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Jayne Belnap - One of the best experts on this subject based on the ideXlab platform.
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Plant Community Resistance to Invasion by Bromus Species: The Roles of Community Attributes, Bromus Interactions with Plant Communities, and Bromus Traits
Springer Series on Environmental Management, 2016Co-Authors: Jeanne C. Chambers, Jayne Belnap, Matthew J. Germino, Cynthia S. Brown, Eugene W. Schupp, Samuel B. St. ClairAbstract:The factors that determine plant community resistance to exotic annual Bromus species (Bromus hereafter) are diverse and context specific. They are influenced by the environmental characteristics and attributes of the community, the traits of Bromus species, and the direct and indirect interactions of Bromus with the plant community. Environmental factors, in particular ambient and soil temperatures, have significant effects on the ability of Bromus to establish and spread. Seasonality of precipitation relative to temperature influences plant community resistance to Bromus through effects on soil water storage, timing of water and nutrient availability, and dominant plant life forms. Differences among plant communities in how well soil resource use by the plant community matches resource supply rates can influence the magnitude of resource fluctuations due to either climate or disturbance and thus the opportunities for invasion. The spatial and temporal patterns of resource availability and acquisition of growth resources by Bromus versus native species strongly influence resistance to invasion. Traits of Bromus that confer a “priority advantage” for resource use in many communities include early-season germination and high growth and reproductive rates. Resistance to Bromus can be overwhelmed by high propagule supply, low innate seed dormancy, and large, if short-lived, seed banks. Biological crusts can inhibit germination and establishment of invasive annual plants, including several annual Bromus species, but are effective only in the absence of disturbance. Herbivores can have negative direct effects on Bromus, but positive indirect effects through decreases in competitors. Management strategies can be improved through increased understanding of community resistance to exotic annual Bromus species.
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exotic annual Bromus invasions comparisons among species and ecoregions in the western united states
In: Germino Matthew J.; Chambers Jeanne C.; Brown Cynthia S eds. 2016. Exotic brome-grasses in arid and semiarid ecosystems of the western US: Causes , 2016Co-Authors: Matthew L Brooks, Jeanne C. Chambers, Cynthia S. Brown, Carla M Dantonio, Jon E Keeley, Jayne BelnapAbstract:Exotic annual Bromus species are widely recognized for their potential to invade, dominate, and alter the structure and function of ecosystems. In this chapter, we summarize the invasion potential, ecosystem threats, and management strategies for different Bromus species within each of five ecoregions of the western United States. We characterize invasion potential and threats in terms of ecosystem resistance to Bromus invasion and ecosystem resilience to disturbance with an emphasis on the importance of fire regimes. We also explain how soil temperature and moisture regimes can be linked to patterns of resistance and resilience and provide a conceptual framework that can be used to evaluate the relative potential for invasion and ecological impact of the dominant exotic annual Bromus species in the western United States.
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Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem
Ecology, 2006Co-Authors: Len Sperry, Jayne Belnap, R D EvansAbstract:The nonnative annual grass Bromus tectorumhas successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical dis- turbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C3 and C4). The response of these communities was compared to an invaded/ disturbed grassland. The invaded/disturbed communities had higher surface NH4 1 input in spring, whereas there were no differences for surface input of NO3 2 . Soil inorganic N was dominated by NH4 1 , but invaded sites had greater subsurface soil NO 3 2 . Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil d 15 N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed com- munities exhibited the opposite pattern. Enriched foliar d 15 N values suggest that Bromus assimilated subsurface NO3 2 , whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil d 15 N; however, the invaded/ disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3 2 concentrations were greater in the invaded communities during periods of ample precipitation, and NO3 2 leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities. Bromus produced a positive feedback loop by leach- ing NO3 2 from decomposing Bromus litter to subsurface soil layers, accessing that deep- soil N pool with deep roots and returning that N to the surface as biomass and subsequent litter. Lack of new inputs combined with continued loss will result in lower total soil N, evidenced by the lower total soil N in the invaded/disturbed communities.
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soil biota can change after exotic plant invasion does this affect ecosystem processes
Ecology, 2005Co-Authors: Jayne Belnap, Susan L Phillips, Susan K Sherrod, Andy MoldenkeAbstract:Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded, recently invaded, and historically invaded sites (all currently or once dominated by Hilaria), germination and survivorship were not affected. In contrast, aboveground Hilaria biomass was significantly greater in recently invaded soils than in the other two soils. We attributed the Hilaria respons...
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exotic plant invasion alters nitrogen dynamics in an arid grassland
Ecological Applications, 2001Co-Authors: R D Evans, Len Sperry, R Rimer, Jayne BelnapAbstract:The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N 2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on litter dynamics. Long-term soil incubations (415 d) were used to measure potential microbial respiration and net N mineralization. Plant-available N was quantified for two years in situ with ion-exchange resin bags, and potential changes in rates of gaseous N loss were estimated by measuring denitrification enzyme activity. Bromus invasion significantly increased litter biomass, and Bromus litter had significantly greater C:N and lignin:N ratios than did native species. The change in litter quantity and chemistry decreased potential rates of net N mineralization in sites with Bromusby decreasing nitrogen available for microbial activity. Inorganic N was 50% lower on Hilaria sites with Bromus during the spring of 1997, but no differences were observed during 1998. The contrasting differences between years are likely due to moisture availability; spring precipitation was 15% greater than average during 1997, but 52% below average during spring of 1998. Bromus may cause a short-term decrease in N loss by decreasing substrate availability and denitrification enzyme activity, but N loss is likely to be greater in invaded sites in the long term because of increased fire frequency and greater N volatilization during fire. We hypothesize that the introduction of Bromus in conjunction with land-use change has es- tablished a series of positive feedbacks that will decrease N availability and alter species composition.
R D Evans - One of the best experts on this subject based on the ideXlab platform.
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Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem
Ecology, 2006Co-Authors: Len Sperry, Jayne Belnap, R D EvansAbstract:The nonnative annual grass Bromus tectorumhas successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical dis- turbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C3 and C4). The response of these communities was compared to an invaded/ disturbed grassland. The invaded/disturbed communities had higher surface NH4 1 input in spring, whereas there were no differences for surface input of NO3 2 . Soil inorganic N was dominated by NH4 1 , but invaded sites had greater subsurface soil NO 3 2 . Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil d 15 N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed com- munities exhibited the opposite pattern. Enriched foliar d 15 N values suggest that Bromus assimilated subsurface NO3 2 , whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil d 15 N; however, the invaded/ disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3 2 concentrations were greater in the invaded communities during periods of ample precipitation, and NO3 2 leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities. Bromus produced a positive feedback loop by leach- ing NO3 2 from decomposing Bromus litter to subsurface soil layers, accessing that deep- soil N pool with deep roots and returning that N to the surface as biomass and subsequent litter. Lack of new inputs combined with continued loss will result in lower total soil N, evidenced by the lower total soil N in the invaded/disturbed communities.
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exotic plant invasion alters nitrogen dynamics in an arid grassland
Ecological Applications, 2001Co-Authors: R D Evans, Len Sperry, R Rimer, Jayne BelnapAbstract:The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N 2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on litter dynamics. Long-term soil incubations (415 d) were used to measure potential microbial respiration and net N mineralization. Plant-available N was quantified for two years in situ with ion-exchange resin bags, and potential changes in rates of gaseous N loss were estimated by measuring denitrification enzyme activity. Bromus invasion significantly increased litter biomass, and Bromus litter had significantly greater C:N and lignin:N ratios than did native species. The change in litter quantity and chemistry decreased potential rates of net N mineralization in sites with Bromusby decreasing nitrogen available for microbial activity. Inorganic N was 50% lower on Hilaria sites with Bromus during the spring of 1997, but no differences were observed during 1998. The contrasting differences between years are likely due to moisture availability; spring precipitation was 15% greater than average during 1997, but 52% below average during spring of 1998. Bromus may cause a short-term decrease in N loss by decreasing substrate availability and denitrification enzyme activity, but N loss is likely to be greater in invaded sites in the long term because of increased fire frequency and greater N volatilization during fire. We hypothesize that the introduction of Bromus in conjunction with land-use change has es- tablished a series of positive feedbacks that will decrease N availability and alter species composition.
Leopoldo Javier Iannone - One of the best experts on this subject based on the ideXlab platform.
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epichloe exudates promote in vitro and in vivo arbuscular mycorrhizal fungi development and plant growth
Plant and Soil, 2018Co-Authors: Leopoldo Javier Iannone, Victoria M Vignale, Martin J Scervino, Victoria M NovasAbstract:Background and aims We studied, through exudates employment, the effect of Epichloe (endophytic fungi), both independently and in association with Bromus auleticus (grass), on arbuscular mycorrhizal fungi (AMF) colonization, host and neighbouring plants biomass production and soil changes.
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beneficial effects of neotyphodium tembladerae and neotyphodium pampeanum on a wild forage grass
Grass and Forage Science, 2012Co-Authors: Leopoldo Javier Iannone, Christopher L Schardl, Padmaja Nagabhyru, Albertina Daniela Pinget, J P De BattistaAbstract:Abstract Asexual, vertically transmitted fungal endophytes of thegenus Neotyphodium are considered to enhance growth,stress resistance and competitiveness of agronomicgrasses, but have been suggested to have neutral ordeleterious effects on wild grasses. We studied whetherthe associations between Bromus auleticus and theirendophytes,NeotyphodiumpampeanumandNeotyphodiumtembladerae,arebeneficialforthiswildforagegrassnativeto South America. In a greenhouse experiment,3-month-old endophyte-infected plants (E+) showedenhanced growth relative to their endophyte-free coun-terparts(E)).Inaone-year-longexperimentinthefield,E+plantsshowedhighersurvivalandregrowthrate,andproduced more biomass and seeds than E) plants. OnlywithrespecttotheseedoutputdidN. tembladeraeseemtobedetrimental,whereasN. pampeanumdidnotaffectthisparameter. No differences were observed with respect tothe germination of seeds produced by E+ or E) plants.LolinealkaloidsweredetectedinN. pampeanum-infectedplants. Our results show that, similar to results withagronomic grasses, in wild grasses, the symbiosis withNeotyphodium species could be mutualistic.Keywords: endophytes, wild grasses, Bromus, growth,reproduction
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phylogenetic divergence morphological and physiological differences distinguish a new neotyphodium endophyte species in the grass Bromus auleticus from south america
Mycologia, 2009Co-Authors: Leopoldo Javier Iannone, Daniel Cabral, Christopher L Schardl, Maria Susana RossiAbstract:The fungi of genus Neotyphodium are systemic, constitutive, symbionts of grasses of subfamily Pooideae. In the southern hemisphere most of these asexual endophytes are the result of the hybridization between two sexual species, Epichlo" festucae and E. typhina, from the northern hemisphere. However the ancestral sexual species have not been detected in this region. Several grasses from Argentina are infected by Neotyphodium species. These endophytes are in general very similar macro- and micromorphologically and phylogenetically conform to species N. tembladerae. However the Neotyphodium spp. endophytes of some hosts, Bromus auleticus and Poa spicifomis var. spiciformis, have not been included in this species. In this work we studied the incidence and characterized the diversity of Neotyphodium species in populations of the native grass Bromus auleticus from Argentina. The incidence of endophytes was 100% in all populations investigated. Two groups of endophytes were differentiated by their morphologies, growth rates, conidial ontogenies and by relative resistance to the fungicide benomyl. Phylogenetic trees inferred from tefA and tubB intron sequences indicated that both N. tembladerae and the novel morphotype were hybrids of E. festucae and E. typhina, but the ancestral E. typhina genotype distinguished them. Isolates from plants that inhabit coastal dunes, xerophytic forests, savannahs and hills were similar morphologically and phylogenetically to N. tembladerae, whereas the endophytes from the humid pampa plains conformed to the novel group. We propose the endophyte of Bromus auleticus from humid pampas as a new species, Neotyphodium pampeanum.
Len Sperry - One of the best experts on this subject based on the ideXlab platform.
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Bromus tectorum invasion alters nitrogen dynamics in an undisturbed arid grassland ecosystem
Ecology, 2006Co-Authors: Len Sperry, Jayne Belnap, R D EvansAbstract:The nonnative annual grass Bromus tectorumhas successfully replaced native vegetation in many arid and semiarid ecosystems. Initial introductions accompanied grazing and agriculture, making it difficult to separate the effects of invasion from physical dis- turbance. This study examined N dynamics in two recently invaded, undisturbed vegetation associations (C3 and C4). The response of these communities was compared to an invaded/ disturbed grassland. The invaded/disturbed communities had higher surface NH4 1 input in spring, whereas there were no differences for surface input of NO3 2 . Soil inorganic N was dominated by NH4 1 , but invaded sites had greater subsurface soil NO 3 2 . Invaded sites had greater total soil N at the surface four years post-invasion in undisturbed communities, but total N was lower in the invaded/disturbed communities. Soil d 15 N increased with depth in the noninvaded and recently invaded communities, whereas the invaded/disturbed com- munities exhibited the opposite pattern. Enriched foliar d 15 N values suggest that Bromus assimilated subsurface NO3 2 , whereas the native grasses were restricted to surface N. A Rayleigh distillation model accurately described decomposition patterns in the noninvaded communities where soil N loss is accompanied by increasing soil d 15 N; however, the invaded/ disturbed communities exhibited the opposite pattern, suggesting redistribution of N within the soil profile. This study suggests that invasion has altered the mechanisms driving nitrogen dynamics. Bromus litter decomposition and soil NO3 2 concentrations were greater in the invaded communities during periods of ample precipitation, and NO3 2 leached from the surface litter, where it was assimilated by Bromus. The primary source of N input in these communities is a biological soil crust that is removed with disturbance, and the lack of N input by the biological soil crust did not balance N loss, resulting in reduced total N in the invaded/disturbed communities. Bromus produced a positive feedback loop by leach- ing NO3 2 from decomposing Bromus litter to subsurface soil layers, accessing that deep- soil N pool with deep roots and returning that N to the surface as biomass and subsequent litter. Lack of new inputs combined with continued loss will result in lower total soil N, evidenced by the lower total soil N in the invaded/disturbed communities.
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exotic plant invasion alters nitrogen dynamics in an arid grassland
Ecological Applications, 2001Co-Authors: R D Evans, Len Sperry, R Rimer, Jayne BelnapAbstract:The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N 2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on litter dynamics. Long-term soil incubations (415 d) were used to measure potential microbial respiration and net N mineralization. Plant-available N was quantified for two years in situ with ion-exchange resin bags, and potential changes in rates of gaseous N loss were estimated by measuring denitrification enzyme activity. Bromus invasion significantly increased litter biomass, and Bromus litter had significantly greater C:N and lignin:N ratios than did native species. The change in litter quantity and chemistry decreased potential rates of net N mineralization in sites with Bromusby decreasing nitrogen available for microbial activity. Inorganic N was 50% lower on Hilaria sites with Bromus during the spring of 1997, but no differences were observed during 1998. The contrasting differences between years are likely due to moisture availability; spring precipitation was 15% greater than average during 1997, but 52% below average during spring of 1998. Bromus may cause a short-term decrease in N loss by decreasing substrate availability and denitrification enzyme activity, but N loss is likely to be greater in invaded sites in the long term because of increased fire frequency and greater N volatilization during fire. We hypothesize that the introduction of Bromus in conjunction with land-use change has es- tablished a series of positive feedbacks that will decrease N availability and alter species composition.
Susan L Phillips - One of the best experts on this subject based on the ideXlab platform.
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soil biota can change after exotic plant invasion does this affect ecosystem processes
Ecology, 2005Co-Authors: Jayne Belnap, Susan L Phillips, Susan K Sherrod, Andy MoldenkeAbstract:Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded, recently invaded, and historically invaded sites (all currently or once dominated by Hilaria), germination and survivorship were not affected. In contrast, aboveground Hilaria biomass was significantly greater in recently invaded soils than in the other two soils. We attributed the Hilaria respons...
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SOIL BIOTA IN AN UNGRAZED GRASSLAND: RESPONSE TO ANNUAL GRASS (Bromus TECTORUM) INVASION
Ecological Applications, 2001Co-Authors: Jayne Belnap, Susan L PhillipsAbstract:Bromus tectorum is an exotic annual grass that currently dominates many western U.S. semi-arid ecosystems, and the effects of this grass on ecosystems in general, and soil biota specifically, are unknown. Bromus recently invaded two ungrazed and unburned perennial bunchgrass communities in southeastern Utah. This study compared the soil food-web structure of the two native grassland associations (Stipa [S] and Hilaria [H]), with and without the presence of Bromus. Perennial grass and total vascular-plant cover were higher in S than in H plots, while quantities of ground litter were similar. Distribution of live and dead plant material was highly clumped in S and fairly homogenous in H. Soil food-web structure was different between H and S, with lower trophic levels more abundant in H and higher trophic levels more abundant in S. In Bromus-invaded plots, the quantity of ground litter was 2.2 times higher in Hilaria–Bromus (HB) than in H plots, and 2.8 times higher in Stipa–Bromus (SB) than in S plots. Soil...
