Ecologically Based Integrated Weed Management to Restore Plant Diversity
Investigations into the use of ecological theory and the principals of succession in combination with on ranch resources to restore native diversity to spotted knapweed infested rangeland continued. Invasive species management treatments were applied and ecosystem assessments were collected on two ranches in western Montana. Seventeen workshops and two field tours addressing ecologically based invasive species management were conducted in 2005 to a total audience of about 650 landowners and managers. Research results were presented at three national and international professional conferences and published in the popular press, proceedings, and scientific journals. Research and educational programs will continue in 2006.
Objective 1) Integrate weed management strategies on spotted knapweed infested rangeland to address the three causes of succession based on site conditions, whole-ranch management objectives, and available ranch resources.
Objective 2) Conduct rangeland ecoassessments to determine the effects of ecologically based management on controlling spotted knapweed and restoring native plant communities.
Objective 3) Determine the economic implications of incorporating ecologically based weed management into ranching systems.
Objective 4) Conduct educational programs for ranchers and agency personnel on ecologically based whole-ranch management and disseminate the results through field tours, the popular press, and the scientific literature.
Two sites in the Bitterroot Valley were established in June and July 2003 to study integration of sheep grazing and biological control insects to reduce the performance of spotted knapweed and provide a disturbance to open safe sites, and seeding with desirable species to increase their availability and occupy safe sites. Each site was divided into two whole plots for the biological control treatment. Three 4.5 by 4.5 meter grazing exclosures were constructed at random within each of the whole plots and used as a control to test the sheep grazing effect on plant community characteristics. Approximately 300 ewes with lambs grazed both sites in July. Three hundred adult Cyphocleonus achates, a biological control root feeding weevil for spotted knapweed, were released onto each site in late July. Native hay was cut in July, and seeds from native forb species were collected throughout the summer and fall. A native seed mix of grasses and forbs was purchased. Baseline data were collected at the time the exclosures were built, before treatments were applied. Density and cover by species were sampled from four randomly placed 0.2 by 0.5 meter frames inside and outside each exclosure. Sheep utilization of spotted knapweed was sampled by clipping the all plants within one 0.2 by 0.5 frame placed inside and outside each exclosure after the grazing treatment was applied. The hay and seeds were applied as five seeding treatments (a no seeding control, perennial native grass species, native forb species, native grass and forb species mixed, and hay) inside and outside the grazing exclosures on 1 by 5 meter plots in the second week of November.
On the Ranch in the Yellowstone Valley, an 80-acre pasture infested with spotted knapweed was sprayed in 1999 with 2,4-D to reduce spotted knapweed. Six 2 m2 exclosures were constructed to measure the effects of grazing on the plant community. Cattle grazing was deferred for two years after the herbicide application to allow grass recovery. The pasture was grazed by 100 ewes with lambs to reduce reestablishment of spotted knapweed. In 2003, the pasture was first grazed be 150 cow-calf pairs in May until approximately 60% of the grass was utilized. This was followed by grazing by 50 ewes and their lambs. Predators were a problem and it was difficult to contain the sheep on the pasture. Six hundred Cyphocleonus achates weevils were released on the pasture in July. In addition, approximately 2,000 weevils were released on another spotted knapweed dominated pasture on the ranch. This pasture was named “the insectary.”
In 2004, the grazing treatments on the two sites in the Bitterroot Valley were modified. Site 1 could not be grazed because the cooperator was denied access to water. Site 2 was grazed by 12 rams from July through October. Density and cover by species were sampled from one randomly placed 0.2 by 0.5 meter frame from each of the five seeding treatments inside and outside each exclosure at both sites. Sweep net sampling was used inside and outside each exclosure to estimate weevil establishment. Spotted knapweed plants were uprooted and the roots were searched for weevil larvae. At Site 2, sheep utilization of spotted knapweed and grass was sampled by clipping the all plants within one 0.2 by 0.5 frame placed inside and outside each exclosure. The number of spotted knapweed flower heads in each of the sample frames was also counted. Five soil samples were collected and pooled from inside and outside each of the exclosures, which will be used to measure nitrogen content, nitrogen mineralization, and the seed bank. Three hundred Cyphocleonus achates weevils were released on each site in early August. In November, three seeding treatments were established at both sites. They were 1) no seeding, 2) broadcasting bluebunch wheatgrass, annual sunflower, and blue flax at a rate of 30, 10 and 10 lbs/acre, respectively, 3) disking the soil to a depth of 5 cm and broadcasting bluebunch wheatgrass, annual sunflower, and blue flax at a rate of 30, 10 and 10 lbs/acre, respectively. The treatments were replicated three times in each of the biological control treatments at each site. Plot sizes are ½ acre.
The grazing treatments were continued on the Yellowstone River Valley ranch project. An electric net fence was used to contain the sheep in the areas of the heaviest spotted knapweed infestation and to prevent predation of the sheep by foxes, coyotes, and wolves. Contained sheep grazing was also used on another pasture targeted for restoration. Utilization was sampled from 1-m2 frames. The electric fence was effective in containing the sheep and excluding all predators with the exception of one grizzly bear.
In 2005, the 2004 management treatments were continued in the Bitterroot Valley project. As in 2004, Site 1 (Lando) could not be grazed because the cooperator was again denied access to water. Alternative arrangements for sheep grazing are being arranged. Site 2 (Danny) was grazed by 12 rams from July through October. Sweep net sampling was used inside and outside each exclosure to estimate weevil establishment. Spotted knapweed plants were uprooted and the roots were searched for weevil larvae. Seeding treatments applied in 2004 were sampled. The cover and density of all species, and the cover of bare ground and litter were measured in 15 randomly placed 0.2 by 0.5 meter frames within each treatment plot. An additional 300 (100/plot) Cyphocleonus achates weevils were released at each site.
The Melin family continues to make progress toward control of their noxious weed problem. They have developed solutions to the predator problems they were having with their sheep flock. The construction of a bear, lion, and wolf proof pen has provided a safe over-night location for the flock. Use of the net electric fence has allowed them to contain the flock on grazing sites targeted for weed management during the day. Grazing management on the 80-acre pasture continued and exclosures were sampled again in 2005. Six grazing exclosures were constructed on a pasture under irrigation. Cattle grazed the pasture in the spring and periodically during the summer. The electric sheep pen was placed around each exclosure and sheep grazed the plots in July. Density, and biomass by species were sampled in August within the exclosures where there was no grazing and outside the exclosures that were grazed by cattle and sheep. I expect the results from this project will show how combining cattle and sheep grazing affects succession on a pasture under irrigation management. My hypothesis is that weeds will increase inside the exclosures compared to outside the exclosures. The Melins had planned to seed another 40-acre pasture they call the airstrip to Russian wildrye with the objective of increasing spring forage production. Pre-seeding sampling was conducted to obtain baseline plant community composition. Density and cover by species, and cover of bare ground and litter were sampled from 40 randomly located 0.2 by 0.5 meter frames. Eight transects were established at random in the insectary where Cyphocleonus achates were released in 2003 and 2004. Density and biomass by species were sampled from 60 0.2 by 0.5 sample frames placed at 10 m intervals along the transects. Insect establishment was confirmed by sweep net sampling and by root dissection.
Impacts and Contributions/Outcomes
Results from this research and demonstration show how management actions affect disturbance, species availability, and species performance to change a plant community from being dominated by an invasive species to being dominated by desirable species. Understanding disturbance, availability, and performance helps landowners and managers design and predict the outcome in integrated weed management. In addition, this project shows how resources available on ranches can be used following ecological principals to manage invasive species and improve productivity. Examples of treatment effects are shown in Tables 11 and 12 and Figures 3 and 4 below from data collected or published during this project.
Results from the Bitterroot Valley project have important implications to management of spotted knapweed. Establishment of seeded species in all grazing and seeding treatments was poor. This suggests that the disturbance by sheep grazing was not great enough to increase site availability for establishment. Litter and bare ground data support the low disturbance associated with sheep grazing. There were no differences in litter or bare ground between grazed and non-grazed treatment plots (Table 1). This was true regardless of the seeding treatment. However, there were differences in litter and bare ground among seeding treatments seed. Litter was greater, and bare ground was less where hay was used as a seeding treatment compared to all other seeding treatments (Table 1). This was true regardless of the grazing treatment. This suggests a reduction of safe sites for species establishment in this treatment. Sheep grazing and hay mulch reduced spotted knapweed flowering plant density (Table 1). Density was lowest where there was no sheep grazing except where the hay seeding treatment was applied. Density was lower where there was sheep grazing compared to no grazing, and it was lowest where hay was applied regardless of the grazing treatment (Table 1). These results suggest that sheep grazing can be used to reduce spotted knapweed availability but that it does not result in disturbance that improves establishment of seeded native grass and forb species. Hay mulch also reduces the availability of spotted knapweed but does not result in an increase in native plants either because the plant propagules or safe sites were not available for their establishment.
The availability of spotted knapweed as measured by the number of flowering plants depended on site, year, grazing treatment, and biological control treatment. At the Lando site that had only one year of grazing, density increased from 2003 to 2004 regardless of the grazing treatment where no biological control weevils were released (Table 2). Where the insects were released, density increased from 2003 to 2004 only where sheep grazed (Table 2). These results suggest an environmental influences such as increased precipitation in 2004 affected density where no insects were released. Where insects were released, the results suggest an interaction between above and below ground herbivory on spotted knapweed density. The weevil attack rate at the Lando site where weevils were released was approximately 10%. No weevils were found on the non-biological control site. At the Danny site, density was no different from 2003 to 2004 where no weevils were released and there was no grazing (Table 3). Grazing decreased density from 2003 to 2004 where no weevils were released. Where weevils were released, density increased where grazing was excluded and decreased where sheep grazed in 2003 and 2004. The weevil attack rate at the Danny site was about 1% where biological controls were released. The predominant grass species at the Danny site were non-native pasture grasses whereas the predominant grasses at the Lando site were annual non-native grasses. Plant community composition will play a large role in succession of spotted knapweed infested communities under grazing, biological control insect, and revegetation management.
Seeding treatment affected the density of spotted knapweed rosettes at the Bitterroot Valley sites. The rosette demographic provides an indication of the future population of the weed. Spotted knapweed rosettes were more numerous where the combination of grasses and forbs were seeded or where hay was applied compared to where only forbs were seeded (Table 4). Where hay was applied the decrease in flowering knapweed and increase in rosette knapweed indicates a change in conditions that favor the younger demographic. A possible explanation is that the increased shading and resulting reduction in photosynthetic carbohydrate production prevented development of flowering plants from rosettes. In addition, the possible increase in soil moisture due to reduced soil temperatures may have favored the survival of rosettes that may be more susceptible to desiccation than mature flowering plants. The affect of grass plus forb seeding is more difficult to explain considering there were no differences in seeded species establishment among seeding treatments.
There was no significant effect of grazing on soil nitrogen dynamics, however, the trends are interesting and justify further exploration. Total available nitrogen (NO3 + NH4) tended to be lower, and potentially mineralizable nitrogen (PMN) tended to be higher, in the grazed plots compared to the plots excluded from grazing at the Danny site after 2 seasons of grazing (Table 5). These trends suggest that available nitrogen is being used more efficiently and that microbial production of available nitrogen is greater where there is grazing compared to where grazing is excluded. This indicates a more active nitrogen cycle where sheep graze compared to where there is no grazing. The nitrogen cycle is a critical ecosystem function that affects productivity. There are many unanswered questions concerning invasive species, management, and the nitrogen cycle that may provide insight into invasions and their management.
A disturbance and seeding study was initiated in 2004 because the disturbance of sheep grazing did not effect establishment of native seeded species. Three seeding treatments were applied to the grazed pastures at the Lando and Danny sites. The treatments were none, seeding, and tilling plus seeding. The species in the seeding mixture were bluebunch wheatgrass at 30 lbs per acre, annual sunflower at 10 lbs per acre, and blue flax at 10 lbs per acre. The effect of the treatments differed between the two sites (Table 6). Densities of flowering knapweed plants and bluebunch wheatgrass tillers were greater at the Lando site than the Danny site (Table 6). Cover of knapweed was greater and cover of cheatgrass was less at the Lando site than the Danny site. I speculate that the differences are due to the greater number of non-native perennial pasture grasses at the Danny site than the Lando site.
The density and cover of spotted knapweed flowering plants and cheatgrass was greater where biological control weevils were released compared to where they were not released when analyzed across both sites (Table 7). Bluebunch wheatgrass density was not different. This suggests that in the short term, the disturbance associated with biological control, in this case disturbance specific to knapweed flowering plants, increased the non-native species. This is not an unusual result. Spurge and knapweed densities have increased in the first year after sheep grazing and decreased in following years. In addition, the non-native species may be able to respond faster than the perennial bunchgrass after a disturbance. I expect bluebunch wheatgrass to increase in the long-term under this type of disturbance.
Seeding treatment affected spotted knapweed flowering plant, rosette, and bluebunch wheatgrass densities. There were no density differences between the no seeding treatment and seeding without tilling treatment (Table 8). Combining tilling and seeding reduced flowering and rosette knapweed densities and increased bluebunch wheatgrass density (Table 8). This result indicates that high seeding rates alone will not improve establishment of desired native species, and a pretty heavy disturbance such as shallow tilling is needed to create safe sites for establishment. This treatment addressed site availability and species availability. It is anticipated that in the long-term, the establishment of a long-lived perennial bunchgrass combined with the reduction in performance of spotted knapweed by sheep grazing and the biocontrol weevil will change the plant community to a native bunch grass community.
The effect of biological control on spotted knapweed rosette density and the density and cover of flax depended on site. Knapweed rosette density and the cover and density of flax were greater on the Lando site than the Danny site (Table 9). I believe this difference is predominantly due to competition by non-native perennial grasses preventing the establishment and survival of rosette knapweed and flax at the Danny site. Knapweed rosette density was greater, and flax density was lower in the biological control treatment than the no biological control treatment at the Danny site. This suggests that establishing flax plants are not competitive with knapweed rosettes on this site.
The affect of the 2004 disturbance and seeding treatments on knapweed rosette density, bluebunch wheatgrass cover and density, and flax cover and density depended on whether they were applied at the Lando or Danny site. At the Lando site, seeding alone decreased knapweed rosette density, had no effect on bluebunch wheatgrass density, and increased flax density compared to the control (Table 10). The small seed size of flax relative to knapweed and bluebunch wheatgrass may explain the increased establishment of flax where it was seeded without disturbance. This result argues for including small seeded species in a restoration seed mix. Tilling plus seeding further decreased knapweed rosette density, greatly increased bluebunch wheatgrass density and cover, and increased flax density and cover compared to the other treatments at the Lando site. The disturbance of shallow tilling was necessary for the high seeding rate to be effective for establishment of the native species. At the Danny site, only tilling and seeding improved the establishment of bluebunch wheatgrass and flax (Table 10). The difference between the two sites is most likely due to the high occurrence of perennial non-native grasses at the Danny site.
Regression analysis predicted sheep management applied for consecutive years woould decrease spotted knapweed flowering plant density (Figure 1). At the Lando site, sheep grazing was only applied in 2003 and knapweed flowering plant density increased in 2004 and decreased in 2005. The regression model predicted an increase in knapweed flowering plant density under this management. At the Danny site where sheep grazed for 3 consecutive years, knapweed flowering plant density decreased each year. The linear model predicted a decrease in knapweed flowering plant density under this management.
Regression analysis shows that native plant species richness, measured as the number of plant species that occurred within a 0.2 by 0.5 meter sample plot, increased exponentially where sheep grazed at the Lando and Danny sites in the Bitterroot Valley (Figure 2). The data used were averaged across all seeding treatments. These models predict that native plant richness will increase where sheep grazing is applied to manage spotted knapweed.
In 2005, 17 workshops and 2 field tours addressing ecologically based invasive species management were conducted to a total audience of about 650 landowners and managers. Results of research associated with this project and ecologically based invasive species management were presented at the Society for Range Management annual meeting in Fort Worth, Texas.
Seventeen workshops and field tours addressing ecologically based invasive species management were conducted in 2004 to a total audience of about 350 landowners and managers. Results of research associated with this project and ecologically based invasive species management were presented at the Society for Range Management annual meeting in Salt Lake City, UT, the Ecological Society of America annual meeting in Portland OR, and the International Society for Ecological Restoration annual meeting in Victoria, B.C., Canada.
A number of educational programs and presentations were conducted in 2003. The establishment of the first study site in the Bitterroot Valley was coordinated with the annual sheep rendezvous of the Montana Wool Growers Association. A field tour was conducted to about 10 ranchers with an impact on about 100,000 acres that support about 20 thousand sheep and goats. The tour described the objectives and methodology of the study. Two programs were presented, one to about 75 people in Missoula County, and one to about 50 people in Ravalli County, as part of a pesticide re-certification program that had an impact on several large ranching operations, many small landowners, and a number of commercial weed management companies (commercial applicators). The results of the sheep grazing study in the Yellowstone Valley were presented at the annual meeting of the Society for Ecological Restoration in Austin, Texas, in November.
Charts and Tables
Table 1. The interaction effect (p<0.05) determined by ANOVA of sheep grazing and seeding treatment on litter cover, bare ground cover and spotted knapweed flowering plant density of two sites combined in Stevensville, Montana, in 2004. Letters following means (N=12) indicate differences among means within columns determined by t-test (α=0.05). The native hay seeding treatment increased litter cover and decreased bare ground cover on both the grazed and non-grazed treatments. Spotted knapweed flowering plant density was lowest in the hay treatment regardless of the grazing treatment. Grazing reduced flowering plant density relative to non-grazing in all other seeding treatments.
Graze treatment Seed treatment Litter (%) Bare ground (%) Density/m2
None None 39 b 17 a 57 a
None Grass 44 b 16 a 77 a
None Forbs 40 b 16 a 81 a
None Grass+Forbs 48 b 13 ab 64 a
None Hay 94 a 0 c 27 c
Grazed None 53 b 16 a 48 b
Grazed Grass 52 b 17 a 41 b
Grazed Forbs 46 b 21 a 45 b
Grazed Grass+Forbs 50 b 19 a 42 b
Grazed Hay 82 a 4 bc 33 c
Table 2. The interaction effect determined by ANOVA of year, biological control, and sheep grazing at the Lando site in Stevensville, Montana, on spotted knapweed flowering plant density (per m2). Letters following means (N=3) indicate differences among means in both columns determined by t-test (α=0.05). Grazing was only applied in 2003. Flowering plant density was greater in 2004 than 2003 in all treatments except no grazing with biocontrol.
Year Graze No bio Bio
03 None 36 b 37 b
03 Graze 37 b 32 b
04 None 71 a 49 ab
04 Graze 55 a 63 a
Table 3. The interaction effect determined by ANOVA of year, biological control, and sheep grazing at the Danny site in Stevensville, Montana, on spotted knapweed flowering plant density (per m2). Letters following means (N=3) indicate differences among means in both columns determined by t-test (α=0.05). Grazing was applied in 2003 and 2004. Flowering plant density was greatest in 2004 where there was no grazing and and where biological control weevils were released, followed by the biological control release site in 2003 regardless of grazing. The next lowest density of flowering plants were measured in 2003 where no biological controls were released in both grazing treatments, and in 2004 where biological controls were combined with sheep grazing. Spotted knapweed density was lowest in 2004 where sheep grazed where no biological controls were released.
Year Graze No bio Bio
03 None 36 c 55 b
03 Graze 35 c 67 b
04 None 42 c 82 a
04 Graze 16 d 33 c
Table 4. The main effect (p<0.05) determined by ANOVA of seeding treatment on spotted knapweed rosette density (per m2) of two sites combined in Stevensville, Montana, in 2004. Means (N=12) were compared using the least significant difference test (LSD, α=0.05). Seeding with grasses combined with forbs and the application of hay had greater rosette density than seeding with forbs only.
Seeding treatment Density/m2
Table 5. The effect of grazing determined by ANOVA on ammonium (NH4), nitrate (NO3) total nitrogen (TN) and partially mineralizable nitrogen (PMN) on the Danny site in 2004. Means (N=6) are followed by standard errors in parentheses. Ammonium and nitrate estimate the available nitrogen at the time of sampling (September) and PMN estimates the microbial activity that drives the nitrogen cycle. Differences between grazed and non-grazed treatments were not significant (p<0.1) indicating that grazing does not affect plant or microbial use of nitrogen. The higher PMN measure in the grazed treatment suggests a trend toward increased nitrogen cycling that warrants further research.
Grazing treatment NH4 NO3 TN PMN
None 1.7 (0.98) 3.7 (2.0) 5.4 (1.9) 70 (15)
Grazed 2.0 (1.10) 3.0 (1.4) 4.7 (2.3) 82 (22)
Table 6. The difference determined by ANOVA between the Lando and Danny sites in spotted knapweed flowering plant density (SKFD) and cover (SKC), bluebunch wheatgrass tiller density (BBD), cheatgrass density (CGD, and cheatgrass cover (CGC). Means (N=18) were compared using the least significant difference test (LSD, α=0.05). The density of spotted knapweed flowering plants and their cover, and the density bluebunch wheatgrass were greater at the Lando site than the Danny site, and cheatgrass cover was greater at the Danny site than the Lando site. There were no significant treatments effects (NS) on cheatgrass density.
Site SKFD SKC BBD CGD CGC
Lando 39 22 18 NS 5
Danny 24 11 6 NS 9
LSD 7 0.8 6 0.8
Table 7. The difference determined by ANOVA between the areas where biological control were release and not released on the Lando and Danny sites in spotted knapweed flowering plant density (SKFD) and cover (SKC), bluebunch wheatgrass tiller density (BBD) cheatgrass density (CGD), and cheatgrass cover (CGC). Means (N=6) were compared using the least significant difference test (LSD, α=0.05). The density and cover of spotted knapweed flowering plants and cheatgrass were greater where biological controls were released than where none were released. There was no difference in bluebunch wheatgrass density between the biological control treatments. These results indicate that the disturbance associated with the release of biological control weevils may favor spotted knapweed and cheatgrass but not bluebunch wheatgrass, at least in the short term (one year after seeding wheatgrass).
Site SKFD SKC BBD CGD CGC
No bio 26 18 11 11.1 5
Bio 37 20 13 17.7 9
LSD 7 0.8 6 4 0.8
Table 8. The effect determined by ANOVA of seeding treatment applied in 2004 and sampled in 2005 on spotted knapweed flowering plant density (SKFD) and cover (SKC), and bluebunch wheatgrass tiller density (BBD) measured in 2005 at the Lando and Danny sites in Stevensville, Montana. Means (N=12) were compared using the least significant difference test (LSD, α=0.05). Tilling combined with seeding, but not seeding alone, decreased spotted knapweed density and cover and increased bluebunch wheatgrass density one year after treatment.
Seeding treatment SKFD SKC BBD
No seeding 34 22 0
Seeding 37 22 1
Till&seeding 23 16 54
Lsd 8 1.0 7
Table 9. The effect determined by ANOVA of biological control on spotted knapweed rosette density (SKJD) and the density and cover of flax at the Lando and Danny sites in the Bitterroot Valley in southwestern Montana. Letters after means (N=6) indicate differences among means within the columns determined by t-test. Knapweed rosette density and flax density and cover were greater at the Lando site than the Danny site. Knapweed rosette density was greater and flax density was lower where biological control weevils were released than not released at the Danny site.
Site Bio SKJD flaxd Flaxc
Lando No 63 a 13 a 2 a
Lando Yes 56 a 13 a 2 a
Danny No 16 c 5 b 1 b
Danny Yes 37 b 3 c 1 b
Table 10. The effect determined by ANOVA of seeding treatments at the Lando and Danny sites on spotted knapweed rosette density (SKJD), bluebunch wheatgrass density (BBD) and cover (BBC), and flax density and cover. Letters after means (N=6) indicate differences among means within the columns determined by t-test. Knapweed rosette density was greater at the Lando site than the Danny site, and cover and density of the seeded bluebunch wheatgrass and flax increased more at the Lando site than the Danny site.
Site Seeding SKJD BBD BBC Flaxd Flaxc
Lando None 80 a 0 c 0 c 0.1 d 0.5 d
Lando Seeding 63 b 1 c 0.4 c 4 c 1.1 c
Lando Till&seeding 35 c 51 a 4 a 35 a 3.9 a
Danny None 29 cd 0 c 0 c 0.3 d 0.5 d
Danny Seeding 31 cd 11 c 0.2 c 2 cd 0.4 d
Danny Till&seeding 20 d 17 c 1.4 b 10 b 2.2 b
Table 11. The effect of 2,4-D and sheep grazing treatments spotted knapweed rosette density, spotted knapweed cover, grass cover and grass biomass at Missoula, Montana, and spotted knapweed and grass biomass and Drummond, Montana. Means are for non-transformed data and are combined over the four years of sampling. Letters following means indicate significant differences between means determined by LSD (“=0.05) calculated from transformed data. The 2,4-D treatment addresses disturbance and species availability and the sheep grazing treatment addresses species performance and species availability. This table was published in the Journal of Range Management 51:371-375.
Spotted Knapweed Grass Spotted knapweed Grass
Treatment Rosettes Cover Cover Biomass Biomass Biomass
—m-2— —%— —%— —g m-2— —————–g m-2—————-
None 14.1 a 39 a 7 b 6.6 b 62.7 a 7.2 b
Sheep 19.1 a 11 b 11 b 6.1 b 32.3 a 10.6 b
2,4-D 2.6 b 10 b 25 a 24.3 a 59.2 a 27.1 a
Sheep+2,4-D 2.6 b 5 c 27 a 17.7 a 27.1 b 21.6 a
Table 12. Utilization by sheep of spotted knapweed biomass in 2003 and 2004 and spotted knapweed flowers and grass biomass in 2004 in the Bitterroot Valley in southwestern Montana.
Grazing treatment knapweed biomass/m2 knapweed flowers/m2 grass biomass
grazing 52 20 12
no grazing 250 998 61
no grazing 351
Figure 1. The change over time determined by regression analysis in spotted knapweed flowering density from 2003 to 2005 under management using sheep grazing at the Lando and Danny sites in the Bitterroot Valley. At the Lando site where sheep grazed only in 2003, spotted knapweed density initially increased and then decreased. The linear model shows an increase over time in knapweed flowering plant density but the model has a poor fit (R2=0.158). At the Danny site where sheep grazed for three years the linear model shows a decrease over time in flowering plant density (R2=0.7212).
Figure 2. The change in native plant species richness over time determined by non-linear regression at the Lando and Danny sites grazed by sheep in the Bitterroot Valley, Montana. The number of native plant species found within a 0.2 by 0.5 meter plot was the measure used for richness.
Figure 2. The change in bluebunch wheatgrass and intermediate wheatgrass density over time where grasses were seeded in combination with the release of the biological control agent Cyphocleonus achates in a spotted knapweed infested grassland community. Error bars indicate one standard error. The grass seeding treatment addresses species availability and the biocontrol treatment addresses disturbance and species performance. Seeding bluebunch wheatgrass, a keystone native grass species, combined with Cyphocleonus achates and sheep grazing are treatments being used in this project to restore native diversity to spotted knapweed infested pastures.
Figure 3. The change in spotted knapweed adult (flowering plant) density from 1999 through 2004 on a site in western Montana where Cyphocleonus achates weevils were released in 1994. Error bars indicate one standard error. Cyphocleonus achates is a biological control insect on spotted knapweed that was applied to research sites in this project as a treatment to reduce the performance of spotted knapweed. It is being used in combination with sheep grazing and seeding desirable species to change the plant community from spotted knapweed dominated to dominated by desirable species based on the principals of succession theory.
Sheley, R.L., J.S. Jacobs, and T.J. Svejcar. 2005. Integrating disturbance and colonization during revegetation of invasive weed-dominated grasslands. Weed Science. 53:307-314.
Jacobs, J.S. and R.L. Sheley. In revision. Integrated management of leafy spurge. J. Range Manage. 8 March 2004.
Sheley, R.L., J.S. Jacobs, and M.F. Carpinelli. Submitted. Rehabilitating weed resistant plant communities using niche-differentiated non-native species. J. Range Manage. 16 Dec. 2003.
Jacobs, J.S., S.R. Windslow, and M.L. Pokorny. Submitted. The Effect of Five Pre-emergent Herbicides on the Emergence and Establishment of Seven Native Wildflowers. Native Plants Journal. 1 December 2005.
Jacobs, J.S. S. E. Sing, and J. M. Martin. Submitted. Interactions of herbivory and competition on invasive weed performance: effects of Cyphocleonus achates and grass-seeding treatments on Centaurea maculosa. Environmental Entomology. 23 December 2005.
Windslow, S.R. and J.S. Jacobs. The effect of five pre-emergent herbicides on wildflowers. Plant Material Center Today. Technical Report. April 2005.
Jacobs, J.S. and A. Knudsen. 2005. Restoring perennial grasses on a leafy spurge infested pasture. Society for Range Management 58th Annual Meeting. Fort Worth, TX.
Pokorny, M.L., J.S. Jacobs, P. Tryon, G. Bennett, and A. Soukkala. 2005. Using an ecological framework to manage invasive species. Society for Range Management 58th Annual Meeting. Fort Worth, TX.
Goodwin, K and J. Jacobs. 2005. Montana Weed Prevention Areas: Partnerships for Range Protection. Cal-IPC Symposium Proceedings.
Jacobs, J.S. and R.L. Sheley. 2003. Integrating 2,4-D and sheep grazing to restore native plants to spotted knapweed-infested rangeland. In Assembling the pieces; restoration, design and landscape ecology. The Society for Ecological Restoration International. Austin, Texas. p. 30.
Jacobs, J.S. Cheatgrass Management, an ecological perspective. In: Proceedings Pest Management Training, October 2003 MSU Extension Service.
Sheley, R.L., J.S. Jacobs, and J.M. Martin. 2004. Integrating 2,4-D and sheep grazing to rehabilitate spotted knapweed infested rangeland. J. Range Manage. 51:371-375.
Jacobs, J.S. and M.L. Pokorny. 2004. Restoring perennial grasses in a spotted knapweed infested rangeland: and eight-year look. Proceedings of the 16th International Conference, Society for Ecological Restoration, August 24-26, 2004, Victoria, Canada. 4 p.
Pokorny, M.L. and J.S. Jacobs. 2004. Going over the edge: Case studies using ecology to restore invaded lands. Proceedings of the 16th International Conference, Society for Ecological Restoration, August 24-26, 2004, Victoria, Canada.
Jacobs, J.S. 2004. Combining a parasite and a competitor to reduce Centaurea maculosa population density. In: Lessons of Lewis and Clark: Ecological Exploration of Inhabited Landscapes. The Ecological Society of America. Portland OR. p. 243-244.
Jacobs, J.S. and M Pokorny. A burning reality; can Linaria dalmatica be controlled after wildfire. Federal Fire Rehabilitation Symposium. Society for Range Management Annual Meeting. Salt Lake City. 29 January 2004.
Jacobs, J.S. and R.L. Sheley. Integrated Management of leafy spurge. TEAM Leafy Spurge Symposium. Society for Range Management Annual Meeting. Salt Lake City. 27 January 2004. Invited.
Jacobs, J.S., 2004 Weevils and wheatgrass winning the war with knapweed. Montana Weed Times. October.
Presentations and Workshops and Instructional Activities
Jacobs, J.S. Ecologically based noxious weed management. Montana State Fish Wildlife and Parks Annual Meeting, Chico, MT. 25 attended.
Jacobs, J.S. Economic and ecological impacts of noxious weeds. Realtor Training, Sheridan MT, 18 November 2005. 15 Attended.
Jacobs, J.S. Integrated weed management in Montana, and how weed management areas work. A meeting to develop cooperative weed management in Saskatchewan. Mankota SK. 19 October 2005. 15 attended.
Jacobs, J.S. and Alan Knudsen. Ecologically based integrated management of leafy spurge. Wyoming managers field tour. 13 September 2005. 14 attended. Jacobs, J.S. Weevils and Wheatgrass: Jacobs, J.S. and A. Knudsen, Ecologically based weed management. Western Montana Weed Tour. 21 July 2005. 50 Attended.
Jacobs, J.S. 2005. Natural Resources and Conservation Service Noxious Weed Management Training. St Mary, Great Falls, Glasgow, Bozeman, Miles City. May, June, July. 40 attended each, invited.
Jacobs, J.S. 2005. Restoration of Weed Infested Sites and Annual Grass Management. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 28 April. 41 attended. invited
Jacobs, J.S. 2005. Ecology and Management of Dalmatian and Yellow Toadflax. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 27 April. 41. invited.
Jacobs, J.S. 2005. Noxious Weed Identification. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 26 April. 41 attended
Jacobs J.S. 2005. Managing Noxious Weeds on Pastures. Pasture Management Workshop. DNRC, Bozeman. 13 April. 20 attended. Invited
Jacobs, J.S. 2005. Integrated Weed Management Strategies: How Does Grazing Fit In? Sheep, Goats, Weeds, and Wildlife Workshop. Missoula, MT. 29 March. 100 Attended.
Jacobs, J.S. 2005. Drought, Heat, and herbicide Management of Noxious Weeds. Montana Weed Coordinators Training. Dillon, MT. 10 March. invited. 50 Attended.
Jacobs, J.S. 2005. Noxious weed management on small acreage. 19 February. Wild West Winter Fest. Bozeman, MT. 10 attended
Integrated Management of Large Populations of Spotted Knapweed. Montana Weed Control Association Annual Conference. Helena, MT. 26 January 2005. 50 attended. invited.
Jacobs, J.S. 2005. Planning Noxious Weed Management. Crop Pest Management. 6 January, 0.5 hr. Bozeman, MT. 35 attended.
Jacobs, J.S. and M.L. Pokorny. Applying ecological concepts and technology developed through research to wildland management and commercial restoration. Bitterroot Restoration Incorporated and The Teller Wildlife Refuge. 16 August 2004. Corvallis, MT.
Jacobs, J.S. and A. Knudsen. Integrated management of leafy spurge. Missoula County Restoration Demonstration Field Tour. 27 July 2004. Lolo, MT. 20 attended.
Jacobs, J. S. and M. L. Pokorny. Ecologically Based Management of Dalmatian Toadflax. After the Fire; Bucksnort Field Tour. 24 June 2004. East Helena, MT. Invited 50 attended.
Jacobs, J.S. 2004. Managing Noxious Weeds. Montana Outdoor Science School. 12 June 2004. Bozeman, MT. 20 attended. invited
Jacobs. J.S. 2004. Canada thistle control in shelterbelts and rangeland. McCone Conservation District/Plant Materials Center Grass Demonstration Plot Tour. Circle MT. 3 June. Invited. 20 attended. Extension Pesticide Training.
Jacobs, J.S. 2004. Ecologically based noxious weed management. Headwaters RC&D Range Weed Committee Meeting. Butte MT. 20 May. Invited. 15 Attended.
Jacobs, J.S. 2004. Integrated Weed Management. FY 2004 NRM EPMT Training. Mammoth, WY. 11 May. 10 Attended. Invited.
Jacobs, J.S. 2004. Effective Weed Management. FY 2004 NRM EPMT Training. Mammoth, WY. 11 May. 10 Attended. Invited.
Jacobs, J.S. 2004. Restoration of Weed Infested Sites. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 28 April. 43 attended
Jacobs, J.S. 2004. Ecology and Management of Dalmatian and Yellow Toadflax. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 28 April. 43 attended
Jacobs, J.S. 2004. Noxious Weed Identification. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 27 April. 43 attended
Jacobs, J.S. 2004. Top Ten Ecological Concepts of Integrated Weed Management. Noxious weed Management Short Course. Western Society of Weed Science. Pray, MT. 27 April. 43 attended
Jacobs, J.S. 2004. Managing Noxious Weeds on Pastures. Pasture Management Workshop. DNRC, Bozeman. 21 April, 19 May, and 6 October. 30, 20, and 24 attended. Invited.
Jacobs, J.S. 2004. Weed Management Plan Evaluation. Master Gardner Weed Management Course. Missoula, MT. 1 May. 35 attended
Jacobs, J.S. 2004. Grazing Management Strategies for Noxious Weeds. Master Gardner Weed Management Course. Missoula, MT. 25 March. 35 attended.
Jacobs, J.S. 2004. A Burning Reality: Should we control Dalmatian Toadflax After Wildfire. MSU-LRES Weeds Group Lunch Bunch Seminar. 23 March. 20 attended.
Pokorny, M.L. and J.S. Jacobs. 2004. What is Ecologically-based Invasive Species Management? Third Annual Agricultural Conference and Expo. University of Montana-Western. Dillon, MT. 9 January. 25 attended. invited
Jacobs, J.S. Cheatgrass Management; an ecological perspective. Ravalli County pesticide application recertification training. 7 October 2003. 50 attended. invited
Jacobs, J.S. Revegetation Strategies. Ravalli County pesticide application recertification training. 7 October 2003. 50 attended. invited
Jacobs, J. S. Grazing strategies on noxious weeds. Missoula County pesticide applicator recertification training. 11 September 2003. 50 attended. Invited.
Rangeland Weed Ecologist
67826-A HWY 205
Burns, OR 99720
Office Phone: 5415738938