Editor’s Choice 102:3

We anticipate that issue 102:3 will be online this week. Consider it an Easter treat without the calories!

The Editor’s Choice paper from this issue is Restoration of a megaherbivore: landscape-level impacts of white rhinoceros in Kruger National Park, South Africa” by Cromsigt & te Beest.

The Swedish University of Agricultural Sciences published a press release on this paper earlier this year.

Editor’s Choice 102:3

Large-bodied herbivores – megaherbivores – have been lost from many ecosystems worldwide.  A growing appreciation of the ecological roles that they play has led to reintroductions of megaherbivores into some ecosystems, for example of muskox and wisent into a “Pleistocene Park” in Siberia, or even calls for surrogates to be introduced into others, such as elephants as replacements for long-extinct marsupial megaherbivores in northern Australia.

So far there is little evidence to show what the consequences for ecosystems could be that result from “rewilding” through the reintroduction of megaherbivores.  A new study by Cromsigt and te Beest provides insights into their effects.  In Kruger National Park, South Africa, white rhinoceroses were hunted to extinction in 1896.  They were reintroduced to the Park between 1961 and 1972, most of them to the south-western corner of the Park, and much of the Park remains unoccupied by white rhinoceroses.  Thus there are zones in the Park with either no rhinos, sparse rhino populations, and comparatively dense rhino populations.  Cromsigt and te Beest studied the impacts of the rhinos on the savanna grasslands of the Park.  They capitalised upon the “natural” experiment that the reintroductions presented, focussing on zones with sparse and dense rhino populations.

Photo credit: Jan Graf

Photo credit: Jan Graf

Rhinos aren’t the only megaherbivores present in Kruger National Park: there are also African elephants and hippopotami (the latter don’t venture far from rivers).  There are also a large range of other grazers, including buffalo, wildebeest, zebras and various antelopes.  Yet the effects of the rhinos could be clearly distinguished.  Where their numbers were greatest, short grasses were more prevalent and there were many more distinct grazing lawns that are maintained by the rhinos.  These effects were consistent across more fertile soils derived from basalts and less fertile soils derived from granite.

Cromsigt and te Beest conclude that the rhinos are important drivers of grassland heterogeneity in these savannas.  An intriguing possibility supported by observational data in this study is that this could also be driven, at least on the infertile granitic soils, by an interaction between rhinos and termites.  Grazing lawns on these soils were usually close to termite mounds, which the authors think may be linked to locally enhanced nutrient availability.  This begs further study about whether there may be positive feedbacks between termites, rhinos, and the distinct plant communities that develop in the grazing lawns.

Time for such studies however may be running out.  Cromsigt and te Beest note that poaching pressure on white rhinos, should it continue at current rates, would result in a second extinction of these animals in Kruger National Park within 20 years, and would end of this “rewilding” experiment.  It is a grim prospect that the opportunities presented to determine the ecosystem effects of a rhino population, reintroduced barely thirty years ago, could instead, in future years, give way to a chance to document trophic downgrading after these megaherbivores have gone.

Peter Bellingham
Associate Editor, Journal of Ecology

 

 

Riparian willow dynamics in Yellowstone – Associate Editor commentary

Large carnivores have succumbed to human pressure worldwide.  They have been hunted to near or complete local extinction or their food sources have been reduced drastically.  A recent review1 shows their continuing decline throughout the world.  The review also highlighted the direct and indirect roles that large carnivores play in structuring trophic cascades, and the sometimes unexpected consequences of reducing numbers of these apex predators.  For example, the large reduction in numbers of lions and leopards in many parts of sub-Saharan Africa has resulted in increasing numbers of olive baboons – a mesopredator – that not only prey upon ungulates, but also affect human welfare because they raid crops, which also forces families to take children out of school to help guard fields2.

Coexistence between humans and large carnivores was never an easy accommodation, even when the human population was much lower.  Restoring large carnivores as a means of reinstating trophic cascades meets resistance because of perceived threats to human livelihood.  A clear example of this is in the western United States where grey wolves were hunted to extinction by 1960 because of perceived threats to livestock.  Their reintroduction to Yellowstone National Park in the mid-1990s was controversial and remains so: there is growing pressure to hunt wolves, which occupy only a small fraction of their former range in the United States3.

Studies in Yellowstone National Park since wolves were reintroduced have highlighted their role in trophic cascades1.  Wolves have direct effects by competing with another predator (coyote) and by preying upon elk, which are abundant in the Park.  This in turn has indirect effects; for example reductions in the number of elk has resulted in reduced browsing pressure on aspen trees1,4. However, attribution of changes in vegetation in Yellowstone National Park solely to the reintroduced wolves is controversial4.

A new study5 adds to a view of complex interactions that drive the regeneration of forests in Yellowstone.  Kristin Marshall and co-authors examined the regeneration of riparian willow forests in the northern portion of the Park during a 30-year period, about half of which was before wolves were reintroduced to the Park.  Herbivory by elk, with their numbers affected by wolves, was one of the predictors of willow regeneration.  However, climatic and landscape factors were also important.  Willows had greatest height growth rates, hence a greater ability to escape the “browse trap”6, if they were in parts of the landscape where moisture was least likely to be limiting, and there were episodes of willow recruitment that resulted from a series of years with above-average precipitation.  A nuanced view seems to be emerging from this well-studied system that the trophic cascades associated with wolves, both in terms of their direct and indirect effects, need to take account of the the interactive effects of other predators1, other mammalian browsers5, climatic, landscape, disturbances such as fire, and historic influences.

Peter Bellingham
Associate Editor, Journal of Ecology

References

1Ripple WJ, Estes JA, Beschta RL, Wilmers CC, Ritchie EG, Hebbelwhite M, Berger J, Elmhagen B. Letnic M, Nelson MP, Schmitz OJ, Smith DW, Wallach AD, Wirsing AJ 2014 Status and ecological effects of the world’s largest carnivores. Science 343, 1241484

2Prugh LR, Stoner CJ, Epps CW, Bean WT, Ripple WJ, Laliberté AS, Brashares JS 2009 The rise of the mesopredator. BioScience 59, 779–791.

3Morell V 2014 Science behind plan to ease wolf protection is flawed, panel says. Science 343, 719.

4Marris E 2014 Legend of the wolf. Nature 507, 158–160.

5Marshall KN, Cooper DJ, Hobbs NT 2014 Interactions among herbivory, climate, topography and plant age shape riparian willow dynamics in northern Yellowstone National Park, USA. Journal of Ecology, doi: 10.1111/1365-2745.12225

6Staver AC, Bond WJ 2014 Is there a ‘browse trap’? Dynamics of herbivore impacts on trees and grasses in an African savannah. Journal of Ecology, doi: 10.1111/1365-2745.12230

Ants plant tomorrow’s rainforest – Gallegos, Hensen & Schleuning

The Biodiversity and Climate Research Centre  (BiK-F) have published a press release on  a paper published in Journal of Ecology,“Secondary dispersal by ants promotes forest regeneration after deforestation” by Gallegos, Hensen & Schleuning

The press release can be accessed via this link and the authors have provided a summary of their paper below.

Secondary dispersal promotes reforestation

Most of the plants in the tropics depend on seed dispersal by animals. Secondary dispersal by invertebrates has the potential to modify patterns of primary seed deposition but has rarely been investigated in studies of forest regeneration. We studied the importance of secondary dispersal by ants in deforested habitats in the Bolivian Andes with a seed addition experiment. We found that seed dispersal by ants promoted germination and the recruitment of seedlings in the deforested areas, probably due to directed dispersal to suitable microhabitats.  This shows that inconspicuous seed dispersal agents, such as ants, can be crucial for promoting plant recruitment and the regeneration of degraded habitats. The overlooked process of secondary dispersal has the potential to aid reforestation measures by seed addition in tropical forests.

Gallegos_Photo JEcol-2013-0591.R3

Silvia C. Gallegos

 

Poaching threatens savannah ecosystems – Cromsigt & te Beest

Today the Swedish University of Agricultural Sciences released a press release on a paper published in Journal of Ecology“Restoration of a megaherbivore: landscape-level impacts of white rhinoceros in Kruger National Park, South Africa” by Cromsigt & te Beest.

The press release can be accessed via this link and the authors have kindly composed a brief summary of their paper below. 

Landscape-level impacts of a reintroduced megagrazer

Megaherbivores (animals weighing ≥ 1,000 kgs) are hypothesized to be key drivers of ecosystem functioning and structure because they are not top-down controlled by predation. However, empirical studies on the ecosystem impact of megaherbivores are strongly biased to one species, the African elephant. There is very little contemporary evidence for ecosystem-scale impacts by other megaherbivore species. We quantified how rhino recolonised Kruger National Park (KNP) following their re-introduction in the 1960s to create a unique ‘recolonization experiment’ and test how this megagrazer is affecting the structure of savannah grasslands. We identified landscapes that rhino recolonised long time ago versus landscapes that were recolonised more recently. We assumed that time since colonization represents a proxy for extent of rhino impact. We recorded grassland heterogeneity on 40 transects covering a total of 30 km. Short grass cover was clearly higher in the high rhino impact than low rhino impact landscape. Moreover, we encountered ~ 20 times more grazing lawns, a specific grassland community, in the high rhino impact landscape. Concluding, white rhinoceros may have started to change the structure and composition of KNP’s savannah grasslands. However, current poaching rates, > 1,000 white rhino per year, will drive rhino to extinction with the next 20 years. Our results highlight that this poaching crisis not only affects the species but threatens the potentially key role of this megaherbivore as a driver of savannah functioning.

Joris Cromsigt
Swedish University of Agricultural Sciences

Editor’s Choice 102:2

Issue 102:2 of the Journal will be online very soon. The Editor’s Choice paper from this issue is “Probabilistic and spatially variable niches inferred from demography” by Diez et al. 

Editor’s Choice 102:2

Why do we find a species in some sites but not in others? Niche theory hypothesizes that a species’ distribution is governed by habitat suitability, species interactions like competitive exclusion, dispersal limitation and source-sink dynamics. Spatial population dynamics form the core of the mechanics of these processes: are suitable sites reached by dispersing seeds?  Can those seeds once germinated, grow and flower, and can they establish a viable population given the local biotic and abiotic conditions? Still, population models based on demographic field data have rarely been used to test niche hypotheses. This paper by Diez and co-authors (2014) presents a conceptual framework that can be used to integrate population dynamics and niche theory.

Diez group_LS

Research team, clockwise from top left: Robert Warren, Scott Eustis, Itamar Giladi, Jeff Diez, Ron Pulliam

Diez et al. (2014) illustrate their framework by applying it to their demographic data of Rattlesnake Plantain (i.e. the orchid Goodyera pubescens) which they studied in six populations for six years. To the basic demographic data of survival, growth and reproduction they fitted Bayesian regression models. In these regressions the effects of light availability and soil moisture were included in a spatially hierarchical  fashion. Together these regression models form an Integral Projection Model (IPM) which was used to see how much the effects of light and moisture on each of the vital rates affected the projected population growth rates. At this point the Bayesian statistics came in handy as they can integrate the uncertainty in the regression parameters to arrive at a distribution of population growth rates. This allowed the authors to calculate, for each of their 2x2m plots, the probability that a low-density population would at least be stable, given the local environmental conditions. Interestingly, these probabilities were well correlated with abundance at the population level, but not with occurrence or abundance at the 4m2 scale. Chance events like limited dispersal and demographic stochasticity are suspect to cause this local mismatch in model habitat suitability and local distributions of individuals.

Goodyera

Species can display a wide range of life histories between populations and across their entire distribution (see e.g. Jongejans et al. 2010). In the case of the Rattlesnake Plantains it was statistically not necessary to include population differences in the responses of individuals to light and moisture. However, it will be interesting to find out whether other species or larger spatial scales will require modelling differential plastic responses between populations, for example based on genetic differences. These important  developments of demographically driven species distribution models promise a more mechanistic understanding of landscape-wide responses of species and communities to changing climatic conditions (see also Vanderwel et al. 2013; Merow et al. 2014).

Eelke Jongejans
Associate Editor, Journal of Ecology

Diez, J. M., Giladi, I., Warren, R., & Pulliam, H. R. (2014). Probabilistic and spatially variable niches inferred from demography. Journal of Ecology, n/a–n/a. doi:10.1111/1365-2745.12215

Jongejans, E., Jorritsma-Wienk, L. D., Becker, U., Dostál, P., Mildén, M., & de Kroon, H. (2010). Region versus site variation in the population dynamics of three short-lived perennials. Journal of Ecology, 98, 279–89. doi:10.1111/j.1365-2745.2009.01612.x

Merow, C., Latimer, A. M., Wilson, A. M., Rebelo, A. G., & Silander, J. A. (2014). On using integral projection models to build demographically driven species distribution models. Ecography, in press

Vanderwel, M. C., Lyutsarev, V. S., & Purves, D. W. (2013). Climate-related variation in mortality and recruitment determine regional forest-type distributions. Global Ecology and Biogeography, 22, 1192–1203. doi:10.1111/geb.12081

Journal of Ecology is part of new BES data archiving policy

Earlier this month Journal of Ecology and the other BES journals introduced a new data archiving policy stating that all future articles accepted for publication will be published with the requirement that data used for the results will be made publicly accessible. This means that once a paper is accepted in one of the BES journals authors will be required to deposit sufficient data to allow each result in the published paper to be recreated and the analyses reported in the paper to be replicated to support the conclusions made. Not all papers contain data, and some authors are able to include all the data in the tables and figures in the paper.  However, for those papers with more data than can be included in the paper, authors will be required to make the data available by deposition in a data repository that guarantees public access and permanent storage. When data are deposited the journals will expect authors to ensure that adequate meta-data accompanies their data deposit so that a third party can reasonably interpret those data correctly. Further details on this requirement can be found on the BES website.

One of the main functions of peer-reviewed journals like Journal of Ecology and the other BES journals is to provide readers with published articles that have been through a rigorous evaluation process by experts and that have, as a result, been given a scientific ’stamp of approval’. The only way to truly verify the results of a research paper is to analyse the original data or replicate the study. However, without access to the original data, results cannot be verified through reanalysis. In addition to allowing verification of study results, sharing data has other benefits to the scientific community. In particular, it allows data to be used for new purposes, including, reanalysis using new statistical techniques or to address new questions, inclusion of data in meta-analyses, and use in teaching. Thus, calls have been made for authors to provide access to their data in publicly accessible repositories that ensure long-term preservation of the data. With the new data archiving policy the BES journals are leading the way in responding to these calls from the ecological community.

This policy follows on from a number of high-profile evolution journals that approved a ‘Joint Data Archiving Policy’ (JDAP) in 2010 (Whitlock et al., 2010) and implemented data archiving mandates for papers published in their journals. Authors interested in further advice on data archiving are advised to read Mike Whitlock’s article ‘Data archiving in ecology and evolution: best practices(Whitlock, 2011).

To facilitate the deposition of ecological data, all of the BES journals have integrated with the Dryad data repository. In recognition of the importance of data archiving to the BES the Society is sponsoring deposits made in this archive. However, there is no requirement that authors use this specific repository for their data. Authors should pick the repository that is best suited to their type of data and is most useful to the ecological community likely to access their data. A list of the most commonly used repositories for ecological data is available on the BES website.

Authors are able to request that their data be embargoed for up to 12 months at the time of depositing. Longer embargo periods can be granted at the editors’ discretion. These embargoes will provide protection of data which, if placed in the public domain, may jeopardise further publications. For sensitive data relating to endangered species or protected locations, authors can transform locality details. In rare situations where authors have limited rights to use of data (e.g., proprietary data), or when data access is politically or culturally-sensitive, editors can waive the archiving requirement.

This policy affects all papers submitted to Journal of Ecology since 6 January.  As these papers start to be published readers will find a ‘Data accessibility’ section in each paper which will include details of where data associated with the articles can be found. The location of the data will also be included in the reference list, with a DOI (Digital Object Identifier) if available, making access to the data easy, and future citation of the data trackable via the Data Citation Index on the Web of Knowledge, thus providing authors with further acknowledgement for the research that they are doing.

In implementing this policy the BES are aware of issues that continue to concern the community. There are currently limitations in making the many forms of ecological data searchable and retrievable. It is hoped that community standards will emerge to facilitate the sharing of ecological data, including the development of standards for data re-use and citation. The quality of data deposited and, in particular, the metadata accompanying it, need to improve for the true value of data to be appreciated. It will be important for researchers to trust that the people accessing their data will treat it with respect and adhere to ethical guidelines and community expectations.

The BES hopes the introduction of its new data archiving policy will encourage greater openness from the ecological community, and that increased access to data will play a significant role in advancing the field for future generations.

Liz Baker
Deputy Head of Publications, British Ecological Society

Whitlock, M.C. (2011) Data archiving in ecology and evolution: best practices. Trends Ecol. Evol. 26, 61-65.

Whitlock, M. C., McPeek, M. A., Rausher, M. D., Rieseberg, L. & Moore, A. J. (2010) Data archivingAmerican Naturalist 175, 145–146.

Interview with Frederic Holzwarth – Many ways to die

Frederic Holzwarth is an ecologist at Universität Leipzig in Germany - I caught up with him back in March last year to chat about his research published in the journal. The title was: Many ways to die – partitioning tree mortality dynamics in a near-natural mixed deciduous forest. You can read the abstract and paper here.

Ecology and Evolution, the BES’ cascade journal: A positive personal experience

About a year ago, the British Ecological Society entered into partnership with Wiley’s cascade journal Ecology and Evolution. When we were approached about this enterprise, many of us agreed that cascading sounded like a great idea and the BES and a host of other ecological journals now contribute to this new journal.

The remit of Ecology and Evolution is to catch those papers that don’t quite make it into the so-called feeder journals, which include the BES stable of five journals and several other ecological journals. These are either studies that look promising, but don’t quite fit with the scope of the journal, or good, publishable studies that we wish that we could publish if we had more space. In the rejection letter from the feeder journal, authors are offered a referral to Ecology and Evolution. If they take up the offer, their manuscript along with any reviews it may have received, are transferred to Ecology and Evolution (provided that the reviewers have given permission for their comments to be passed on as well).

Once referred, manuscripts are evaluated by the Editors of Ecology and Evolution for publication, peer review, revision, or rejection. The transfer of reviews from the feeder journals can obviously speed this process up considerably.

I know from recent personal experience that Ecology and Evolution makes the often bitter pill of rejection easier to take.

As Executive Editor for Journal of Ecology, one of the feeder journals for Ecology and Evolution, it has been instructive recently to have gone through this process. One of my own manuscripts, originally submitted to a BES journal (not Journal of Ecology!) was roundly rejected without review by an Editor with the offer of referral (proving that Editors definitely don’t give other Editors special treatment!). Swallowing my pride, I immediately took up this offer and my manuscript was transferred within Scholar One to Ecology and Evolution where the Editors sent it out for peer review. I didn’t have to do much more than answer a few questions within Scholar One; no reformatting for the new journal, no new cover letter, etc. After revisions following peer review the manuscript was accepted and has now appeared online in Early View.

The cascade process worked very well for me. I’m very happy with the outcome. Ecology and Evolution is Open Access so I had to find funds for the Article Publication Charge (thank you SIUC’s Cope Fund), but this was discounted by 20% because of the referral from a BES journal. BES members can also get a 10% benefit when they directly submit to Ecology and Ecology.  The journal also requires authors to archive their data, a policy that the BES journals are now mandating as well. I chose to archive my data with Dryad which turned out to be very straightforward.

All in all, a very pleasant experience that I hope authors of papers that I refer following a decision at Journal of Ecology benefit from too.  My paper “Intraspecific variation among clones of a naïve rare grass affects competition with a non-native, invasive forb” is available at DOI: 10.1002/ece3.919 with the archived data at DOI:10.5061/dryad.k68n1 .

Editor’s Choice 102:1

The Editor’s Choice paper from issue 102:1 of the Journal is The phenology–substrate-match hypothesis explains decomposition rates of evergreen and deciduous oak leaves by Pearse, Cobb & Karban. Read Associate Editor Rien Aerts’ commentary on the paper below.

Editor’s Choice 102:1

Litter decomposition is the major pathway of energy and biomass transfer in most terrestrial ecosystems and plays a key role in biogeochemical cycling.  Given its major importance in ecological processes, there is a vast literature on litter decomposition and its controls.  This started with the seminal papers of Waksman and Tenney (1928) and Tenney and Waksman (1929) on the chemical and climatic controls on litter decomposition. Surprisingly, not much further progress was made during the next 50 years. However, since the 1980’s an overwhelming number of papers has been published on the chemical controls on litter decomposition and on the effects of climate and of soil factors (both biotic and abiotic).

These studies showed that although both climate and substrate quality (litter species identity) are good predictors of litter decomposition at large spatial scales, they often fail to predict litter decomposition at small spatial scales. This is a serious problem as many decomposition studies seek to predict carbon and nutrient fluxes at those small scales and we need a proper mechanistic understanding of decomposition at small spatial scales to enable robust scaling –up to large scales in Earth System Models (ESMs) in a changing world.

DSC01469

It has become clear that much of the variation in litter decomposition at small scales is caused by spatial heterogeneity in the presence and abundance of guilds of decomposing organisms (bacteria, fungi, detritivores) and their interactions with particular litters. This was first described by Hunt et al. (1988) with their Home Field Advantage (HFA) hypothesis which postulates that at a particular spot there is a close match between the dominant litter type and the decomposers, leading to higher decomposition rates compared to a situation where allochtonous litter was introduced. Despite the logic behind this hypothesis, more recent studies showed that the HFA hypothesis often failed to predict litter decomposition rates and that it was very context dependent. These shortcomings have led Fréschet et al. (2012) to postulate the Substrate quality Matrix quality Interaction (SMI) hypothesis, which is in fact a generalization of the HFA hypothesis. The SMI hypothesis states that the match between the litter substrate and the soil matrix (the combination of the decomposers and the abiotic environment) affects the rate of litter decomposition. In contrast with the HFA, the SMI hypothesis can explain situations where there is a better match between allochtonous litter and the home site than between autochtonous litter and the home site, a situation which has been found in several studies.

In their very interesting paper, The phenology–substrate-match hypothesis explains decomposition rates of evergreen and deciduous oak leaves, Pearse and colleagues build forth on the HFA and SMI hypotheses by proposing that litter decomposition rates can be influenced by the timing of leaf senescence and fall, because of temporal changes in the composition of the decomposer community, which is in turn partly driven by changes in the quality of the soil matrix litter. Based on this, their Phenology-Substrate-Match (PSM) hypothesis predicts that a lagged match between litter type and soil matrix will result in an optimum decomposition environment. They conducted a decomposition experiment with litter of both a deciduous oak (leaves are shed in autumn) and an evergreen oak (leaves are shed in spring) in both autumn and spring. In agreement with their PSM hypothesis, they found that deciduous oak litter decomposed faster compared to evergreen litter when incubated in spring, and evergreen litter decomposed faster compared to deciduous litter when incubated in autumn.

PearsePearseSwett

Photo credit: Richard Cobb

Although the PSM hypothesis is so far only supported by a very limited dataset, the idea behind this hypothesis is very appealing. Moreover, the temporal context of the match between litter substrate and decomposer community has been largely overlooked so far and the present theory is an important addition to our understanding of the controls on litter decomposition. It also urges us to seriously consider the timing of the start of decomposition studies and to do this in agreement with the actual timing of litter fall of the studied species. From this paper it is clear that this can really make a difference. The PSM hypothesis also strongly suggests that in a rapidly warming world, where the timing of leaf senescence and litter fall is changing, this may have serious repercussions for the phenological match between decomposers and their substrate.  So, in my opinion, this paper is a ‘must read’ for all ecologists interested in the controls on litter decomposition rates.

Rien Aerts
Associate Editor, Journal of Ecology


Fréschet, G.T., Aerts, R. & Cornelissen, J.H.C. (2012) Multiple mechanisms for trait effects on litter decomposition: moving beyond home-field advantage with a new hypothesis.
Journal of Ecology, 100, 619-630.

Hunt, H.W., Ingham, E.R., Coleman, D.C., Elliot, E.T. & Reid, C.P.P. (1988) Nitrogen limitation of production and decomposition in prairie, mountain meadow, and pine forest. Ecology, 69, 1009-1016.

Tenney, F. G. & Waksman, S. A. (1929) Composition of natural organic materials and their decomposition in the soil: IV. The nature and rapidity of decomposition of the various organic complexes in different plant materials, under aerobic conditions. Soil Science,  28, 55-84.

Waksman, S. A. & Tenney, F. G. (1928) Composition of natural organic materials and , their decomposition in the soil: III. The influence of nature of plant upon the rapidity of its decomposition. Soil Science, 26, 155-171.

Scaling up to communities and ecosystems by J.P. Grime

Blog commentary by J.P. Grime on a set of papers (1965-2007) from the Journal of Ecology reproduced online in December 2013

 Thank you, Editors, for this opportunity to reflect on the circumstances, motivating forces and memorable events associated with 15 publications in the Journal of Ecology involving numerous co-authors. It is a particular pleasure to acknowledge support we have received from several generations of editors and reviewers of the Journal.

The papers have been arranged in chronological order but I have chosen to comment on them in small groups and to insert short headings that seek to summarise the long-term objectives and developing philosophy of the Unit of Comparative Plant Ecology (UCPE) and its successor, the Buxton Climate Change Impacts Laboratory (BCCIL).

A TWO-PRONGED APPROACH

As a post-doc in Sheffield in the early 1960’s and subsequently as an ecologist at the Connecticut Agricultural Experiment Station I was fascinated by the problem of how to characterise the ecology of large numbers of plant species to provide a succinct and orderly basis for investigating how communities assemble  and can be managed and conserved. Already Roy Clapham (Head of Department of Botany at Sheffield) had initiated the Biological Flora of the British Isles that was compiling accounts of the field ecology and biological attributes of species in the Journal of Ecology. This “one species at a time” approach was an admirable agenda in many ways but failed to rapidly address the effects of increasing pressures of changing land-use and pollution on a declining British flora.

By the time I returned to Sheffield in 1965 my mind was focussed on a simple plan—we could use controlled environment facilities to establish, on a statistical basis, how traits suspected to be critical determinants of plant ecologies varied across species and in relation to variation in other important traits. Independently of this activity but in parallel, we would conduct large-scale surveys to document the field ecology of species and the composition of plant communities in an area of 3000 km2 in north centralEngland. Using this two-pronged approach our objective would be to recognise recurrent sets of trait values (plant functional types) under standardized lab conditions and to examine their role in the assembly and functioning of plant communities.

In view of the unconventional and arduous nature of the plan that I was pressing upon colleagues it was necessary that I was “active within both prongs” particularly when the scale and repetitive nature of both the lab and the field operations became evident. Here, therefore, it is appropriate to record my gratitude to Ian Rorison, Nuala Ruttle and later, Rod Hunt, as they shouldered the administrative burden allowing me to concentrate on lab and field commitments.

SCREENING TRAITS IN THE LABORATORY

GROUP 1

1 ) Grime, J.P. & Jeffrey, D.W. (1965) Seedling establishment in vertical gradients of sunlight. Journal of Ecology, 53, 621-642.

2) Grime, J.P., Macpherson-Stuart S.F. & Dearman, R.S. (1968) An Investigation of Leaf Palatability Using Snail Cepaea nemoralis L. Journal of Ecology, 56, 405-420.

3) Grime, J.P. & Hunt, R. (1975) Relative growth-rate – Its range and adaptive significance in a local flora. Journal of Ecology, 63, 393-422.

4) Grime, J.P., Mason, G., Curtis, A.V., Rodman, J., Band, S.R., Mowforth, M.A.G., Neal, A.M. & Shaw, S. (1981) A Comparative-Study of Germination Characteristics in a Local Flora. Journal of Ecology, 69, 1017-1059.

Laboratory screening of traits on large numbers of species has been a frequent activity at UCPE for more than four decades and remains a valuable tool for recognising patterns of functional specialisation and their underlying constraints and tradeoffs. However, I am sometimes deflated when I see our hard-won screening data incorporated into meta-analyses. Larger data-sets do not always add greater assurance if they rely upon a hotchpotch of methods or, worse, subjective exclusion of data.

In a historical perspective, Paper 4 was the most important screening operation conducted at UCPE. It provided estimates of relative growth rate across 135 species most of which were native plants of common occurrence in inland Britain. This long (4year), and laborious study vindicated the two-pronged approach in that the significance of the results emerged by synergy with the distributional data from the field surveys. Inherently slow-growing species were associated with various kinds of infertile, unproductive habitats and fast-growers were restricted to productive soils. A further synergy between lab and field was apparent. The fast-growers fell into two categories. The first consisted of ephemerals of disturbed habitats and the second was made up of robust, often clonal species. Recognition of this widespread pattern was directly responsible for the development of the CSR theory of primary functional types (Grime 1974).

Two papers (1,7) in this group have not achieved the status of paper 4 but can now be recognised as early contributions, alongside  those from Harper, King, Roberts, Westoby, Fenner, Grubb,The Baskins, and many other experts who have brought our understanding of seed and seedling ecology to a point where both are key components of what Grime and Pierce (2012) now describe as the proximal filter of plant community assembly.

The remaining paper in this group (paper 2) established the value of snails in comparative assays of leaf palatability. This paper also prompted the use of these creatures to track food chains in contrasted grasslands at the Winnats Pass (Grime and Blythe, J E, 1968). They may eventually provide techniques with which to assess the relative importance of herbivores and decomposers in ecosystems.

FIELD SURVEYS AND PHENOLOGY STUDIES

GROUP 2

3) Lloyd, P.S., Grime, J.P. & Rorison, I.H. (1971) Grassland Vegetation of Sheffield Region .1. General Features. Journal of Ecology, 59, 863-886.

8) Sydes, C. & Grime, J.P. (1981a) Effects of Tree Leaf Litter on Herbaceous Vegetation in Deciduous Woodland. 1. Field Investigations. Journal of Ecology, 69, 237-248.

Paper 3 co-authored by the three founder members of UCPE was the first to emerge from a series of vegetation surveys that continued into the 1980’s, making the 3000 kmareaaround Sheffield the most thoroughly described flora in Inland Britain. This first survey was composed of 657 1-m 2 samples positioned at random and at a standardised density in old grasslands distributed across the 5 major geological strata of the region.

Already in relation to Group1 it has been explained that the primary objective of the surveys was to use them in conjunction with data from the screening of variation in traits across the local flora. This interaction between field and laboratory sources provided numerous insights into the ecology of species and plant communities and was directly helpful in conservation and management. We continue to pursue this research strategy and with the completion of two further surveys the database has swollen to a total of approximately 10,000 samples now curated by John Hodgson in Hathersage, a village close to Sheffield. Of course, in addition to my “two-pronged” aspirations these field data are increasingly valuable in their own right as a detailed record of “how plant communities used to be” and it is exciting to report that recently Carly Stevens and John Hodgson have resurveyed grasslands first visited and recorded by UCPE in 1965.

The UCPE surveys have an additional potential with specific reference to the impacts of climate change. In the final months of Survey 1 in 1968 sampling was augmented to ensure that as far as possible coverage extended across all available combinations of slope and aspect. This allowed slope-aspect polargraphs to be produced for common species, some close to their geographical limits and exhibiting strong aspect preferences. These remain available in an “Ecological Atlas of Grassland Plants” by Grime and Lloyd (1973) Eventually these venerable diagrams will provide a baseline against which to search for the shifts in plant distributions predicted in various climate change scenarios.  Already the same source is in use as a sensitive indicator of changes in vegetation management

GROUP 3

5) Al-Mufti, M.M., Sydes, C.L., Furness, S.B., Grime, J.P. & Band, S.R. (1977) Quantitative-Analysis of Shoot Phenology and Dominance in Herbaceous Vegetation. Journal of Ecology, 65, 759-791.

6) Thompson, K. & Grime, J.P. (1979) Seasonal variation in the seed banks of herbaceous species in 10 contrasting habitats. Journal of Ecology, 67, 893-921.

Not all of the data we needed from the field could be obtained on the basis of single visits by the recording team. There was a particular need to document the seasonal behaviour of shoots and seeds. This could not be done at the scale and with the intensity of the vegetation surveys. Instead, we mounted two projects in each of which sampling was conducted throughout the year from a set of contrasted communities broadly representative of soil types and disturbance regimes widely distributed within the survey area. At intervals throughout the year both the seed phenology team and the shoot phenology team applied “hit and run” tactics. In order to maintain such intensive programmes, commando-style planning and execution was necessary to minimise delays in tight sampling schedules. In the seed sampling work our sites provided an extraordinary range of conditions extending from the undisturbed charm of Bellamy’s Bank in Millersdale (mentioned in Izaak Walton’s The Compleat Angler (1653) to the various challenges of Orgreave Cinder Tip. Ken Thomson wrote about Orgreave in, paper 6, page 897 commenting that “The site suffered occasional burning and continual disturbance by small boys”. And yes, that’s right–this is where the striking miners, the police and their horses later added to the disturbance factor.

Although the commando- style seasonal sampling by the shoot phenology team closely resembled that of the seed-bank specialists, there were few similarities  in the associated laboratory work. The task of sorting plant fragments into species, followed by oven-drying and weighing, absorbed much of the time between sampling occasions. However, this effort was fully justified by results that confirmed and quantified a humped relationship between rising shoot biomass + litter and species richness that has been subsequently recorded on numerous occasions in many parts of the world.

MICROCOSM EXPERIMENTS

In the 1980’s Bob Peet at the University of North Carolina invited researchers in various labs around the world to collaborate in a network of field experiments in which we would seek to explain the basis of coexistence in species–rich grasslands. At that time most of the clues about coexistence derived from theoretical models or field experiments in which species-rich communities were subjected to resource manipulations or treatments that simulated various kinds of vegetation management. I recognised what had been achieved but concluded that there were limits to further progress using such approaches. Manipulations of ancient, complex ecosystems with incompletely known histories have the potential to set in motion chain reactions that may be hard to follow and have scant relevance to the functioning of real ecosystems. Against this uncertain background I decided to conduct a radically different experiment in which simplified ecosystems would be allowed to assemble from seed under controlled conditions and we would examine the consequences for community development of leaving something outin order to assess its importance. The something in this experiment consisted of arbuscular mycorrhizal fungi. The differences between infected and control communities after one year were sufficient even for Nature (Grime et al,1987) but this episode is etched into our memories for another reason. Twenty-four hours after the experiment was harvested on the 7th floor of the Biology Building our growth room was incinerated by an electrical fault, two staff were briefly trapped between floors in an adjacent lift and order was restored by the Sheffield fire service.

GROUP 3

9) Sydes, C. & Grime, J.P. (1981b) Effects of Tree Leaf Litter on Herbaceous Vegetation in Deciduous Woodland .2. An Experimental Investigation. Journal of Ecology, 69, 249-262.

11) Fraser, L.H. & Grime, J.P. (1999) Interacting effects of herbivory and fertility on a synthesized plant community. Journal of Ecology, 87, 514-525.

13) Booth, R.E. & Grime, J.P. (2003) Effects of genetic impoverishment on plant community diversity. Journal of Ecology, 91, 721-730.

14) Fridley, J.D., Grime, J.P. & Bilton, M. (2007) Genetic identity of interspecific neighbours mediates plant responses to competition and environmental variation in a species-rich grassland. Journal of Ecology, 95, 908-915.

15) Whitlock, R., Grime, J.P., Booth, R. & Burke, T. (2007) The role of genotypic diversity in determining grassland community structure under constant environmental conditions. Journal of Ecology, 95, 895-907.

After this baptism of fire, synthesis of ecosystems in microcosms has become a constant feature of our research, but I have no hesitation in nominating papers 13,14 and15 as the ones that most completely exemplify the virtues of  this approach  particularly where (as with so many staff at UCPE and BCCIL over the years) it is in the hands of talented and dedicated scientists. Rosemary Booth (paper 13) led the way in this extraordinary and eventually successful effort to demonstrate the deleterious impact of genetic impoverishment on the species diversity of limestone grassland. Remarkably, even before this 5-year experiment could start it was necessary for her to develop and apply cloning techniques to produce the large stocks of genetically identical individuals, required to synthesise communities with controlled levels of genetic diversity. A long phase of community maintenance and recording was then required before colleagues Whitlock (paper 14) and Fridley (paper 15) could bring their particular skills to the party.

In retrospect, without formal attachment to any particular framework, there were earlier Journal of Ecology papers that used synthesised communities in our laboratory. In paper 9 the contrasting abilities of woodland plants of differing shapes, sizes and phenology were compared in terms of their capacity to penetrate through layers of tree litter in synthesised communities.

Synthesised communities allowed to develop in the presence and absence of invertebrate herbivores on rich and poor soils have been used by UCPE to  question David Tilman’s assertion (Tilman 1982) that the success of stress tolerators on infertile soil relates to their superior ability to absorb limiting nutrients from low external concentrations.  An alternative explanation is reported in paper 11 where it is shown that the persistence of stress tolerators on poor soils relates to their stronger resistance to herbivores. As our study records, the promotion of stress tolerators by herbivores can be artificially extended to more fertile conditions provided that potential predators of the herbivores are excluded from the microcosms.

One of the current objectives of research at the Buxton laboratory is to establish by experiment the relative merits and weaknesses of (a) climate manipulations applied directly to natural ecosystems and (b) manipulations of ecosystems synthesised and simplified in microcosms. Our provisional conclusion is that both are essential to achieving an appropriate balance between preserving contact with reality and analysis of mechanism.

FINAL COMMENT

In other journals (Ecology 1965, Oikos 1993) I have expressed the view that the ultimate destination of Ecology should be for it to become a distinctive, compact, predictive science capable of scaling up to community, ecosystem and global perspectives. I hope that the papers collated and commented upon here adequately explain my convictions concerning the best route to this destination. Ecology cannot assume a place in the front rank of sciences addressing environmental and human problems unless it establishes reliable generalisations about how organisms function within ecosystems, cause them to vary from place to place, and allow them to suffer degradation under specific human pressures. Vapid, abstract theorising about supposed general benefits of high biodiversity may bring temporary consolations to those worried about food security, declining resources and dwindling populations but they are no substitute for systematic development and testing of ecological theories of wide ambit such as those examined in papers 10 and 12. The enduring strength of the Journal of Ecology over many years resides in testable, evidence-based science. Long may it continue!

J.P. Grime 
The University of Sheffield

REFERENCES

Walton I, (1653) The Compleat Angler. By T. Maxey for R. Marriot, London.

Grime J.P. (1965) Comparative experiments as a key to the ecology of flowering plants. Ecology 54, 513-515.

Grime J.P. and Blythe G.M. (1968) An investigation of the relationships between snails and vegetation at the WInnats Pass. Journal of Ecology 57,45-66.

Grime J.P. (1973) An Ecological Atlas of Grassland Plants. Edward Arnold, London.

Grime J.P. (1974) Vegetation classification by reference to strategies. Nature 250, 26-31.

Tilman D. (1982) Resource competition and community structure. Princeton University Press, Princeton.

Grime J.P.,Mackey J.M.L., Hillier S.H. and Read, D.J. (1987) Floristic diversity in a model system using experimental microcosms. Nature 328, 420-422.

Grime J.P. (1999) Ecology sans frontiers. Oikos 68, 385-392.

Grime J.P. and Pierce S. (2012) The evolutionary strategies that shape ecosystems. Wiley/Blackwell, Chichester.

People and Places

1

The UCPE group resting after a long day in the field

2

On the pampus with UCPE

3

Screening for genetic responses using plants taken from the long-term, climate manipulation experiment

4

Ken and Andrew enjoying the bracing conditions of the South Pennines

5

Andrew and Phil mending a rain shelter

6

Finally Andrew simulating sheep grazing at dusk on a 30-degree slope – it’s been a long day

7

Rosemary during the long haul to measure the effects of genetic impoverishment

8

Success!

9

Life in a microcosm (Jason and Chris) with genetics under control

10

Professor Phil Grime