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Danthonia californica Bolander (Poaceae)is a native perennial bunchgrass commonly used in the restoration of prairie ecosystems in the western United States. Plants of this species simultaneously produce both chasmogamous (potentially outcrossed) and cleistogamous (obligately self‐fertilized) seeds. Restoration practitioners almost exclusively use chasmogamous seeds for outplanting, which are predicted to perform better in novel environments due to their greater genetic diversity. Meanwhile, cleistogamous seeds may exhibit greater local adaptation to the conditions in which the maternal plant exists. We performed a common garden experiment at two sites in the Willamette Valley, Oregon, to assess the influence of seed type and source population (eight populations from a latitudinal gradient) on seedling emergence and found no evidence of local adaptation for either seed type. Cleistogamous seeds outperformed chasmogamous seeds, regardless of whether seeds were sourced directly from the common gardens (local seeds) or other populations (nonlocal seeds). Furthermore, average seed weight had a strong positive effect on seedling emergence, despite the fact that chasmogamous seeds had significantly greater mass than cleistogamous seeds. At one common garden, we observed that seeds of both types sourced from north of our planting site performed significantly better than local or southern‐sourced seeds. We also found a significant seed type and distance‐dependent interaction, with cleistogamous seedling emergence peaking approximately 125 km from the garden. These results suggest that cleistogamous seeds should be considered for greater use in D. californica restoration. [ABSTRACT FROM AUTHOR]

Ecological restoration often relies on disturbance as a tool for establishing target plant communities, but disturbance can be a double‐edged sword, at times initiating invasion and unintended outcomes. Here we test how fire disturbance, designed to enhance restoration seeding success, combines with climate and initial vegetation conditions to shift perennial versus annual grass dominance and overall community diversity in Pacific Northwest grasslands. We seeded both native and introduced perennial grasses and native forbs in paired, replicated burned‐unburned plots in three sites along a latitudinal climate gradient from southern Oregon to central‐western Washington. Past restoration and climate manipulations at each site had increased the variation of starting conditions between plots. Burning promoted the expansion of extant forbs and perennial grasses across all sites. Burning also enhanced the seeding success of native perennial grass and native forbs at the northern and central site, and the success of introduced perennial grasses across all three sites. Annual grass dominance was driven more by latitude than burning, with annuals maintaining their dominance in the south and perennials in the north. At the same time, unrestored grasslands surrounding all sites remained dominated by perennial grasses, suggesting that initial plot clearing may have allowed for annual grass invasion in the southern site. When paired with disturbance, further warming may increase the risk of annual grass dominance, a potentially persistent state. [ABSTRACT FROM AUTHOR]

Aim: How climate change will alter plant functional group composition is a critical question given the well‐recognized effects of plant functional groups on ecosystem services. While climate can have direct effects on different functional groups, indirect effects mediated through changes in biotic interactions have the potential to amplify or counteract direct climatic effects. As a result, identifying the underlying causes for climate effects on plant communities is important to conservation and restoration initiatives. Location: Western Pacific Northwest (Oregon and Washington), USA. Methods: Utilizing a 3‐year experiment in three prairie sites across a 520‐km latitudinal climate gradient, we manipulated temperature and precipitation and recorded plant cover at the peak of each growing season. We used structural equation models to examine how abiotic drivers (i.e. temperature, moisture and soil nitrogen) controlled functional group cover, and how these groups in turn determined overall plant diversity. Results: Warming increased the cover of introduced annual species, causing subsequent declines in other functional groups and diversity. While we found direct effects of temperature and moisture on extant vegetation (i.e. native annuals, native perennials and introduced perennials), these effects were typically amplified by introduced annuals. Competition for moisture and light or space, rather than nitrogen, were critical mechanisms of community change in this seasonally water‐limited Mediterranean‐climate system. Diversity declines were driven by reductions in native annual cover and increasing dominance by introduced annuals. Main conclusions: A shift towards increasing introduced annual dominance in this system may be akin to that previously experienced in California grasslands, resulting in the "Californication" of Pacific Northwest prairies. Such a phenomenon may challenge local land managers in their efforts to maintain species‐rich and functionally diverse prairie ecosystems in the future. [ABSTRACT FROM AUTHOR]

With ongoing climate change, populations are expected to exhibit shifts in demographic performance that will alter where a species can persist. This presents unique challenges for managing plant populations and may require ongoing interventions, including in situ management or introduction into new locations. However, few studies have examined how climate change may affect plant demographic performance for a suite of species, or how effective management actions could be in mitigating climate change effects. Over the course of two experiments spanning 6 yr and four sites across a latitudinal gradient in the Pacific Northwest, United States, we manipulated temperature, precipitation, and disturbance intensity, and quantified effects on the demography of eight native annual prairie species. Each year we planted seeds and monitored germination, survival, and reproduction. We found that disturbance strongly influenced demographic performance and that seven of the eight species had increasingly poor performance with warmer conditions. Across species and sites, we observed 11% recruitment (the proportion of seeds planted that survived to reproduction) following high disturbance, but just 3.9% and 2.3% under intermediate and low disturbance, respectively. Moreover, mean seed production following high disturbance was often more than tenfold greater than under intermediate and low disturbance. Importantly, most species exhibited precipitous declines in their population growth rates (λ) under warmer‐than‐ambient experimental conditions and may require more frequent disturbance intervention to sustain populations. Aristida oligantha, a C4 grass, was the only species to have λ increase with warmer conditions. These results suggest that rising temperatures may cause many native annual plant species to decline, highlighting the urgency for adaptive management practices that facilitate their restoration or introduction to newly suitable locations. Frequent and intense disturbances are critical to reduce competitors and promote native annuals' persistence, but even such efforts may prove futile under future climate regimes. [ABSTRACT FROM AUTHOR]

Summary: Demographic studies measure drivers of plant fecundity including seed production and survival, but few address both abiotic and biotic drivers of germination such as variation in climate among sites, population density, maternal plants, seed type and fungal pathogen abundance.We examined germination and microbial communities of seeds of Danthonia californica, which are either chasmogamous (external, wind‐pollinated) or cleistogamous (internal, self‐fertilized) and Festuca roemeri, which are solely chasmogamous. Seed populations were sourced across environmental gradients. We tested germination and used high‐throughput sequencing to characterize seed fungal community structure.For F. roemeri, maternal plants significantly influenced germination as did climate and pathogens; germination increased from wetter, cooler sites. For D. californica, the main drivers of germination were maternal plant, seed type and pathogens; on average, more chasmogamous seeds germinated. Fungal communities depended largely on seed type, with fewer fungi associated with cleistogamous seeds, but the communities also depended on site factors such as vapor pressure deficit, plant density and whether the seeds had germinated.Putative pathogens that were negatively correlated with germination were more abundant for both D. californica and F. roemeri chasmogamous seeds than D. californica cleistogamous seeds. In D. californica, cleistogamous and chasmogamous seeds contain vastly different fungal communities. [ABSTRACT FROM AUTHOR]

Spatial gradients in population growth, such as across latitudinal or elevational gradients, are often assumed to primarily be driven by variation in climate, and are frequently used to infer species' responses to climate change. Here, we use a novel demographic, mixed‐model approach to dissect the contributions of climate variables vs. other latitudinal or local site effects on spatiotemporal variation in population performance in three perennial bunchgrasses. For all three species, we find that performance of local populations decreases with warmer and drier conditions, despite latitudinal trends of decreasing population growth toward the cooler and wetter northern portion of each species' range. Thus, latitudinal gradients in performance are not predictive of either local or species‐wide responses to climate. This pattern could be common, as many environmental drivers, such as habitat quality or species' interactions, are likely to vary with latitude or elevation, and thus influence or oppose climate responses. [ABSTRACT FROM AUTHOR]

Predicting species' range shifts under future climate is a central goal of conservation ecology. Studying populations within and beyond multiple species' current ranges can help identify whether demographic responses to climate change exhibit directionality, indicative of range shifts, and whether responses are uniform across a suite of species.We quantified the demographic responses of six native perennial prairie species planted within and, for two species, beyond their northern range limits to a 3‐year experimental manipulation of temperature and precipitation at three sites spanning a latitudinal climate gradient in the Pacific Northwest, USA. We estimated population growth rates (λ) using integral projection models and tested for opposing responses to climate in different demographic vital rates (demographic compensation).Where species successfully established reproductive populations, warming negatively affected λ at sites within species' current ranges. Contrarily, warming and drought positively affected λ for the two species planted beyond their northern range limits. Most species failed to establish a reproductive population at one or more sites within their current ranges, due to extremely low germination and seedling survival. We found little evidence of demographic compensation buffering populations to the climate treatments.Synthesis. These results support predictions across a suite of species that ranges will need to shift with climate change as populations within current ranges become increasingly vulnerable to decline. Species capable of dispersing beyond their leading edges may be more likely to persist, as our evidence suggests that projected changes in climate may benefit such populations. If species are unable to disperse to new habitat on their own, assisted migration may need to be considered to prevent the widespread loss of vulnerable species. [ABSTRACT FROM AUTHOR]

1. Dracula orchids mimic mushrooms in appearance and scent, and are pollinated by mushroom flies. This study examined the guilds of insect visitors to Dracula species and to co‐occurring mushrooms in an Ecuadorean cloud forest. Significant visitor overlap was documented (mostly in the genera Zygothrica and Hirtodrosophila; Drosophilidae). To test the brood‐site mimicry hypothesis, behavioural observations were also performed and rearing success was examined. 2. Many fly species that visit Dracula are also found on mushrooms. Furthermore, the presence of pollinia enabled us to document the fact that particular individuals visiting mushrooms also visit Dracula. Roughly two‐thirds of the visitors to these unusual flowers are fungal‐associated, and the rest appear to be Dracula specialists. 3. A variety of behaviours common on both host groups were observed, including courtship semaphoring, feeding, sheltering, defending territory, and mating. Given this suite of shared reproductive behaviour, it was hypothesised that flies may also oviposit in both substrates. Flies were reared from mushrooms, Dracula spp., and other flowers (controls) to determine which substrate led to the highest fitness for the flies. Very few flies emerged from the Dracula flowers and there was no species overlap between the emergent insects and the known pollinators. 4. Despite the fact that there is evidence for brood‐site mimicry, the Dracula situation is complex. All the flies could derive many of the same fitness benefits from the flowers as they do from mushrooms (shelter, food, mating), but they are clearly not gaining the same fitness benefit, in terms of progeny, on flowers compared with mushrooms. [ABSTRACT FROM AUTHOR]

Plant phenology will likely shift with climate change, but how temperature and/or moisture regimes will control phenological responses is not well understood. This is particularly true in Mediterranean climate ecosystems where the warmest temperatures and greatest moisture availability are seasonally asynchronous. We examined plant phenological responses at both the population and community levels to four climate treatments (control, warming, drought, and warming plus additional precipitation) embedded within three prairies across a 520 km latitudinal Mediterranean climate gradient within the Pacific Northwest, USA. At the population level, we monitored flowering and abundances in spring 2017 of eight range‐restricted focal species planted both within and north of their current ranges. At the community level, we used normalized difference vegetation index (NDVI) measured from fall 2016 to summer 2018 to estimate peak live biomass, senescence, seasonal patterns, and growing season length. We found that warming exerted a stronger control than our moisture manipulations on phenology at both the population and community levels. Warming advanced flowering regardless of whether a species was within or beyond its current range. Importantly, many of our focal species had low abundances, particularly in the south, suggesting that establishment, in addition to phenological shifts, may be a strong constraint on their future viability. At the community level, warming advanced the date of peak biomass regardless of site or year. The date of senescence advanced regardless of year for the southern and central sites but only in 2018 for the northern site. Growing season length contracted due to warming at the southern and central sites (~3 weeks) but was unaffected at the northern site. Our results emphasize that future temperature changes may exert strong influence on the timing of a variety of plant phenological events, especially those events that occur when temperature is most limiting, even in seasonally water‐limited Mediterranean ecosystems. [ABSTRACT FROM AUTHOR]

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Flowers use olfactory and visual signals to communicate with pollinators. Disentangling the relative contributions and potential synergies between signals remains a challenge. Understanding the perceptual biases exploited by floral mimicry illuminates the evolution of these signals. Here, we disentangle the olfactory and visual components of Dracula lafleurii, which mimics mushrooms in size, shape, color and scent, and is pollinated by mushroom-associated flies., To decouple signals, we used three-dimensional printing to produce realistic artificial flower molds that were color matched and cast using scent-free surgical silicone, to which we could add scent. We used GC- MS to measure scents in co-occurring mushrooms, and related orchids, and used these scents in field experiments., By combining silicone flower parts with real floral organs, we created chimeras that identified the mushroom-like labellum as a source of volatile attraction. In addition, we showed remarkable overlap in the volatile chemistry between D. lafleurii and co-occurring mushrooms., The characters defining the genus Dracula - a mushroom-like, 'gilled' labellum and a showy, patterned calyx - enhance pollinator attraction by exploiting the visual and chemosensory perceptual biases of drosophilid flies. Our techniques for the manipulation of complex traits in a nonmodel system not conducive to gene silencing or selective breeding are useful for other systems. [ABSTRACT FROM AUTHOR]

Loss of forests due to non-native invasive pests (including insects, nematodes, and pathogens) is a global phe-nomenon with profound population, community, ecosystem, and economic impacts. We review the magnitude of pest-associated forest loss worldwide and discuss the major ecological and evolutionary causes and conse-quences of these invasions. After compiling and analyzing a dataset of pest invasions from 21 countries, we show that the number of forest pest invasions recorded for a given country has a significant positive relation-ship with trade (as indicated by gross domestic product) and is not associated with the amount of forested land within that country. We recommend revisions to existing international protocols for preventing pest entry and proliferation, including prohibiting shipments of non-essential plants and plant products unless quarantined. Because invasions often originate from taxa that are scientifically described only after their introduction, cur-rent phytosanitary regulations - which target specific, already named organisms - are ineffective. [ABSTRACT FROM AUTHOR]

The enemy-release hypothesis (ERH) states that species become more successful in their introduced range than in their native range because they leave behind natural enemies in their native range and are thus "released" from enemy pressures in their introduced range. The ERH is popularly cited to explain the invasive properties of many species and is the underpinning of biological control. We tested the prediction that plant populations are more strongly regulated by natural enemies (herbivores and pathogens) in their native range than in their introduced range with enemy-removal experiments using pesticides. These experiments were replicated at multiple sites in both the native and invaded ranges of the grass Brachypodium sylvaticum. In support of the ERH, enemies consistently regulated populations in the native range. There were more tillers and more seeds produced in treated vs. untreated plots in the native range, and few seedlings survived in the native range. Contrary to the ERH, total measured leaf damage was similar in both ranges, though the enemies that caused it differed. There was more damage by generalist mollusks and pathogens in the native range, and more damage by generalist insect herbivores in the invaded range. Demographic analysis showed that population growth rates were lower in the native range than in the invaded range, and that sexually produced seedlings constituted a smaller fraction of the total in the native range. Our removal experiment showed that enemies regulate plant populations in their native range and suggest that generalist enemies, not just specialists, are important for population regulation. [ABSTRACT FROM AUTHOR]

Pathogens and herbivores can severely reduce host fitness, potentially leading to altered succession rates and changes in plant community composition. Thus, to predict vegetation dynamics under climate change, it is necessary to understand how plant pathogens and herbivores will respond. Pathogens and herbivores are predicted to increase under climate warming because the amount of time available for growth and reproduction will increase. To test this prediction, we used a warming experiment in which heaters were suspended over a natural montane meadow for 12 years. In the summer of 2002, we quantified damage by all the observable (aboveground) pathogens and herbivores on six of the most common plant species (Artemisia tridentata, Helianthella quinquenervis, Erigeron speciosus, Potentilla gracilis, Potentilla hippiana, and Lathyrus leucanthus). We found that plants in the earlier melting plots generally had the most damage and were attacked by a larger number of species, which is consistent with predictions. However, although the overall trend was an increase in damage with warmer temperatures and earlier snowmelt, some pathogens and herbivores performed better in cooler or later melting plots. The idiosyncratic response of each species to environmental conditions suggests that there are likely to be changes in community composition as the planet warms. [ABSTRACT FROM AUTHOR]

Summary • Witches’ brooms on Berberis vulgari s are induced by a systemically infecting rust fungus, Puccinia arrhenatheri . These witches’ brooms bear yellow discolored leaves on which the fungus exposes its gametes in a sugary nectar. During the spermatial stage of the fungus the infected leaves emit a strong, flowery scent. • An exclusion-experiment was used to evaluate whether fungal reproductive success, defined by the ability of the fungus to produce aeciospores, depended on gamete transfer by insects. To determine whether insects were attracted to the infected leaves, and if so, why, visitation to infected and uninfected leaves was quantified and volatiles produced by leaves, infected leaves and flowers were analyzed. • The production of aeciospores was significantly higher on witches’ brooms with insect visitation. Visitation rates were higher and visits were longer on witches’ brooms than on uninfected branches. A wide diversity of visitors, mainly Diptera and Hymenoptera, was observed. The volatiles emitted by infected leaves were composed of sweet floral fragrances and insect pheromones. • Our results suggest that sexual reproduction of the pathogen requires out-crossing by insects and that infected leaves attract insects by floral mimicry (bright yellow color and the production of sugary nectar and volatiles). [ABSTRACT FROM AUTHOR]

Premise Methods Results Conclusions Understanding how population dynamics vary in space and time is critical for understanding the basic life history and conservation needs of a species, especially for narrow endemic species whose populations are often in similar environments and therefore at increased risk of extinction under climate change. Here, we investigated the spatial and temporal variation in population dynamics of Ranunculus austro‐oreganus, a perennial buttercup endemic to fragmented prairie habitat in one county in southern Oregon.We performed demographic surveys of three populations of R. austro‐oreganus over 4 years (2015–2018). We used size‐structured population models and life table response experiments to investigate vital rates driving spatiotemporal variation in population growth.Overall, R. austro‐oreganus had positive or stable stochastic population growth rates, though individual vital rates and overall population growth varied substantially among sites and years. All populations had their greatest growth in the same year, suggesting potential synchrony associated with climate conditions. Differences in survival contributed most to spatial variation in population growth, while differences in reproduction contributed most to temporal variation in population growth.Populations of this extremely narrow endemic appear stable, with positive growth during our study window. These results suggest that populations of R. austro‐oreganus are able to persist if their habitat is not eliminated by land‐use change. Nonetheless, its narrow distribution and synchronous population dynamics suggest the need for continued monitoring, particularly with ongoing habitat loss and climate change. [ABSTRACT FROM AUTHOR]

Phenology—recurring seasonal events in an organism's life cycle—is largely driven by local climates <1 km2 (microclimates), and changes in phenology are frequently used to indicate a species' or community response to climate change. Phenological shifts can result in trophic asynchrony, population declines of higher‐level consumers, and reduction of plant fitness. While timing of phenological events is often correlated with elevation, studies have shown that microclimates created by areas of heterogeneous topography can be decoupled from regional climate patterns and that the distribution of microclimates does not always follow the elevation gradient. To examine the interaction between regional weather patterns and microclimate, and the subsequent effect of microclimate on phenology, we conducted standardized weekly spring phenology surveys of 18 native forest plants at the H.J. Andrews Experimental Forest in the Western Cascades from 2009 to 2016. We saw a high degree of inter‐annual variability of microclimate within and across sites, resulting in a changing pattern of microclimate diversity across the landscape from year to year. Most importantly, we saw that years with regional conditions predicted by continued climate change showed a loss of diversity in both microclimate and phenological events, with a more rapid advancement in bud break occurring at higher elevation sites. This study highlights the importance of understanding the interactions between regional and local processes that determine microclimate conditions and how those conditions influence patterns of plant phenology within forest communities, across mountain landscapes and over time, with implications for the capacity of mountainous regions to buffer local communities against the effects of climate change. [ABSTRACT FROM AUTHOR]