bluuebunny/crossref_metadata_2025_split huggingface dataset:
Life‐history trade‐offs during the seed‐to‐seedling transition in a subtropical wet forest community
Authors: Muscarella Robert , Uriarte María , Forero‐Montaña Jimena , Comita Liza S. , Swenson Nathan G. , Thompson Jill , Nytch Christopher J. , Jonckheere Inge , Zimmerman Jess K. 
Published: May 2013

Summary

The transition from seed to established seedling (STS) represents a major bottleneck in plant demography with implications for community dynamics and the maintenance of species diversity. The relative strength of seed limitation versus seedling establishment limitation can reveal life‐history trade‐offs that contribute to the maintenance of community diversity. If seed limitation dominates, chance arrival to open sites may play a key role in maintaining diversity. If seedling establishment limitation dominates, however, species relative abundances may depend more on tolerance to environmental and biotic conditions during seedling establishment (i.e. species‐specific regeneration niche).

We used three years of seed rain and seedling recruitment data for 19 species of tropical woody plants collected in the Luquillo Forest Dynamics Plot in Puerto Rico to (i) examine a trade‐off between seed and seedling establishment limitation and (ii) quantify the biotic and abiotic factors that mediate the STS transition.

We did not find evidence of a life‐history trade‐off in the form of a negative correlation between seed and seedling establishment limitation. However, species varied considerably in the relative levels of seed and seedling establishment limitation they displayed. Seed mass correlated negatively with seedling establishment limitation but not with seed limitation. We found striking differences in STS transition between life‐forms categorized as trees (including two palms) and lianas; lianas exhibited significantly higher STS transition rates than trees.

The biotic and abiotic variables most strongly associated with successful STS transition differed between life‐forms. For trees, conspecific seed density and temporal fruiting concentration had negative effects on seedling establishment, while seed mass had a positive effect. A significant interaction between leaf litter input at a plot and seed size suggested that large‐seeded species had higher STS transition probability in plots with more leaf litter biomass. This effect was reversed for small‐seeded species. For lianas, leaf litter had a negative effect on STS transition and temporal fruiting concentration had a positive effect.

Synthesis. Our analyses demonstrate the multidimensional axes of regeneration niches and how they can be related to seed size. Long‐term data sets are critical for understanding these relationships because the relevant factors vary along large spatial and temporal scales.
Independent variations of plant and soil mixtures reveal soil feedback effects on plant community overyielding
Authors: Hendriks Marloes , Mommer Liesje , de Caluwe Hannie , Smit‐Tiekstra Annemiek E. , van der Putten Wim H. , de Kroon Hans 
Published: May 2013

Summary

Recent studies have shown that the positive relationship between plant diversity and plant biomass (‘overyielding’) can be explained by soil pathogens depressing productivity more in low than in high diverse plant communities. However, tests of such soil effects in field studies were constrained by experimental limitations to manipulate soil community composition independent of plant community composition. Here, we report of an experiment where feedback effects to plants were tested for both plant and soil monocultures and mixtures.

Our results demonstrate that overyielding is the result of plant species in mixture being more growth‐limited by ‘own’ soil biota than by soil biota of other plant species. This effect disappeared when the soils had been sterilized by gamma‐irradiation. Mixing plants themselves did not result in overyielding except when grown in the soil of one of the species (Leucanthemum vulgare), where growth of one species disproportionally increased in mixture compared to monoculture.

Soil nutrient availability could not explain differences in growth between the non‐sterilized soils. Therefore, our results suggest that plant species–specific soil biota rather than the plants have contributed to the plant community overyielding.

Species biomass ranking in mixtures highly differed between non‐sterilized soils of different histories of soil conditioning, whilst the ranking was more consistent in sterilized soil. Sterilized soils of different origin differed significantly in nutrient availability. These results suggest that shifts in competitive hierarchies depend on plant species–specific interactions influenced by soil biota and cannot be induced by mineral nitrogen.

Synthesis. Our results show that overyielding in four plant species mixtures can be due to species‐specific interactions between plants and their specific soil biota. Neither mixing the plant species alone nor the differential responses of species to mineral nitrogen influenced community productivity, but mixing soil biota did.
Effects of litter on seedling establishment in natural and semi‐natural grasslands: a meta‐analysis
Authors: Loydi Alejandro , Eckstein R. Lutz , Otte Annette , Donath Tobias W. 
Published: May 2013

SummaryPlant litter is a key component in terrestrial ecosystems. It plays a major role in nutrient cycles and community organization. Land use and climate change may change the accumulation of litter in herbaceous ecosystems and affect plant community dynamics. Additionally, the transfer of seeds containing plant material (i.e. litter) is a widespread technique in grassland restoration.Ecosystem responses to litter represent the outcome of interactions, whose sign and strength will depend on many variables (e.g. litter amount, seed size). A previous meta‐analysis (from 1999) reported that litter had an overall negative effect on seed germination and seedling establishment in different ecosystems. However, recent studies indicated that this might not be the case in grassland ecosystems.We used 914 data from 46 independent studies to analyse the effects of litter on seedling (i) emergence, (ii) survival and (iii) biomass, employing meta‐analytical techniques. Each data set was stratified according to methodology, grassland type, irrigation conditions, litter amount and seed size.We found an overall neutral effect of litter presence on seedling emergence and survival and a positive effect on seedling biomass. However, whereas for field experiments the response remained neutral, it was positive for common garden studies. In glasshouse experiments, litter effects were negative for emergence and positive for biomass.Litter may have a positive effect on seedling recruitment in dry grasslands or under water‐limited conditions, or in the presence of low to medium litter amounts (< 500 g m−2). However, high litter amounts (> 500 g m−2) will inhibit seedling recruitment. Large seeds showed a more positive response to litter presence with respect to seedling emergence and survival, but not concerning biomass.Synthesis. Under dry conditions (e.g. dry grasslands or dry periods) or with low to medium litter amounts, litter presence has a positive effect on seedling establishment. However, climate and land use change may promote litter accumulation and reduce seedling establishment, affecting grasslands composition and ecosystem functions.
Spatial and temporal variability in positive and negative plant–bryophyte interactions along a latitudinal gradient
Authors: Doxford Simon W. , Ooi Mark K. J. , Freckleton Robert P. 
Published: May 2013

Summary

According to the Stress Gradient Hypothesis, facilitation and competition are considered to be important at opposite ends of an environmental gradient. However, recent research has questioned the generality of this idea. One limitation is that the small‐scale and short‐term nature of much research into plant interactions limits our understanding of how their strength and importance changes over large temporal and spatial scales.

Here, we experimentally measured the interactions between bryophytes and a community of winter annuals in sand dunes along a c. 1500 km latitudinal gradient over two generations. We carried out bryophyte‐removal experiments within permanent quadrates at eight field sites along the Atlantic coast of Western Europe, to measure the spatio‐temporal variation in the strength and direction of biotic interactions.

We found a striking contrast in the nature of plant–bryophyte interactions observed in consecutive years of study, using three measures of plant demographics: density, plant performance and population growth. In the first year facilitation dominated, but showed an overall decline in strength from south to north. In the following year facilitation was largely replaced by competition, which also declined in strength from south to north along the latitudinal gradient.

Interaction strengths are correlated with population growth rate, so that facilitation dominated in sites and years where population growth was low, whereas when population growth was high competition appeared to be more important. This is consistent with the Stress Gradient Hypothesis, but further to previous studies we demonstrate that this mechanism operates over time and in terms of population growth rates.

The effects of bryophyte removal were more strongly related to population density and population growth than to individual plant performance (i.e. reproductive output). This result suggests interactions are most important during germination and early establishment of annuals, and not in terms of inter‐plant competition for resources.

Synthesis: This study is one of the first to show that there may be extreme spatio‐temporal variation in the strength and direction of interactions, with substantial changes in their impact over a short time period. Our results suggest that the Stress Gradient Hypothesis may operate within and along gradients, as well as inter‐annually. This may therefore play a role in buffering population dynamics.
Enemy damage of exotic plant species is similar to that of natives and increases with productivity
Authors: Dostál Petr , Allan Eric , Dawson Wayne , van Kleunen Mark , Bartish Igor , Fischer Markus 
Published: May 2013

Summary

In their colonized ranges, exotic plants may be released from some of the herbivores or pathogens of their home ranges but these can be replaced by novel enemies. It is of basic and practical interest to understand which characteristics of invaded communities control accumulation of the new pests. Key questions are whether enemy load on exotic species is smaller than on native competitors as suggested by the enemy release hypothesis (ERH) and whether this difference is most pronounced in resource‐rich habitats as predicted by the resource–enemy release hypothesis (R‐ERH).

In 72 populations of 12 exotic invasive species, we scored all visible above‐ground damage morphotypes caused by herbivores and fungal pathogens. In addition, we quantified levels of leaf herbivory and fruit damage. We then assessed whether variation in damage diversity and levels was explained by habitat fertility, by relatedness between exotic species and the native community or rather by native species diversity.

In a second part of the study, we also tested the ERH and the R‐ERH by comparing damage of plants in 28 pairs of co‐occurring native and exotic populations, representing nine congeneric pairs of native and exotic species.

In the first part of the study, diversity of damage morphotypes and damage levels of exotic populations were greater in resource‐rich habitats. Co‐occurrence of closely related, native species in the community significantly increased the probability of fruit damage. Herbivory on exotics was less likely in communities with high phylogenetic diversity.

In the second part of the study, exotic and native congeneric populations incurred similar damage diversity and levels, irrespective of whether they co‐occurred in nutrient‐poor or nutrient‐rich habitats.

Synthesis. We identified habitat productivity as a major community factor affecting accumulation of enemy damage by exotic populations. Similar damage levels in exotic and native congeneric populations, even in species pairs from fertile habitats, suggest that the enemy release hypothesis or the R‐ERH cannot always explain the invasiveness of introduced species.
Are stored carbohydrates necessary for seed production in temperate deciduous trees?
Authors: Ichie Tomoaki , Igarashi Shuichi , Yoshida Shohei , Kenzo Tanaka , Masaki Takashi , Tayasu Ichiro 
Published: May 2013

Summary

Many tree species undergo large fluctuations from year to year in seed production, a phenomenon known as masting. The resource budget model, based on the assumption that abundant seeding in a masting year depends on the abundance of resources stored over several years, is a key hypothesis in explaining the mechanism of masting. But do masting species really need such long‐term storage to produce a large seed crop?

To test this hypothesis, we studied the relationship between the carbon accumulation period for seed production, as estimated by radiocarbon (14C) analyses, and the coefficient of variation of annual seed production in 10 canopy tree species in a temperate deciduous forest. These species differ widely in their reproductive intervals.

In all the species studied, the accumulation period was < 1.4 years before seed maturation. Moreover, without taking species or reproductive intervals into account, there was no significant correlation between the carbon accumulation period and the fluctuation of annual seed production; both remained at an even level.

Synthesis. Our results suggest that temperate canopy trees used photosynthates produced in the current and/or the previous year for seed production, regardless of reproductive intervals. It might therefore be necessary to reconsider the importance of stored carbohydrate resources for masting.
Trait‐based climate change predictions of plant community structure in arid steppes
Authors: Frenette‐Dussault Cédric , Shipley Bill , Meziane Driss , Hingrat Yves 
Published: May 2013

Summary

Global climate change is possibly one of the most important challenges for current and future human populations due to its wide‐ranging effects on ecosystems. Global prediction models suggest that in some areas of the world (e.g. Northern Africa, Central America) an increase in aridity might strongly disturb agricultural production and affect food security. To counterbalance these negative effects, reliable predictive models are needed to anticipate ecosystem changes.

We tested the ability of the Community Assembly by Trait‐based Selection (CATS) model that is based on the principle of maximum entropy and trait‐based environmental filtering, to predict actual and future plant community composition in the arid steppes of eastern Morocco. Specifically, we asked whether this model was adequate for predicting actual community composition, based on predicted community‐weighted mean (CWM) traits, and what would be the changes in community composition under various scenarios of climate change for the period 2080—2099.

The CATS model could predict > 90% of actual community composition if the actual CWM traits were known but only ˜40% if the CWM values were predicted from estimated aridity and grazing values. The predictions of community composition for 2080—2099 suggested that, regardless of the climate change scenario considered, the dominant group in grazed and ungrazed sites would shift from ruderal species to stress‐tolerant sub‐shrubs, which would constitute up over 80% of total community composition in some cases.

Synthesis. Our findings suggest that effects of climate change will strongly modify plant community structure in arid steppes, possibly accentuating the process of desertification, and reducing the pastoral value of the vegetation. Future research efforts should concentrate on the identification of strong trait–environment relationships to improve model predictions.
Hierarchical responses of plant–soil interactions to climate change: consequences for the global carbon cycle
Authors: Bardgett Richard D. , Manning Pete , Morriën Elly , De Vries Franciska T. 
Published: May 2013

Summary

Interactions between plant and soil communities play a major role in determining the impact of climate change on ecosystem functioning and the carbon cycle, and the mechanisms involved operate over a wide range of spatial and temporal scales.

We present a framework for understanding the consequences of climate‐induced changes in plant–soil feedback for the carbon cycle. The framework describes a hierarchy of mechanisms by which changes in climate impact on ecosystem carbon dynamics at three levels of response, namely individual and community reordering and species immigration and loss.

For each level, we identify the mechanisms by which climate change impacts on plant–soil interactions with consequences for the carbon cycle. We also demonstrate that the potential for decoupling of plant–soil interactions increases across the three levels of response, being greatest with species immigration and/or loss, for example, if plants were to undergo a biome shift, but their associated soil communities did not. Such decoupling is a largely unrecognized, but potentially important regulator of the future global carbon cycle.

Synthesis. The framework presented here highlights a need for a new approach to the study of climate change impacts on plant–soil interactions and carbon cycling that integrates this hierarchy of responses, and incorporates the decoupling of above‐ground and below‐ground networks, across a range of temporal and spatial scales, and ecosystems.
Complex plant–soil interactions enhance plant species diversity by delaying community convergence
Authors: Fukami Tadashi , Nakajima Mifuyu 
Published: May 2013

Summary

A plant that causes specific changes to soil biota may either positively or negatively affect the performance of the plant that subsequently grows in that location. These effects, known as plant–soil feedback, can affect plant species diversity at multiple spatial scales.

It has been hypothesized that positive plant–soil feedback reduces alpha (local) diversity by allowing dominance by early‐arriving species, but increases gamma (regional) diversity by promoting community divergence (increased beta diversity) through the emergence of alternative stable states. In contrast, negative plant–soil feedback has been thought to increase alpha diversity by allowing local species coexistence, but to reduce gamma diversity by promoting community convergence (reduced beta diversity). Although widely accepted, these hypotheses do not consider the possibility that plant species differ in their effect on, and their response to, a given other species via soil biota. In reality, plant–soil interactions can be complex, with the strength of the interactions variable between plant species. Using a basic simulation model of plant community assembly, we investigated how complex plant–soil interactions might affect plant diversity during succession.

When we included only positive or negative intraspecific plant–soil feedback in the model, with no variation in the strength of interspecific plant–soil interactions, results were consistent with the conventional hypotheses. When we allowed the strength of plant–soil interactions to differ between species, plant–soil interactions enhanced alpha diversity initially and beta and gamma diversity subsequently. Diversity enhancement occurred not necessarily because alternative stable states emerged, but primarily because complex plant–soil interactions lengthened the time during which local species composition changed. Due to the longer time for changes in species composition, the high level of beta and gamma diversity at the early stage of succession was maintained for a long time despite eventual community convergence. Thus, diversity enhancement was often transient, though long‐lasting, making the conventional concept of alternative stable states inadequate for explaining diversity.

Synthesis. Based on these findings, we propose the new hypothesis that complex plant–soil interactions enhance plant species diversity by delaying community convergence. This hypothesis highlights the role of plant–soil interactions as a driver of long‐lasting transient dynamics of community assembly.
Plant–soil feedbacks: the past, the present and future challenges
Authors: van der Putten Wim H. , Bardgett Richard D. , Bever James D. , Bezemer T. Martijn , Casper Brenda B. , Fukami Tadashi , Kardol Paul , Klironomos John N. , Kulmatiski Andrew , Schweitzer Jennifer A. , Suding Katherine N. , Van de Voorde Tess F. J. , Wardle David A. 
Published: May 2013

Summary

Plant–soil feedbacks is becoming an important concept for explaining vegetation dynamics, the invasiveness of introduced exotic species in new habitats and how terrestrial ecosystems respond to global land use and climate change. Using a new conceptual model, we show how critical alterations in plant–soil feedback interactions can change the assemblage of plant communities. We highlight recent advances, define terms and identify future challenges in this area of research and discuss how variations in strengths and directions of plant–soil feedbacks can explain succession, invasion, response to climate warming and diversity‐productivity relationships.

While there has been a rapid increase in understanding the biological, chemical and physical mechanisms and their interdependencies underlying plant–soil feedback interactions, further progress is to be expected from applying new experimental techniques and technologies, linking empirical studies to modelling and field‐based studies that can include plant–soil feedback interactions on longer time scales that also include long‐term processes such as litter decomposition and mineralization.

Significant progress has also been made in analysing consequences of plant–soil feedbacks for biodiversity‐functioning relationships, plant fitness and selection.

To further integrate plant–soil feedbacks into ecological theory, it will be important to determine where and how observed patterns may be generalized, and how they may influence evolution.

Synthesis. Gaining a greater understanding of plant–soil feedbacks and underlying mechanisms is improving our ability to predict consequences of these interactions for plant community composition and productivity under a variety of conditions. Future research will enable better prediction and mitigation of the consequences of human‐induced global changes, improve efforts of restoration and conservation and promote sustainable provision of ecosystem services in a rapidly changing world.