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Book review: “Pollination and Floral Ecology” by Pat Willmer

Review of “Pollination and Floral Ecology” by Pat Willmer (2011) Princeton University Press. £65. pp. 832.

Some backstory: In early 2012 I was asked by the review editor of the journal Annals of Botany to review this book, and I jumped at the chance as it’s the first major single-author overview of the field of pollination ecology for a number of years, by a well respected academic in the field. Unfortunately the review took a lot longer than I expected, in part because I was also coordinating my department’s Research Excellence Framework submission, on top of other teaching, research and admin duties, and it was taking up quite a bit of my time.

In addition I had mixed feelings about the book and wanted my review to do it justice, not be over-critical but at the same time highlight what I saw as flaws. In the words of the Fairport Convention song, Who Knows Where the Time Goes? – my review was only completed last Christmas and duly submitted. Turns out that the journal has a backlog of book reviews to publish and the editor asked that, given it’s been a couple of years since the book was published, would I mind if the review was posted on the Annals of Botany blog rather than in the printed journal. I happily agreed as it’s likely to get more readers on the blog, and said I’d also post it on my own blog. So here it is:

Any text book that tries to assess and summarise the whole of a multidisciplinary research field such as pollination ecology and floral biology is required to be four things: (1) comprehensive in its scope; (2) up to date in its coverage of the literature; (3) accurate in its assessment of the current state of the field; and (4) authoritative in the conclusions it presents.

This volume by Professor Pat Willmer of the University of St Andrews certainly ticks the first box. It’s a huge book, and covers everything relating to the evolution of flower attraction and reward systems, ecological interactions with pollinators, biochemistry, physiology, agriculture and conservation; all in 29 chapters split into three sections, with 87 pages of references. The literature extends to 2010, which is impressive for a book published in 2011 (though see my comments below about completeness of the literature). Specialist terms are highlighted in bold to direct the reader to the glossary at the back, a useful device even if there are a few inaccuracies, which I’ll mention later.

So far so good, and the author is to be congratulated on putting together such a comprehensive, not to mention timely, single-author book. It’s clearly the summation of a career devoted to studying pollinators and flowers, and the author’s passion for her subject is apparent throughout.

However when we come to points 3 and 4, things are less straightforward. There are some issues with accuracy that are troubling in a book aimed at newcomers to the field as well as established researchers. To give just a few examples:

– on p.18 we are told that asclepiads have “one stamen” (they have five); on p.169 and in the glossary that asclepiad pollinia are the pollen grains from one anther (they are the contents of half an anther); and on p.170 that the pollinaria are “glued” to pollinators (they actually clip on).

– in the glossary, tree ferns are referred to as “cycads”, an error that is repeated on p.89.

– on p.88 there is a statement suggesting that tree fern spores were dispersed by “animal fur” 300 million years ago, long before the evolution of mammals, and that this (and dispersal of spores of fungi and mosses) is the equivalent of pollination: it is not, it equates to seed dispersal.

These are troubling errors of basic botany that are forgivable in an early draft of the book (everyone makes mistakes) but not in the final published version, after it’s been read, reviewed, checked and edited. If the book goes to a second edition I hope that these (and other) mistakes will be fixed. But they do hint at a fundamental problem with a book (and a field) as large and complex as this: a single author is arguably unlikely to be able to do justice to all of the subject matter.

There are parts of the book where it is unclear (to me at least) what the author is actually saying. For example, on p.96 there is a graph which, it is suggested, demonstrates that pollination by animals is “technically uncommon when assessed in terms of the numbers of broad taxonomic groups that use it”, though the legend to the figure claims that “most orders of plants have no families” that possess wind pollination. This is confusing: what is to be concluded by someone new to the field? Is animal pollination common or rare? Likewise, on p.91 we are told that the “first angiosperms…would probably have had their pollen moved mainly by wind…”, but then on p.92 that “an element of insect pollination could be regarded as almost ancestral”. Which is correct?

There are other aspects to the book that are simply out of date; for example the linear, rather deterministic schemes set out in Figures 4.6 and 4.8 showing that Cretaceous flowers were open and radially symmetrical, and only later evolved into complex, bilateral flowers in the Tertiary, ignores fossil discoveries showing that orchids evolved in the Cretaceous (Ramírez et al., 2007). Likewise, discussion of “counterproductive” crypsis in flowers (p.124) neglects recent findings of cryptic, wasp-pollinated plants in South Africa (e.g. Shuttleworth & Johnson, 2009).

There is a theme emerging here: some of the botany that the book presents is inaccurate, confused or out-dated. Fortunately the zoological aspects of the book are much better, as one might hope from a Professor of Zoology.

The final criterion, that the book should be “authoritative in the conclusions it presents”, is however, in my view, the main weakness of this volume. The author is unhappy with recent developments in the field, particularly as they relate to community-scale assessments of plant–pollinator interactions, in terms of network analyses and predictive utility of pollination syndromes. Clearly Professor Willmer is on a mission to rebalance what she perceives as failings within some of the current trends in studying pollination. A book review is not the place for a technical dissection of the author’s arguments, which is best left to the peer-reviewed literature (though I would argue that that’s also the place to present some of the criticisms the author introduces, rather than into a text book such as this). I could focus the whole of this review on these topics because: (a) they take up a large proportion of the book, about one-third of the text pages; and (b) they are highlighted on the cover as being one of the main contributions of the book; specifically, that the author provides a critique of previous work that does not distinguish between “casual visitors and true pollinators” that can in turn result in “misleading conclusions about flower evolution and animal-flower mutualism”. Unfortunately her targets are straw men, and one – I believe quite telling – example will suffice.

On p.447 there is a criticism of the use by Waser et al. (1996) of Charles Robertson’s historical data set, and specifically that the analyses they present “…did not distinguish visitors from pollinators even though Robertson’s database did include information on this”. However Waser et al. clearly state (p.1045 of their paper) that only pollinators were included in the analyses, not all flower visitors, and that “visitation is not a synonym for pollination…non-pollinating visitors are excluded (as in Robertson 1928)” (p.1048).

Why should Professor Willmer make a statement to the contrary? Evidently she wishes to impress upon her readers that (in her opinion) there are fundamental problems in current approaches to studying pollination at a community level. But even if that were the case (and I don’t believe it is) misrepresenting previous studies to suit an argument is poor scholarship at best.

Regardless of whether some of her criticism is well founded, the author does not seem to appreciate that plant–flower visitor interaction networks are ecologically important regardless of whether or not a flower visitor acts as a pollinator. More fundamentally, true pollination networks possess similar attributes to flower visitor networks, for example a nested pattern of interactions, and arguments about level of generalisation of species are a matter of scale, not category (Ollerton et al., 2003).

At the end of her Preface, Professor Willmer reveals to us quite a lot about her personal attitude to research when she states that some readers might find her approach “too traditional” in an “era where ecological modelers [might be claimed to] have more to tell us than old-style field workers”. What the author fails to appreciate is that this is a grossly false dichotomy and that most of the pollination ecologists who have embraced new analytical methodologies for understanding plant–pollinator interactions are also “old-style field workers” with considerable experience of studying the ecology of flowers and their pollinators beyond the computer screen.

In summary this is a book that, for all its good qualities of comprehensiveness and (mostly) up to date coverage, should be read with caution: parts of it are neither as accurate nor as authorative as the field of pollination and floral ecology deserves.

LITERATURE CITED

Ollerton J, Johnson SD, Cranmer L, Kellie, S. 2003. The pollination ecology of an assemblage of grassland asclepiads in South Africa. Annals of Botany 92: 807-834.

Ramírez SR, Gravendeel B, Singer RB, Marshall CR, Pierce NE. 2007. Dating the origin of the Orchidaceae from a fossil orchid with its pollinator. Nature 448: 1042-1045.

Shuttleworth A, Johnson SD. 2009. The importance of scent and nectar filters in a specialized wasp-pollination system. Functional Ecology 23: 931-940.

Waser NM, Chittka L, Price MV, Williams N, Ollerton J. 1996. Generalization in pollination systems, and why it matters. Ecology 77: 1043-1060.

Budget cuts to Kew are cultural vandalism

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The Royal Botanic Gardens, Kew, is a beautiful place to visit, a tourist destination for visitors to London, and a green island in an urban ocean. That’s the public face of the Gardens. What is less well appreciated to most of the casual strollers around the flower beds and glasshouses, is that Kew is arguably the most important centre for botanical research anywhere in the world. During its long history it has produced, and continues to deliver, top rate science that informs international conservation strategies, agriculture and horticulture, as well as basic plant science in ecology and evolutionary biology.

It’s also a welcoming, inclusive place that embraces scientific visitors from all over the world, as I know from personal experience. Although I’ve never had a formal relationship with staff at Kew, I’ve benefitted enormously from informal links, which have facilitated research and teaching, including annual trips to the Kew Herbarium for my final year undergraduate students.

I first visited Kew as a naive 20 year old to look at their living plant collection during research for what became my first ever publication: “Adaptations to arid environments in the Asclepiadaceae” (British Cactus and Succulent Journal 1986). So started a long appreciation of Kew and what it freely offers teachers and researchers, which has included access to specimens prior to overseas research trips, to assess distribution and flowering times; identification of specimens we’ve collected on those trips; and primary data for our study of fly pollination in the genus Ceropegia. I’ve also used their archives for my work on John Tweedie. Kew is an incredible resource that, in any civilised and culturally aware country, would be cherished and supported. Unfortunately it appears that I do not live in such a country.

Rumours have been circulating for a while about an impending, massive budget cut at Kew, on top of financial savings that have already been made. Now it appears that those proposed cuts are much bigger than anyone had thought and 120 posts, mainly in science, are threatened. I won’t repeat the depressing statistics underlying all of this – I’ll just urge you to visit the online campaign against these cuts, read the details, watch the David Attenborough video, sign the petition, and share it with friends and colleagues.

Please don’t let Kew wither away; it’s too important to UK science, conservation and education to allow it to be gutted without a fight.

Disturbed birds? Results of a visitor access study to the Upper Nene Valley

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Human activities can have significant impacts on wildlife in quite subtle ways that are not always appreciated by those of us who enjoy going out to look at nature. For example, simply walking close to sensitive areas such as bird nesting or roosting sites has the potential to drive those birds from an area. This was the theme of a workshop we attended yesterday afternoon, hosted by the local Wildlife Trust as part of the Nene Valley Nature Improvement Area (NIA) Project.

During the afternoon Colin Wilkinson from the RSPB presented the results of a survey that had been commissioned to assess the level of public access and usage of the Upper Nene Valley gravel pits. These pits have Special Protected Area status due to the numbers of migratory over-wintering birds that use them. They are also well used by the public but at the moment we have no idea what impact this is having on the birds, though there is anecdotal evidence that it is considerable at some sites.

The consultants who conducted the study used a combination of face-to-face interviews, site surveys, etc. There’s too much in the report to go into all of the detail – you can access the full text here – but I’ve copied the highlights from the summary below:

The majority (98%) of visitors were on a short visit from their home
Group size for interviewed groups ranged from 1-8; 51% of interviewees were visiting on their own. Stanwick Lakes was notable in that group size tended to be larger here.
Half of the 939 interviewees had dogs with them (636 dogs in total).
Across all sites and survey periods, dog walking was the most common main activity (48% of interviewees).
During the winter, a higher proportion of people interviewed were dog walking (48% of interviews during the winter compared to 36% in the spring at the 6 locations surveyed in both seasons).
Over the winter, the main activities given by interviewees were: dog walking (53%), walking (26%), and wildlife watching (6%).
Most (77%) interviewees had arrived by car to the survey point
Most interviewees were frequent visitors (60% indicated that they visited at least once a week).
Most visits were short: 50% of visitors stated that they spent less than one hour on site and, in total, 88% spent less than two hours at the survey location.
The quality of the site was the most common reason for choice of site (61% interviewees), but was not the most common ‘main’ reason’; 32% interviewees gave proximity to home as the main factor underpinning their choice of site. Proximity to home seemed particularly important for dog walkers (44%) and those fishing (40%).
A total of 863 visitor routes were collected, either through lines on paper maps during the interview or via GPS units which were given out.
There were significant differences between sites in the lengths of routes taken by visitors. There were also differences between activities. The mean route length for dog walkers was 3.1km. For cyclists the average route was 7.3km while those fishing tended to have the shortest routes (0.6km average).
At three of the six sites that were surveyed in the winter and the spring/summer, the median route length increased in the spring/summer when compared to the winter, stayed the same at two and fell at one, suggesting no real pattern of people walking further in the summer .
A relatively high proportion (78% of interviewees) indicated that they were aware of the importance of the area for wintering birds. Around a quarter (24%) of all interviewees responded that they were aware that of the international importance of the area for nature conservation.
908 postcodes were mapped reflecting the home postcodes of visitors. The two main settlements were Northampton (137 postcodes from the winter interviews fell within the settlement) and Wellingborough (88 postcodes from the winter interviews).
Dog walkers and joggers lived closest to the site at which they were visiting, with median values of 2.3 and 2.9km respectively
Visitor rates (visits per household) declined rapidly with distance such that a relatively small proportion of people visit from distances beyond 3km of the surveyed access points.

The challenge now will be to understand if and how these visitors are impacting on the abundance and diversity of birds in the Upper Nene Valley, and what can be done to minimise any disturbance. Clearly there’s a balance to be struck between public recreation and wildlife protection, and this will be the theme of future work by the Nene Valley NIA Project.

What are YOU doing for our pollinators this year? (reduce, reuse, recycle part 6)

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Earlier this year I was asked to write a short article by my former PhD student, and still a current collaborator, Dr Sam Tarrant. Sam works for the RSPB as the CEMEX UK-funded Biodiversity Advisor, and wanted something on pollinator conservation that could be circulated in the CEMEX company’s e-newsletter. In the spirit of reworking and reusing odd bits of writing, I thought I’d post it here too.

Insects are vital for our country’s economy. Don’t believe me? Then read on….

Beneath a large black mulberry tree near the University of Northampton’s Newton Building there is a plaque that commemorates its planting “On Shakespeare Commemoration Day, 3^rd May 1916”. Despite its age this tree annually produces large crops of succulent berries, aided by the fact that wind eddies are sufficient to disperse its pollen, ensuring pollination and fruit set. Each year it’s a scramble between students, lecturers and birds, to see who can eat the most.

In contrast, the old apple trees in the grounds possess a different strategy – pollination by insects that move from flower to flower each spring. This form of pollination is both more sophisticated and less reliable than wind pollination, and is currently under considerable threat: whilst there will never be a shortage of wind currents in Britain, insect pollinators are in decline.

The apples trees are not alone in requiring insects to pollinate them, so to do other farm and garden crops, including oil seed rape, field beans, courgettes, runner beans, and strawberries and other soft fruit. It’s worth at least £440 million annually to the British economy, and most of it is done by wild bees and hoverflies, rather than managed hives of honey bees.

But all is not well with these insects in Britain – they are in decline. Although the extent of the “pollination crisis” is debated by scientists, long term records show us that these insects are under pressure: 23 species of bee and flower-visiting wasp have gone extinct since the mid 1800s, as have 18 species of butterflies. Less obviously, other species have considerably reduced in abundance so that they are now found in only a small part of their previous distribution.

There are lots of gardeners who want to “do something” for the pollinators, and keeping honey bees is often mentioned. By all means, if you wish to help the honey bees (which are suffering their own problems) then keep a hive or two. That will not, however, help our wild, native pollinators; the analogy I use is that it’s the equivalent of trying to help our declining songbirds by opening a chicken farm!

If you want to make a real difference for pollinators in your own garden, here are a few ideas:

start by planting nectar and pollen rich flowers; there’s a useful list on the Royal Horticultural Society’s website (see below).
allow plants such as clover and dandelion to flower in your lawn, bees love them.
as well as food, pollinators also need nest and egg laying sites, so you could help by allowing some of the far corners of your plot to run a little wild.
wait until late Spring to cut back hollow stemmed perennials as they are used as hibernating places by some of our bees.
allow mason bees to nest in old walls and don’t worry about them, the wall won’t fall down.
And finally, stop using pesticides!

Changing some of our gardening habits can help a group of insects on which we rely and which supports our economy in a very real way.

Further reading and information:

Bees Wasps and Ants Recording Society: http://www.bwars.com/

Bumblebee Conservation Trust: http://www.bumblebeeconservation.org.uk/

Butterfly Conservation: http://www.butterfly-conservation.org/

Hoverfly Recording Scheme: http://www.hoverfly.org.uk/

Royal Horticultural Society’s list of plants for pollinators: http://www.rhs.org.uk/Gardening/Sustainable-gardening/Plants-for-pollinators

Rewilding redux

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In an earlier posting I briefly mentioned George Monbiot’s current fascination with the concept of rewilding and provided a link to an animated video he had narrated. As my first year lectures on species interactions and community structure have come to an end, one of the students on the course has pointed out that George has recently narrated another video called “How Wolves Change Rivers”, which deals with the effects of the reintroduction of wolves to Yellowstone National Park in the USA. Following a 70 year absence, the presence of the wolves resulted in a trophic cascade which significantly changed, in a positive way, both the biodiversity and the functioning of the Yellowstone ecosystem, as well as aspects of the physical geography of the National Park, notably river behaviour.

It’s only a short video (four and a half minutes in length) and I strongly recommend that you watch it. Not only is it powerful in its imagery and its music, but it’s also underpinned by some powerful, peer-reviewed science. For example see this review by William Ripple and Robert Beschta, from Oregon State University, of the positive effects cascading from the presence of wolves in just the first 15 years following reintroduction.

At the end of my lecture on Thursday I showed the video to my class and the response was very positive; the students seemed to be impressed and I hope it brought home the importance of what I’d been talking about this term, that ecological interactions matter. Given the flooding problems we’ve experienced in Britain this winter, some of which seems to be related to how our rivers and flood plains are (mis)managed, perhaps there’s a case to be made for reintroducing wolves, bears and beavers to the Somerset Levels or the Thames Valley. Given that these areas lie in the heartlands of Conservative and Liberal Democrat voting, it’s not likely to happen under the current coalition government. But we can dream.

There were hummingbirds over the White Cliffs of Dover

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Biogeography has been on my mind of late, in part stimulated by thinking about the work we’re writing up on the frequency of wind versus animal pollination in plant communities in different parts of the world that I mentioned in one of my earlier Brazil posts. André has added more communities to the data set following some field work in Uruguay, and we are collaborating with Bo Dalsgaard and his colleagues in Denmark on analysing how historical and contemporary climates may have shaped the patterns we’re seeing. It follows on neatly from the previous work Bo has done on climate and hummingbird-flower interactions. I’ll report back when we have more to say.

The other reason for thinking about biogeography is that a couple of recent scientific reports have captured my attention. The first dealt with new fossil discoveries of species related to that enigmatic South American bird the hoatzin (Opisthocomus hoazin). The report can be read here but in summary, the evidence suggests that the bird family to which hoatzins belong was once much more widespread and may have originated in Europe. Hoatzins are not the only such example: hummingbirds, which are also currently restricted to the Americas, were found in Europe in earlier times, according to reports from back in 2004 and more recently in 2007. It appears that contemporary biogeography may not reflect past biogeography for some (perhaps most?) groups of species.

As a lesson in contemporary biogeography, it’s often been pointed out that the famous Vera Lynn song The White Cliffs of Dover falls short in its scientific accuracy:

There’ll be bluebirds over
The White Cliffs of Dover
Tomorrow, just you wait and see

Bluebirds are members of the genus Sialia, a group of three species which do not naturally occur in Britain, in fact are not present in Europe at all. So you’re not likely to hear them singing in southern England. But perhaps the genus was present in the distant past? Who knows? In the meantime we may have to change the lyrics to the song. Unless the writer was predicting what might happen in the future when continental drift means that Europe and the Americas will be much closer together.

The other report that caught my eye was of an interesting study that has compared plants and birds in cities across the globe, and looked at how urbanisation reduced the diversity of the native species compared to non-urban areas nearby. However I do hope that the lead author was being misquoted when she said that: “Owing to the fact that cities around the world share similar structural characteristics – buildings, roads etc – it is thought that cities share a similar biota no matter where they are in the world”. She goes on to say that they had discovered that some species: “are shared across cities, such as pigeons and annual meadow grass, but overall, the composition of cities reflects the unique biotic heritage of their geographic location”. Well yes, of course: any of our undergraduate students taking the second year module in biogeography could have told you that! As a serious hypothesis to test it lacked rigour: few tropical birds and plants could survive in temperate-zone cities, for example. There’s more to the study than just this, of course, as you can see from the abstract. Nonetheless it was an odd statement to make in my view.

The Wikipedia definition of biogeography that I linked to at the beginning of this post is perhaps a little limited in its scope: “the study of the distribution of species and ecosystems in geographic space and through geological time” doesn’t cover the species interactions that have been a focus of my research, for instance. Perhaps “macroecology” fits it better, though (as I’ve mentioned before) there’s been a lot of debate in the scientific literature about where biogeography ends and macroecology begins, or whether the two are synonymous. My own view is that the two overlap considerably, but that macroecology is bringing a lot of new tools and approaches to the study of organisms at large spatial scales. Whether that warrants the definition of a different discipline is debatable, but like all such debates (e.g. the difference between ecology and natural history as recently discussed on the Dynamic Ecology blog) it provides us with a way of reassessing our own views on the work we do, which is always a good thing.

Ménage à trois mutualism

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Relationships involving a “household of three” hold a fascination that is part prurient and part wonderment: prurient for perhaps obvious reasons, and wonderment as it’s sometimes hard enough to make a ménage à deux work! Historically this domestic arrangement has been the lifestyle of choice of a surprisingly large and diverse set of influential thinkers and creative individuals, including Aldous Huxley, Lord Nelson, Carl Jung, Erwin Schrödinger, and Hattie Jacques. Indeed, one of my favourite musicians, David Crosby, wrote a song about such relationships (Triad) which got him kicked out of The Byrds.

In nature, ménage à trois are occasionally encountered and may be more common than we think, and have been on my mind because this week I’ve been talking about mutualistic relationships with my first year undergraduates. Mutualisms are interactions between species in which both benefit, as opposed to exploitative relationships such as predation or parasitism in which one of the partners is at a disadvantage (being eaten is a great disadvantage….) Mutualistic interactions are common and important, and include many (but not all) plant-pollinator interactions, seed dispersal by birds and other animals, mycorrhizal relationships between plants and fungi, and many more. As well as studying plant-pollinator interactions, I’ve a long-standing interest in the full breadth of these examples of “biological barter“, in all their varied forms.

In most cases mutualistic relationships involve pairs of species (for example a plant and a pollinator) although these species pairs are embedded within a larger network of interactions: that plant may have many pollinators, and those pollinators may service other plants. In this sense it requires just two partners to make the interaction work – a “household of two”. More rarely, research on the biodiversity of species interactions throws up examples of “households” involving three species, and a fascinating case has recently been worked out and published by Jonathan Pauli and colleagues. This involves three-toed sloths and their relationship with the algae and moths that colonise the sloth’s fur – you can read the abstract here. In summary, the algae benefit from nutrients provided by the moths living in the fur; the sloths eat the algae to supplement a restricted diet of leaves; the moths benefit from the sloths transporting them to defecation sites where they lay their eggs, then recolonise the sloths. This slothy ménage à trois is a wonderful instance of interdependency within nature.

The other case of a three-part mutualism with which I’m familiar is that between anemonefish, and sea anemones and the algae which are housed in their tentacles. The fish and the anemones provide mutual defence of one another, whilst the algae photosynthesise and provide carbohydrates to the anemone, and benefit from the nitrogenous waste produced by the fish. It’s a system that I’ve done a little work on with marine biologist colleagues, specifically the broad scale biogeography of the interaction and its local assemblage structure, but we’ve not studied the whole three-part system.

What other three-part examples are there in nature? I’d be very interested to hear about any of which you’re aware.

It begs a question as to whether three is an upper limit to the number of species that can engage in such relationships? Are there any four- or five-part mutualisms? Or are these too unstable over evolutionary time, because if one species goes extinct it could cause the extinction of other species? Interesting questions about fascinating interactions!

Ordinary by Choice

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Until the system changed a few years ago it was a requirement of all course leaders at the University of Northampton to attend Award Boards at which the students graduating that year were named and their degree classification confirmed. It was not popular with academics, as you can imagine, as we spent half a day waiting for the turn of “our” course. Typically we would take manuscripts to revise or crosswords to complete, or a good book to read, until such time as it came to our own students. As each student’s name was read aloud, their degree classification was confirmed: “First Class Honours”, “Two-One” (Upper Second Class Honours), “Third” (Third Class Honours), and so forth.

One category was rarely used: “Ordinary by Choice”, meaning that the student had not completed a final year dissertation and had opted to take an Ordinary, as opposed to Honours, degree. It is a phrase that I was always struck by: except for a (perfectly respectable) Higher Education qualification, would anyone elect to be “Ordinary by Choice”? Do we want that for our lives, our country, our society, or even our environment: Ordinary by Choice?

The phrase came to mind last week when I heard about an interview with Owen Paterson, Secretary of State for Environment, Food and Rural Affairs in the current British Government. Paterson, who coincidently studied at the precursor to the British School of Leather Technology here at Northampton, said that in the future it might be perfectly acceptable to build on ancient woodland if the destruction of that site was offset by planting trees elsewhere. A spokesperson for his department later said that it was “highly unlikely” that such development would ever occur on ancient woodland, but that’s not the same as “never”.

In fact such destruction of ancient woodlands is currently being proposed by the development of the High Speed Rail 2 (HS2) line from London to points north. An analysis by the Wildlife Trusts of the currently proposed HS2 route shows that it will pass through “10 Sites of Special Scientific Interest (SSSIs), more than 50 ancient woodlands and numerous local wildlife sites”. Important wildlife sites are perhaps not as safe as government would have us believe.

From the outset let me say that in my opinion this notion of “biodiversity offsetting“, in which one can apparently trade like-for-like in the destruction and recreation of natural habitats, putting back or even enhancing the biodiversity of a region, is pure fantasy dreamt up by government. It can’t be done. It’s not possible. The reason? There are no complete inventories of the biodiversity of any patch of planet earth. None. Not even of a few square metres of arable grassland in rural England, a simple habitat in comparison to the fantastically complex biodiversity of an ancient woodland. Such All-Taxa Biodiversity Inventories (ATBIs) have been proposed in the past, but never completed.

Now I am using a strict definition of biodiversity to include all of the diversity of life within an area, including not only plants, birds, mammals, and large insects, but also the many smaller insects and other invertebrates, algae, protists, fungi, and bacteria. But that’s not what the proponents of “biodiversity offsetting” such as Owen Paterson have in mind when they champion the system. What they really mean is “species offsetting”: for example cutting down an oak forest and replacing it with young oak trees planted some distance way; or destroying a wetland used by over-wintering birds and creating an artificial wetland at another locality. In both cases the species in question will persist: oaks will grow and birds will over-winter. The assumption is that the other elements of biodiversity, the neglected micr0-invertebrates, bacteria, lichens, fungi, and so on, will also return. It may take some time, perhaps hundreds of years, but (goes the logic) they will eventually come back and the habitat will contain the richness of species that there was previously.

This may happen, but not for all species, particularly naturally rare organisms with small populations and low dispersal abilities. The fact that (as I’ve noted) we have no complete inventories of biodiversity for anywhere on the planet means that we currently cannot be certain about how “biodiversity”, as opposed to “some of the larger and obvious elements of biodiversity”, can spread and re-establish. In contrast, all of the available evidence suggests that the historical continuity of a site is vital to its current biodiversity. Let me give you an example, in fact from a data set that I’ve never published.

About the time I arrived in Northampton (in 1995) I started to develop a more serious interest in fungi – moulds, mushrooms, and toadstools. Together with colleagues in the department and some of my students I began to systematically identify the fungi in a long, narrow patch of woodland (the “Shelter Belt”) on Park Campus. Early on I set out a series of 1m x 1m quadrats and every week for two months I recorded which fungi appeared. It was a short survey but very revealing because it was clear that there were differences in the diversity of fungi in different parts of the Shelter Belt, and that some areas had much richer diversity than others, even over a distance of a few tens of metres.

In fact the western side of the Shelter Belt contained almost twice as many species of fungi as the eastern side. In addition there were few species on the eastern side that were unique to that area: most species were also found in the western portion. This is despite the fact that the woodland appeared very homogenous: a linear strip dominated mainly by the non-native Black Pine (Pinus nigra) with an under-storey of common small trees such as Holly (Ilex aquifolium), Elder (Sambucus nigra) and Hawthorn (Crataegus monogyna).

A likely reason for this difference was revealed when we studied some old maps of the area; a sixteenth century map showed that there was a hedgerow on the site of the western part of the Shelter Belt from at least Tudor times, and probably much earlier. This hedgerow may have been planted as a boundary for livestock, or may have been a remnant of an even older patch of woodland that was felled and managed to partition agricultural fields. The presence of plants which are known ancient woodland indicator species, such as Wood Anemone (Anemone nemorosa), Bluebell (Hyacinthoides non-scripta) and Dog’s Mercury (Mercurialis perennis) was further evidence.

So an ancient hedgerow, now erased and replaced by later planting that was at least 50 years old (it appears on Google Earth historical imagery for 1945), was continuing to influence the biodiversity of a site long after it was gone. But that influence was subtle and involved a neglected element of wildlife that is nonetheless vital to the natural world: fungi, which act as decomposers, consumers and recyclers, and without which a woodland could not function.

The definition of “ancient woodland” in England and Wales is an area of woodland that existed prior to 1600 and the Shelter Belt example shows why this definition is important: the history of a site has a huge impact on its biodiversity. Simply planting a new woodland of young trees will not replace what is lost by the destruction of a site with historical continuity of habitat which is supporting slow-spreading species.

Government and the public have a choice: we can sanction the destruction of truly biodiverse sites such as ancient woodland and replace them with ordinary ones, such as new planting of trees on farmland. Is that what we want, an environment in Britain that is Ordinary by Choice?

Two turtle doves……?

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On the Second Day of Christmas my true love sent to me
Two Turtle Doves
and a Partridge in a Pear Tree.

So goes part of The Twelve Days of Christmas, a song that can be dated back to the late 18th century, and which celebrates the period between Christmas Day and the 5th January. The chances are that few people under the age of 50 will have seen the culturally iconic turtle dove in the wild in Britain as it’s a species which has reduced in numbers by a spectacular 93% across Britain since the 1970s, as this graph shows. Not only that, but the British Trust for Ornithology suggests that the turtle dove is “one of the most strongly declining bird species across Europe since 1980”. Clearly this is an issue not just for the U.K. and organisations such as the RSPB have responded with schemes focused on turtle dove conservation.

If you’ve been following the various news items about nature and conservation over the festive period you’d be forgiven for being a little confused by the mixed messages. On the one hand the turtle dove and other farmland species, as well as wetland birds, were shown to be suffering long term declines in the State of the U.K.’s Birds report for 2013. But then we have the National Trust telling us that 2013 was the best year for wildlife for a long while, with nature thriving in the long, hot summer. Which of these is true? Both of them are, of course, it’s just that the scales at which they are assessing their results are very different. Whilst analyses of single years are important and can provide some grounds for conservation optimism, it’s the long term trends that really matter. And for many species these trends are not looking good.

With this in mind it was hoped that the budget announcement by the Department for Environment, Food and Rural Affairs (Defra) might contain some good news for Christmas, but it was not to be: overall, there will be less money available for agri-environmental schemes on UK farms in the foreseeable future, a situation that the RSPB states “falls short of what nature needs for recovery” and the Wildlife Trusts describes as “a missed opportunity to boost investment in wildlife-friendly and progressive farming“. As always, Mark Avery’s blog had some forceful opinions on the subject and is a recommended read on this topic.

On the Twelfth Day of Christmas my true love sent to me
Twelve drummers drumming…..

…hopefully drumming up government support for some real action in 2014, rather than fine words and greenwash, to begin to reverse the loss of our native biodiversity. Happy New Year everyone.

Thank the insects for Christmas (REBLOG)

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It’s become a tradition (ok, only for the past two years, but a tradition has to start somewhere!) for me to post a version of this festive blog entry. I’ve updated the stats for 2013. Hope you enjoy it.

Christmas! A time to relax and enjoy ourselves, to share time with family and friends, and to unwind during the cold and gloom of winter. Whatever your faith, or lack of it, Christmas should be about taking a break and reflecting on the year that has passed. We’re helped in that respect by the ceremonial seasonal trimmings: the Christmas tree, strings of flashing lights, baubles and tinsel. So while you’re kissing a loved one under the mistletoe, admiring that glossy holly wreath, or tucking into your Christmas dinner, spare a thought for the insects.

“What in Saint Nicholas’s name” you are asking ”have insects got to do with Christmas?!” Well, like the turkey, we’d be stuffed without them: they play an essential part in providing us with the things we associate with Christmas. If we had no flies, wasps, bees and other bugs acting as pollinators there’d be no berries on your mistletoe or your holly. Kissing and admiring would be a less festive affair and that’s just for starters. These insects also pollinate many of the vegetables, herbs and spices on your plate, as well as some of the forage that went to fatten your roast bird or tender joint of meat. Not to forget much of what went into the nut roast that’s feeding the vegetarian relatives.

The economic value of insect pollination in the UK was estimated by the recent National Ecosystem Assessment to be about £430 million per year. In fact this is a huge under valuation because the labour costs alone of paying people to hand pollinate those crops would run into billions of pounds. This sounds far fetched but it’s already happening to fruit crops in parts of China. The answer is to encourage wild insects, not artificially managed honey bees, because collectively the former are far more abundant, and often more effective, as pollinators. Their diversity is an insurance against losing any one species in the future. The NEA’s valuation is also too low because it only deals with commercial edible crops, and does not include those we grow in our gardens and allotments. It also does not take account of ornamental crops such as mistletoe and holly, both of which are dioecious species, which is to say that individuals are either male or female, rather than hermaphrodite as are most plants. This means that the plants cannot self pollinate and insects are absolutely vital to their reproduction and to the production of the decorative berries we so value (a holly wreath without berries is just a big spiky doughnut, in my opinion).

Whilst researching the economic value of the annual mistletoe and holly crops for this blog posting last year I had a conversation with Jonathan Briggs over at Mistletoe Matters and he told me that “the mistletoe trade in Britain is entirely unregulated and not documented in any tangible way”, and the same is true of holly. We therefore have no idea what the economic value of these non-food crops actually is. But some back-of-the-red-and-gold-Christmas-lunch-napkin calculations can at least give us an insight. Auction reports for 2013 show that on average the best quality berried holly was selling for £2.50 per kg whilst equivalent quality holly without berries sold for only 80p per kg. In other words, pollination by insects increases the value of that crop by more than 300%! Similarly the high quality mistletoe averaged £1.20 per kg, whilst the second grade stuff was only 40p per kg. And the best holly wreaths (presumably with berries!) were averaging £7.00 each.

These are wholesale prices, of course; retail cost to the customer is much greater. A decent holly wreath will set you back between £15 and £30 whilst online shopping for mistletoe is in the £5 to £20 range, depending on how much you want. The national census of 2011 shows us that there are 23.4 million households in England and Wales, plus there are 2.36 million in Scotland and 0.70 million in Northern Ireland. Let’s round it down and say there’s 26 million households in the whole of the UK. Let’s also be very conservative and estimate that only 5% of those households bought one holly wreath and some mistletoe at a total cost of £20. Multiply that by the small proportion of households buying these festive crops and you arrive at a figure of about £26.5 million! And that doesn’t include non-household use in shops, offices and businesses. So there you have it: an industry worth a few tens of millions (at least) all being ultimately supported by insects.

With pollination, timing is everything, and Jonathan also made the point that spring flowering mistletoe and holly can be important early nectar sources for insects. Therefore despite the poor summer weather in 2012, that year was a good one for mistletoe berries because the pollination happened before the heavy rains began. Despite being quite common plants, rather little research has been done on either holly or mistletoe pollination in the UK and it would make for an interesting student project. The Landscape and Biodiversity Research Group here at the University has for many years been working to understand the ecology of plants and pollinators, and how to best conserve them. In this blog I’ve referred a few times to some ongoing projects researching how the wider landscape is supporting pollinators in habitats such as country house gardens (Hilary Erenler’s PhD work which she completed this year) and urban centres (ongoing PhD work by Muzafar Hussain). There’s also the work completed a few years ago by Sam Tarrant and Lutfor Rahman on pollinator (and other) biodiversity on restored landfill sites. Plus research that’s recently started by Kat Harrold on how whole landscapes support pollinators in the Nene Valley Nature Improvement Area. This is all part of a broader programme of research into the conservation of biodiversity in our region and beyond, including our Biodiversity Index, a contribution to the Shared Enterprise Empowering Delivery (SEED) sustainability project.

Biodiversity matters and its importance to our society is being increasingly recognised by government, business and the public. So if you make one New Year’s resolution on the 31st December, let it be that you will put away your garden bug sprays for 2014 and learn to love the insects (even wasps!) who give us so much and help to support our economy in a very real way. It costs us nothing; all we need to give them is well managed, diverse, unpolluted habitats in which to live. Have a great Christmas everyone!