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Corvallis, OR, United States

Lawrence B.A.,Oregon State University | Kaye T.N.,Oregon State University | Kaye T.N.,Institute for Applied Ecology
Restoration Ecology | Year: 2011

A suite of ecological and genetic factors are likely to contribute to reintroduction performance. Potential factors include the ecological similarity between seed source and introduction site, population size and genetic diversity of seed sources, and the habitat quality of the introduction site. We conducted common garden experiments with golden paintbrush (Castilleja levisecta), an endangered species from the Pacific Northwest, U.S.A., in order to test hypotheses about reintroduction performance and to provide management recommendations. Ten common gardens, each composed of C. levisecta individuals grown from seed from six of the remaining populations, were planted into field conditions and monitored during two growing seasons. Plant community characteristics were important predictors of observed variation in C. levisecta performance. Exotic species-cover at common garden sites was associated with a reduction in performance of first-year C. levisecta transplants, while survival to the second growing season increased with increasing similarity in plant functional groups between source and common garden sites. Although measures of genetic diversity, population size, and geographic distance are often used to make conservation decisions during species recovery, here they were poor predictors of C. levisecta performance and establishment. We recommend choosing material for reintroduction from ecologically similar habitats, rather than those most proximate geographically, and selecting recovery sites with low exotic species abundance. © 2009 Society for Ecological Restoration International. Source

Thorpe A.S.,Institute for Applied Ecology | Aschehoug E.T.,University of Montana | Atwater D.Z.,University of Montana | Callaway R.M.,University of Montana
Journal of Ecology | Year: 2011

Interactions among plants and their consumers, pollinators and dispersers are central to evolutionary theory, but interactions among plants themselves have received much less attention. Thus focusing more attention on the evolutionary role of plant-plant interactions may provide greater insight into the processes that organize communities. Here, we integrate divergent themes in the literature in an effort to provide a synthesis of empirical evidence and ideas about how plant interactions may affect evolution and how evolution may affect plant interactions. First, we discuss the idea of niche partitioning evolving through competitive interactions among plants, the idea of niche construction evolving through facilitative interactions, and the connections between these ideas and more recent research on diversity and ecosystem function and trait-based community organization. We then review how a history of coexistence within a region might affect competitive outcomes and explore the mechanisms by which plants exert selective forces on each other. Next, we consider recent research on invasions suggesting that plant interactions can reflect regional evolutionary trajectories. Finally, we place these lines of research into the context of extended phenotypes and the geographic mosaic of co-evolution. Synthesis. Our synthesis of separate lines of inquiry is a step towards understanding the evolutionary importance of interactions among plants, and suggests that the evolutionary consequences of interactions contribute to communities that are more than assemblages of independent populations. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society. Source

Thorpe A.S.,Institute for Applied Ecology | Thorpe A.S.,University of Montana | Callaway R.M.,University of Montana
Biological Invasions | Year: 2011

The success of some invasive plants may be due in part to native organisms lacking adaptation to species-specific biochemical traits of invaders-the Novel Weapons Hypothesis. We tested this hypothesis in the context of soil microbial communities by comparing the effects of Centaurea stoebe and the root exudate (±)-catechin, on ammonification and nitrification in both the non-native and native ranges of this species. In a non-native range (Montana), soil nitrate (NO3 -) concentrations were lower in invaded than uninvaded grasslands. This did not appear to be due only to higher uptake rates as both C. stoebe plants and catechin significantly reduced resin extractable NO3 -, the maximum rate of nitrification, and gross nitrification in Montana soils. Thus, reduced NO3 - in invaded communities may be due in part to the inhibition of nitrifying bacteria by secondary metabolites produced by C. stoebe. The effects of C. stoebe on N-related processes were different in Romanian grasslands, where C. stoebe is native. In Romanian soil, C. stoebe had no effect on resin extractable NH4 + or NO3 - (compared to other plant species), the maximum rate of nitrification, nor gross nitrification. A relatively high concentration of catechin reduced the maximum rate of nitrification in situ, but substantially less than in Montana. In vivo, gross ammonification was lowest when treated with catechin. Our results suggest biogeographic differences in the way a plant species alters nitrogen cycling through the direct effects of root exudates and adds to a growing body of literature demonstrating the important belowground effects of invasive plants. © Springer Science+Business Media B.V.2010. Source

Pollock J.L.,University of Montana | Kogan L.A.,University of Montana | Thorpe A.S.,Institute for Applied Ecology | Holben W.E.,University of Montana
Journal of Chemical Ecology | Year: 2011

Understanding the effects of allelopathic plant chemicals on soil microorganisms is critical to understanding their ecological roles and importance in exotic plant invasion. Centaurea stoebe Lam. (spotted knapweed), an aggressive invasive weed in North America, secretes a racemic mixture of (±)-catechin as a root exudate. This enantiomeric, polyphenolic compound has been reported to have allelopathic effects on surrounding flora and microflora. To better understand how catechin affects microbial communities in the root zone of spotted knapweed, we assessed its impact on the total culturable bacterial component and numerous individual bacterial populations from Romanian (native range) and Montana (invaded range) soils. Catechin suppressed total culturable count numbers from the bacterial community and inhibited growth of some, but not all, soil bacterial populations tested. The native soil bacterial community was significantly more resistant to inhibitory effects of catechin than either the invaded or non-invaded soils. We further show that the inhibitory effect of catechin on nine different soil bacterial strains from seven genera was reversible, demonstrating that it acts via a bacteriostatic rather than bactericidal mechanism. These findings suggest that catechin might affect bacterial community composition and activity in the root zone. © 2011 Springer Science+Business Media, LLC. Source

Crone E.E.,University of Montana | Menges E.S.,Archbold Biological Station | Ellis M.M.,University of Montana | Bell T.,Chicago State University | And 12 more authors.
Ecology Letters | Year: 2011

Matrix projection models are among the most widely used tools in plant ecology. However, the way in which plant ecologists use and interpret these models differs from the way in which they are presented in the broader academic literature. In contrast to calls from earlier reviews, most studies of plant populations are based on < 5 matrices and present simple metrics such as deterministic population growth rates. However, plant ecologists also cautioned against literal interpretation of model predictions. Although academic studies have emphasized testing quantitative model predictions, such forecasts are not the way in which plant ecologists find matrix models to be most useful. Improving forecasting ability would necessitate increased model complexity and longer studies. Therefore, in addition to longer term studies with better links to environmental drivers, priorities for research include critically evaluating relative/comparative uses of matrix models and asking how we can use many short-term studies to understand long-term population dynamics. © 2010 Blackwell Publishing Ltd/CNRS. Source

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