bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resilience to chronic defoliation in a dioecious understorey tropical rain forest palm
Authors: Lopez‐Toledo Leonel , Anten Niels P. R. , Endress Bryan A. , Ackerly David D. , Martínez‐Ramos Miguel 
Published: May 2013

Summary1. Perennial plants often endure chronic loss of leaf area due to recurrent physical damage, herbivory and, for species used as non‐timber forest products, due to leaf harvesting. However, little is known about functional and demographic resilience (extent and speed of recovery) of plants subjected to varying levels of chronic defoliation.2. We used a dioecious, understorey palm (Chamaedorea elegans) to evaluate temporal trajectories and rates of recovery of leaf functional traits and vital rates (survival, growth and reproduction) after being subjected to experimental chronic defoliation regimes.3. Pristine populations of mature C. elegans, categorized by gender (male and female), were subjected to five defoliation levels (0%, 33%, 50%, 66% or 100% of newly produced leaves) every 6 months over a period of 3 years (1997–2000). To evaluate recovery from defoliation, surviving palms were monitored for 3 years after the cessation of the defoliation treatment (2000–2003). We recorded leaf functional traits (leaf persistence, leaf production rate, leaf size and leaf area) and annual rates of mortality, growth and reproduction.4. Cumulative effects of chronic defoliation concomitantly reduced leaf traits, survival, growth and reproduction, and this effect was stronger in female than in male palms, independent of plant size. Recovery from defoliation was faster in males than in females, but proceeded gradually overall. Survival increased first, followed by growth, while reproductive traits showed the slowest recovery rate. Recovery was independent of plant size. Notably, 3 years after defoliation treatment, the standing leaf area and probability of reproduction had not recovered to pre‐defoliation levels. Additionally, we found that the occurrence of a severe drought in the first year (2000) after defoliation ceased led to decreased survival, growth and reproduction and the ability of plants to recover from defoliation.5. Synthesis. Chronic defoliation reduces fitness components of C. elegans palms differentially between genders. Recovery is gradual and is slower and less complete in females compared with males. The lower level of resilience to chronic defoliation shown by female plants may have profound consequences for the dynamics and genetic variability of populations of tropical understorey plants undergoing prolonged defoliation. Such effects may be aggravated by severe drought episodes that are expected to increase in frequency according to global climate change predictions.
Multiple competitive mechanisms underlie the effects of a strong invader on early‐ to late‐seral tree seedlings
Authors: Urgenson Lauren S. , Reichard Sarah H. , Halpern Charles B. 
Published: May 2013

Summary1. Certain non‐native invaders reduce the species diversity and alter the structure of natural communities by displacing native species with differing life histories, successional roles or resource requirements. Few studies have tested the potential for these ‘strong invaders’ to exert multiple mechanisms of control on natives that differ in these traits.2. We assessed the mechanisms by which bohemian knotweed (Polygonum × bohemicum) regulates seedling growth and survival among early‐, mid‐ and late‐seral tree species in a riparian forest ecosystem in western North America. We used general linear mixed models to compare seedling performance (survival, height and diameter growth, biomass allocation and ectomycorrhizal colonization of root systems) over two growing seasons in paired experimental plots from which knotweed was either removed or retained (controls). Seedling performance was assessed relative to the effects of knotweed on light and soil resources and the traits of the native species.3. Results from paired t‐tests suggest that knotweed had a significant effect on light availability (>85% reduction), but small, mostly non‐significant effects on measured soil properties. Knotweed imposed strong controls on growth and survival of all three tree species. The apparent mechanisms of interaction varied in a manner consistent with species’ ecophysiologies. Reduced survival of early‐ and mid‐seral species was correlated with light limitation beneath knotweed (≤ 7% of ambient levels): light transmittance was significantly higher (79%) above surviving seedlings. Knotweed also exerted strong controls on the late‐seral species, reducing survival by 24% and height and diameter growth by 91–122% and 37–55%. These effects were not correlated with reductions in light. Instead, in the presence of knotweed, ectomycorrhizal colonization was significantly reduced (64%) and root/shoot ratio was significantly increased, suggesting a disruption of soil mutualisms.4. Synthesis. We demonstrate that strong invaders can displace co‐occurring native species through multiple mechanisms that are consistent with the functional traits of native species. To our knowledge, this is the first study to relate community‐level impacts of an invader to the combined effects of resource exploitation and interference of below‐ground mutualisms. Where invaders have the ability to displace early‐ to late‐seral dominants, the consequences for community structure and ecosystem functioning can be profound.
Species and organ specificity of fungal endophytes in herbaceous grassland plants
Authors: Wearn James A. , Sutton Brian C. , Morley Neil J. , Gange Alan C. 
Published: May 2013

Summary1. aFoliar endophytic fungi in herbaceous plants are known to be diverse, yet studies characterizing the fungal communities in roots and shoots of plants across time are absent. These fungi are supposedly ubiquitous in nature, infecting plants through airborne spores. As many foliar endophytes can also exist in soil, we hypothesized that there would be a strong similarity between root and shoot endophytes in any given plant species and that differences between plant species would be greater than those between organs within a species.2. Leaf and root fungal endophyte communities were assessed in field‐collected plants of three co‐occurring grassland forbs (Cirsium arvense, Plantago lanceolata and Rumex acetosa) in two contrasting seasons (winter and summer). The former two species are mycorrhizal, whilst the latter species is not so.3. The highest fungal species richness was recorded from P. lanceolata with R. acetosa hosting the least endophyte diversity. Endophyte communities were more diverse in root than leaf tissues and in summer than in winter. Similarity of endophyte communities between different host plant species and organs within an individual host was very low. Negative correlations were found between mycorrhizal colonization and endophyte presence in the roots of C. arvense and P. lanceolata, suggesting some degree of antagonism or competition between the fungi. Consistent positive associations were found between the number of endophyte species in roots and shoots of plants.4. Synthesis. In contrast to previous studies, the results show that many endophytes do not occur ubiquitously, but instead exhibit both plant and tissue specificity. There is a strong seasonal change in endophyte communities, but the differences between roots and shoots at any one time can be just as large. This dissimilarity suggests a lack of systemic growth by the fungi from one tissue to another. Mycorrhizas may interact negatively with other root endophytes, indicating that the latter should not be ignored in future mycorrhizal studies. We should begin to think of individual plants as ecosystems of interacting microbes, whose community is structured by plant genetics and environmental conditions, coupled with interactions between the microbes themselves.
Spatial variation in below‐ground seed germination and divergent mycorrhizal associations correlate with spatial segregation of three co‐occurring orchid species
Authors: Jacquemyn Hans , Brys Rein , Lievens Bart , Wiegand Thorsten 
Published: May 2013

Summary1. Understanding the many factors that affect community composition and coexistence of species in natural environments is one of the central goals in ecology. As germination and establishment of seedlings in orchids are crucially dependent on mycorrhizal availability, the diversity and spatial distribution of orchid mycorrhizal fungi are likely factors that contribute to orchid coexistence.2. In this study, we combined molecular identification techniques with seed germination experiments and spatial point pattern analyses to investigate to what extent differences in mycorrhizal association patterns affected spatial variation in seed germination and the above‐ground distribution of three co‐occurring terrestrial orchid species (Anacamptis morio, Gymnadenia conopsea and Orchis mascula).3. The three species associated with a different set of mycorrhizal fungi, except A. morio and G. conopsea, which shared one fungal associate. The number of fungal lineages detected associating with each species also differed between species, being highest in G. conopsea, which associated with five lineages, and restricted to a single lineage in O. mascula.4. Seed germination experiments showed that below‐ground seed germination was restricted to locations where orchid individuals were most abundant, and quickly declined with increasing distance from the nearest above‐ground congener. Spatial point pattern analyses indicated significant fine‐scale spatial clustering that was highest in O. mascula and lowest in G. conopsea. Moreover, the spatial distributions of the three species were independent from each other, except for A. morio and G. conopsea.5. Synthesis. Our results support previous findings that co‐occurring orchid species tend to use different mycorrhizal partners. Although the possibility that variation in local environmental conditions affected seed germination could not be completely ruled out, our results suggest that the presence of specific mycorrhizal fungi contributed, at least partly, to the spatial distribution and coexistence of the investigated orchid species.
Snail grazing facilitates growth of two morphologically similar bloom‐forming Ulva species through different mechanisms
Authors: Guidone Michele , Thornber Carol S. , Vincent Emily 
Published: May 2013

Summary

Herbivores can facilitate macrophyte growth through stimulation of overcompensation pathways, removal of neighbouring or fouling competitors or increasing nutrient availability via nitrogenous waste inputs.
We examined the facilitative relationship between the mud snail
Ilyanassa obsoleta and two morphologically similar bloom‐forming
Ulva species,
Ulva compressa and
Ulva rigida. Through mesocosm experiments, we determined the occurrence and underlying mechanisms responsible for facilitating
Ulva growth. In situ snail enclosure experiments determined the occurrence of this facilitative pathway under natural conditions.
We found that both
U. compressa and
U. rigida are facilitated by
I. obsoleta, but despite their morphological similarity, the primary facilitative mechanism differed for each species.
Ulva compressa experienced increased growth via snail nitrogenous waste inputs, while
U. rigida was facilitated by the removal of fouling microalgae. These results suggest that physiological differences exist between these two species, potentially sustaining their coexistence within blooms.
Ground tissue assays showed
I. obsoleta preference for microalgal foulers in whole‐tissue assays was driven by
Ulva blade morphology rather than chemical or nutritive properties. This indicates that the underlying mechanism for
I. obsoleta's facilitation via grazing is an inability of the snail's radula to effectively puncture
Ulva blades, confining their grazing activities to fouling organisms on the blade surface.
In contrast to our mesocosm results, in situ experiments failed to find a positive impact of mud snail presence on
Ulva blade growth. However,
Ulva blades within these experiments were located at a highly eutrophic site and isolated from potential competitors. Consequently, this may have created an environment where
I. obsoleta facilitation was not required for maximum
Ulva growth.

Synthesis. We demonstrated two mechanisms by which top‐down forces can facilitate macroalgal growth: herbivore nitrogenous waste inputs and removal of microalgal fouling organisms. This facilitation may occur within the large mats of macroalgae that form during bloom events, exacerbating bloom conditions.
Pollination mode predicts phenological response to climate change in terrestrial orchids: a case study from central Europe
Authors: Molnár Attila , Tökölyi Jácint , Végvári Zsolt , Sramkó Gábor , Sulyok József , Barta Zoltán 
Published: May 2013

Summary

Herbarium collections contain long‐term data for a wide range of taxa and provide unique opportunities to evaluate the importance of life‐history components in driving species‐specific responses to climate change. In this paper, we analyse the relationships between change in flowering dates and life‐history traits within a phylogenetic framework. The study is based on an extensive data set of herbarium specimens of orchids collected in Hungary between 1837 and 2009, supplemented by recent field observations (1980–2011).
Of the 39 taxa investigated, 31 (79%) showed apparent advancement in mean flowering time. Among these, advancement was statistically significant in nine taxa. The rest (eight taxa) showed non‐significant delays in flowering. Averaging across all taxa, flowering time advanced by 3 days (3.8% of flowering period) during the last 50 years compared with the period before 1960. In taxa showing significant advancement, flowering times advanced by 7.7 days (8.6% of the flowering period). The most extreme advancement was 13.9 days.
Multivariate models were used to evaluate ways in which life history may affect phenological responses to climate change. Pollination mode (i.e. deceptive vs. rewarding vs. autogamous), life span (i.e. short‐lived vs. long‐lived), biogeographical distribution type (i.e. Mediterranean vs. non‐Mediterranean) and flowering time (i.e. mean date of blooming) emerged as important factors that influence changes in flowering through time. Phylogenetic relatedness did not predict phenological response. The strongest response was observed in orchids that flower relatively early in spring, exhibit an autogamous or deceptive pollination mechanism, have a long life span and possess a Mediterranean centre of distribution.
Synthesis. Our investigation demonstrates that the majority of Hungarian orchids have shifted their yearly mean flowering to earlier dates during the past 50 years. Certain life‐history traits, but not phylogenetic relatedness, were found to be important in predicting climatic responsiveness in European terrestrial orchids.
Can floral traits predict an invasive plant's impact on native plant–pollinator communities?
Authors: Gibson Michelle R. , Richardson David M. , Pauw Anton 
Published: May 2013

Summary
The possession of certain floral traits can determine which insects visit a plant species. If two species possess similar floral traits that determine shared flower visitors, floral traits can be said to mediate plant–plant interactions. Such indirect interactions are important for understanding fundamental relationships of plant communities, such as competition and facilitation but thus far have only been tested within a native community context.
We test whether floral‐trait similarity can be used to predict interactions between an invasive plant and co‐occurring native species in South Africa's Cape Floristic Region. We surveyed flower visitation at invaded and uninvaded plots across four sites and correlated floral‐trait similarity between invasive and native species with both invasion impact on native flower visitation and flower visitor overlap of natives and the invasive species.
Similarity of all traits (categorical and continuous) and categorical traits alone explained invasion impact (flower visitor overlap) between the native and invasive species. The majority of flower visitor overlap was attributed to the native honeybee Apis mellifera subsp. capensis.
This study is the first to show that floral traits can be used to predict novel plant–plant interactions, even amongst ecologically generalized flower visitors and plants and to predict potential impacts of an invasive species on native flowering communities. However, floral traits were not useful for predicting changes in visitation to plant species.
Synthesis. Results advance our understanding of the role of plant traits in ecological communities and reveal that they are important in mediating not only plant–pollinator interactions but also plant–plant interactions. Our findings also shed light on invasive–native plant interactions via pollinators and have the potential to predict certain invasion impacts.
Size is not everything for desiccation‐sensitive seeds
Authors: Hill James P. , Edwards Will , Franks Peter J. 
Published: May 2013

Summary

Almost 50% of all seed plants produce desiccation‐sensitive seeds. For these species, pre‐germination survival may be equally as important a basis of seed trait selection as seedling establishment. However, few studies have explored correlations among seed traits considered influential in the retention of viability prior to germination.
We examine four physiological traits: critical water content (Wr50), the mean seed water content when a cohort of seeds reaches 50% mortality, desiccation rate (t0.368), the time taken for each seed to reach a relative water content of 36.8%, mean time to germination (TG), the time taken for 50% of seeds within a cohort to germinate; and specific relative water content (WM), the proportion of available water to dry seed mass; two morphological traits: seed size (MD), dry seed mass and seed coat ratio (SCR), the proportional mass between the seed coat and dry seed mass; and one phenological variable: mean monthly rainfall at mean time of seed dispersal (RM) in 16 plant species that produce desiccation‐sensitive seeds from a seasonal tropical forest in Cairns, Queensland.
We first test for relationships among species, and then assess relationships between species in trait space via principal component analysis (PCA). Regression analysis revealed a significant negative relationship between RM and SCR, so that species that had dispersal periods at times of high moisture availability invested proportionally less into seed coats. No other pairwise trait combinations were significantly related. PCA revealed two axes of trait space. The first axis was associated with the traits SCR, TG, t0.368, RM and WM, and explained 44.1% of the variation between species. There were strong positive loadings for SCR, TG and t0.368, and strong negative loadings for RM and WM. Traits with strong loadings on the second axis (total variance 21%) were MD and Wr50 and WM. There were strong positive loadings for Wr50 and strong negative loadings for MD and WM.
Synthesis. Our findings reveal an axis of trait variability among desiccation‐sensitive seeds that is orthogonal to size. These traits might be important in surviving pre‐germination environmental conditions, independent of the advantages and/or disadvantages that size has been shown to confer on seed survival and seedling establishment. The implication of this finding is that seed size alone may not account for pre‐germination viability in desiccation‐sensitive seeds and may be inadequate to predict long‐term persistence of these species if climate changes occur on the scale predicted.
Variation and constraints of local adaptation of a long‐lived plant, its pollinators and specialist herbivores
Authors: Kalske Aino , Muola Anne , Laukkanen Liisa , Mutikainen Pia , Leimu Roosa 
Published: May 2013

Summary

Due to geographically variable species interactions, plants may become locally adapted to their sympatric herbivores and pollinators. However, adaptation to the abiotic environment may significantly affect plant interactions with herbivores and pollinators. Local adaptation to the abiotic environment may constrain local adaptation to herbivores and pollinators under contrasting selection pressures, resulting in trade‐offs in local adaptation.
We studied local adaptation of a perennial herb, Vincetoxicum hirundinaria, in a reciprocal transplant experiment among four populations and measured plant fitness, pollination success and resistance to two specialist herbivores. We also estimated local adaptation of these two herbivores and generalist pollinators to their sympatric plant populations. Local adaptation was compared with within‐population genetic variation, genetic and geographical divergence, and with divergence in terms of population size, environmental conditions and plant secondary chemistry. We further compared local adaptation to the environment, to local adaptation to herbivores and pollinators to detect possible trade‐offs in local adaptation.
The existence and degree of local adaptation varied among the plant populations. Plants from two populations were locally adapted to their sympatric leaf herbivores and plants from two populations were locally adapted to their abiotic environment. Herbivores from one population were locally adapted to their sympatric plant population. Local adaptation of V. hirundinaria to the seed predator increased with increasing among‐population divergence in precipitation and temperature. Local adaptation to the seed predator and the environment increased with increasing population genetic variation. Local adaptation of V. hirundinaria in fitness and in herbivore resistance also correlated positively, suggesting lack of trade‐offs in local adaptation.
Synthesis. These results demonstrate that species interactions can lead to a mosaic of locally adapted plant, herbivore and pollinator populations. In addition to natural enemies, genetic variation, the abiotic environment and mutualistic interactions contribute to the evolution of local adaptation in long‐lived plants. These results provide new insights into the patterns and causes of variation in local adaptation and are among the first to demonstrate that conflicting selection pressures within a population do not constrain local adaptation in multiple traits.