Tag Archives: Conservation

Plant-pollinator networks in the tropics: a new review just published.


As an ecologist who has carried out field work in the temperate zone (UK), the subtropics (Tenerife and South Africa) and the tropics (parts of South America, Africa and Australia)  I’ve always found the idea that the study of ecology can be divided into “tropical” and “non-tropical” a bit odd.  It’s as if the way that the natural world works somehow changes at about 23 degrees north or south of the equator, making things “different” around the equator.  The tropics are a very special, diverse place, it’s true, but so are many places outside the tropics.

With this in mind I was pleased when I was asked by some of my Brazilian colleagues to contribute to a chapter in a new book entitled Ecological Networks in the Tropics. It was an opportunity to review what is known about plant-pollinator networks in the tropics and the ways in which they are very similar to such networks at lower latitudes. Here’s the details of the chapter, followed by the abstract.  If anyone wants a copy please drop me an email:

Vizentin-Bugoni J, PKM Maruyama, CS Souza, J Ollerton, AR Rech, M Sazima. (2018) Plant-pollinator networks in the tropics: a review. pp 73-91 In Dáttilo W & V. Rico-Gray. Ecological networks in the Tropics. Springer.


Most tropical plants rely on animals for pollination, thus engaging in complex interaction networks. Here, we present a global overview of pollination networks and point out research gaps and emerging differences between tropical and non-tropical areas. Our review highlights an uneven global distribution of studies biased towards non-tropical areas. Moreover, within the tropics, there is a bias towards the Neotropical region where partial networks represent 70.1% of the published studies. Additionally, most networks sampled so far (95.6%) were assembled by inferring interactions by surveying plants (a phytocentric approach). These biases may limit accurate global comparisons of the structure and dynamics of tropical and non-tropical pollination networks. Noteworthy differences of tropical networks (in comparison to the non-tropical ones) include higher species richness which, in turn, promotes lower connectance but higher modularity due to both the higher diversity as well as the integration of more vertebrate pollinators. These interaction patterns are influenced by several ecological, evolutionary, and historical processes, and also sampling artifacts. We propose a neutral–niche continuum model for interactions in pollination systems. This is, arguably, supported by evidence that a high diversity of functional traits promotes greater importance of niche-based processes (i.e., forbidden links caused by morphological mismatching and phenological non-overlap) in determining which interactions occur, rather than random chance of encounter based on abundances (neutrality). We conclude by discussing the possible existence and direction of a latitudinal gradient of specialization in pollination networks.



Filed under Bees, Biodiversity, Biogeography, Macroecology, Mutualism, Pollination

Local and regional specialization in plant–pollinator networks: a new study just published

Euphorbia canariensis pollinators 2016-04-29 17 58 00

A fundamental feature of the natural world is that no species exists in isolation: all organisms interact with other organisms during their lives. These interactions take many forms and the outcome varies with the type of interactions. For example predator-prey interactions are clearly negative for the prey species, but positive for the predator. Other interactions result in positive outcomes for both species, including relationships between pollinators such as bees, birds and flies, and the flowers that they pollinate. An important feature of such interactions is how specialized or generalized it is; that is, how many different pollinators are actually involved in pollinating a particular type of flower, or how many types of flower does a specific pollinator visits.

In a newly published study, I have collaborated with colleagues from Denmark and Brazil to assess how local specialization (within a community) relates to regional specialization (across communities) using two separate data sets from the Brazilian rupestrian grasslands and Canary Island/North African succulent scrub vegetation.

Here’s the citation with a link to the paper (drop me a line if you can’t access it and need a PDF):

Carstensen, D.W., Trøjelsgaard, K., Ollerton, J. and Morellato, L.P.C. (2017) Local and regional specialization in plant–pollinator networks. Oikos (in press) doi:10.1111/oik.04436

The abstract is as follows:

“Specialization of species is often studied in ecology but its quantification and meaning is disputed. More recently, ecological network analysis has been widely used as a tool to quantify specialization, but here its true meaning is also debated. However, irrespective of the tool used, the geographic scale at which specialization is measured remains central. Consequently, we use data sets of plant–pollinator networks from Brazil and the Canary Islands to explore specialization at local and regional scales. We ask how local specialization of a species is related to its regional specialization, and whether or not species tend to interact with a non-random set of partners in local communities. Local and regional specialization were strongly correlated around the 1:1 line, indicating that species conserve their specialization levels across spatial scales. Furthermore, most plants and pollinators also showed link conservatism repeatedly across local communities, and thus seem to be constrained in their fundamental niche. However, some species are more constrained than others, indicating true specialists. We argue that several geographically separated populations should be evaluated in order to provide a robust evaluation of species specialization.”

This is what those two different habitats look like:

If you would like more information on plant-pollinator networks, including details of an edible game for Christmas (!), follow this link to the standingoutinmyfield blog.

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Filed under Bees, Biodiversity, Biogeography, Brazil, Macroecology, Mutualism, Pollination, Tenerife

How many trees are there in Amazonia: two recent studies reached very different conclusions – UPDATED

The region of South America that we know as “Amazonia” has arguably the greatest biological diversity of any part of the planet, certainly as far as plants are concerned.  In some places the number of tree species per hectare exceeds 400, an order of magnitude greater than the number for the whole of the British Isles.  However estimating the total number of even the described plant species in this vast area has proven controversial, as two recent studies exemplify.  The first study was by ter Steege et al. (2016) and entitled “The discovery of the Amazonian tree flora with an updated checklist of all known tree taxa“, whilst the second is from just last month: Cardoso et al. (2017) “Amazon plant diversity revealed by a taxonomically verified species list“.  Both of them are open access so click on the links if you want to read the full studies.

One might expect that two such studies focused on Amazonia, both using vouchered herbarium records, would reach broadly similar conclusions as to the number of tree species in the region.  Not a bit of it: ter Steege et al. (2016) report 11,676 species, whilst Cardoso et al. (2017) say that the figure is 6,727.  That’s almost a two-fold difference!  Why the discrepancy?  Inspired by an initial tweet by University of Glasgow taxonomist Roderic Page, I downloaded the data from both studies and looked at it closely.

Here’s a scatter plot of the number of tree species per plant family reported by both studies:

Amazon tree diversity


The red line shows where we would expect the data points to lie if both studies had reported the same number of tree species per family.  Clearly few families lie on this line and most are above it as we might expect: as I’ve said, ter Steege et al. (2016) concluded that there were far more tree species overall and this is reflected at the family level.  Note that I’ve graphed this using a log scale and what might seem to be small differences are actually very large indeed.

Although the findings from two studies are highly correlated (diverse families are diverse in both studies, ditto families with low diversity) the actual level of that species richness is very different.  For example, in the Annonaceae, ter Steege et al. report  480 species, Cardoso et al. report 388; in the Clusiaceae the figures are 247 versus 135.  Other families are excluded from one data set or the other: ter Steege et al. reckon there 7 species of trees in the Dilleniaceae whereas Cardoso et al. cite zero.  Here’s a link to the data set if you want to explore further.  

So what’s going on here?  Why do two studies with similar aims, published about 12 months apart, come to such different conclusions.  As far as I can see there are three reasons for this.

First of all, the studies used slightly different taxonomies when it came to considering families and species.  So for example, Cardoso et al. recognise the family Peraceae which ter Steege et al. do not.  Although I haven’t done it, I’m sure that if one were to dig down to the species level there would be differences in which species were accepted and which were considered synonyms.

Secondly, the exact definition of what constitutes a “tree” varies between botanists, and the non-botanists who are no doubt responsible for some of the plant collections: some consider anything to be woody and tall-ish to be a “tree”, others have more strict definitions.  Notes about growth form taken in the field consequently get included in herbarium databases and may be inaccurate, especially for the uncommon species that have rarely been seen in the field.

The final reason, and the one that seems to be responsible for most of the discrepancy, is the definition of what constitutes “Amazonia”.  In the first study ter Steege et al. defined it as including the “forests and savannahs of the Amazon basin and Guiana Shield”.  In contrast Cardoso et al. considered only “lowland Amazon rain forests”.  That’s a big difference as there’s lot of savannah in this region, as well as other habitat types.  When we did field work in Guyana some years ago we could travel very quickly between savannah and rainforest.  It was clear to us that there is a range of trees that are restricted to one habitat or another, including species of Dilleniaceae (mentioned above) that are savannah specialists (hence the family’s exclusion from the Cardoso et al. study).

Now neither of these studies is “wrong” in the sense of being inaccurate or misguided: both are great studies involving a huge effort on the part of the authors.  But the limitations and definitions of geography and taxonomy that I’ve highlighted do mean that they need to be treated as rather different and not directly comparable.

So how many tree species are there in Amazonia?  If we consider just the rainforest then it’s 6,727 (Cardoso et al. 2017).  If we consider all habitats in the region, including rainforest plus savannah etc., then the figure is 11,676 species (ter Steege et al. 2016).  One of the implications of this is that the non-rainforest “Amazonian” habitats collectively contain 4949 tree species.  Thus a large proportion of the diversity of the region is in habitats, such as savannah, which are less of a focus for conservation efforts and not as well known to the general public, but are at least as threatened by agriculture and mining as rainforest.

Thanks to Roderic Page for initially highlighting this on Twitter, and Sandy Knapp for discussion.

UPDATE:  In retrospect my conclusion above regarding the proportion of trees in non-lowland rainforest habitats was much too high, as a couple of commenters have noted below.  It’s worth reading what they have to say, and my responses.  It’s likely that the taxonomic differences between the two studies are at least as great as the geographical ones, but then taxonomic opinions vary hugely.  Just serves to emphasise what a controversial and problematic question this is!




Filed under Biodiversity, Biogeography

Plant-pollinator networks, the time dimension, and conservation: a new study just published

Biella network

After rather a long gestation period, involving much re-analysis and rewriting, we’ve finally published Paolo Biella’s research from his Master’s thesis.  It’s a really neat plant-pollinator network study from mid-elevation grasslands in Italy’s Northern Apennine.  In it we have considered the way in which such networks could be analysed in relation to plant phenology (i.e. the timing of when they flower) rather than arbitrary time slices (e.g. months, weeks).  We have also discussed how this approach may inform conservation strategies in grasslands such as these.  The full citation with a link is:

Biella, P., Ollerton, J., Barcella, M. & Assini, S. (2017) Network analysis of phenological units to detect important species in plant-pollinator assemblages: can it inform conservation strategies?  Community Ecology 18: 1-10 

I’m happy to send a PDF to anyone who is interested in seeing the full study.

Here’s the abstract:

Conservation of species is often focused either only on those that are endangered, or on maximising the number recorded on species lists. However, species share space and time with others, thus interacting and building frameworks of relationships that can be unravelled by community-level network analysis. It is these relationships that ultimately drive ecosystem function via the transfer of energy and nutrients. However interactions are rarely considered in conservation planning. Network analysis can be used to detect key species (“hubs”) that play an important role in cohesiveness of networks. We applied this approach to plant-pollinator communities on two montane Northern Apennine grasslands, paying special attention to the modules and the identity of hubs. We performed season-wide sampling and then focused the network analyses on time units consistent with plant phenology. After testing for significance of modules, only some modules were found to be significantly segregated from others. Thus, networks were organized around a structured core of modules with a set of companion species that were not organized into compartments. Using a network approach we obtained a list of important plant and pollinator species, including three Network Hubs of utmost importance, and other hubs of particular biogeographical interest. By having a lot of links and high partner diversity, hubs should convey stability to networks. Due to their role in the networks, taking into account such key species when considering the management of sites could help to preserve the greatest number of interactions and thus support many other species.


Filed under Bees, Biodiversity, Butterflies, Hoverflies, Pollination, Wasps

The Biodiversity Impact of Waterside Campus: an interim report on the bird surveys


In previous posts I’ve discussed the work that we are doing monitoring the effects of building a large, new campus for the University of Northampton (see: Monitoring the biodiversity impact of the new Waterside Campus and a video I did of a talk about this project).  We have finally got round to writing an an interim report on the bird surveys we have been conducting (2014-2016), repeating the initial baseline surveys that were carried out in 2012-13.  The executive summary is below and you can download a PDF of the full report here.

As you will see it’s a mixed picture, with some losses and some gains of species, but we are broadly optimistic that the planned landscaping and habitat creation will have a positive effect come the 2018 opening date of Waterside Campus.  It’s important to note that studies such as this which follow up initial ecological surveys and assess the subsequent impact over time are extremely rare as there is no statutory obligation to do so.

Winter surveys will begin shortly and I will report back late next year, time willing.  Any questions or comments, please let me know.


Executive summary

  • Surveys of winter and spring bird diversity are being carried out to assess the effects of construction activities and habitat creation on local biodiversity at the University of Northampton’s new Waterside Campus.


  • These results are compared to pre-construction baseline surveys in winter 2012-13 and spring 2013, undertaken as part of the ecological impact assessment of the site.


  • Results after two repeat sets of surveys (winter 2014-15 and 2015-16; spring 2015 and 2016) are presented, with birds grouped into RSPB Green, Amber and Red categories.


  • Winter bird diversity has dropped from 41 species to 31 species; more Red and Amber listed birds have been lost than Green listed species.


  • Spring bird diversity has dropped from 40 to 36 species; more Green and Amber listed birds were lost, but the number of Red listed species increased slightly.


  • As well as losing species the site has gained birds that were not recorded in the baseline surveys, including Green-listed Coot and Treecreeper, the Amber-listed Stock dove, and the Red-listed House sparrow.


  • In addition, most of the “missing” birds are known to occur at sites 500m to 1000m from Waterside and could return following the end of construction and appropriate habitat creation.


  • Surveys will continue until after Waterside Campus opens in 2018, and analyses will be undertaken to tease out how these changes in bird numbers are related to changes to both the local and regional environments.


  • Outputs from this project so far include two conference presentations and two final year dissertations (one completed and one planned). At least one peer-reviewed research paper is anticipated.

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Filed under Biodiversity, Birds, Nene Valley NIA, University of Northampton, Urban biodiversity

Managing for Pollinators – a special issue of the Natural Areas Journal

Inula at Ravensthorpe 20160710_145426The October issue of the Natural Areas Journal is a special one devoted to the topic of “Managing for Pollinators”.  All of the papers have a North American focus but I think that they will be of general interest to anyone, anywhere in the world, who is concerned with how best to manage habitats for pollinators.  Here’s the contents page of the issue, copied and pasted from the site; I’m not sure if the full text links will work if you or your institution does not have full text access, but you should at least be able to view the abstracts:

Editorial: Pollinators are in Our Nature Full Access

Introduction by USFS Chief Tidwell – Pollinators and Pollination open access

pg(s) 361–361

Citation : Full Text : PDF (227 KB)

National Seed Strategy: Restoring Pollinator Habitat Begins with the Right Seed in the Right Place at the Right Time Full Access

Peggy Olwell and Lindsey Riibe
pg(s) 363–365

Citation : Full Text : PDF (1479 KB)

Hummingbird Conservation in Mexico: The Natural Protected Areas System Full Access

M.C. Arizmendi, H. Berlanga, C. Rodríguez-Flores, V. Vargas-Canales, L. Montes-Leyva and R. Lira
pg(s) 366–376

Abstract & References : Full Text : PDF (1302 KB)

Floral Guilds of Bees in Sagebrush Steppe: Comparing Bee Usage of Wildflowers Available for Postfire Restoration Full Access

James H. Cane and Byron Love
pg(s) 377–391

Abstract & References : Full Text : PDF (1500 KB)

The Role of Floral Density in Determining Bee Foraging Behavior: A Natural Experiment Full Access

Bethanne Bruninga-Socolar, Elizabeth E. Crone and Rachael Winfree
pg(s) 392–399

Abstract & References : Full Text : PDF (1219 KB)

Common Methods for Tallgrass Prairie Restoration and Their Potential Effects on Bee Diversity Full Access

Alexandra Harmon-Threatt and Kristen Chin
pg(s) 400–411

Abstract & References : Full Text : PDF (300 KB)

Status, Threats and Conservation Recommendations for Wild Bumble Bees (Bombus spp.) in Ontario, Canada: A Review for Policymakers and Practitioners Full Access

Sheila R. Colla
pg(s) 412–426

Abstract & References : Full Text : PDF (420 KB)

Conserving Pollinators in North American Forests: A Review Full Access

James L. Hanula, Michael D. Ulyshen and Scott Horn
pg(s) 427–439

Abstract & References : Full Text : PDF (1711 KB)

Dispersal Limitation, Climate Change, and Practical Tools for Butterfly Conservation in Intensively Used Landscapes Full Access

Laura E. Coristine, Peter Soroye, Rosana Nobre Soares, Cassandra Robillard and Jeremy T. Kerr
pg(s) 440–452

Abstract & References : Full Text : PDF (4647 KB) : Supplementary Materials

Revised State Wildlife Action Plans Offer New Opportunities for Pollinator Conservation in the USA Full Access

Jonathan R. Mawdsley and Mark Humpert
pg(s) 453–457

Abstract & References : Full Text : PDF (249 KB)

Diet Overlap of Mammalian Herbivores and Native Bees: Implications for Managing Co-occurring Grazers and Pollinators Full Access

Sandra J. DeBano, Samantha M. Roof, Mary M. Rowland and Lauren A. Smith
pg(s) 458–477

Abstract & References : Full Text : PDF (1537 KB)

The Role of Honey Bees as Pollinators in Natural Areas Full Access

Clare E. Aslan, Christina T. Liang, Ben Galindo, Hill Kimberly and Walter Topete
pg(s) 478–488

Abstract & References : Full Text : PDF (467 KB)

Food Chain Restoration for Pollinators: Regional Habitat Recovery Strategies Involving Protected Areas of the Southwest Full Access

Steve Buckley and Gary Paul Nabhan
pg(s) 489–497

Abstract & References : Full Text : PDF (732 KB)

Forbs: Foundation for Restoration of Monarch Butterflies, other Pollinators, and Greater Sage-Grouse in the Western United States Full Access

R. Kasten Dumroese, Tara Luna, Jeremiah R. Pinto and Thomas D. Landis
pg(s) 499–511

Abstract & References : Full Text : PDF (1716 KB)

Using Pollinator Seed Mixes in Landscape Restoration Boosts Bee Visitation and Reproduction in the Rare Local Endemic Santa Susana Tarweed,Deinandra minthornii Full Access

Mary B. Galea, Victoria Wojcik and Christopher Dunn
pg(s) 512–522

Abstract & References : Full Text : PDF (2880 KB)

Save Our Bats, Save Our Tequila: Industry and Science Join Forces to Help Bats and Agaves Full Access

Roberto-Emiliano Trejo-Salazar, Luis E. Eguiarte, David Suro-Piñera and Rodrigo A. Medellin
pg(s) 523–530

Abstract & References : Full Text : PDF (463 KB)

The Importance of Phenological Diversity in Seed Mixes for Pollinator Restoration Full Access

Kayri Havens and Pati Vitt
pg(s) 531–537

Abstract & References : Full Text : PDF (2208 KB) : Supplementary Materials

Stewardship in Action Full Access

Sarah Riehl
pg(s) 538–541

Citation : Full Text : PDF (595 KB)

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Filed under Bees, Biodiversity, Birds, Butterflies, Honey bees, Hoverflies, Mammals, Mutualism, Pollination, Wasps

The macroecology of animal versus wind pollination – a new study just published

In collaboration with colleagues in Brazil, Denmark, and elsewhere in the UK, we’ve just published a new research paper which looks at the global spatial distribution of wind and animal pollinated plant species, and the underlying historical and contemporary ecological causes of that distribution.  It’s a study that builds on my “How many flowering plants are animal pollinated?” paper in Oikos, and has been a long time in its gestation.  We’re very excited by its findings and plan to develop this project in the future.

As a bonus we made the cover of the journal with the amazing image below!  Big thanks to Pedro Viana and Jesper Sonne for the photos.

Here’s the citation with a link to the publisher’s website; the abstract is below.  If anyone wants a PDF copy, please ask.

Rech AR, Dalsgaard B, Sandel B, Sonne J, Svenning J-C, Holmes N & Ollerton J (2016) The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability. Plant Ecology & Diversity 9: 253-262



Background: The relative frequency of wind- and animal-pollinated plants are non-randomly distributed across the globe and numerous hypotheses have been raised for the greater occurrence of wind pollination in some habitats and towards higher latitudes. To date, however, there has been no comprehensive global investigation of these hypotheses.

Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal vs. wind pollination.

Methods: We analysed 67 plant communities ranging from 70º north to 34º south. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and late-Quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection.

Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination.

Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns.



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Filed under Biodiversity, Biogeography, Brazil, Climate change, Macroecology, Pollination

Two-day Steven Falk bee ID course at Oxford University Museum 15th-16th October 2016

Male B lap on Salvia cropped P1120309

One of the most exciting, pollinator-related publishing events of last year was the publication of Steven Falk’s eagerly-anticipated Field Guide to the Bees of Britain and Ireland.  Not only does this book provide a state-of-the art account of the natural history and identification keys for all of the bees currently known from Britain (over 270 species) but it’s backed up by Steven’s own Flikr site with more photographs of the bees, including lots of close ups, and an ongoing list of updates and corrections.

But as Steven himself acknowledges, the identification of many of our bees is a challenge, even with the book and the additional imagery.  Anyone who is really keen to get to grips with bee identification is therefore recommended to book onto a hands-on identification course.  Steven has just announced that he is running a two-day course in Oxford on 15th to 16th October, at a cost of £60 per person – here’s a link to the booking page.  Seems like good value to me!

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Bees and pesticides – a major new study just published – UPDATED

Male B lap on Salvia cropped P1120309

An important new study about the effects of neonicotinoid pesticides on wild bees has just been published in the journal Nature Communications – here’s the details and a link to the paper, which is open access:

Woodcock, B. A. et al. (2016) Impacts of neonicotinoid use on long-term population changes in wild bees in England. Nat. Commun. 7:12459 doi: 10.1038/ncomms12459

As I’ve previously discussed on this blog (e.g. here and here) there are widespread concerns amongst environmentalists, and some scientists, about the impact that these relatively new pesticides are having on pollinators and other biodiversity.  The Woodcock et al. paper is a major contribution to this discussion as it uses a huge dataset to model the changes in populations of 62 wild bee species that are known to forage on oilseed rape (canola) over 18 years.  These changes can be related to the spatial extent of oilseed rape cultivation and the authors found that whilst bees “….foraging on oilseed rape benefit from the…[nectar and pollen provided by]….this crop….[they]….were on average three times more negatively affected by exposure to neonicotinoids than…” bees which didn’t forage on the crop.

The authors further conclude that “This study provides the first evidence for community level national scale impacts on the persistence of wild bee populations resulting from exposure to neonicotinoid treated oilseed rape crops.”

Neonicotinoid pesticides are, of course, not the whole story when it comes to understanding declines in pollinator diversity and abundance.  But these pesticides are the latest in a long history of changes to British agriculture that have had significant consequences for the biodiversity of our country (as we showed in our study of bee and wasp extinctions).

Reactions to the study have been, well, predictable.  A long feature on the BBC News website* quoted a representative from Bayer as saying:

“we believe….[the study’s]….findings would be more correctly headlined that intensive agriculture is causing some issues with pollinators…..  Whether this is due to the use of insecticides is not clear; a lack of nesting sites and pollen and nectar sources in these areas may also be critical factors.”

Which rather ignores the fact that this was a comparative study of bees that forage on oilseed rape versus those that don’t.

Likewise the National Farmer’s Union’s position was that:

“While this study claims to provide an important contribution to the evidence base underpinning the current EU moratorium on some uses of neonicotinoids, experts reviewing all the evidence have concluded that there are still major gaps in our knowledge and a limited evidence base to guide policymakers”

Which sounds to me like a statement designed to fudge the issue: the “experts reviewing all the evidence” would not have reviewed this particular study!  And which begs the question – how much evidence and how many studies would be enough for the NFU?

The study’s authors do not make any suggestions as to what the next step should be in this continuing saga but are quoted as saying that “simplistic solutions” such as banning these pesticides are not the answer because this will encourage use of pesticides that are even more damaging.  That may be the case but it’s clear that an independent root-and-branch reassessment of the use of pesticides (and herbicides) in UK agriculture is long overdue.


*As an aside, this BBC News piece wrongly states that bumblebees were not included in the study, which is not the case.


UPDATE:  After I published this post I noticed that Manu Saunders has also written about the bee study, plus a second study that I’d not seen linking neonicotinoid use to declining butterfly populations in California.  Here’s a link to Manu’s blog.



Filed under Bees, Biodiversity, Ecosystem services, Neonicotinoids, Pollination

The biodiversity of restored landfill sites: a new study of snails just published

Snails - 20160813_124310

The latest paper in a series* studying the biodiversity of restored landfill sites in comparison to nearby nature reserves has just been published.  This work comes from the linked PhD research of two of our former students, Dr Lutfor Rahman and Dr Sam Tarrant.

This new paper deals with the larger snails to be found on these novel grasslands and assesses the value of such sites for conserving the diversity of an ecologically important group of molluscs.  Snails play a vital role in nutrient turnover and are a major food source for higher trophic levels, such as some birds, small mammals, and beetles.

The take home message from the study:  restored landfill sites are as rich in species as nature reserves, but a higher proportion is of non-native, introduced species.

Here’s a link to the paper, with the abstract below; it’s paywalled but if you’d like a PDF, just ask:

Rahman, L. Md., Tarrant, S.,Ollerton, J. & McCollin, D. (2016) Effect of soil conditions and landscape factors on macro-snail communities in newly created grasslands of restored landfill sites in the UK.  Zoology and Ecology (in press)



Though restored landfill sites provide habitat for a number of taxa, their potential for land snails remains unexplored. In this study, large-sized land snails (>5 mm) were surveyed using transect sampling at nine restored landfill sites and nine corresponding nature sites in the East Midlands region of the UK, during 2008. The effect of restoration was investigated by examining the composition, richness and diversity (Shannon index) of land snail species in relation to habitat and landscape structure. Thirteen macro-snail species were recorded in total, and rarefied species richness and diversity at restored landfill sites was not found to be statistically different from that of reference sites. One third of the snail species at restored landfill sites accounting for 30% of their total abundance were non-native species. Soil electrical conductivity was the strongest predictor of richness and diversity of land snails. Road density was found to be positively related to snail species diversity. Given the high percentage of introduced species at study sites, further research is needed to elucidate management implications of restored landfill sites and dynamics of native vs. non-native species.


*The other papers in this series are:

Rahman, L. Md., Tarrant, S., McCollin, D. & Ollerton, J. (2015) Vegetation cover and grasslands in the vicinity accelerate development of carabid beetle assemblages on restored landfill sites. Zoology and Ecology 25: 347-354

Tarrant, S., Ollerton, J., Rahman, L. Md., Griffin, J. & McCollin, D. (2013) Grassland restoration on landfill sites in the East Midlands, UK: an evaluation of floral resources and pollinating insects. Restoration Ecology 21: 560–568

Rahman, L. Md., Tarrant, S., McCollin, D. Ollerton, J. (2013) Plant community composition and attributes reveal conservation implications for newly created grassland on capped landfill sites. Journal for Nature Conservation 21: 198-205

Rahman, L. Md., Tarrant, S., McCollin, D. & Ollerton, J. (2012) Influence of habitat quality, landscape structure and food resources on breeding skylark (Alauda arvensis) territory distribution on restored landfill sites. Landscape and Urban Planning 105: 281–287

Rahman, L. Md., Tarrant, S., McCollin, D. and Ollerton, J. (2011) The conservation value of restored landfill sites in the East Midlands, UK for supporting bird communities. Biodiversity and Conservation 20: 1879-1893

Again, if you’d like PDFs of any of these, just ask.





Filed under Biodiversity, Snails, University of Northampton