Weather affects post‐fire recovery of sagebrush‐steppe communities and model transferability among sites

AbstractEcological restoration of shrub–steppe communities in the western United States is often hampered by invasion of exotic annual grasses during the process. An important question is how to create restored communities that can better resist reinvasion by these weeds. One hypothesis is that communities comprised of species that are functionally similar to the invader will best resist invasion, while an alternative hypothesis is that structurally more complex and diverse communities will result in more effective competitive exclusion. In this field experiment, we examined the effects of restored community structure on the invasion success of three annual grass weeds (downy brome, jointed goatgrass, and cereal rye). We created replicated community plots that varied in species composition, structural complexity and density, then seeded in annual grass weeds and measured their biomass and seed production the following year, and their cover after 1 and 3 yr. Annual grass weeds were not strongly suppressed by any of the restored communities, indicating that it was difficult for native species to completely capture available resources and exclude annual grass weeds in the first years after planting. Perennial grass monocultures, particularly of the early seral grass bottlebrush squirreltail, were the most highly invaded communities, while structurally complex and diverse mixtures of shrubs (big sagebrush, rubber rabbitbrush), perennial grasses (bluebunch wheatgrass and bottlebrush squirreltail) and forbs (Lewis flax, Utah sweetvetch, hairy golden aster, gooseberryleaf globemallow) were more resistant to invasion. These results suggest that restoration of sagebrush steppe communities resistant to annual grass invasion benefits from higher species diversity; significant reduction of weed propagule pressure prior to restoration may be required.

Download Full-text

Re-introducing fire in sagebrush steppe experiencing decreased fire frequency: does burning promote spatial and temporal heterogeneity?

International Journal of Wildland Fire ◽

10.1071/wf20018 ◽

2020 ◽

Vol 29 (8) ◽

pp. 686

Author(s):

Kirk W. Davies ◽

Jon D. Bates

Keyword(s):

Fire Frequency ◽

Community Response ◽

Sagebrush Steppe ◽

Spatial And Temporal Variability ◽

Long Term Effects ◽

Vegetation Shifts ◽

Burned Areas ◽

Shrub Steppe ◽

Steppe Communities ◽

Fire Exclusion

Fire frequency has decreased in many shrub-steppe communities. Re-introducing fire may be needed to increase spatial and temporal variability in vegetation, but is often hindered by concerns of undesired vegetation shifts. These concerns arise, in part, because long-term effects of fire re-introduction in these communities after prolonged fire exclusion and other departures from historical conditions are unknown. To better understand the effects of re-introducing fire, we evaluated plant community response to re-introducing fire for 12 years post fire in six mountain big sagebrush communities. Herbaceous biomass production was 1.7-fold greater in burned compared with unburned areas at the conclusion of the study. Exotic annual grasses appeared to be problematic in the first 8 years post fire, but became inconsequential (~1% cover) by the end of the study. Re-introducing fire promoted other shrubs (excluding sagebrush) that were probably inhibited by competition from sagebrush. Sagebrush cover and density remained low in burned areas for the duration of the study, because of limited recruitment in the years immediately post fire and competition from herbaceous vegetation. Re-introducing fire appears to increase temporal and spatial heterogeneity in shrub-steppe communities experiencing prolonged fire exclusion and, therefore, may be needed to maintain a diversity of plant communities.

Download Full-text

Relationships Between Western Juniper (Juniperus occidentalis) and Understory Vegetation

Invasive Plant Science and Management ◽

10.1614/ipsm-07-008.1 ◽

2008 ◽

Vol 1 (1) ◽

pp. 3-11 ◽

Cited By ~ 20

Author(s):

D. E. Coultrap ◽

K. O. Fulgham ◽

D. L. Lancaster ◽

J. Gustafson ◽

D. F. Lile ◽

...

Keyword(s):

Canopy Cover ◽

Understory Vegetation ◽

Sagebrush Steppe ◽

Grass Cover ◽

Bare Ground ◽

Western Juniper ◽

Steppe Communities ◽

Juniper Woodland ◽

Successional Stages ◽

The Impact

AbstractWestern juniper has been actively invading sagebrush plant communities for about 130 yr. Western juniper canopy cover generally increases as western juniper invades sagebrush steppe communities and succession progresses toward a western juniper woodland. Our goal was to estimate the impact of juniper invasion and canopy increase on understory vegetation structure and productivity on 101 sites in northeastern California. The primary objectives of this study were to: (1) examine the influence of increasing western juniper canopy cover on the composition and productivity of understory vegetation; and (2) assess the effects of western juniper removal on understory vegetation. Sites in early, mid-, and late successional stages and sites on the same soils that had not been invaded were selected. Sites where western juniper had been removed by prescribed fire, mechanical, or chemical methods were compared to adjacent untreated sites. Western juniper canopy cover, understory cover and species composition, productivity, and bare ground were determined at each site during May through July 2005 and 2006. Regression analysis was used to evaluate the relationship between western juniper canopy cover and understory vegetation parameters. Logistic regression was used to detect understory differences between treated (juniper removed) and untreated (juniper not removed) sites. A significant relationship was found between western juniper canopy cover and understory species richness, shrub cover, forb cover, total grass cover, cheatgrass cover, herbaceous productivity, and bare ground. Removal of western juniper increased total grass cover, cheatgrass cover, and productivity, and reduced bare ground. The results of this study support findings by researchers in other states that western juniper influences plant community structure and productivity, and removal of western juniper might reverse these changes in structure, but also might increase opportunities for invasion of cheatgrass.

Download Full-text

Seasonal Movements and Home-Range Use by Female Pronghorns in Sagebrush-Steppe Communities of Western South Dakota

Journal of Mammalogy ◽

10.1644/07-mamm-a-395.1 ◽

2009 ◽

Vol 90 (2) ◽

pp. 433-441 ◽

Cited By ~ 42

Author(s):

Christopher N. Jacques ◽

Jonathan A. Jenks ◽

Robert W. Klaver

Keyword(s):

Home Range ◽

South Dakota ◽

Sagebrush Steppe ◽

Seasonal Movements ◽

Range Use ◽

Steppe Communities ◽

Home Range Use

Download Full-text

Point sampling for leaf area index in sagebrush steppe communities.

Journal of Range Management ◽

10.2458/azu_jrm_v54i5_clark ◽

2006 ◽

Vol 54 (5) ◽

Author(s):

P.E. Clark ◽

M.S. Seyfried

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Sagebrush Steppe ◽

Area Index ◽

Point Sampling ◽

Steppe Communities

Download Full-text

Indicators of Ventenata (Ventenata dubia) Invasion in Sagebrush Steppe Rangelands

Invasive Plant Science and Management ◽

10.1017/inp.2018.7 ◽

2018 ◽

Vol 11 (1) ◽

pp. 1-9 ◽

Cited By ~ 11

Author(s):

Lisa C. Jones ◽

Nicholas Norton ◽

Timothy S. Prather

Keyword(s):

Diversity Index ◽

Soil Depth ◽

Abiotic Factors ◽

Clay Content ◽

Sagebrush Steppe ◽

Scaling Analysis ◽

Forage Production ◽

Chi Square ◽

Study Region ◽

Steppe Communities

AbstractVentenata [Ventenata dubia (Leers) Coss.], an invasive winter annual grass, significantly reduces forage production in grassland systems and displaces species within both perennial- and annual-dominated grasslands within the Inland Northwest. The range of V. dubia is expanding into sagebrush steppe communities, an expansive habitat critical for forage production, wildlife, and recreation. Currently, there is limited knowledge of V. dubia’s distribution and abundance within sagebrush steppe communities. We performed field surveys at 15 locations in sagebrush steppe rangelands in southern Idaho and eastern Oregon to assess where V. dubia occurs, with the aim of providing insight about its niche in this new habitat. Specifically, we evaluated biotic and abiotic factors of the plant community as indicators of V. dubia presence. We also correlated species diversity measures with no, low (<12.5%), and high (>12.5%) V. dubia cover. Though widely distributed throughout the study region, V. dubia only appeared in 45% of the 225 plots, and foliar cover was typically less than 50%. It was primarily found in ephemerally wet microhabitats. Species richness and the Shannon diversity index were lowest in plots with high V. dubia cover. Nonmetric multidimensional scaling analysis revealed that V. dubia and medusahead [Taeniatherum caput-medusae (L.) Nevski] were closely associated. Furthermore, chi-square indicator analysis showed that T. caput-medusae was more prevalent, while mountain big sagebrush [Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle] was less prevalent, in plots containing V. dubia. Abiotic factors that explained variation in V. dubia abundance included rock cover, soil depth, and a north/south aspect. Higher V. dubia cover also correlated with higher clay content and lower phosphorus and potassium concentrations in the soil. We suggest that at this point, detection survey efforts to locate incipient infestations of V. dubia in sagebrush steppe communities should focus on moist areas and sites susceptible to invasion by T. caput-medusae.

Download Full-text