasses, and total herbage were sign% cantly reduced by late-summer burning. Tallgrass and annual grass standing crop did not differ between burn treatments. Forb stand- ing crop on burned plots averaged about twice that of unburned plots. Follow-up treatment with 2,4-D[(2,4-dichlorophenoxy)- acetic acid] significantly reduced forb standing crop compared,to atrazine[6-chloro-N-ethyl-~~l-methylethyl)-1,3,5-t~azine-2,4-~- amine]. Standing crop of tallgrasses and total perennial grasses was greater on plots treated with 2,4-D than on plots treated with no herbicide or with atrazine. Because late-summer burning did not severely reduce herbage production nor drastically alter com- munity composition for more than 1 year, late-summer burning may,be a viable alternative for brush control and for improving wildlife habitat in high-seral tallgrass prairie. If management objectives require reduced forb production and increased peren- nial grass production following late-summer burning, application of 2,4-D would be an appropriate management practice. Key Words: atrazine, burning, 2,4-D, herbicides, range improve-
Community ecological theory may play an important role in the development of a science of restoration ecology. Not only will the practice of restoration bene- fit from an increased focus on theory, but basic re- search in community ecology will also benefit. We pose several major thematic questions that are rele- vant to restoration from the perspective of community ecological theory and, for each, identify specific areas that are in critical need of further research to advance the science of restoration ecology. We ask, what are appropriate restoration endpoints from a community ecology perspective? The problem of measuring resto- ration at the community level, particularly given the high amount of variability inherent in most natural communities, is not easy, and may require a focus on restoration of community function (e.g., trophic struc- ture) rather than a focus on the restoration of particu- lar species. We ask, what are the benefits and limita- tions of using species composition or biodiversity measures as endpoints in restoration ecology? Since reestablishing all native species may rarely be possi- ble, research is needed on the relationship between species richness and community stability of restored sites and on functional redundancy among species in regional colonist "pools." Efforts targeted at restoring system function must take into account the role of in- dividual species, particularly if some species play a disproportionate role in processing material or are strong interactors. We ask, is restoration of habitat a sufficient approach to reestablish species and func- tion? Many untested assumptions concerning the rela- tionship between physical habitat structure and resto- ration ecology are being made in practical restoration efforts. We need rigorous testing of these assump- tions, particularly to determine how generally they apply to different taxa and habitats. We ask, to what extent can empirical and theoretical work on commu- nity succession and dispersal contribute to restoration ecology? We distinguish systems in which succession theory may be broadly applicable from those in which it is probably not. If community development is highly predictable, it may be feasible to manipulate natural succession processes to accelerate restoration. We close by stressing that the science of restoration ecology is so intertwined with basic ecological theory that practical restoration efforts should rely heavily on what is known from theoretical and empirical re- search on how communities develop and are struc- tured over time.
Tallgrass prairies provide an important source of hay and summer forage in eastern Nebraska. A study was conducted in 1989 and 1990 on 2 late seral tallgrass prairies near Lincoln and Virginia, Nebraska to determine if production of selected compo- nents of tallgrass prairie communities could be altered by burn- ing (not burned, or burned in either early, mid-, or late spring) and applying fertilizer (0 and 67-23 kg N-P ha-') and atrazine (6- chloro-N-ethyl-N'-(l-methylethyl)-l,3,5-triazine-2,4-diamine) (0 and 2.2 kg a.i. ha.'). Vegetation was harvested the year treat- ments were applied at about 30-day intervals starting in June and ending in August. Maximum big bluestem (Andropogon ger- ardii var. gerardii Vitman) accumulated standing crop (ASC) on unburned areas and areas burned in mid-spring occurred later in 1990 than in 1989. Burning in late spring 1989 maintained big bluestem ASC above 1,100 kg ha.' through July, whereas big bluestem ASC declined below 840 kg ha.' in July on areas where other burn treatments were applied. In 1990, big bluestem ASC exceeded 1,570 kg ha.' in June on areas burned in early and mid- spring and exceeded 1,500 kg ha-' in July on areas that were not burned or burned in mid- or late spring. From July to August 1990 big bluestem ASC declined below 730 kg ha-' for all treat- ments except the late spring burn treatment where ASC was 1,340 kg ha". Burning in late spring reduced prairie dropseed (Sporobolus heterolepis (A. Gray) A. Gray) and tall dropseed (S. asper (Michx.) Kunth.) ASC by at least 67% in June 1990 com- pared to areas burned in early and mid-spring. Cool-season grass ASC at Virginia declined 86% in June when burned in late spring compared to areas that were not burned. Fertilization increased big bluestem ASC by about 23 and 29% in June and July. Vegetation response to atrazine was variable. Atrazine had a negligible effect on big bluestem ASC. Burning late seral tall- grass prairie in late spring increased big bluestem ASC later in the growing season and decreased cool-season grasses more effec- tively than burning earlier in the spring.
Yellow starthistle is a problematic invasive plant in the western United States. Attempts to control it often include the use of herbicides although herbicides can have detrimental effects on desired native species. We studied the effect of clopyralid on a native bunchgrass and vernal pool community in the Central Valley of California. Areas invaded by yellow starthistle were treated with clopyralid, and the presence and cover of all species was monitored for 2 yr. There were significant differences in species cover between treated and untreated plots 2 yr after treatment (P = 0.0001). These included a decline in cover of yellow starthistle and other native and exotic members of the Asteraceae and Apiaceae families in both years and a decline of exotic members of the Fabaceae family in the second year. There also were decreases in the frequency of the Asteraceae (P < 0.0001), Apiaceae (P < 0.05), Fabaceae (P < 0.05), and Polygonaceae (P < 0.05) families 1 yr after treatment, and the Asteraceae (P < 0.05) and Fabaceae (P < 0.05) families 2 yr after treatment. We also observed a significant negative effect of clopyralid on fecundity measures of a native Viola species during the first year of application (P = 0.0074). This effect did not persist into the second year, when violets were more common and produced more flowers in treated plots (0.02 < P < 0.05). Nomenclature: Clopyralid; yellow starthistle, Centaurea solstitialis L. CENSO.
The primary approach used for reducing “weeds” in the native grasslands of the North American Great Plains is the application of a broadleaf-selective herbicide, which could have important implications to native plant and arthropod diversity. The objectives of this study were to identify the influence of herbicides on the forb and arthropod community composition, richness, and density, and determine relationships among the forb and arthropod communities in a tallgrass prairie of the North American Great Plains. In 1994, arthropod and forb communities were evaluated in eight treatment units and then a broadleaf-selective herbicide was applied to four of these units. Sampling of arthropod and forb communities were sampled under similar conditions in 1995 for post-treatment effects. These communities were highly variable across years regardless of treatment (herbicide and no herbicide). The herbicide treatment caused a reduction in overall forb dominance the year after treatment. Species richness increased from 1994–1995 in both treatments but the increase was less in the herbicide treatment. The herbicide application had no overall effect on forb species composition. The lack of effect of herbicide on the forb community composition coupled with a significant effect on species richness suggests that an important effect of herbicide application was a reduction of rare forbs. Analysis of these tallgrass communities did not yield significant differences in arthropod abundance or richness between grasslands treated with a herbicide and grasslands not treated with a herbicide. The arthropod community was defined by extreme variability across years reflecting extreme fluctuations regardless of herbicide application.
Understory vegetation was studied following treatment by herbicides and fire on grazed pastures within the Cross Timbers vegetation type. Tebuthiuron and triclopyr at 2.2 kg ha ⁻¹ were applied in March and June of 1983, respectively. The pastures were burned in late spring of 1985, 1986 and 1987. Frequency of horseweed, rosette panicgrass, and little bluestem increased with both herbicides, but the increase was usually larger with tebuthiuron than triclopyr. Burning as a follow-up to either herbicide had little effect on frequency of rosette panicgrass and little bluestem. Horseweed increased following burning in 1985 and 1987. Standing crop of grasses and forbs increased dramatically following herbicide treatments. Grass production was greater with tebuthiuron, whereas production of forbs and browse was generally greater with triclopyr.
Three hundred ninety-two species, subspecies, and varieties have been recorded at Nine-Mile Prairie, a relict tall-grass prairie that has been reduced from 323 to 97 ha in the past 50 years. There are 218 native and 17 introduced herbaceous perennial species, and 73 native and 24 introduced annuals. Analogous numbers for biennials are 15 and 11, for shrubs are 14 and one, for trees are ten and three, and for woody vines are six and none. One hundred twenty-one native species are of central and eastern North American phytogeographic affinity, and 109 are of transcontinental affinity. Seventy-nine of the Prairie's native species occur only in the central part of the continent, but only 27 are characteristic of the western and central parts. Five habitats are utilized to categorize the vegetation: wooded ravine, upland prairie, disturbed upland prairie, wet prairie, and aquatic. Data are presented on the distribution of growth habits and phytogeographic affinities for the habitats. The upland prairies have more native and introduced species than either the wet prairies or ravines. However, the relative proportions of growth habits, flowering phenologies, and phytogeographic affinities are not the same in the various habitats. The flora of the wooded ravines is mostly of eastern affinity, while that of the upland prairies has strong western and central phytogeographic elements.
The productivity and native species diversity of Great Plains grasslands have been substantially reduced by past management that facilitated the establishment of invasive exotic weeds and displacement of native species. Management strategies are needed to rapidly restore the productive capacity and biological diversity of these degraded grasslands. Critically important phases of the grassland restoration process are the reintroduction and establishment of native species. Weed interference is the primary constraint to successful establishment of native plants. The goal of our research is to develop strategies that use multiple technologies, including herbicides, to expedite grassland revegetation with native grasses and forbs. Imidazolinone herbicides (AC 263,333, imazapyr, and imazethapyr) were used successfully to improve establishment of native perennial grasses (big bluestem, switchgrass, little bluestem) and selected forbs (blackeyed-susan, purple prairieclover, Illinois bundleflower, trailing crownvetch, and upright prairie coneflower) on cropland and as components of a strategy to revegetate leafy spurge- infested rangeland with native tallgrasses. Imazethapyr at 70 or 110 g ai/ha applied at planting resulted in stands of big bluestem and little bluestem that were similar or superior to stands established where atrazine was applied. Seedling grasses were susceptible to imazapyr at two of three study sites. Imazapyr at 560 g ai/ha plus sulfometuron at 100 g ai/ha applied in fall was the optimum treatment for suppression of leafy spurge and exotic cool-season grasses and establishment of big bluestem and switchgrass on degraded rangeland sites. Establishment of selected forbs was improved by PRE treatment with AC 263,222 or imazethapyr at 70 g ai/ha. This research provides evidence that the imidazolinone herbicides can be important components of integrated weed management strategies designed to reverse deterioration of grasslands by reestablishing native species, improving grassland productivity, and decreasing the prevalence of exotic weeds.
Two herbicide treatments were initiated in southeastern Nebraska on a Wymore silty clay loam (clayey range site) during the spring of 1979, to change species composition of overgrazed, native range from cool- to warm-season grasses. Treatments consisted of late spring applications of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazione] at 2.24 kg/ha, and glyphosate [N-(phosphonomethyl)glycine] at 1.12 kg/ha. Both herbicide treatments significantly (P<.05) reduced smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass (Poa pratensis L.) production and relative species composition while increasing big bluestem (Andropogon gerardii Vitman) in 1979 and the effects were maintained during the second growing season. Warm-season herbage yield, primarily big bluestem, was greater following herbicide treatments (5345 kg/ha) compared to control (1610 kg/ha). Herbage yields of cool-season grasses from herbicide treated plots were reduced. However, total herbage yield was higher on herbicide treated plots during the first and second year after treatment. Total, warm-season and cool-season herbage yields for both years were not different between atrazine and glyphosate treated plots. Both herbicide treatments have potential for rapid recovery of overgrazed, native tallgrass prairies in eastern Nebraska when sufficient warm-season tallgrass remnants are present.
It is becoming increasingly clear that prescriptions for rangeland weed control are not sustainable because they treat the symptoms of weeds rather than their cause. Future restoration of invasive plant–infested rangeland must be based on ecological principles and concepts that provide for predictable outcomes. A generalized objective for ecologically based weed management is to develop and maintain a healthy plant community that is largely invasion resistant. Successional management based on ecological principles involves modifying the processes controlling the three general causes of succession: disturbance, colonization, and species performance. The processes controlling plant community dynamics can be modified to allow predictable successional trajectories. Successional management can lead to biomass optimization models for grazing management, spread vector analysis, and using resource availability to direct weedy plant communities toward those that are desired. Our challenge is to develop ecological principles on which management can be based.
Abstract Prescribed fire is often used to restore grassland systems to presettlement conditions; however, fire also has the potential to facilitate the invasion of exotic plants. Managers of wildlands and nature reserves must decide whether and how to apply prescribed burning to the best advantage in the face of this dilemma. Herbicide is also used to control exotic plants, but interactions between fire and herbicides have not been well studied. Potentilla recta is an exotic plant invading Dancing Prairie Preserve in northwest Montana. We used a complete factorial design with all combinations of spring burn, fall burn, no burn, picloram herbicide, and no herbicide to determine the effects of fire, season of burn, and their interaction with herbicide on the recruitment and population growth of P. recta over a 5-year period. Recruitment of P. recta was higher in burn plots compared with controls the first year after the fire, but this did not lead to significant population growth in subsequent years, possibly due to drier than normal conditions that occurred most years of the study. Effect of season of burn was variable among years but was higher in fall compared with spring burn plots across all years. Herbicide effectively eliminated P. recta from sample plots for 3–5 years. By the end of the study density of P. recta was greater in herbicide plots that were burned than those that were not. Results suggest that prescribed fire will enhance germination of P. recta, but this will not always lead to increased population growth. Prescribed fire may reduce the long-term efficacy of herbicide applied to control P. recta and will be most beneficial at Dancing Prairie when conducted in the spring rather than the fall. Results of prescribed fire on exotic plant invasions in semiarid environments will be difficult to predict because they are strongly dependent on stochastic climatic events.
Late successional, dense Artemisia tridentata (big sagebrush) stands restrict associated plant species production, resulting in a monotypic, shrub-dominated community that threatens biodiversity preservation and ecosystem function. Traditional practices to control A. tridentata can severely reduce or temporarily eliminate A. tridentata and other plant species. Thinning A. tridentata with low rates of the herbicide tebuthiuron enhances herbaceous plant production, community structure, ecosystem functioning, and biodiversity. Tebuthiuron was applied at rates of 0.11–1.0 kg ai/ha to A. tridentata-dominated plots at Ten Sleep (1979), Lander (1993), and Waltman (1993), Wyoming. Changes in A. tridentata canopy cover, associated plant species biomass, and community composition were evaluated 13 and 14 years post-treatment at Ten Sleep, and 2 and 4 years post-treatment at Lander and Waltman. At all sites A. tridentata canopy cover decreased proportionally with increased tebuthiuron rate. Biomass of grasses increased as shrub biomass and cover decreased with increasing tebuthiuron rate. Forb biomass varied between treatments across sample year and site. Shifts from shrub-dominated control to grass-dominated treatment plots were attributable to biomass differences of A. tridentata and 2–3 grass species among treatments. The number of plant species was not significantly different between treatments at any site. Similarity indexes revealed progressively greater dissimilar plant composition between the control and sequential treatment plots of increased tebuthiuron rate. Incremental rates of tebuthiuron produce gradual changes in plant species composition without reducing species richness, which may have utility in certain restoration projects.
Disturbance, diversity, and species interactions in tallgrass prairie Pp 140-156
- S L Collins
- E M Steinauer
Collins, S. L. and E. M. Steinauer. 1998. Disturbance, diversity, and species interactions in tallgrass prairie. Pp 140-156. in Knapp, A. K., J. M. Briggs, D. C. Hartnett, and S. L. Collins, editors. eds. Grassland Dynamics: Long-term Ecological Research in Tallgrass Prairie. Oxford Press. New York.
Mechanisms of colonization and species persistence in plant communities Pp 173-188 Restoration Ecology: a Synthetic Approach to Ecological Research
- K L Gross
Gross, K. L. 1987. Mechanisms of colonization and species persistence in plant communities. Pp 173-188. in Jordan III, W. R., M. E. Gilpin, and J. D. Aber, editors. eds. Restoration Ecology: a Synthetic Approach to Ecological Research. Cambridge University Press. Cambridge, U.K.
Floristic composition and characterization of Spring Creek Prairie, Nebraska. M.S. thesis
- K L Kottas
Kottas, K. L. 2002. Floristic composition and characterization of Spring Creek Prairie, Nebraska. M.S. thesis. University of Nebraska-Lincoln.
National Oceanic and Atmospheric Administration 2003 Climatological data annual summary. National Oceanic and Atmospheric Administration, National Climatic Center
- [ Noaa
[NOAA] National Oceanic and Atmospheric Administration 2003. Climatological data annual summary. National Oceanic and Atmospheric Administration, National Climatic Center. Asheville, N.C.
SAS/STAT User's guide. Version 8. SAS Institute
- Sas Institute
SAS Institute Inc 1999. SAS/STAT User's guide. Version 8. SAS Institute. Cary, N.C.