Tag Archives: Conservation

Beexploitation in social media – UPDATED

2019-07-28 11.15.10

UPDATE:  I should really have linked to Charlotte de Keyzer’s “bee-washing” site – https://www.bee-washing.com/ – it’s making much the same argument in a more comprehensive and elegant way.  That’s what happens when you post blogs first thing in the morning before the (bee pollinated!) coffee has properly kicked your brain into gear…..

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I am fond of new words – neologisms – and if pollinators can be included, so much the better.  For example see my recent post about autobeeography.  That refers to memoirs which focus around work or encounters with bees, of course.  So here’s a new one:  “beexploitation”.

Beexploitaton is a play on blaxpoitation of course, and refers to articles, campaigns, social media, etc., that seeks to make financial or reputational gain from making wild and unsubstantiated claims about pollinators, most often honeybees.  Here’s an egregious example that caught my eye this morning and stimulated this post:  https://www.boredpanda.com/influencer-bee-b-fondation-de-france/

Worryingly, this is set up by the French Government and is aimed at raising money from well meaning people to “save the bees”.  But it’s full of nonsense claims such as that bees pollinate cocoa plants to give us chocolate.  They don’t – the pollinators of cocoa are primarily, perhaps exclusively, small flies.  There are other errors too and we know that honeybees, globally, are not as important as wild pollinators for crop plants.  We need to highlight and critique this sort of rubbish because it diverts money and attention away from genuinely well thought out initiatives to conserve pollinators.

As always, I’m happy to receive comments and other examples of beexploitation.

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Filed under Bees, Biodiversity, Pollination

The role of press freedom in protecting the environment

Ollerton et al Press freedom Figure 1

Recently I’ve been working with a couple of journalist colleagues at the University of Northampton on a short article exploring the relationship between press freedom and environmental protection in different countries.  That piece has just been published on the Democratic Audit website – here’s the link.

I think that the findings are really interesting, and timely in an age when press freedoms are being eroded and journalists physically attacked and even murdered.

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Filed under Biodiversity, Biodiversity and culture, University of Northampton

Celebrating the environmental and historical heritage of the Nene Valley

One of the great privileges of the job I have is working with individuals and organisations across all aspects of conservation and science; people who are asking the most fundamental of ecological or evolutionary questions, through to those addressing on-the-ground questions of habitat management and restoration.  One of my current roles is as a board member for Nenescape Landscape Partnership Scheme, funded by the Heritage Lottery Fund (2016-2021) and involving multiple Northamptonshire partners, with the University of Northampton acting as the Competent Authority for the financing of the scheme.  Our students and staff are also involved in various ways, volunteering their time and expertise.

Friday and Saturday this week was taken up representing the University and the Nenescape board at events that showcased Nenescape-funded projects.  First up was the East Northants Greenway project where we admired the new benches that had been installed, the clearance of rubbish along this former railway, tree planting, the All Aboard for Rushden Art Codes project, and a new mural, and chatted with local residents who seem to be very happy with the work that’s been done.  Then it was along to Rushden Transport Museum to look at the work that’s been done on the old railway goods shed.  On Saturday I was up at Ferry Meadows near Peterborough to try out the new boardwalk that has been installed and to see the restoration of Heron Meadow as a site for overwintering wild fowl and waders.  I now have temporary tattoos of pollinators…. Later in the afternoon I headed to Stanwick Lakes for a celebration of the new barn and heritage garden that’s been created as part of the Settlers of the Nene Valley project, complete with a Viking re-enactment group.  Here are some images from the two days:

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2019-09-21 17.47.26

2019-09-21 17.38.28

 

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Filed under Biodiversity, Biodiversity and culture, Nene Valley NIA, Nenescape, Northants LNP, University of Northampton

Chequered skippers are back: extinct English butterfly breeds for the first time in over 40 years!

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Last year I wrote about our involvement with the chequered skipper reintroduction project that’s happening in north Northamptonshire, and specifically the work of University of Northampton postgraduate researcher Jamie Wildman.  For the past month we’ve been sitting on some news that we were not allowed reveal: the reintroduction has been a success!  That is to say, adult butterflies emerged in May this year, having overwintered as pupae, and have been seen breeding in Rockingham Forest.  The secrecy was to prevent hordes of butterfly twitchers (buttwitchers?) descending on the site and possibly doing unintentional harm as they searched for the adults.  The population just isn’t large enough to be able to withstand that sort of pressure.

The BBC has run with the story this morning – here’s the link – and we have issued a piece via the university’s press team: the link to that is here.

In a time when the media is dominated by profoundly depressing stories about wildlife and the environment it’s great to be able to end the week with some positive news.  Here’s to the long-term success of this lovely little critter!

 

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Filed under Biodiversity, Butterflies, University of Northampton

Is there really a “battle for the soul of biodiversity” going on at IPBES? UPDATED x 3

Carved demon

No.  But perhaps I should give some context to both question and answer…

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) describes itself as “the intergovernmental body which assesses the state of biodiversity and of the ecosystem services it provides to society, in response to requests from decision makers”.   Sounds a little dry, I agree, but in fact IPBES is the most exciting and innovative international environmental body to have emerged in recent years.  Exciting because its remit is specifically to assess how society is affecting global biodiversity in toto, but also its value to humans.  Innovative because it’s a broad church that is trying to bring together the knowledge and expertise of both natural and social scientists, practitioners, indigenous peoples, and stakeholders of all kinds. This broad approach is something which some other international bodies have not, traditionally, been so keen to adopt.

IPBES has its critics who see it as superfluous in that its mission overlaps too much with that of organisations such as the Convention on Biological Diversity, the Ecosystem Services Partnership, and the United Nations Environment Programme.  However I certainly think that there’s room for such an organisation.  We need as many voices as possible shouting about how important these issues are, at all levels of society, from the work of local conservation volunteers and the People’s Walk for Wildlife upwards to the highest levels of international governance.  So I’m a supporter of what IPBES is trying to do; perhaps I’m biased but I was especially impressed by the fact that the first major output of IPBES was a badly needed Assessment Report on Pollinators, Pollination and Food Production for which I acted as an expert peer reviewer over its two iterations.  I’ve written posts about this a couple of times – see for example this one.

In recent weeks, however, there’s been some reports of in-fighting within IPBES, and between IPBES and other organisations, that science journalists have seen as being a major war of ideas.  It culminated in Nature publishing a piece entitled “The battle for the soul of biodiversity“, backed up by an editorial suggesting that “the global body for biodiversity science and policy must heal rifts“.

The crux of the perceived disagreements centre on terminology and concepts as much as anything, and specifically the notion of ‘ecosystem services’ versus ‘nature’s contributions to people”.  These seem to me to be saying much the same thing using different words, and I have to say that I was shocked when I read those articles and wondered what the hell was going on: was IPBES really falling apart before it had even managed to firmly establish itself (remember it only launched in 2013)?  Or was this just journalistic hyperbole of the kind that serves no real purpose other than to increase sales and page views?

I have no inside track to IPBES’s workings so I kept an eye on developments.  I was delighted, therefore, to see the 19th September issue of Nature publish four letters from IPBES insiders and experts from other organisations.  All of these, plus the articles I linked to above, are open access.

The first letter is from Jasper Montana of Sheffield University pointing out that “ideas need time to mature” and that “debates are grist to the mill of innovation for environmental governance”.  In other words, IPBES is a young organisation and the sorts of terminology being used are far from mature: terms such as “ecosystem services” and “natural capital” are at most a few decades old.  Clearly there is an urgency in building governance systems that can effectively conserve biodiversity, but debates around the best terms to use will not hinder that process.

The second letter from Bernardo Strassburg in Brazil entitled “honour guidelines that reconcile world views” pointed out that IPBES’s own guide to such concepts notes that the ecosystem services approach is just one of several, all perfectly valid, ways of viewing the relationships between people and nature, and of seeing people as part of nature.

The next letter is from IPBES chair Sir Bob Watson assuring us that “squabbles don’t obscure the bigger picture” and that a diversity of opinions and ideas is one of IPBES’s strengths.  It’s worth noting here that the original model for IPBES was the IPCC (Intergovernmental Panel on Climate Change) which has in the past been criticised for not allowing a diversity of opinions among contributors to its reports.  You can’t please all the people all of the time, and clearly not Nature journalists….

Finally Rudolf de Groot, chair of the Ecosystem Services Partnership, plus colleagues Pavan Sukhdev & Mark Gough, argued that “sparring makes us strong” and write the most critical of the four letters, stating that they “strongly object to the tone and content” of the original article.  They assure us that the Ecosystem Services Partnership and IPBES are not in competition and that there is mutual respect for different opinions and concepts.  Furthermore “both organizations…stand united against biodiversity loss and ecosystem degradation…. Irrespective of the terminology used, our community is undivided in our knowledge that we fundamentally depend on nature in countless ways.”

So there you have it.  The Nature article and editorial were, in my opinion and those of the letter writers, over the top, exaggerating debates and disagreements that, whilst certainly real, do not endanger IPBES nor its mission.  I urge you to read the original articles then the letters, and make up your own mind.  Comments welcome as always.

UPDATE 1:  Just after I tweeted this post the Natural Capital Coalition added it to the bottom of a tweet thread that they had started when the original articles were published.  I confess that I missed these first time round but the thread adds extra detail to why the articles were misleading.  Well worth reading – here’s the start of the thread:

 

UPDATE 2:  It seems Nature is happy to continue the exchange of views following the article; the current issue of the journal contains another letter (once again open access), this time from Jim Harris (Cranfield University) and Janne S. Kotiah (University of Jyväskylä, Finland) pointing out that “the debate around which framework to use to value biodiversity could stem from the relatively recent coining and adoption of the concept of nature’s contribution to people (NCP).  Google Scholar returns only 19 hits for NCP and nearly 100,000 for ecosystem services, mainly because the latter has been in use for much longer“.

They go on to say (as all the correspondents on this article have) that they see no reason why the two worldviews of NCP and ecosystem services are irreconcilable. NCP seems new and different because it’s unfamiliar jargon   All of this reminded me of one of my first posts on this blog – “Business and biodiversity: oil and water?” which documented an event that I attended in London called “Biodiversity & ecosystem services: new collaboration opportunities for academics with businesses” .  It’s worth quoting what I said with regard to jargon within the field:

“In the workshop I attended there was some discussion as to whether technical language such as “biodiversity”, “natural capital” and “ecosystem services” (which one contributor referred to as “eco-babble”) deters senior business managers from engaging with nature conservation. I pointed out that words and phrases such as “email”, “internet” and “world wide web” were not so very long ago similarly considered to be technical jargon but are now part of our every day language.”

I still stand by this: technical language is only a barrier to engagement if people do not take the time to understand the jargon.  And jargon can become everyday language very swiftly.

UPDATE 3: This issue rolls on and Nature is still allowing commentary.  Just before Christmas Jonathan Davies and Peter Stoett wrote on behalf of the authors of the biodiversity section of the newest Global Environment Outlook (GEO-6) from UNEP  (due March 2019) that “Biodiversity loss is dire, don’t get distracted“.

 

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Filed under Biodiversity, Ecosystem services, IPBES, Pollination

British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators – a recently published study

Balfour et al Figure 1

Natural history records of plant flowering and pollinator foraging, much of them collected by well informed amateurs, have huge scientific importance. One of the values of such records to ecology is that it allows us to document where these species occur in space and when they are active in time. This can be done at a range of spatial and temporal scales, but large-scale patterns (for example at a country level) are, I think, especially useful because they provide scientific evidence that can inform national conservation strategies.

During 2017 I collaborated with a young early career researcher at the University of Sussex, Dr Nick Balfour, on an analysis of the phenologies of British pollinators and insect pollinated plants.  That study was recently published (see citation below) and I think that the results are fascinating.

Nick did most of the leg work on this, which involved assessing more than one million records that document the activity times of aculeate wasps, bees, butterflies and hoverflies held in the databases by three of the UK’s main insect recording organisations, the Bees, Wasps and Ants Recording Society (BWARS), the UK Butterfly Monitoring Scheme (UKBMS) and the Hoverfly Recording Scheme (HRS).  Information on flowering times was taken from a standard British flora (Clapham et al. 1990 – Flora of the British Isles. Cambridge University Press).

As well as looking at annual flight periods and flowering trends for these organisms we also focused on pollinator and plant species that were endangered or extinct. Here are some headline results and thoughts on what the work shows:

  • About two-thirds (62%) of pollinator species peak in their flight times in the late summer (July and August), though there was some variation between the different groups – see the figure from the paper above).  Particularly noticeable was the double peak of the bees, with the first peak denoting the activity of many early-emerging solitary bees, such as species of the genus Andrena, whilst the second peak is other solitary bees plus of course the bumblebees which by that time have built up their colonies.
  • A rather fixed phenological pattern with respect to different types of plants was also apparent, which I was not expecting at all: insect pollinated trees tend to flower first, followed by shrubs, then herbaceous species (again, refer to the figure above). This might be because larger plants such as trees and shrubs can store more resources from the previous year that will give them a head start in flowering the following year, but that idea needs testing.
  • Putting those first two points together, what it means is that trees tend to be pollinated by those earlier emerging bees and hoverflies, whereas the herbs are mainly pollinated by species that are active later.
  • When looking at the extinct and endangered pollinators, the large majority of them (83%) were species with a peak flight times in the late summer, a much larger proportion than would be expected given that 62% of all species are active at that time. However this was mainly influenced by extinct bee species and the same pattern was not observed in other groups.
  • The obvious explanation for that last point is that historical changes in land use have led to a dramatic reduction in late summer flowering herbaceous species and the subsequent loss of floral resources has been highly detrimental to those bees. But intriguingly no such pattern was apparent for the endangered pollinators and clearly there are complex reasons why pollinators should become rare or extinct, a point that I have discussed previously on the blog.
  • The lack of late summer flowering resources for pollinators is a contentious issue however as plant conservation groups have in the past recommend that meadows and road verges are cut in late summer to maximise plant species richness.  Mowing road verges once or twice a year certainly benefits plant diversity, as this recent review by Jakobsson et al. (2018) demonstrates.  But there’s very little data available that assesses how timing of cutting can affect pollinators.  The only study that I know of (and if I’ve missed any, please let me know) that has considered this is the PhD work of one of my former students, Dr Sam Tarrant who looked at pollinators and plants on restored landfill sites compared to nearby nature reserves.  In a paper that we published in the journal Restoration Ecology in 2012 we showed that on restored landfill sites the abundance of pollinators in autumn surveys (conducted September-October) was just as high as for summer surveys.  On nature reserves, which are routinely cut from mid-July onward, this was not the case.

Here’s the full citation of Nick’s study with a link to the publisher’s website, and a copy of the abstract is below.  If anyone wants a PDF, drop me a line:

Balfour, N., Ollerton, J., Castellanos, M.C., Ratnieks, F.L.W. (2018) British phenological records indicate high diversity and extinction rates among late-summer-flying pollinators. Biological Conservation 222: 278-283

Abstract:

The long-term decline of wild and managed insect pollinators is a threat to both agricultural output and biodiversity, and has been linked to decreasing floral resources. Further insight into the temporal relationships of pollinators and their flowering partners is required to inform conservation efforts. Here we examined the
phenology of British: (i) pollinator activity; (ii) insect-pollinated plant flowering; and (iii) extinct and endangered pollinator and plant species. Over 1 million records were collated from the historical databases of three British insect monitoring organisations, a global biodiversity database and an authoritative text covering the national flora. Almost two-thirds (62%) of pollinator species have peak flight observations during late-summer
(July and August). This was the case across three of the groups studied: aculeate wasps (71% of species), bees (60%), and butterflies (72%), the exception being hoverflies (49%). When species geographical range (a proxy for abundance) was accounted for, a clear late-summer peak was clear across all groups. By contrast, there is marked temporal partitioning in the flowering of the major plant groups: insect-pollinated tree species blossoming predominantly during May (74%), shrubs in June (69%), and herbs in July (83%). There was a positive correlation between the number of pollinator species on the wing and the richness of both flowering insect pollinated herbs and trees/shrubs species, per calendar month. In addition, significantly greater extinctions occurred in late-summer-flying pollinator species than expected (83% of extinct species vs. 62% of all species). This trend was driven primarily by bee extinctions (80% vs. 60%) and was not apparent in other groups. We contend that this is principally due to declines in late-summer resource supplies, which are almost entirely provisioned by herbs, a consequence of historical land-use change. We hypothesize that the seasonality of interspecific competition and the blooming of trees and mass-flowering crops may have partially buffered spring flying pollinators from the impacts of historical change.

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

Hunting the Chequered Skipper: an encounter with England’s latest species reintroduction project

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If you have been following recent conservation news on social media you’ll know that this week was an important one for invertebrates.  The Chequered Skipper, a butterfly last seen in England in 1976, has been reintroduced to the country as part of the Back From the Brink initiative.  The Chequered Skipper project is led by Butterfly Conservation and a team travelled to a site in Belgium earlier in the week where about 40 skippers were captured.  These insects were transported back to the UK where they were held overnight in mesh cages at a secret location in order to acclimatise them, then released into the wild.  The release was filmed as part of next week’s BBC Springwatch series – look out for it.

The exact location of the reintroduction is secret.  However I can tell you that it’s occurred in the Rockingham Forest area of north Northamptonshire, in habitat that (over the past couple of years) has been managed specifically for this reintroduction, in order to create a network of sites across which the species could disperse in the future.  This area was the last stronghold of the species in England prior to its extirpation.  No one knows why it went extinct here, but hung on and did well in Scotland, but it may relate to climate: 1976, as many of the middle-aged will remember, was a very hot, dry summer, and this butterfly likes it warm and humid.

Yesterday I had the privilege of seeing this reintroduction first hand when I visited the site with my colleague Dr Duncan McCollin.  Duncan and I are supervising a PhD student, Jamie Wildman, along with Prof. Tom Brereton, Head of Monitoring at Butterfly Conservation (BC), and the University of Northampton’s Visiting Professor in Conservation Science.  Jamie’s project will focus on understanding the habitat requirements for Chequered Skipper, and monitoring the success of the reintroduction.  I’m also hoping that it might be possible for Jamie to assess the role of this species as a pollinator of the plants it visits.  Butterflies as pollinators is a very under-researched area.

Here’s a shot of the Four Mus-skipper-teers* just before we set off to help BC volunteers to locate the skippers and record their behaviour:

Four Mouse-skipper-teers 2018-05-26 11.10.19.jpg

 

The day started unpromisingly.  It was cool and overcast, and little was flying except some hardy Common Carder Bees.  But around lunchtime things began to warm up and gradually the sun broke through and we started to see flying Lepidoptera that we excitedly chased, only to be disappointed by yet another Mother Shipton or Silver Y.  But no skippers.

As we encountered some of the BC volunteers who were also tracking the insects we were told that we had “just missed one” or that they “saw one down that ride, we marked the spot”.  One volunteer wanted to show me a photo of a Chequered Skipper that he’d just taken “so I could get my eye in”.  I politely refused; I wanted to see the real thing and didn’t want to jinx it with a digital preview.

Finally, our efforts were rewarded and we found the first skipper of several we later encountered.  The image at the head of this post is that butterfly, a sight that has not been seen in England in more than 40 years.  An exciting and privileged encounter.  The county Butterfly Recorder, David James (on the right in this next shot), is ecstatic that the reintroduction has occurred “on his patch” but also nervous at the responsibility it represents:

Skipper crew 2018-05-26 13.15.06

Later we spent time helping Jamie follow a female skipper who was showing egg-laying behaviour, moving slowly for short distances along a shrubby edge, occasionally nectaring on Bugle, and diving deep into the vegetation to (we hope) oviposit on grass leaves:

 

Skipper watching 2018-05-26 15.10.18

Although I’ve over-cropped this next image of the skipper on Bugle, I thought I’d leave it as I like the different textures and patterns, and the slightly blurry ambience:

Skipper nectaring 2018-05-26 13.06.08

The primary aim of Butterfly Conservation’s project is to return a small part of England’s lost biological heritage.  But it’s about more than just the Chequered Skipper.  It’s also about understanding how managing a network of sites for this flagship species can benefit other organisms.  The wide woodland rides that have been created are packed with plant species, amongst them at least five grasses that could be used as caterpillar food sources for the skippers, plus more than 20 nectar sources were flowering that they (and other flower visiting insects) could use.  Those other insects were plentiful too: over the day I spotted five species of bumblebees, several different day flying moths, lots of Dark-edged Bee Flies, and a few different solitary bees and syrphids flies.  We heard calling cuckoos, and four different warblers: chiffchaffs, garden warbler, whitethroats, and blackcaps.  Red kites (another incredibly successful species reintroduction) floated overhead skimming the treetops as they their cried to one another.

Rockingham Forest is a lovely part of Northamptonshire, well worth a visit.  The Chequered Skipper will be a wonderful addition to its biodiversity.  Of course there are no guarantees that the reintroduction part of the project will be a success, but if it isn’t it won’t be because of a lack of commitment from the people involved.  If the population does become established then in the future the location will be made public and butterfly enthusiasts will be able to come and pay homage to one of the few butterflies with a pub named after it.

 

*You get the puns you deserve on this blog…..

 

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Filed under Bees, Biodiversity, Birds, Butterflies, Pollination, University of Northampton

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

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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.

Abstract:

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.

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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!

 

 

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