Mediterranean annual grasses in western North America: kids in a candy store

Norton, Jay B.; Monaco, Thomas A.; Norton, Urszula

doi:10.1007/s11104-007-9364-8

Cited by 65 publications

(41 citation statements)

References 46 publications

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“…This effect is mediated by fundamental changes to the vegetation community coincident with establishment of exotic plants (Fischer et al 1996, Wambolt et al 2001, Beck et al 2009, Miller et al 2011), and appears to affect recruitment more strongly than adult survival. The historic importance of wildfire in maintaining the sagebrush ecosystem is debated (Baker 2006, Norton et al 2007, Baker 2011), but it is generally agreed that the introduction of cheatgrass has fundamentally changed the way ecologists and managers must view the contemporary role of fire in sagebrush communities (Baker 2011). A negative correlation between modern fires and sage-grouse population dynamics has been established previously (Connelly et al 2000), and several authors have evaluated specific response of sagebrush habitats to fire (Fischer et al 1996, Wambolt et al 2001, Beck et al 2009).…”

Section: Discussionmentioning

confidence: 99%

“…More frequent drought, coupled with increased ignition frequency (Price and Rind 1994) will lead to more frequent and larger fires in the western United States (Brown et al 2004, Pechony andShindell 2010). Exotic grasses such as cheatgrass also respond favorably to amplified atmospheric CO 2 (Smith et al 1987, Norton et al 2007, perhaps further improving the species' competitive ability. We may therefore expect recent trends in sagebrush conversion to exotic grassland (Prater et al 2006, Miller et al 2011) to increase, which our research suggests will negatively impact sage-grouse populations by reducing adult survival and decreasing long-term levels of recruitment in impacted areas.…”

Section: Discussionmentioning

confidence: 99%

“…These disturbances fundamentally change sagebrush plant communities through subsequent dominance of exotic grasses such as cheatgrass (Bromus tectorum), which prevents reestablishment of native vegetation following wildfire (Norton et al 2007, Miller et al 2011. Post-wildfire establishment of exotic grassland is predicted to reduce sage-grouse habitat in the Great Basin by as much as 58% in the next 30 years (Miller et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

et al. 2012

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Life histories determine how organisms interact with their environment and predict how populations respond to environmental change. Understanding relationships between life histories and environmental variability is therefore crucial for effective conservation under changing environmental conditions. Greater sage‐grouse (Centrocercus urophasianus) is a species of major conservation concern in western North America following widespread disturbance of the sagebrush ecosystems to which they are endemic. Using robust design and Pradel capture‐mark‐recapture models, we evaluated the influence of climatic processes and disturbance associated with post‐wildfire exotic grass invasion on annual survival, per‐capita recruitment, and population growth of breeding male sage‐grouse in eastern Nevada, USA. Climatic processes, indexed by annual rainfall and maximum summertime temperatures, had a strong relationship with recruitment and adult survival, respectively. The range of variation in recruitment during the study was greater than the range of variation in survival, consistent with a life‐history strategy that features lengthened lifespan to capitalize on periodically favorable reproductive conditions. Annual variation in precipitation variables (e.g., rainfall or snow depth) explained as much as 75% of the annual variance in population size during the study. Our results are consistent with bottom‐up regulation of sage‐grouse populations, where abundance is determined in large part by climate‐driven variation in resource availability. Exotic grasslands had a negative influence on recruitment that was interactive with annual rainfall; recruitment was consistently low in areas with a substantial exotic grassland footprint even following years of favorable rainfall. We found males breeding at leks with substantial exotic grassland impacts had lower annual survival compared to males at leks surrounded by native sagebrush habitats. However, models containing an interaction between exotic grasslands and maximum summer temperature were not clearly superior to models that considered only additive effects of the two variables. This research has significant implications for sage‐grouse persistence in a changing climate, where more frequent drought and increased spread of exotic grasslands will have negative impacts on sage‐grouse populations.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

et al. 2012

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“…Several authors have suggested that decreasing N availability and restoring a more conservative N cycle with lower N turnover should decrease the competitive advantage of invasive annual grasses like cheatgrass (Blumenthal et al 2003, Norton et al 2007, Brunson et al 2010). In areas dominated by cheatgrass, this could involve direct manipulation of N availability (e.g., sugar amendments or repeated fire), manipulation of litter, or seeding a competitor.…”

Section: Introductionmentioning

confidence: 99%

The role of resource limitation in restoration of sagebrush ecosystems dominated by cheatgrass (Bromus tectorum)

et al. 2015

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Abstract. Success of invasive annual grasses is often linked to increases in resources, and restoration ecologists have suggested that decreasing nitrogen (N) availability and restoring more conservative N cycles with lower N turnover should decrease the competitive advantage of these invaders and facilitate establishment of native perennials. We developed a multivariate conceptual model of the likely effects of environmental factors (precipitation and temperature) and potential management treatments (repeated burning, litter manipulation, and seeding an annual competitor) on soil N availability and success of cheatgrass, the most widespread invader in the western United States. We examined effects of the treatments in a five year field study in a cold desert shrubland. We used generalized linear mixed-effects models to examine differences among treatments over time, and structural equation modeling (SEM) to evaluate component hypotheses of the conceptual model. We hypothesized that burning would result in a pulse in soil available N due to heat-induced soil organic matter denaturation, but that subsequent fires would volatilize soil and biomass N resulting in progressive N deficiency. However, soil available N in burned plots was never lower than pre-burn levels, likely because burn temperatures were too cool to volatilize N from soils or aboveground biomass. Repeated burning decreased litter biomass, but there were generally no differences in soil available N between litter intact and litter removed plots. Litter removal had a negative effect on cheatgrass success likely due to effects on seed entrapment and plant establishment rather than N mineralization. Plots seeded with wheat generally had the lowest cheatgrass success, but available N was similar to other treatments, and decreased cheatgrass success was likely due to competition for other soil nutrients or water and reduced litter. In this semi-arid shrubland, long-term trends in available soil N and cheatgrass success were most strongly associated with precipitation and winter minimum temperatures. Treatments did not result in longer-term decreases in soil N, but indicated that integrated restoration approaches that reduce litter and seed banks and increase competitive interactions may be effective at reducing cheatgrass success and facilitating establishment of natives.

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“…Increases in soil nitrogen deposition are often positively correlated with non-indigenous and indigenous invasive species fitness, establishment and spread (Abraham et al 2009, Bell and Treshow 2002, Burke and Grime 1996, Hobbs et al 1988, Metcalfe and Fowler 1998, SchererLorenzen et al 2000, Vasquez 2008, Wedin and Tilman 1996, McLendon and Redente 1991, Melgoza and Nowak 1991, Kolb et al 2002, Brooks 2003, Norton et al 2007, Vasquez 2008and references therein, MacKown et al 2009, James et al 2011 and references therein).…”

mentioning

confidence: 99%

Community and Ecosystem Effects of Buffelgrass (Pennisetum ciliare) and Nitrogen Deposition in the Sonoran Desert

Lyons

Maldonado-Leal

Owen

2013

Invasive plant sci. manag.

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Buffelgrass is a non-indigenous, invasive, C4 grass that was introduced throughout much of southern Texas, the Southwestern United States, and northern and central Mexico to improve degraded rangelands. The successful introduction and spread of buffelgrass follows a trajectory similar to that of other invasive C4 grasses in arid and semiarid ecosystems. In the Plains of Sonora of the Sonoran Desert (Mexico) buffelgrass is favored by widespread removal of native vegetation and seeding, but, why, following initial introduction, the species persists remains unclear. In this study, we addressed two concerns associated with buffelgrass invasion in the Plains of Sonora. We hypothesized that under arid rangeland conditions, buffelgrass outcompetes native herbaceous species (1) through rapid acquisition of limiting nutrients (here assumed to be nitrogen) and (2) under conditions with high nitrogen input. In summer 2002, a 2 by 2 factorial experiment was established with buffelgrass removal and nitrogen addition in both intact desert and converted buffelgrass grassland habitats. In winter 2003, we found that, regardless of habitat type, buffelgrass removal had a positive effect on abundance, biomass, and richness of native herbaceous species while addition of nitrogen, as urea (at 50 kg N ha−1yr−1 or 9.18 lbs N ac−1yr−1), and disturbance resulted in reduction in abundance and biomass. Nitrogen addition did not negatively alter buffelgrass cover. Nitrogen addition had the expected result of increasing initial, peak and total NO3 and NH4 mineralization with the exception of NO3 measures in intact desert. Removal of buffelgrass did not result in significant increases in soil NO3 or NH4 with the exception of peak NH4 in intact desert. Results of this study support observations that native herbaceous species are displaced by buffelgrass invasion and that nitrogen pollution will likely favor buffelgrass over the native herbaceous species in this ecosystem.

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Mediterranean annual grasses in western North America: kids in a candy store

Cited by 65 publications

References 46 publications

Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

The role of resource limitation in restoration of sagebrush ecosystems dominated by cheatgrass (Bromus tectorum)

Community and Ecosystem Effects of Buffelgrass (Pennisetum ciliare) and Nitrogen Deposition in the Sonoran Desert

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