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Data from: Large herbivores trigger spatiotemporal changes in forest plant diversity
Beguin, Julien; Côté, Steeve D.; Vellend, Mark — 2022-04-18 <p class="MsoNormal"><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale-dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (</span><em><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">Odocoileus virginianus</span></em><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided a rare opportunity to test </span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">whether deer herbivory represents a direct filter on plant communities or if it mainly acts to suppress dominant plants which, in turn, release other plant species from strong negative plant-plant interactions. These two hypotheses make different predictions about changes in community composition, alpha and beta diversity in different</span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;"> vegetation layers and at different spatial scales. Our results showed that deer had strong effects on plant community composition and successional trajectories, but the resulting impacts on plant alpha and beta diversity patterns were markedly scale-dependent in both time and space. Responses of tree and non-tree vegetation layers were strongly asymmetric. Deer acted both as a direct filter and as a suppressor of dominant plant species during early forest succession, but the magnitude of both processes was specific to tree and non-tree vegetation layers. Although our data supported the </span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">ungulate-driven </span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">homogenization hypothesis, </span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;">compositional shifts and changes of alpha diversity were poor predictors of beta diversity loss.</span><span style="font-family:'Times New Roman';font-size:12 , 0000pt;"> Our findings underscore the importance of long-term studies in revealing non-linear temporal community trends, and they challenge managers to prioritize particular community properties and scales of interest, given contrasting trends of composition, alpha, and beta diversity across spatial scales.</span></p>
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Data from: Characterizing the contribution of plasticity and genetic differentiation to community-level trait responses to environmental change
Lajoie, Geneviève; Vellend, Mark — 2019-02-07 The match between functional trait variation in communities and environmental gradients is maintained by three processes: phenotypic plasticity and genetic differentiation (intraspecific processes), and species turnover (interspecific). Recently, evidence has emerged suggesting that intraspecific variation might have a potentially large role in driving functional community composition and response to environmental change. However, empirical evidence quantifying the respective importance of phenotypic plasticity and genetic differentiation relative to species turnover is still lacking. We performed a reciprocal transplant experiment using a common herbaceous plant species (Oxalis montana) among low-, mid-, and high-elevation sites to first quantify the contributions of plasticity and genetic differentiation in driving intraspecific variation in three traits: height, specific leaf area and leaf area. We next compared the contributions of these intraspecific drivers of community trait-environment matching to that of species turnover, which had been previously assessed along the same elevational gradient. Plasticity was the dominant driver of intraspecific trait variation across elevation in all traits, with only a small contribution of genetic differentiation among populations. Local adaptation was not detected to a major extent along the gradient. Fitness components were greatest in O. montana plants with trait values closest to the local community-weighted means, thus supporting the common assumption that community-weighted mean trait values represent selective optima. Our results suggest that community-level trait responses to ongoing climate change should be mostly mediated by species turnover, even at the small spatial scale of our study, with an especially small contribution of evolutionary adaptation within species. https://creativecommons.org/publicdomain/zero/1.0/
Université de Montréal Dataverse Translation missing: fr.blacklight.search.logo
Models for Predicting leaf traits across functional groups using reflectance spectroscopy
Borealis
Kothari, Shan; Beauchamp-Rioux, Rosalie; Blanchard, Florence; Crofts, Anna L.; Girard, Alizée; Guilbeault-Mayers, Xavier; Hacker, Paul; Pardo, Juliana; Schweiger, Anna K.; Demers-Thibeault, Sabrina; Bruneau, Anne; Coops, Nicholas C.; Kalacska, Margaret; Vellend, Mark; Laliberté, Etienne — 2022-11-14 (2022-11-12) This repository contains the partial least-squares regression (PLSR) model coefficients to accompany the paper "Predicting leaf traits across functional groups using reflectance spectroscopy" by Kothari et al. (2023) <em>New Phytologist</em> (DOI: 10.1111/nph.18713). The repository includes the models in various sets of .csv files along with a README that contains detailed instructions about what the models mean and how to use them. 2023-04-06 Update: We have added models to predict EWT for fresh leaves under field conditions rather than rehydrated leaves. These models are found in the folder EWTCorrectedModels. It is recommended to use these rather than the other EWT models for most purposes.
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Data from: Adaptation to elevated CO2 in different biodiversity contexts
Dryad
Kleynhans, Elizabeth J.; Otto, Sarah P.; Reich, Peter B.; Vellend, Mark — 2017-06-03 In the absence of migration, species persistence depends on adaption to a changing environment, but whether and how adaptation to global change is altered by community diversity is not understood. Community diversity may prevent, enhance or alter how species adapt to changing conditions by influencing population sizes, genetic diversity and/or the fitness landscape experienced by focal species. We tested the impact of community diversity on adaptation by performing a reciprocal transplant experiment on grasses that evolved for 14 years under ambient and elevated CO2, in communities of low or high species-richness. Using biomass as a fitness proxy, we find evidence for local adaptation to elevated CO2, but only for plants assayed in a community of similar diversity to the one experienced during the period of selection. Our results indicate that the biological community shapes the very nature of the fitness landscape within which species evolve in response to elevated CO2.
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Data from: Non-climatic constraints on upper elevational plant range expansion under climate change
Brown, Carissa D.; Vellend, Mark — 2014-08-29 We are limited in our ability to predict climate-change-induced range shifts by our inadequate understanding of how non-climatic factors contribute to determining range limits along putatively climatic gradients. Here, we present a unique combination of observations and experiments demonstrating that seed predation and soil properties strongly limit regeneration beyond the upper elevational range limit of sugar maple, a tree species of major economic importance. Most strikingly, regeneration beyond the range limit occurred almost exclusively when seeds were experimentally protected from predators. Regeneration from seed was depressed on soil from beyond the range edge when this soil was transplanted to sites within the range, with indirect evidence suggesting that fungal pathogens play a role. Non-climatic factors are clearly in need of careful attention when attempting to predict the biotic consequences of climate change. At minimum, we can expect non-climatic factors to create substantial time lags between the creation of more favourable climatic conditions and range expansion.
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Data from: Herbivory and pollen limitation at the upper elevational range limit of two forest understory plants of eastern North America
Dryad
Rivest, Sébastien; Vellend, Mark — 2018-08-10 Studies of species’ range limits focus most often on abiotic factors, although the strength of biotic interactions might also vary along environmental gradients and have strong demographic effects. For example, pollinator abundance might decrease at range limits due to harsh environmental conditions, and reduced plant density can reduce attractiveness to pollinators and increase or decrease herbivory. We tested for variation in the strength of pollen limitation and herbivory by ungulates along a gradient leading to the upper elevational range limits of Trillium erectum (Melanthiaceae) and Erythronium americanum (Liliaceae) in Mont-Mégantic National Park, Québec, Canada. In T. erectum, pollen limitation was higher at the range limit, but seed set decreased only slightly with elevation and only in one of two years. In contrast, herbivory of T. erectum increased from <10% at low elevations to >60% at the upper elevational range limit. In E. americanum, we found no evidence of pollen limitation despite a significant decrease in seed set with elevation, and herbivory was low across the entire gradient. Overall, our results demonstrate the potential for relatively strong negative interactions (herbivory) and weak positive interactions (pollination) at plant range edges, although this was clearly species-specific. To the extent that these interactions have important demographic consequences – highly likely for herbivory on Trillium, based on previous studies – such interactions might play a role in determining plant species’ range limits along putatively climatic gradients.
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Earlier spring reduces potential for gene flow via reduced flowering synchrony across an elevational gradient
Dryad
Rivest, Sébastien; Lajoie, Geneviève; Watts, David; Vellend, Mark — 2021-03-20 <p style="text-align:justify;"><b>Premise</b>: One of the best-documented ecological responses to climate warming involves temporal shifts of phenological events. However, we lack an understanding of how phenological responses to climate change vary among populations of the same species. Such variability has the potential to affect flowering synchrony among populations and hence the potential for gene flow.</p> <p style="text-align:justify;"><b>Methods</b>: To test if an earlier start of the growing season affects the potential for gene flow among populations, we quantified the distributions of flowering times of two spring-flowering plants (<i>Trillium erectum</i> and <i>Erythronium americanum</i>) over six years along an elevation gradient. We developed a novel model-based metric of potential gene flow between pairs of populations to quantify the potential for pollen-mediated gene flow based on flowering phenology.</p> <p style="text-align:justify;"><b>Results</b>: For both species investigated, earlier onset of spring led to greater separation of peak flowering dates across the elevation gradient. For <i>T. erectum</i>, but not <i>E. americanum</i>, this<i> </i>was also associated with a reduction in potential gene flow.</p> <p style="text-align:justify;"><b>Conclusion</b>: Our study suggests that climate change could decrease gene flow via phenological separation among populations along climatic gradients. We also provide a novel method for quantifying potential pollen-mediated gene flow using data on flowering phenology, based on a quantitative, more biologically interpretable model than other available metrics.</p>

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