MPG Ranch

Missoula, MT, United States

MPG Ranch

Missoula, MT, United States
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Shaw A.N.,MPG Ranch | Mummey D.L.,MPG Ranch
PLoS ONE | Year: 2017

The genetics of native plants influence the success of ecological restoration, yet genetic variability of local seed collections and commercial seed releases remains unclear for most taxa. Poa secunda, a common native grass species in Intermountain West grasslands and a frequent component of restoration seed mixes, is one such species. Here, we evaluate the genetic variation of local Poa secunda collections in the context of wild populations and commercial seed releases. We evaluated AFLP markers for seven Poa secunda collections made over a 4000-hectare area and four commercial releases (High Plains, MT-1, Opportunity, and Sherman). We compare the genetic distance and distribution of genetic variation within and between local collections and commercial releases. The extent and patterns of genetic variation in our local collections indicate subtle site differences with most variation occurring within rather than between collections. Identical genetic matches were usually, but not always, found within 5 m2 collection sites. Our results suggest that the genetic variation in two Poa secunda releases (High Plains and MT-1) is similar to our local collections. Our results affirm that guidelines for Poa secunda seed collection should follow recommendations for selfing species, by collecting from many sites over large individual sites. © 2017 Shaw, Mummey. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Lekberg Y.,MPG Ranch | Lekberg Y.,University of Montana | Gibbons S.M.,MPG Ranch | Gibbons S.M.,University of Chicago | And 2 more authors.
ISME Journal | Year: 2013

Invasions by non-native plants can alter ecosystem functions and reduce native plant diversity, but relatively little is known about their effect on belowground microbial communities. We show that invasions by knapweed (Centaurea stoebe) and leafy spurge (Euphorbia esula, hereafter spurge) - but not cheatgrass (Bromus tectorum) - support a higher abundance and diversity of symbiotic arbuscular mycorrhizal fungi (AMF) than multi-species native plant communities. The higher AMF richness associated with knapweed and spurge is unlikely due to a co-invasion by AMF, because a separate sampling showed that individual native forbs hosted a similar AMF abundance and richness as exotic forbs. Native grasses associated with fewer AMF taxa, which could explain the reduced AMF richness in native, grass-dominated communities. The three invasive plant species harbored distinct AMF communities, and analyses of co-occurring native and invasive plants indicate that differences were partly driven by the invasive plants and were not the result of pre-invasion conditions. Our results suggest that invasions by mycotrophic plants that replace poorer hosts can increase AMF abundance and richness. The high AMF richness in monodominant plant invasions also indicates that the proposed positive relationship between above and belowground diversity is not always strong. Finally, the disparate responses among exotic plants and consistent results between grasses and forbs suggest that AMF respond more to plant functional group than plant provenance. © 2013 International Society for Microbial Ecology All rights reserved.

Lekberg Y.,MPG Ranch | Lekberg Y.,University of Montana | Koide R.T.,Brigham Young University
Botany | Year: 2014

Our knowledge of arbuscular mycorrhizal (AM) function is largely based on results from short-term studies in controlled environments. While these have provided many important insights into the potential effects of the symbiosis on the two symbionts and their communities, they may have also inadvertently led to faulty assumptions about the function of the symbiosis in natural settings. Here we highlight the consequences of failing to consider the AM symbiosis from the perspectives of community ecology and evolutionary biology. Also, we argue that by distinguishing between physiological and evolutionary viewpoints, we may be able to resolve controversies regarding the mutualistic vs. parasitic nature of the symbiosis. Further, while most AM research has emphasized resource transfers, primarily phosphate and carbohydrate, our perceptions of parasitism, cheating, bet-hedging, and partner choice would most likely change if we considered other services. Finally, to gain a fuller understanding of the role of the AM symbiosis in nature, we need to better integrate physiological processes of plants and their AM fungi with their naturally occurring temporal and spatial patterns. It is our hope that this article will generate some fruitful discussions and make a contribution toward this end.

Lekberg Y.,University of Montana | Waller L.P.,MPG Ranch
Fungal Ecology | Year: 2016

Plant species can influence communities of arbuscular mycorrhizal fungi (AMF) by hosting different AMF taxon identities and/or richness. We used presence/absence data from a recent global survey of AMF communities to assess how often AMF communities differ among plant species, and to explore whether differences result from dissimilarities in AMF taxon identity or richness. We found that AMF communities clustered among plant species in 24% of sites, and that plant species were more likely to differ in AMF taxon richness (23% of sites) than the particular taxa with which they associate (5% of sites). Overall though, the variation in both AMF richness and identity was often as great . within as . between plant species, suggesting that plant species identity may be less important for structuring local AMF communities than other factors, such as environmental conditions, fungal interactions or even stochastic distributions of AMF. This has implications for how we should view plant-AMF interactions and community patterns. © 2016 Elsevier Ltd and British Mycological Society.

Bunn R.A.,Western Washington University | Lekberg Y.,MPG Ranch | Lekberg Y.,University of Montana | Gallagher C.,Western Washington University | And 2 more authors.
Ecology and Evolution | Year: 2014

Controlled experiments show that arbuscular mycorrhizal fungi (AMF) can increase competitiveness of exotic plants, potentially increasing invasion success. We surveyed AMF abundance and community composition in Centaurea stoebe and Potentilla recta invasions in the western USA to assess whether patterns were consistent with mycorrhizal-mediated invasions. We asked whether (1) AMF abundance and community composition differ between native and exotic forbs, (2) associations between native plants and AMF shift with invading exotic plants, and (3) AMF abundance and/or community composition differ in areas where exotic plants are highly invasive and in areas where they are not. We collected soil and roots from invaded and native forb communities along invasion gradients and in regions with different invasion densities. We used AMF root colonization as a measure of AMF abundance and characterized AMF communities in roots using 454-sequencing of the LSU-rDNA region. All plants were highly colonized (>60%), but exotic forbs tended to be more colonized than natives (P < 0.001). We identified 30 AMF operational taxonomic units (OTUs) across sites, and community composition was best predicted by abiotic factors (soil texture, pH). Two OTUs in the genera Glomus and Rhizophagus dominated in most communities, and their dominance increased with invasion density (r = 0.57, P = 0.010), while overall OTU richness decreased with invasion density (r = -0.61, P = 0.006). Samples along P. recta invasion gradients revealed small and reciprocal shifts in AMF communities with >45% fungal OTUs shared between neighboring native and P. recta plants. Overall, we observed significant, but modest, differences in AMF colonization and communities between co-occurring exotic and native forbs and among exotic forbs across regions that differ in invasion pressure. While experimental manipulations are required to assess functional consequences, the observed patterns are not consistent with those expected from strong mycorrhizal-mediated invasions. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Bunn R.A.,Western Washington University | Ramsey P.W.,MPG Ranch | Lekberg Y.,MPG Ranch | Lekberg Y.,University of Montana
Journal of Ecology | Year: 2015

Divergent hypotheses have been proposed that suggest plant invasions either enhance or degrade the mutualism between plants and arbuscular mycorrhizal (AM) fungi, but their relative support remains unknown. We conducted a meta-analysis using 67 publications, involving 70 native and 55 invasive plant species to assess support for the enhanced mutualism hypothesis, the degraded mutualism hypothesis and an alternative hypothesis that factors other than invasive status (such as plant functional group) better predict AM function following invasion. We used multiple measurements to test these hypotheses: AM fungal colonization, growth responses to AM fungi and AM fungal-mediated shifts in competitive interactions among native and invasive plants. Additionally, we assessed whether invasive plants alter AM associations in native plants and whether native and invasive plants host different AM fungal abundances and communities. Arbuscular mycorrhizal fungal colonization (%) and average growth responses did not differ between native and invasive plants. However, growth responses (±) were dampened among invasive plants, and the positive correlation between AM fungal colonization and growth response in native plants was absent in invasive plants. Rather than plant invasive status, plant functional group was a significant explanatory factor; forbs were generally more colonized and exhibited positive growth responses (when grown alone and in competition), whereas grass responses were neutral to negative. Arbuscular mycorrhizal fungal abundance (measured by percentage colonization, extraradical hyphal and spore densities, as well as neutral lipid fatty acid and glomalin concentrations) did not differ between native and invasive plants, but invasive plants hosted different AM fungal communities in 78% of studies. AM fungal colonization of native plants was lower when grown with, or after, invasive plants, likely due to the prevalence of non-mycorrhizal plants in studies of neighbour and legacy effects. Synthesis. Neither the degraded nor the enhanced mutualism hypothesis was supported, suggesting that invasions do not select for directional shifts in AM associations. Instead, our results indicate that AM fungi are most likely to influence invasion trajectories when native and invasive plants belong to different functional groups. Neither the degraded nor the enhanced mutualism hypothesis was supported, suggesting that invasions do not select for directional shifts in arbuscular mycorrhizal (AM) associations. Instead, our results indicate that AM fungi are most likely to influence invasion trajectories when native and invasive plants belong to different functional groups. © 2015 British Ecological Society.

Lekberg Y.,Copenhagen University | Schnoor T.,Lund University | Kjoller R.,Copenhagen University | Gibbons S.M.,MPG Ranch | And 4 more authors.
Journal of Ecology | Year: 2012

1. Disturbance is assumed to be a major driver of plant community composition, but whether similar processes operate on associated soil microbial communities is less known. Based on the assumed trade-off between disturbance tolerance and competiveness, we hypothesize that a severe disturbance applied within a semi-natural grassland would shift the arbuscular mycorrhizal (AM) fungal community towards disturbance-tolerant fungi that are rare in undisturbed soils. 2. We used 454-sequencing of the large subunit rDNA region to characterize AM fungal communities in Plantago lanceolata roots grown in the field for 4months and exposed either to no disturbance or to severe disturbance where fungi from undisturbed soil were either permitted or prevented from re-colonizing the disturbed area. This allowed for a distinction between AM fungi that survived the disturbance and those that quickly re-colonized after a disturbance. To identify AM fungi that could potentially colonize the experimental plants, we also analysed roots from adjacent, undisturbed vegetation. 3. We found 32 fungal operational taxonomic units (OTUs) distributed across five known AM fungal families. Contrary to our expectations, disturbance did not significantly alter the community composition and OTU richness. Instead, OTU abundances were positively correlated across treatments; i.e., common OTUs in undisturbed soil were also common after the severe disturbance. However, the distribution of OTUs within and between plots was largely unpredictable, with approximately 40% of all sequences within a sample belonging to a single OTU of varying identity. The distribution of two plant species that are often poorly colonized by AM fungi (Dianthus deltoides and Carex arenaria) correlated significantly with the OTU composition, which may indicate that host quality could be an additional driver of fungal communities. 4. Synthesis. Our results suggest that factors other than disturbance drive the relative abundance of OTUs in this grassland and question the long-held assumption that communities shift in a predictable manner after a disturbance event. The reassembly of this fungal community indicates a high community resilience, but substantial local stochasticity and dominance by single OTUs, which could be due to priority effects among abundant AM fungi possessing a similar - and high - degree of disturbance tolerance. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.

Herget M.E.,University of Wyoming | Hufford K.M.,University of Wyoming | Mummey D.L.,MPG Ranch | Shreading L.N.,MPG Ranch
PLoS ONE | Year: 2015

Local, wild-collected seeds of native plants are recommended for use in ecological restoration to maintain patterns of adaptive variation. However, some environments are so drastically altered by exotic, invasive weeds that original environmental conditions may no longer exist. Under these circumstances, cultivated varieties selected for improved germination and vigor may have a competitive advantage at highly disturbed sites. This study investigated differences in early establishment and seedling performance between wild and cultivated seed sources of the native grass, Poa secunda, both with and without competition from the invasive exotic grass, Bromus tectorum.We measured seedling survival and above-ground biomass at two experimental sites in western Montana, and found that the source of seeds selected for restoration can influence establishment at the restoration site. Cultivars had an overall advantage when compared with local genotypes, supporting evidence of greater vigor among cultivated varieties of native species. This advantage, however, declined rapidly in the presence of B. tectorum and most accessions were not significantly different for growth and survival in competition plots. Only one cultivar had a consistent advantage despite a strong decline in its performance when competing with invasive plants. As a result, cultivated varieties did not meet expectations for greater establishment and persistence relative to local genotypes in the presence of invasive, exotic species. We recommend the use of representative local or regional wild seed sources in restoration to minimize commercial selection, and a mix of individual accessions (wild, or cultivated when necessary) in highly invaded settings to capture vigorous genotypes and increase the odds native plants will establish at restoration sites. © 2015 Herget et al.

Madsen M.D.,U.S. Department of Agriculture | Davies K.W.,U.S. Department of Agriculture | Mummey D.L.,MPG Ranch | Svejcar T.J.,U.S. Department of Agriculture
Rangeland Ecology and Management | Year: 2014

Cost-efficient strategies for revegetating annual grass-infested rangelands are limited. Restoration efforts typically comprise a combination of pre-emergent herbicide application and seeding to restore desired plant materials. However, practitioners struggle with applying herbicide at rates sufficient to achieve weed control without damaging nontarget species. The objective of this research was to determine if seed enhancement technologies using activated carbon would improve selectivity of the pre-emergent herbicide imazapic. Bluebunch wheatgrass (Pseudoroegneria spicata) seed was either untreated, coated with activated carbon, or incorporated into "herbicide protection pods" (HPPs) made of activated carbon through a newly developed seed extrusion technique. In a grow-room facility, bluebunch wheatgrass seeds were sown in pots that contained seed of the exotic-annual grass downy brome (Bromus tectorum). After planting, pots were sprayed with 70, 105, 140, or 210 g acid equivalent (ae) · ha-1 of imazapic or left unsprayed. Where herbicide was not applied, downy brome biomass dominated the growing space. Imazapic effectively controlled downy brome and untreated bluebunch wheatgrass. Seed coating improved bluebunch wheatgrass tolerance to imazapic at 70 g ae · ha-1. HPPs provided protection from imazapic at all application rates. When untreated seeds and HPPs are compared at the four levels of herbicide application (excluding the no herbicide level), HPPs on average were 4.8-, 3.8-, and 19.0-fold higher than untreated seeds in density, height, and biomass, respectively. These results indicate that HPPs and, to a lesser extent, activated carbon-coated seed have the potential to further enhance a single-entry revegetation program by providing land practitioners with the ability to apply imazapic at rates necessary for weed control while minimizing nontarget plant injury. Additional research is merited for further development and evaluation of these seed enhancement technologies, including field studies, before they can be recommended as restoration treatments. © 2014 The Society for Range Management.

PubMed | University of British Columbia, University of Guelph, MPG Ranch and U.S. Department of Agriculture
Type: Journal Article | Journal: Science (New York, N.Y.) | Year: 2017

Feedback with soil biota is an important determinant of terrestrial plant diversity. However, the factors regulating plant-soil feedback, which varies from positive to negative among plant species, remain uncertain. In a large-scale study involving 55 species and 550 populations of North American trees, the type of mycorrhizal association explained much of the variation in plant-soil feedbacks. In soil collected beneath conspecifics, arbuscular mycorrhizal trees experienced negative feedback, whereas ectomycorrhizal trees displayed positive feedback. Additionally, arbuscular mycorrhizal trees exhibited strong conspecific inhibition at multiple spatial scales, whereas ectomycorrhizal trees exhibited conspecific facilitation locally and less severe conspecific inhibition regionally. These results suggest that mycorrhizal type, through effects on plant-soil feedbacks, could be an important contributor to population regulation and community structure in temperate forests.

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