Progress 07/01/02 to 06/30/08

Outputs
OUTPUTS: The exotic annual cheatgrass dominates a significant portion of western rangelands and results in the loss of perennial species and large, frequent fires. We conducted 3 experiments in 4 western states and integrated activities focused on control of cheatgrass and other weeds and restoration of native species on western rangelands. Experiment 1 tested 25 seed varieties for competitive ability with cheatgrass. Differences occurred among plant accessions, but 4 native plant accessions performed very well. Experiment 2 used 6 native species to examine if different growth forms reduce cheatgrass and if decreased soil N availability decreases cheatgrass. Sucrose application reduced nutrient availability for 1 year following sugar application. Concomitantly, cheatgrass biomass and seed production were reduced. We also found that (1) sagebrush had the biggest reduction on cheatgrass plant size; (2) increasing density of cheatgrass negatively affected perennial establishment; (3) native plants had little effect on establishment of secondary weeds; (4) sugar application decreased establishment of medusahead but not squarrose knapweed. Experiment 3 investigated if prescribed fire and herbicide applied at a larger scale reduces cheatgrass. The herbicide treatment reduced cheatgrass and greater target plant density during the first growing season after seeding. In addition to these formal experiments: (1) An important practical outcome was modifications to the Truax Rough Rider Rangeland drill that improve its effectiveness for row and broadcast seeding. (2) Soil biological communities were patterned by a site's soil pH and surface cover type and were affected by sugar applications. (3) Sagebrush communities had consistently thicker A horizons than annual grass communities and had lower silt and clay contents, but soils of annual grass had higher mineral N. (4) We initiated 3 sophisticated approaches to data analyses to provide additional insight into ecological interactions and to generalize over a broad area. (5) Cheatgrass communities are a less-suitable habitat for granivores, which in turn reduces seed removal. One major focus of our integrated efforts was to assess economic and social impacts of restoration. Economic analyses indicated that restoration strategies negatively impact ranch financials. Social impacts, assessed through surveys, indicated that different groups of stakeholders have different meanings of restoration and different concepts of the key drivers that would enable restoration strategies to be socially acceptable. Our integrated activities also involved outreach education: (1) A unit on weed ecology, management, and research was developed for K-12 teachers. (2) A case study was developed for an undergraduate course. (3) Undergraduate students gained research and education experiences through a competitive mini-grant program. (4) Research findings were communicated in field tours. (5) A traveling exhibit was designed to promote learning for different audiences at middle schools, libraries, museums, nature centers, or town halls. (6) Web pages were constructed in a manner similar to that for the traveling exhibit. PARTICIPANTS: Participants in this project included students, staff, and faculty at 4 universities and staff and scientists at 6 federal agencies. This project supported 1 postdoctoral, 4 Ph. D., and 6 M.S. students; 44% of individuals who participated with the project were female. TARGET AUDIENCES: Targeted audiences include scientists, researchers, and land managers interested in Great Basin rangelands. Our integrated activities involved outreach education to increase student and public awareness of invasive species issues and to develop educational tools that convey solutions to invasive species and native plant restoration problems. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Selected varieties of bluebunch wheatgrass and thickspike wheatgrass are promising plant materials for restoration of cheatgrass-dominated rangelands. Land management strategies that reduce nutrient availability reduce cheatgrass, but unless nutrient sequestration is sustained, cheatgrass quickly recovers. Given adequate environmental conditions and continuous seed availability, many native species established in cheatgrass-dominated areas. Nonetheless, weed control and native plant restoration are constrained by certain site characteristics. A powerful aspect of our project is the distribution of study sites across the Great Basin, but this distribution also brings significant challenges in terms of data synthesis and analysis that we met with advanced statistical techniques. We also found a tradeoff between ecological and economic benefits from restoration: our economic and social studies indicate that it is not economically viable for ranchers to undertake restoration, and cost-share mechanisms or innovative policy tools are needed to ensure that cheatgrass control efforts are ecologically feasible, socially acceptable, and economically equitable.

Publications

• Mazzola MB, Allcock KG, Chambers JC, Blank RR, Nowak RS (2008) Effects of nitrogen availability and cheatgrass competition on the establishment of Vavilov Siberian wheatgrass. Rangeland Ecology & Management 61:475-484.

Progress 01/01/07 to 12/31/07

Outputs
As pinyon-juniper woodlands in the western United States increase in distribution and density, understory growth declines and the occurrence of crown fires increases, leaving mountain sides open to both soil erosion and invasion by exotic species. We examined if the loss in understory cover that occurred with increasing tree cover was reflected in the density and diversity of the seed bank. Multivariate analyses indicated that cover and diversity of standing vegetation changed as tree cover increased. However, the seed bank did not differ in overall seed density or species diversity because seeds of the 13 species that comprised 86% of the seed bank occurred in similar density across the tree-cover groups. Sixty-three percent of the species that were in the seed bank were absent from the vegetation (mostly annual forbs). In addition, 49% of the species that occurred in the standing vegetation were not in the seed bank (mostly perennial forbs and shrubs). Only Artemisia tridentata Nutt., Bromus tectorum L. and Collinsia parviflora Lindl. displayed positive Spearman rank correlations between percent cover in the vegetation and density in the seed bank. Thus, much of the standing vegetation was not represented in the seed bank, and the few species that dominated the seed bank occurred across varying covers of pinyon-juniper. Because prescribed fire is increasingly used as a restoration tool for invaded pinyon-juniper, we examined immediate and longer-term (i.e. two growing seasons) responses of the germinable seed bank to a spring prescribed fire. Prior to the burn, the germinable seed bank under shrubs contained the highest seed density and highest species richness followed by interspace and tree microsites. Shrub litter was consumed by the burn, causing complete loss of the seed bank from that microsite and depleting the A. tridentata seed bank. Interestingly, germinable seed density in soil under P. monophylla trees increased immediately following the burn with 70% of that increase from the annual forb Descurainia pinnata. Two growing seasons following the prescribed burn, no overall differences in germinable seed density between burned and unburned plots occurred, but seed bank species composition differed, with seed banks in the prescribed burn having a greater abundance of Eriogonum elatum, E. microthecum, and Gayophytum diffusum compared to unburned having a greater abundance of A. tridentata, Lappula occidentalis, and Descurainia pinnata. Our results indicate that rapid restoration to pre-fire vegetation cannot rely upon the soil seed bank. For rapid recovery, land managers should select sites for prescribed burns that have fire-tolerant perennial vegetation.

Impacts
Reversing the expansion of pinyon-juniper woodlands and restoring previous vegetation often are desired. To help determine if natural revegetation will occur at different levels of tree dominance, we examined if the loss in understory cover that occurred with increasing tree cover was reflected in the density and diversity of the seed bank. Overall, seed banks did not differ in seed density or species diversity because only a few species, which were mainly annual forbs and a few ubiquitous grasses, made up the bulk of the seed bank, and seed density for these species did not change as tree cover increased. Furthermore, much of the standing vegetation was not represented in the seed bank. Because seed densities for more desirable perennial grasses and shrubs were low at all levels of tree cover, managers cannot rely upon recruitment from the natural seed bank to quickly re-establish desirable species after disturbance.

Publications

• Allen EA, Chambers JC, Nowak RS (2008) Effects of a spring prescribed burn on the soil seed bank in sagebrush steppe exhibiting pinyon-juniper expansion. Western North American Naturalist (accepted).
• Allen EA, Nowak RS. (2008) Effect of pinyon-juniper tree cover on the soil seed bank. Rangeland Ecology & Management (in press).

Progress 01/01/06 to 12/31/06

Outputs
The exotic annual cheatgrass dominates a significant portion of western rangelands and results in the loss of perennial species and large, frequent fires. We conducted 3 experiments in 4 western states and integrated activities focused on control of cheatgrass and other weeds and restoration of native species on western rangelands. Experiment 1 tested 25 seed varieties for competitive ability with cheatgrass. Differences occurred among plant accessions, but 4 native plant accessions performed very well. Experiment 2 used 6 native species to examine if different growth forms reduce cheatgrass and if decreased soil N availability decreases cheatgrass. Sucrose application reduced nutrient availability for 1 year following sugar application. Concomitantly, cheatgrass biomass and seed production were reduced. We also found that (1) sagebrush had the biggest reduction on cheatgrass plant size; (2) increasing density of cheatgrass negatively affected perennial establishment; (3) native plants had little effect on establishment of secondary weeds; (4) sugar application decreased establishment of medusahead but not squarrose knapweed. Experiment 3 investigated if prescribed fire and herbicide applied at a larger scale reduces cheatgrass. The herbicide treatment reduced cheatgrass and greater target plant density during the first growing season after seeding. In addition to these formal experiments: (1) An important practical outcome was modifications to the Truax Rough Rider Rangeland drill that improve its effectiveness for row and broadcast seeding. (2) Soil biological communities were patterned by a site's soil pH and surface cover type and were affected by sugar applications. (3) Sagebrush communities had consistently thicker A horizons than annual grass communities and had lower silt and clay contents, but soils of annual grass had higher mineral N. (4) We initiated 3 sophisticated approaches to data analyses to provide additional insight into ecological interactions and to generalize over a broad area. (5) Cheatgrass communities are a less-suitable habitat for granivores, which in turn reduces seed removal.

Impacts
Selected varieties of bluebunch wheatgrass and thickspike wheatgrass are promising plant materials for restoration of cheatgrass-dominated rangelands. Land management strategies that reduce nutrient availability reduce cheatgrass, but unless nutrient sequestration is sustained, cheatgrass quickly recovers. Given adequate environmental conditions and continuous seed availability, many native species established in cheatgrass-dominated areas. Nonetheless, weed control and native plant restoration are constrained by certain site characteristics. A powerful aspect of our project is the distribution of study sites across the Great Basin, but this distribution also brings significant challenges in terms of data synthesis and analysis that we met with advanced statistical techniques. We also found a tradeoff between ecological and economic benefits from restoration: our economic and social studies indicate that it is not economically viable for ranchers to undertake restoration, and cost-share mechanisms or innovative policy tools are needed to ensure that cheatgrass control efforts are ecologically feasible, socially acceptable, and economically equitable. Our integrated activities involved outreach education to increase student and public awareness of invasive species issues and to develop educational tools that convey solutions to invasive species and native plant restoration problems.

Publications

• Allcock K., Nowak R, Blank B, Jones T, Monaco T, Doescher P, Tanaka T, Ogle D, St. John L, Pellant M, Pyke D, Satyal V, Tanaka J, Schupp E, Call C (2006) Integrating weed management and restoration on western rangelands. Ecological Restoration 24:199-200.
• Busso CA, Mazzola M, Perryman BL (2005) Seed germination and viability of Wyoming sagebrush in northern Nevada. Interciencia 30:631-637.

Progress 01/01/05 to 12/31/05

Outputs
Tasks completed: (1) Data and samples were collected from the 2003 and 2004 seedings for Experiments 1 and 2 from 8 study sites across the 4 states of Idaho, Nevada, Oregon, and Utah. (2) Results from the 2004 season were presented and discussed at a meeting of project participants in March 2005, and plans for further data collection and analyses were made. (3) Analyses of data from 2004 and 2005 seasons were presented in several posters and talks at the Ecological Society of America/INTECOL joint annual meeting in Montreal, Canada in August 2005. (4) We completed vegetation, soil, and seed bank sampling and setup of permanent plots for Experiment 3. (5) Experimental treatments (herbicide, prescribed burn) were applied to Experiment 3 plots. (6) Experiment 3 plots were seeded with target species mixes. (7) We conducted field tours for federal agency personnel in June and November. (8) Assessment of fire and herbicide effects on soil seed bank is underway. Experiment 1 (transition stage) results: (a) Herbicide treatments negatively affected cheatgrass density and positively affected native plant density. The negative effect of herbicide on cheatgrass in the 2003 plantings was still evident in the second season after planting. (b) Some species that did poorly in the first growing season after 2003 plantings (Sandburg bluegrass and Siberian wheatgrass) had substantially higher densities in the second season. (c) Bluebunch Wheatgrass, Thickspike Wheatgrass and Snake River Wheatgrass had higher densities in herbicide plots. (d) There were differences within species between accessions, indicating the importance of both species and plant material origin for restoration. (e) Several native accessions (including Bluebunch Wheatgrass and Snake River Wheatgrass) performed as well as or better than crested wheatgrass in both 2003 and 2004 plantings. Experiment 2 (plant functional type) results: (a) The effect of experimental application of sugar to reduce soil nutrients attenuated with time and by the second growing season nutrient levels were similar in sugared and non-sugared plots. (b) In plots from the 2003 planting, target species densities were higher in plots that had been sugared or where cheatgrass had been removed. (c) Sandburg Bluegrass was negatively impacted by sugar application. (d) The reduction of cheatgrass seed output in 2003 resulted in lower cheatgrass density in sugared plots in the second growing season, but second season seed output per plant was equal in sugared and non-sugared plots. (e) Sugar application in 2004-2005 reduced cheatgrass seed output and in some cases density in 2004 plantings. (f) None of the plant functional types reduced cheatgrass density more than the others during the first year after planting. (g) Secondary weeds grew vigorously in all treatments where they were planted. Experiment 3 (management application) results: (a) Initial soil analyses indicated that herbicide treatment increased available nitrogen in the plots while reducing available phosphorus. More detailed investigations of soil nutrients are planned for 2006.

Impacts
Our results thus far in the project have the following implications: (1) Several readily-available native plant materials have performed at least as well as or better than crested wheatgrass. Native plant materials could be used in the place of non-native crested wheatgrass without sacrificing re-vegetation success. (2) Herbicide application, sugar application, or weeding, all of which reduced cheatgrass density, increased target species establishment. Techniques such as herbicide application, burning, or other methods of reducing cheatgrass prior to planting could increase success of restoration efforts. (3) Sugar application reduced cheatgrass seed output and subsequent year's density at most sites; however this is not a cost-effective way to reduce resources on a large scale. Nonetheless, cheatgrass control may be more successful on nitrogen-depleted lands, and other management techniques that reduce soil nitrogen may enhance cheatgrass control efforts. (4) There were differences in establishment success within species between different accessions, indicating the importance of basing selection of restoration stock on both species and plant material origin.

Publications

• No publications reported this period

Progress 01/01/04 to 12/31/04

Outputs
During the 2004 calendar year, the following tasks have been completed: (1) Data and samples have been collected from Experiments 1 and 2 throughout the growing season from 8 study sites located across the 4 states of Idaho, Nevada, Oregon, and Utah. Samples have been processed, and preliminary data analyses were conducted. Results were presented at a meeting in December that was attended by state and federal agency personnel. Preliminary results revealed that (a) herbicide treatments negatively affected cheatgrass density and positively affected native plant density; (b) plant performance within a species varied considerably, but a number of native plant varieties for some grass species did almost as well as the crested wheatgrass hybrid; (c) sites that typically have lower precipitation had higher soil biological crust cover; (d) application of sugar greatly decreased soil nitrate availability, and cheatgrass seed production and plant size was also significantly reduced by sugar treatments; (e) increased seeding rates increased plant density, but not proportionally; and (f) performance of secondary weeds (medusahead, skeletonweed, squarose knapweed) to different treatments (+/- cheatgrass, +/- sugar) did not vary in a consistent manner, suggesting very complex ecological interactions among cheatgrass, secondary weeds, and native species. Other completed tasks include: (2) Preparations were made for the repeated trials of Experiments 1 and 2, which included herbicide treatments during the spring; cleaning and testing of seed collected in the previous fall; and seeding the second set of replicate plots for Experiments 1 and 2 during the fall at each of the 8 study sites in the 4 cooperating states. (3) Modifications to the rangeland drill were completed to improve placement and burial of seed. (4) The study area for Experiment 3 was cleared for use by BLM, and then the study site was prepared, initial vegetation characterized, and fall seeding of the sterile annual hybrid was made to initiate the seed-burn-seed treatment. (5) Field tours with ranchers, state and federal agency personnel, and NGO's were conducted.

Impacts
We expect to identify: (1) If any of 25 readily-available, native plant materials will compete effectively with cheatgrass and other secondary weeds, and hence may be used as a transition stage during revegetation. (2) If the competitive interactions between cheatgrass and 6 native species change with soil N availability. (3) If a mix of native species that differ in growth form, rooting characteristics, and phenology is a viable method to sequester soil resources. (4) Determine the effectiveness of 4 different restoration treatments, two that are targeted at reducing the cheatgrass seedbank (prescribed fire and prescribed grazing treatments), a third that examines if an annual cover crop can be used to tie up soil N, and a fourth that investigates if a competitive native species (identified in earlier studies) further enhance cheatgrass control.

Publications

• No publications reported this period

Progress 01/01/03 to 12/31/03

Outputs
During the 2003 calendar year, the following tasks have been completed: (1) The final preparations for each site were completed. Herbicide treatments were applied during the spring to the appropriate areas to reduce cheatgrass in preparation for the first set of experiments. Seed collected in the previous fall was cleaned, then tested for purity and viability. Seed for Experiment 1 was prepared, and seeding packets for Experiment 2 were organized for each state. During the fall, Experiments 1 and 2 were seeded at each of the 8 study sites in the 4 cooperating states. (2) The rangeland drill was modified to improve placement and burial of seed prior to the fall seedings. Observations during the seedings indicated further improvements to the range drill, and this will be completed during 2004. (3) Basic measurement protocols were established, and they are currently undergoing fine-tuning. (4) The study area for Experiment 3 has been identified, and the clearance process has been initiated.

Impacts
We expect to identify: (1) If any of 25 readily-available, native plant materials will compete effectively with cheatgrass and other secondary weeds, and hence may be used as a transition stage during revegetation. (2) If the competitive interactions between cheatgrass and 6 native species change with soil N availability. (3) If a mix of native species that differ in growth form, rooting characteristics, and phenology is a viable method to sequester soil resources. (4) Determine the effectiveness of 4 different restoration treatments, two that are targeted at reducing the cheatgrass seedbank (prescribed fire and prescribed grazing treatments), a third that examines if an annual cover crop can be used to tie up soil N, and a fourth that investigates if a competitive native species (identified in earlier studies) further enhance cheatgrass control.

Publications

• No publications reported this period

Progress 01/01/02 to 12/31/02

Outputs
Most of our efforts to date have been focused on finalizing plot locations, obtaining clearances from BLM, finalizing experimental and sampling details, and conducting pretreatment site characterization. Specific accomplishments include: 1. Eight study sites, each approximately 50 acres, have been established, with 2 sites in each of the 4 states Idaho, Nevada, Oregon, and Utah. All study areas are on Wyoming big sagebrush range sites with soils that are typical of the general area but are currently cheatgrass dominated (typically <20% relative cover native perennials). Site are fairly level and do not have a significant surface cover of rocks. Within each state, 1 study area is near the low end of the typical precipitation range for Wyoming big sagebrush (e.g. 8-10" precipitation zone) and the other study area is near the high end (e.g. 10-12" precipitation zone). Secondary weeds are present at 4 study areas: both study areas in Idaho (rush skeletonweed at 1 site and medusahead at the other), 1 site in Oregon (medusahead), and 1 site in Utah (squarose knapweed). 2. Because all study sites are on BLM land, clearances (cultural, TES, etc.) had to be completed before we could begin the experimental treatments. These clearances are completed or nearly completed at all sites. 3. The research team has met three times to finalize most of the experimental and sampling details. The research team will meet once more in early summer 2003 to finalize sampling protocols. 4. Vegetation data and soil samples have been obtained from each site to characterize the pretreatment site environment. These data are important for understanding differences both within and between sites to improve the analysis and for interpretation of experimental results. In addition, we have collected and cleaned sagebrush seed to be used in the Fall 2003 seedings, began design of a web site for the project (with the assistance of Robert Moore), and designed procedures for producing and archiving metadata and its accompanying datasets.

Impacts
We expect to identify: 1. if any of 25 readily-available, native plant materials will compete effectively with cheatgrass, and hence may be used as a transition stage during revegetation. 2. if the competitive interactions between cheatgrass and 6 native species change with soil N availability or with species mixtures. 3. if a mix of species that differ in growth form, rooting characteristics, and phenology is a viable alternative to "sugaring" soils, i.e. to sequester soil N. 4. the effectiveness of 4 different restoration treatments. Two of the restoration techniques (a prescribed fire and a prescribed grazing treatment) are targeted at reducing the cheatgrass seed bank, a third technique examines if an annual cover crop can be used to tie up soil N, and the fourth investigates if more competitive native species (identified in the first 2 experiments) further enhance cheatgrass control.

Publications

• No publications reported this period