What is it that determines if a bird should deposit a seed from a fruit in a specific place or not? I the Early View paper “Seed dispersal in heterogeneous landscapes: linking field observations with spatially explicit models”, Jessica E Lavabre ad colleagues combines modelling with empirical studies to find out! Below is the author’s summary of the study.

Frugivorous birds play a critical role in the population dynamics of many fleshy-fruited plants by defining the template for the establishment of new individuals. Because successful germination and subsequent seedling survival is highly dependent upon the micro-habitat where a seed arrives, it is crucial to understand which factors drive seed deposition. In our study, we aimed to take an important step forward in understanding the complex mechanisms that generate the spatial patterns of seed dispersal. Few studies have previously modelled seed dispersal in a real landscape, mostly because real vegetation structure is often highly heterogeneous. Here, we have taken advantage of a simple study system to parametrize mechanistic seed-dispersal models with empirical field data, and we built three models that test three seed-dispersal predictors: distance from the source tree, microhabitat type, and a combination of both distance from the source and microhabitat type.

To our greatest surprise, the third model, combining distance and microhabitat type, did not perform significantly better than the other two, simpler models. Additionally, our results suggested that what we had initially considered as one population could instead be two functionally distinct patches, with distinct seed dispersal dynamics. Altogether, these results reinforce the hypothesis that functionally distinct groups of frugivore species generate scale specific seed rain patterns.

A sexual reproduction system should confer higher mutation rates and hence evolutionary rate than asexual ones. Is it really so? Find out in the Early View paper “Asexual plants change just as often and just as fast as do sexual plants when introduced to a new range” by Rhiannon L. Dalrymple and colleagues. Below is their summary of the study:

Many of the world’s most invasive plant species can reproduce asexually. However, asexuality might be a double edged sword for introduced species. Shortly after introduction, asexual species might have the upper hand because they do not need a partner for promptly increasing in numbers and establishing populations in the new range. Classic theory tells us that sexual reproduction should fuel the processes of adaption through the creation of variation on which natural selection can act. While asexuality may be of advantage in the early phases of introduction, it may lead to an evolutionary dead end.

We measured the rate of changes in multiple asexual species distributed through Australia’s east coast and New Zealand. We have provided evidence that multiple asexual species have undergone rapid morphological changes in response to the novel environments in their introduced range. We then compared the proportion of asexual species that demonstrated a significant change in at least one trait, and the rates at which these changes progressed, to comparable data on sexual species. This was the first test of the difference in potential for rapid change afforded by sexuality, cross species and in the natural world. Our results were astounding: we found no significant difference in the rate or frequency of rapid changes between asexual and sexual species. That is, sex and genetic recombination do not increase the rate or potential for change in this context. Introduction to a novel environment, a population may experience strong selective forces. The new environmental conditions force rapid and significant changes in the phenotype of both asexual and sexual species. It appears that in the process of introduction – it may be adapt or fail, regardless of breeding system.

The most exciting aspect of this study “Increase of fast nutrient cycling in grassland microcosms through insect herbivory depends on plant functional composition and species diversity” (Nietschke et al)- for me – was to take our experiences and results from the field site – the Jena Experiment that was designed for elucidating mechanisms of diversity effects – and to incorporate them into a microcosm experiment under well controlled conditions.

Here, we aimed at tracking the way of nutrients from the intact plant, over an insect herbivore and its feeding characteristics, into the soil, and over to another trophic level – And to judge the role of plant diversity and functional composition along that way.

• Some aspects of the course showed very clearly (e.g. the release of nutrients with feeding and the relevance of the plant functional groups),
• some were surprising (e.g. both throughfall pH and P increased with herbivory intensity and faeces accumulation – diversity having a similar effects, although independently of herbivore intensity),
• and yet others were challenging (e.g. clear soil microbial responses only occurred at high levels of herbivory).

Finally, stepping back a little and taking our field site results into account, formed a broader picture and gave some new perspectives.

Besides the change of perspective the study brought about and the various methods we applied, it was very inspiring and rewarding to work together in a team of people that have realized quite different niches within Biodiversity Ecosystem Functioning-space.

Synthesis and integration are critical elements of knowledge synthesis. Using/reusing the work we have already done is a sign of maturation as a discipline, and a very positive step forward to accelerate inquiry by identifying research gaps, opportunities, and effectively summarizing the strength of evidence to date. We are not only poised for potentially profound novel tests of ideas in ecology, evolution, and environmental science, but we are collaborating in news ways, sharing datasets more freely, and more transparently sharing workflows and insights. Oikos supports this movement in all the ways that we can for now and hopefully even more dramatically as we evolve too.  Hence, we are launching a new formal synthesis section for publications.

Meta-analyses and systematic reviews are but two forms of synthesis. Nonetheless, these reviews are currently the most easily aligned with the traditional peer-reviewed ‘publication’ as paper model. This is admittedly a small step, but we need these contributions to inform evidence-based decisions not just for additional research but for management and application. We now have a section devoted to reviews that include quantitative summaries of evidence from within studies or aggregated datasets, i.e. include effect size estimates and appropriate statistics, and also includes systematic reviews that summarize the state of the art of research for a sub-discipline or topic at the scale of studies (i.e. attributes associated with the research, similar to the meta-data of the datasets but without the data from each study listed). We recognize there are many other forms of synthesis that we need to share, and consequently, we will work hard to ensure that we consider these contributions as well (i.e. how to effectively synthesize evidence in all forms, aggregate, and use datasets for novel synthesis).  In handling these papers, similar to all reviews really, we will strive for rapid turnaround, and if sent out for review, we will also work hard to ensure that referees expert in synthesis can provide you with input.

The editorial associated with this section is now OA and online.
Let’s work together to find that big picture.

Can invasive species actually alter their environment so that more nutrients are available for them? Find out in the Early View paper “Non-additive effects of invasive tree litter shift seasonal N release: a potential invasion feedback” by Michael J. Schuster and Jeffrey S. Dukes. Below is their summary of the study:

Many woody invasive species change their environment to better fit their needs for resources, particularly soil nutrients like nitrogen. One way that they can do this is by accelerating the decomposition of leaf litter—an important step in recycling leaf nitrogen into a form that can be used by plants. However, much of what we know about the decomposition of invasive species’ litters, and their impacts on soil fertility, is based on observations of litter from an individual species decomposing by itself. This is problematic because litters rarely decompose by themselves in nature. More commonly, litters of multiple species are mixed together and decompose more quickly or more slowly than we would expect based on the decomposition rates of each species separately. Thus, we designed a litter bag experiment to examine how the litter of four invasive tree species decomposed differently when mixed with that of four native species, and how this difference might change as the invader became more dominant in the litter layer.

One year and 448 litter bags later, we found some surprising results. Indeed, native-invasive litter mixtures commonly decomposed at different rates than would have been predicted, but whether mixtures lost mass faster or slower than the predicted rate did not follow a strong, consistent pattern. In contrast, the release of nitrogen from these mixtures followed a very clear pattern of being slowed early on, but catching up to or exceeding the amount of nitrogen that would have been predicted at the end of the experiment. Implicitly, native-invasive mixtures were consolidating the release of their nitrogen until later on in the decomposition process, a time that corresponded to the period during which plants, especially the fast-growing invasive species, require the most nitrogen. This pattern was stronger in mixtures comprised mostly of the invasive species and for invaders that produced more nitrogen-rich litter. These findings, in concert with others’ on invasive species and nutrient cycling, led us to suggest that these invasive species might be shifting the release of nitrogen from the litter layer to a time when they are better able to use that nitrogen, and that this might be an important contributing factor to the success of some invasive species.