Roberto Salguero-Gómez interviews Hal Caswell

Last year Roberto Salguero-Gómez (Associate Editor, Journal of Ecology) interviewed Hal Caswell and you can listen to the interview in its entirety below.

hal caswell tai chi

Hal doing tai chi. Listen right to the end of the interview for the context

Roberto and Hal are co-authors on “The COMPADRE Plant Matrix Database: an open online repository for plant demography“, which was published in Journal of Ecology in issue 1 of 2015.

 

Roberto is one of the co-organisers of the British Ecological Society’s “Demography Beyond The Population” symposium which is being held in Sheffield in March. Registration is currently open.

Editor’s Choice 103:2

Issue 103:2 of Journal of Ecology will be online very soon. The Editor’s Choice paper for this issue is Early human impact (5000–3000 BC) affects mountain forest dynamics in the Alps by Schwörer et al. One of Journal of Ecology’s Editors, Amy Austin, has written a commentary about the paper below.

Editor’s Choice 103:2

When we think about human impact on the landscape, visions of deforestation in the Amazon, conversion of grasslands for crop cultivation, or even urbanization of rural areas with sprawling housing developments, often come to mind.  But the truth of the matter is that we, as human beings, have been modifying the natural landscape for thousands of years, and in some places much more intensively than others. The Editor’s Choice paper for this issue of the Journal of Ecology (103:2) explores the effects of human activity on forest biodiversity in the European Alps, but the time frame is not what one might expect – humans were altering biodiversity in these forests more than 5000 years ago!

The alpine Lake Iffigsee (2065 m asl.) in the Swiss Alps

The alpine Lake Iffigsee (2065 m asl.) in the Swiss Alps

And what did the humans do?  They burned and cleared the forest, and then burned some more and then grazed their animals. Moreover, all of this happened long before industrial civilization took hold of Europe.  These dramatic land-use changes resulted in alterations in the dominant vegetation, from Abies alba (silver fir), a fire-sensitive species, to broad scale expansion of Picea abies (Norway spruce) between 5000 and 3000 years ago. While simultaneous climate changes were happening, Schwörer et al. were able to link fire frequency and extent, resulting from human activity, to the expansion of P. abies in the palaeoecological record.

Coring platform on Lake Iffigsee that was used to retrieve the sediment cores.

Coring platform on Lake Iffigsee that was used to retrieve the sediment cores.

How did they discover this?  A combination of approaches, including sediment cores for pollen and microscopic charcoal analysis, macrofossils, and radiocarbon dating of vegetation remains, with intensive sampling in two different locations in the Northern Swiss Alps, was used.  The question that comes to mind is, as with many studies exploring human impact, how can we be sure it was humans and not climatic variability that caused these shifts?  What this study presents is a step forward in the empirical demonstration of human impact. Due to the number of other studies in the region examining climatic change and vegetation distribution (Heiri et al., 2003), the authors were able to show that shifting treeline at the upper elevation site was due to human clearing and fire, rather than natural responses to regional climatic variation.  Other studies have evaluated the importance of large herbivores in determining forest openness and vegetation structure in lowland Europe (Mitchell, 2005; Sandom et al., 2014), but this was the first studies to show how human activity related to pastoralism resulted in detectable changes in forest community composition. The authors even went a step further, suggesting that based on their analysis, moderate human activity in the form of grazing and controlled fires could counteract effects of climate change, and keep silver fir from invading the alpine grasslands as global temperatures rise.

Lake Lauenensee (1382 m asl.)

Lake Lauenensee (1382 m asl.)

This study is being published at a time when there is a renewed interest in understanding and using palaeoecological changes, both to establish the magnitude of human-environment interactions in the recent past, but also to use this information as a tool for predictions of human activity in the future. This application of palaeoecological tools was highlighted as priority in a recent review in Journal of Ecology that focuses on 50 key questions for the discipline (Seddon et al., 2014). For this reason, it is a timely and interesting contribution. Take a closer look!

Amy Austin

Editor, Journal of Ecology

References 

Heiri, O., Lotter, A. F., Hausmann, S. & Kienast, F. (2003) A chironomid-based Holocene summer air temperature reconstruction from the Swiss Alps. Holocene, 13, 477-484.

Mitchell, F. J. G. (2005) How open were European primeval forests? Hypothesis testing using palaeoecological data. Journal of Ecology, 93, 168-177.

Sandom, C. J., Ejrnaes, R., Hansen, M. D. D. & Svenning, J. C. (2014) High herbivore density associated with vegetation diversity in interglacial ecosystems. Proceedings of the National Academy of Sciences of the United States of America, 111, 4162-4167.

Seddon, A. W. R., Mackay, A. W., Baker, A. G., Birks, H. J. B., Breman, E., Buck, C. E., Ellis, E. C., Froyd, C. A., Gill, J. L., Gillson, L., Johnson, E. A., Jones, V. J., Juggins, S., Macias-Fauria, M., Mills, K., Morris, J. L., Nogués-Bravo, D., Punyasena, S. W., Roland, T. P., Tanentzap, A. J., Willis, K. J., Aberhan, M., van Asperen, E. N., Austin, W. E. N., Battarbee, R. W., Bhagwat, S., Belanger, C. L., Bennett, K. D., Birks, H. H., Bronk Ramsey, C., Brooks, S. J., de Bruyn, M., Butler, P. G., Chambers, F. M., Clarke, S. J., Davies, A. L., Dearing, J. A., Ezard, T. H. G., Feurdean, A., Flower, R. J., Gell, P., Hausmann, S., Hogan, E. J., Hopkins, M. J., Jeffers, E. S., Korhola, A. A., Marchant, R., Kiefer, T., Lamentowicz, M., Larocque-Tobler, I., López-Merino, L., Liow, L. H., McGowan, S., Miller, J. H., Montoya, E., Morton, O., Nogué, S., Onoufriou, C., Boush, L. P., Rodriguez-Sanchez, F., Rose, N. L., Sayer, C. D., Shaw, H. E., Payne, R., Simpson, G., Sohar, K., Whitehouse, N. J., Williams, J. W. & Witkowski, A. (2014) Looking forward through the past: Identification of 50 priority research questions in palaeoecology. Journal of Ecology, 102, 256-267.

 

Special Feature: Peat’s muddy past

What is so special about peat?  To the untrained eye, these ecosystems appear to be desolate swamps, with limited value, biodiversity- or other-wise.  To the seasoned wetland ecologist, the more apt question is what isn’t special about peat?  These long-neglected ecosystems are vital reservoirs of fresh water for us thirsty humans; they contain 10 times as much carbon as all of the world’s forests, whilst occupying only 3% of the Earth’s surface; and house a rich diversity of species found nowhere else.  Yet as we begin to learn more about the world’s peatlands, we master the technologies needed to exploit them rapidly and irreversibly (Fig. 1).

Fig 1_cole

Fig. 1 A drained peatland in Indonesian Borneo, with young oil palm plants in the foreground and heavily degraded peat swamp forest in the background.

To be scientifically accurate, the irreversible component of peatland conversion is an assumption, wanting of sufficient evidence from “the field” due to the recent nature of large-scale exploitation.  But any ecosystem we see today is a product of its evolving past; a period over which it has encountered disturbances and presented a response.  From these patterns of responses, we can measure the resilience of the ecosystem (Cole et al., 2014a) and develop hypotheses as to how it may respond to future disturbances.  In its simplest form, resilience is described as the ability of an ecosystem to maintain its structure and function despite perturbation (Holling, 1973).

How resilient are peatlands?  Specifically, how have the tropical peat swamp forests of Southeast Asia responded to disturbance in the past?  We sought to answer these questions for the coastal peatlands of Sarawak, in Malaysian Borneo (Cole et al., 2015) (Fig. 2).

The plug is rapidly being pulled on these sweaty, mosquito-ridden jungles as industrial-scale agriculture spreads like wildfire across the region.  Dipterocarp forests, rich in a variety of fruit-bearing trees, ‘black-water’-adapted fish and nimble mammals, are being drained, flattened and converted into monoculture landscapes where oil palms (Elaeis guineensis) can quickly bring economic profit to even the inexperienced farmer.  Though wild-fires themselves are in fact a rare phenomenon in intact peatlands, the recent elevation in burning has been blamed primarily on the recent expansion of agriculture, and brought huge environmental, health and political challenges to the region.  But how frequent were fires in the past?  And what impact did they have on the vegetation?

Unlike in the temperate zone, tropical peat swamps are naturally forested.  It is the pollen grains and fern spores produced by this vegetation that provide the answers to our questions and insights into the resilience of these ecosystems.  Fossilised grains, deposited tens to millions of years in the past, are one of the primary datasets available in palaeoecology.  Often referred to as (the less archaic-sounding) long-term ecology, the discipline extends the scope of ‘short-term’ ecology through using deposited remains to study plants and animals and their interactions with the environments of the past.

We used pollen grains, fern spores and fossil charcoal to explore drivers and impacts of disturbance in three peatland areas in northern Borneo.  Peat cores were collected from three coastal sites in Sarawak (Fig. 2), where peat extends over approximately 13% of the States’ land surface.  The depths of the cores ranged from c. 1.5 to 3m, and radiocarbon dating of sediment samples from each demonstrated that they covered a period of 2000 to 7000 years before present (BP).

fig 2_cole

Fig. 2 The three degraded peatland sites (red circles; DPL, PSF & CPL) from which cores were collected for this palaeoecological study, in Sarawak, Malaysian Borneo. Sarawak’s peatlands are shown in brown and its major towns in blue.

Once I’d spent many more hours than I’d like to remember counting and identifying microscopic pollen grains, I was able to look for answers to our key research questions:

  • How has the vegetation in these peatland ecosystems changed through time?
  • What factors disturbed the peat swamp forest vegetation?
  • How did these ecosystems respond to the different disturbances?

Vegetation change

Our data demonstrated that peat swamp forest vegetation has persisted in these coastal peatlands since the onset of ecosystem development c. 4000yrs BP.  At this time, coastal progradation, resulting from sea-level fall, provided land suitable for peat to accumulate.  Apart from fluctuations between pioneer and mature peat swamp forest species over this period, reflecting local disturbances and dynamic internal responses (Fig. 3), the only significant vegetation change observed was shown in the last 500 years in two of the cores.  Increases in plant taxa associated with degraded peatlands suggested the introduction of humans and land use change to these coastal ecosystems.

fig 3_cole

Fig. 3 Relatively intact peat swamp forest patch, near to the site where the “PSF” core was extracted (Fig. 2).

Disturbances

There were three drivers of vegetation change that we focused on in this study, each with its associated palaeoecological proxy: climatic variability, such as El Niño Southern Oscillation (ENSO) activity, identified through a literature review; local and regional fire inferred from fossil macro- and microcharcoal respectively, and anthropogenic activity indicated by pollen and spores of plants common in open areas, such as grasses (Poaceae) and sedges (Cyperaceae).  The literature reported increasing intensity of ENSO events in this region over the late Holocene, subjecting northern Borneo to arid conditions.  Burning, both from local and regional fires, occurred throughout the past in all three sites, though elevated dramatically in the last c. 500 years in parallel with greater levels of open vegetation indicators.

Vegetation response

Only within the recent past, from c. 200-500 years BP, did the peat swamp forest vegetation show signs of being ‘disturbed’.  Prior to this period, episodes of more intense ENSO and burning did not appear to correspond with notable declines in the peat swamp forest taxa, suggesting ecosystem resilience to these forms of perturbation.  However, given that elevated levels of open vegetation indicators and charcoal do correlate with the declines observed in the recent past, and in the period when literature and interviews suggest humans started exploiting these environments, it is likely that anthropogenic activities are responsible.  Though a lack of sufficient data prevents us from inferring whether these changes equate to a recent loss of ecosystem resilience, we have made several conclusions:

  • These peat swamp forests have shown resilience to natural disturbances in the past;
  • Levels of disturbance within the last c. 500 years have exceeded those recorded in the previous 5000 years, and humans are the main culprits;
  • Recent, coincident instability and declines in peat swamp forest taxa suggest a notable anthropogenic impact on this ecosystem, potentially challenging the future persistence of these forests.

Back to the future

So, what more do we need to know about these vital* ecosystems?  Our study has provided some baseline data and information on the functioning of the coastal peat swamp forests of northern Borneo, but there are many other patches of peat around the island, and indeed the whole region to investigate.  In order to design more sustainable management practices for these unique ecosystems, it is important that we find out more about their ecology, past and present, and in particular their ability to respond to different disturbances.  With fire posing a major threat to the persistence of Southeast Asian peatlands, and the resultant carbon emissions posing a major threat to us, we need to gather insights from patterns of past recovery and build an understanding of peat swamp forest resilience.  And fast, before there’s no mud left.

*I hope I have convinced you of their extreme importance by now!

Lydia Cole

 

References

Cole, L.E.S., Bhagwat, S.A. & Willis, K.J. (2014a) Recovery and resilience of tropical forests after disturbance. Nature Communications, 5:3906, 1-7. Doi: 10.1038/ncomms4906.

Cole, L.E.S., Bhagwat, S.A. & Willis, K.J. (2015) Long-term disturbance dynamics and resilience of tropical peat swamp forests. Journal of Ecology – Special Issue on Forest Resilience. Doi: 10.1111/1365-2745.12329.

Gaveau et al. (2014) Major atmospheric emissions from peat fires in Southeast Asia during non-drought years: evidence from the 2013 Sumatran fires. Nature, 4:6112. Doi: 10.1038/srep06112.

Holling, C.S. (1973) Resilience and stability of ecological systems. Annual Review of Ecology and Systematics, 4, 1–23.

Page, S.E., Siegert, F., Rieley, J.O., Boehm, H.-D.V., Jaya, A. & Limin, S. (2002) The amount of carbon released from peat and forest fires in Indonesia during 1997. Nature, 420, 61–65.


New Special Feature: Forest Resilience, Tipping Points and Global Change Processes

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How capable are forests in bouncing back from disturbances? Are they becoming less resilient during this time of rapid environmental change? Can forests deal with the changes, or are they approaching critical thresholds (i.e., tipping points) that will result in a permanent shift towards a different ecosystem state? These critical questions in forest research have increasingly been receiving global attention.

Incidentally, we humans are largely responsible for the current local and global changes that are taking place, which are affecting forests in manifold ways. We are, however, at the same time very much dependant on a large range of forest products and services that are critical for our existence. Knowing how forests will change and how this will have a knock-on effect on the services forests provide is therefore of vital importance for our sustainable future.

This Special Feature brings together contributions from the INTECOL 2013 conference and presents research that addresses these important questions and issues across a range of spatio-temporal scales. The papers presented in this Special Feature include plot-level observational (Camarero et al. 2015; Jakovac et al. 2015; Standish et al. 2015), experimental (Holmgren et al. 2015), paleo-ecological (Cole et al. 2015), and global modelling (Steinkamp & Hickler 2015) studies, as well as a synthesis paper covering the current state of affairs in forest resilience and tipping point research (Reyer et al. 2015).

The contributions to this Special Feature foster a deeper understanding of forest resilience and potential tipping points under local and global change. This Special Feature shows that it remains largely unclear how and if local and global change processes reduce resilience and/or whether they can lead to abrupt vegetation composition and/or species shifts. We have to develop a better understanding of the mechanisms and feedback loops involved in forest resilience and potential tipping points, and the aforementioned contributions will proof useful in guiding further research to safeguard sustainable forests.

Niels Brouwers, Christopher Reyer, Anja Rammig & Fanny Langerwisch

Special Feature Guest Editors, Journal of Ecology

#BESsfe on reflection by Ignasi Bartomeus

Last week quite a few members of Journal of Ecology’s Editorial team were in Lille for the joint BES/SFE Annual Meeting. It was a fantastic few days. Associate Editor Ignasi Bartomeus has written about his highlights below.

#BESsfe

Quick summary of the talks that surprised me most:

Lots of Pollination biology talks: the most surprising finding was from K. Ohashi who showed with comparative analysis across plant species and elegant experiments in the lab that old flowers change their colour (reflectance) quite often, especially when these plants are visited by bees (which are central place foragers, and re-visit sites often). Matthias Schleuning also had a nice talk showing strong trait matching between plant floral traits and hummingbird pollinator traits. I wondered why bee-flower matching is not as strong (presumably).

Also lots of networks stuff: M. Dheling showed an amazing method to relate plant and pollinator traits via their interactions in a network. The 4rth corner analysis! I had the kind of moment where you wonder why you didn’t come up with it before, as it seems so obvious once he explained it. The plenary talk by Pedro Jordano was also a great summary of the potential that a network approach has for explaining a variety of questions, ranging from responses to global change to evolutionary process. On a more methodological point, Marta Sales-Pardo tempted me with an algorithm to detect under-sampled links. I may try it soon.

BEF talks: I skipped most of them this time, but I really liked Rudolf Rohr’s talk using a series of Lotka-Volterra models to show that BEF is positive only when no competitive exclusion and no environmental filtering is modelled. Otherwise the relationship is broken. That fits really well with our observation that dominance patterns and differential extinction risks in natural pollination systems also weaken the experimental BEF relationship.

And as always, the best part is the people that you meet and talk with.

Ignasi Bartomeus
Associate Editor, Journal of Ecology

Editor’s Choice 103:1

Editor’s Choice 103:1

Issue 103:1 of the Journal will be online soon. The latest Editor’s Choice paper is “Earthworm invasion, white-tailed deer and seedling establishment in deciduous forests of north-eastern North America” by Dobson & Blossey. Associate Editor Frank S. Gilliam has written a commentary on the paper below.

The herbaceous layer of eastern hardwood forests: small of stature, large on importance

To those of us who do research on the dynamics of the herbaceous layer in forest ecosystems, the essential role of this lowest of vegetation strata in maintaining the structure and function of those ecosystems is no mystery.  To others, however, it may come as a surprise that, despite that its relative biomass is far less than 0.1% of total standing above-ground biomass of forests; the herb layer serves a function that belies its diminutive stature.  For example, up to 90% of more of the plant biodiversity of forest communities is found in the herb layer.  Furthermore, it can represent 5% of net primary productivity and produce nearly 20% of litterfall, material which tends to have far higher concentrations of N, P, K, and Mg, thus facilitating rapid recycling of macronutrients (Gilliam 2014).

photo 4

Geranium maculatum seedling (photo credit: Annise Dobson)

Forest disturbance ecology: a complexity of agents

Another characteristic of the herb layer of forests is its sensitivity to a wide variety of endogenous and exogenous disturbances of both natural and anthropogenic origin.  The more intense and extensive of these disturbances, such as forest harvesting or fire, can initiate secondary forest succession, which actually can be mitigated by composition of the herb layer itself, wherein the herb layer serves as a regeneration filter for seedlings of eventual canopy dominant species.  Other disturbances are perhaps more subtle (since they do not directly impact the forest overstorey), yet are no less profound in their effects.  Essentially all of these are of anthropogenic origin.  These can include plant species invasions (Ehrenfeld 2010), earthworm activity (Hale et al. 2006), and browsing by white-tail deer (Waller 2014).  As is virtually always the case involving human activities that interfere with ecosystem function, these effects often occur simultaneously (Whitfeld et al. 2014) .

Interactive effects of forest disturbance:  deer browsing and earthworm invasion

soil profile

The forest floor profile from as forest invaded (above) and uninvaded (below) by earthworms (photo credit: Grant Dobson)

The Editor’s Choice in this issue of Journal of Ecology is “Earthworm invasion, white-tailed deer and seedling establishment in deciduous forests of northeastern North America,” by Annise Dobson and Bernd Blossey.  The authors tackle the challenge of simultaneous effects of anthropogenic disturbance head-on by establishing a field experiment that manipulates deer browsing and earthworm activity in a factorial design in the Finger Lakes Region of New York.  Among the compelling aspects of this study is that they used transplants of 15 prominent herb-layer species in the temperate hardwood forests of the region, essentially allowing herb composition to be an additional manipulated variable.  Thus, part of the novel aspect of this study was in combining these variables in an experimental setting in the field.

Enemies above versus enemies below

Although most plant ecologists are aware of the deleterious effect that overbrowsing by burgeoning populations of deer can have on forests (Waller 2014), I suspect that many who might read this are at least somewhat surprised to consider earthworms as agents of disturbance in eastern hardwood forests of the United States.  I recall learning as a child that earthworms serve an important role in ‘tilling’ the soil, simultaneously aerating and fertilizing the soil.  The reality, however, is that they can increase decomposition to the extent that there is minimal humus layers in impacted forests, and can enhance herbivore and pathogen attacks (Hale et al. 2006).  Dobson’s and Blossey’s results suggest that earthworm activity (using the surrogate metric of earthworm biomass) decreased seedling survivorship in virtually all herbaceous species (12 out of 15).  In addition, the negative effects of earthworms exceeded that of deer browsing. Interestingly, there were no interactive effects of deer and earthworms.

Lumbricus terrestris and Annise Dobson (photo credit: Grant Dobson)

Lumbricus terrestris and Annise Dobson (photo credit: Grant Dobson)

Some surprising findings:  other trophic interactions

I found this paper to be intriguing for a variety of reasons. As previously stated, it tackles the challenge of multiple stressors by examining them interactively.  Furthermore, the use of transplants of important herb layer species eliminates confounding that can be unavoidable in field studies, wherein ‘replicate’ sites are often not true replicates of each other because of natural spatial variation in herb composition. I also found quite interesting the novel findings regarding other trophic interactions: earthworms increased likelihood of insect attacks on herbs, whereas deer browsing decreased extent of rodent attacks.

Frank S. Gilliam

Associate Editor, Journal of Ecology

References 

Ehrenfeld, J.G. (2010) Ecosystem consequences of biological invasions.  Annual Review of Ecology, Evolution, and Systematics, 41, 59-80.

Gilliam, F.S. (2014) The Herbaceous Layer in Forests of Eastern North America, 2nd edition. Oxford University Press, New York.

Hale, C.M., Frelich, L.E. & Reich, P.B. (2006) Changes in cold-temperate hardwood forest understory plant communities in response to invasion by European earthworms. Ecology, 87, 1637-1649.

Waller, D.M. (2014) Effects of deer on forest herb layers. The Herbaceous Layer in Forests of Eastern North America, 2nd edition (ed F.S. Gilliam), pp.369-399. Oxford University Press, New York..

Whitfeld, T.J.S., Roth, A.M., Lodge, A.G., Eisenhauer, N., Frelich, L.E. & Reich, P.B. (2014) Resident plant diversity and introduced earthworms have contrasting effects on the success of invasive plants. Biological Invasions, 16, 2181–2193.

Greetings from Lille! #BESsfe

Ho ho ho, off to Lille we go!

Well, this is exciting the BES is in France! Obviously there are talks and lots of conference things happening but there’s also a Christmas market with wooden chalets selling Christmas decorations and festive food, and an exciting museum which I’m hoping I can visit between talks. For those of you who like such things the Sunrise Fun Run is not to be missed, I know I wouldn’t. Talks that caught my eye include

Wednesday

Woodroffe on wild dogs looks fascinating, how can we preserve this iconic species in the face of climate change?

Loeuille explores the interplay between eco-evolutionary dynamics and agriculture.

Froy decomposes the population-level responses to climate and determines the relative importance of within- vs between-individual variation, is plasticity the key?

Kunstler can traits may be used to predict competitive interactions in forests at large scales? It seems that trait values that favour tolerance to competition also render species slow growing in absence of competition, could this be the answer to the coexistence paradox?

Eichhorn mechanisms generating lumpy size distributions, does asymmetric competition hold the key?

Barot Are low rates of nutrient acquisition a form of altruism?

Thursday

Koricheva how not to bodge your meta-analysis!

Van der Vaart Using ABC for IBMs – can you estimate a complex model’s parameters? Come along and find out.

Preece why were some species domesticated and others not? Top team at work here.

De Roos Solving evolutionary problems in continuous time, a software package to do the hard work for you!

De Deyn what traits predict plant soil feedbacks? Perhaps not the ones you expect – see also Dawson.

Friday

Jones getting better as you age, well yes it can happen apparently, but when and why?

Berger how to provision your kids as you age, have marmots got the right idea?

Maurel insights from the garden – do traits or timing/size of introduction influence invasion success?

As ever come along and meet the editors at the BES stand (Richard Bardgett and I will be there, plus several Associate Editors) or follow us living tweeting from the talks, it’s going to be awesome!

Mark Rees

Editor, Journal of Ecology

Happy World Soil Day from Journal of Ecology

Soils Virtual Issue

On Friday 5 December it is World Soil Day and in celebration Journal of Ecology has published a Virtual Issue on soils http://bit.ly/1rMUXyI. The Virtual Issue has been edited by Journal of Ecology’s Richard Bardgett and Amy Austin. For more information about the VI see the below blurb, then visit the Journal homepage to see which papers have been included.

Soils_web ad

In December 2013, the 68th United Nation’s General Assembly designated December 5th as World Soil Day to raise global awareness of the importance of soil as a critical component of the natural system and vital contributor to human wellbeing. To celebrate World Soil Day, and the UN’s forthcoming International Year of Soils 2015, we have compiled a Virtual Issue to highlight recent papers in Journal of Ecology with a below-ground focus.

Although there is a long history of plant ecologists exploring broad relationships between plant communities and their underlying soils, it is fair to say that plant and soil ecologists have, until recently, mostly worked in separate arenas. This, however, has changed in recent years, as plant ecologists have become increasingly aware of the importance of soil for understanding plant population and community dynamics, and the regulation of major biogeochemical processes. In addition, soil scientists have come to appreciate the important role that plants have in modulating many aspects of soil chemistry, nutrient availability and carbon and nutrient turnover. Reflecting these interests, the topic of plant-soil (below-ground) interactions is now among the most popular in the Journal, with 14% of all our published papers being under this header. This research area also has featured prominently in our recent Special Features, including Plant-Soil Feedbacks in a Changing World, Plant-Mediated Interactions Between Above- and Below-ground Communities, and Plant-Soil Interactions and the Carbon Cycle. The Journal is now firmly established as a leading venue for the publication of the most ground-breaking research on the ecological and evolutionary importance of plant-soil interactions in a changing world.

For this Virtual Issue, we have selected 20 papers recently published in Journal of Ecologythat demonstrate the breadth and international scope of soil-related research, and illustrate how ecologists are pushing our understanding of the ecological and evolutionary significance of plant-soil interactions forward. The papers cover topics such as below-ground controls on invasions, the role of soil biota in plant-plant interactions, and the influence of plant and soil community change on biogeochemical processes. We very much hope you enjoy reading these papers brought together in this collection and invite you to submit your ‘ground’ breaking research on plant-soil interactions to Journal of Ecology as a part of the celebration of the International Year of Soils.

Richard Bardgett & Amy Austin

Editor’s Choice 102:6

Issue 102:6 of Journal of Ecology is online now. The latest Editor’s Choice paper was chosen by Editor Amy Austin and the paper is “Tropical rabbitfish and the deforestation of a warming temperate sea” by Vergés et al. Associate Editor Yvonne Buckley has written a commentary on the paper below.

Rock slime and Rabbitfish

A tropical herbivore moves north, invading warmer areas and devouring the diverse native vegetation. Invaded areas are denuded and barren, the native herbivores nowhere to be seen. Who would have thought the rather cutely named rabbitfish would have such a devastating impact?

Editor's Choice 102.6 rabbitfish

Close-up of a rabbitfish juvenile (photo credit: Zafer Kizilkaya)

Soon after the Suez canal opened tropical rabbitfish species entered the Mediterranean and spread into the warmer areas. Vergés et al. not only documented and mapped the impact of tropical rabbitfish in the Mediterranean in relation to sea surface temperature but carried out some neat experiments and video-taped fish feeding behaviour to determine the mechanism of impact. Why do these range-shifting herbivores devastate the macro-algal forests – is it a greater consumption rate or a difference in the way they eat? Underwater cameras were used to catch the rabbitfish in the act.

Invasive rabbitfish in Turkey (photo credit: Zafer Kizilkaya)

Invasive rabbitfish in Turkey (photo credit: Zafer Kizilkaya)

There were small differences in the amount of macroalgal biomass removed by the native and non-native species, but the big difference in eating patterns was that one particular species of rabbitfish consumed the “rock slime” or Epilithic Algal Matrix at a very high rate. Rock slime is a nursery for macroalgae, so the rabbitfish were eating the baby algae, preventing recruitment.

Dr Fiona Tomas and Dr Adriana Vergés setting up feeding preference experiments in barren Adrasan (Turkey), where algal forests are nowhere to be found. (photo credit: Murat Draman).

Dr Fiona Tomas and Dr Adriana Vergés setting up feeding preference experiments in barren Adrasan (Turkey), where algal forests are nowhere to be found. (photo credit: Murat Draman).

When invaders find an unexploited niche they can have a very large impact. As species move around in response to climate change, we may expect more unexpectedly large impacts, particularly as species which have evolved in more diverse communities move into less diverse temperate ecosystems where not all of the potential niches are filled.

Yvonne Buckley
Associate Editor, Journal of Ecology

Special Feature: Grass–woodland transitions

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Grasslands, woodlands and savannas occupy large portions of the Earth´s surface, but are particularly prevalent in dryland, temperate and tropical/subtropical regions. These vegetation types play a key role in the functioning of the biosphere and in supporting the needs of human population through the provision of multiple ecosystem services. An important part of the world’s grasslands and savannas is undergoing a rapid shift from herbaceous to woody-plant dominance, which is promoting large changes in their structure and functioning, and thus on the services they provide.

In the introduction to the Special feature, Sala & Maestre (2014) discuss the importance of having a mechanistic understanding of the factors driving grassland/woodland transitions and of their ecological consequences, and illustrate how the different articles included in the special feature contribute to fill important gaps in our knowledge of this topic.

Anadon, Sala & Maestre (2014) used models of current distribution of treeless vegetation, savanna and forest coupled with an ensemble of global circulation models, to forecast how climate change will affect the distribution of these vegetation types, and of the transition zones between them, in tropical and subtropical Americas. Using data from The Konza Prairie Research Natural Area spanning multiple decades,  Ratajczak et al. (2014) explore the role of fire as an important driver of grass-woodland dynamics in mesic grasslands. Abades, Gaxiola & Marquet (2014) describe the theory behind the spatial structure of woodlands and grasslands, and point out the importance of critical transitions associated with percolation phenomena as a potential mechanism that may underlie grass-woodland transitions.  Archer & Predick (2014) evaluate the known and potential consequences of management actions on a wide range of ecosystem services provided by grasslands and woodlands, the scientific challenges to quantifying these services and the trade-offs existing among them. They also provide a roadmap of priority areas for research that can reduce uncertainty and improve predictions of the outcomes of brush management activities. Using an extensive database with over 900 study sites coupled to an ecosystem water balance model, Bradford et al. (2014) evaluate in this issue the hydrological impacts of the removal of big sagebrush (Artemisia tridentata) in shrub steppe ecosystems across western North America. In the last article from the special feature, Gaitán et al. (2014) used 311 sites located across a broad natural gradient in Patagonian rangelands and structural equation modelling to evaluate the relative importance of climate (temperature and precipitation) and vegetation structure (grass/shrub cover and species richness) as drivers of aboveground net primary productivity (ANPP), precipitation-use efficiency (the ratio of annual ANPP to annual precipitation) and precipitation marginal response (the slope of the annual precipitation-ANPP relationship).

Understanding the causes and consequences of grass-woodland transitions requires the joint consideration of the multiple drivers affecting this phenomenon and their consequences for ecosystem functioning and services. The collection of reviews, empirical and modelling studies included in this Special Feature contribute towards this goal, and will motivate further research in these and other important issues on grass-woodland transitions.

Osvaldo Sala & Fernando Maestre