Bottom line is that the global coffee production in 2019/20 was the result of 24 TRILLION flower visits by bees! That’s down a little from the previous year, but it’s still a LOT of visits by a HELL of a lot bees!
Humans affect the land on which they live in many different ways, and this in turn influences local biodiversity. Sometimes this has positive effects on local wildlife: consider the diversity of birds to be found in well-managed suburban gardens, for example. But often the effect is negative, especially when the land is intensively managed or habitats are destroyed, for example via deforestation or urban development.
This is not a new phenomenon – according to a recent study, most of the habitable parts of the planet have been shaped by humans for at least 12,000 years (see Ellis et al. 2021). What is new, however, is the scale and the speed with which land-use is changing, which are far greater than they have been historically. An important question is the extent to which this change in land-use intensity is affecting pollinator diversity in different parts of the world. Over the past 18 months I’ve been collaborating on a project led by Joe Millard (as part of his PhD) and Tim Newbold which uses the Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (PREDICTS) database to address that very question.
The study was global in scale and used data from 12,170 sites to assess the affect of land-use intensity on 4502 pollinating species. The findings are really fascinating; highlights include:
In comparison to natural vegetation, low levels of land-use intensity can have a positive effect on the diversity of pollinators.
For most land categories, greater intensity of land-use results in significant reductions in diversity and abundance of pollinators, however. For example, for urban sites there’s a 43% drop in number of species and a drop in 62% pollinator abundance from the least to the most intensive urban sites.
On cropland, strong negative responses of pollinators to increasing intensity are only found in tropical areas, although different taxonomic groups vary in their responses.
The latter finding is especially concerning given that: (i) most pollinator diversity is found in the tropics; (ii) the majority of tropical crops are insect pollinated; and (3) tropical agriculture is becoming increasingly intensive and land use is likely to rapidly change in the coming decades.
The full reference for the study, with all authors, is:
Millard, J., Outhwaite, C.L., Kinnersley, R., Freeman, R., Gregory, R.D., Adedoja, O., Gavini, S., Kioko, E., Kuhlmann, M., Ollerton, J., Ren, Z.-X. & Newbold, T. (2021) Global effects of land-use intensity on local pollinator biodiversity. Nature Communications 12, 2902. https://doi.org/10.1038/s41467-021-23228-3
The terms ‘Natural Capital’, ‘Ecosystem Services’, and ‘Nature-Based Solutions’ seem to generate one of two emotions in some people: confusion and irritation. Confusion stems from not appreciating that these are different, though closely related, concepts, as I will show below. Irritation often is the result of seeing ecosystem ‘valuation’ as a neo-liberal plot to somehow ‘sell-off nature’. I’ve discussed this irritation in the past – see this old post for instance about ‘How do we value nature?‘ – so I’m not going to dwell on it: some people see the advantage of using these concepts, others don’t. And that’s fine. But I will touch briefly on the confusion aspect because it pertains to a discussion on Twitter this morning that was stimulated by this tweet from Prof. James Bullock, in which he saw the three concepts as re-packaging on the same ideas under different (and confusing) names.
James and I have been friends for a long time, and there’s things we agree on and things we disagree on. And that’s also fine. But as I pointed out in my response to the tweet, I think that these concepts are different, and that they logically flow together. To me, Ecosystem Services are the benefits to society provided by Natural Capital. Nature-Based Solutions are strategies or schemes for targeting Natural Capital creation or enhancement (e.g. flood meadows or woodland) to provide Ecosystem Services (e.g. flood management or carbon storage).
The analogy that I used (which a few people seemed to appreciate) is that this is the difference between books, what we learn from books, and decisions on how to produce more books.
Over the past few months I’ve done a large number of online talks for a variety of audiences, including natural history and gardening societies, beekeeping groups, private companies, university estates departments, and ecological consultancies. I thought it would be useful to provide a list of what I offer, with a short description. All talks are accessible and understandable to a broad audience, and can be tailored to the individual needs of the group:
Pollinators & Pollination: Nature and Society is an introduction to the importance of pollinators and the pollination services that they provide to both wild and crop plants. The name, of course, reflects that of my recent book.
The Politics of Pollination is an account of how society (governments, organisations and individuals) has responded to the current “pollination crisis” (if that’s what it actually is…)
Bees in Cities: an Introduction to Urban Pollinatorsfocuses on the positive roles that urban environments can play for pollinators, and the potential threats of city living.
Pollinators in Gardens gives practical advice on how to make your garden “pollinator friendly”.
Pollinator Conservation: Threats and Opportunities describes how and why pollinators are declining and what we can do about it at the individual and societal level.
Habitat Creation and Management for Pollinators gives an introduction to how NGOs, estates departments, consultancies, and so forth, can effectively support pollinators in ways that go beyond just planting flowers and putting up a few “bee hotels”.
To Be a Flower is an introduction to how flowers function and the ways in which they manipulate the behaviour of their pollinators to ensure reproduction.
Darwin’s Unrequited Isle: a Personal Natural History of Tenerife describes some of the field work that we’ve been doing on this most fascinating of the Canary Islands.
Biodiversity: What Is It and Why Should We Care? gives a very general overview of the topic of biodiversity and ecosystem services.
Talks typically last for around 50 minutes, following which I’m happy to answer questions and discuss any issues that have arisen. I also offer a half- or full-day of training for those organisations that need more depth, for example ecological consultancies. Note that I charge for all of my talks and training. If you would like to enquire about any of this, please use the form on the Contact page.
Yesterday I was delighted to finally receive an advance copy of my book Pollinators & Pollination: Nature and Society! It’s been over three years in the writing and production, much longer than I had anticipated. But, as I describe in its pages, the book is the culmination of >50 years of experience, study and research. So perhaps three years isn’t so bad…
2 More than just bees: the diversity of pollinators
3 To be a flower
4 Fidelity and promiscuity in Darwin’s entangled bank
5 The evolution of pollination strategies
6 A matter of time: from daily cycles to climate change
7 Agricultural perspectives
8 Urban environments
9 The significance of gardens
10 The shifting fates of pollinators
11 New bees on the block
12 Managing, restoring and connecting habitats
13 The politics of pollination
14 Studying pollinators and pollination
As you can see it’s a very wide-ranging overview of the subject, and written to be accessible to both specialists and non-specialists alike. To quote what I wrote in the Preface:
“While the book is aimed at a very broad audience, and is intended to be comprehensible to anyone with an interest in science and the environment, and their intersection with human societies, I hope it will also be of interest to those dealing professionally with plants and pollinators. The subject is vast, and those working on bee or hoverfly biology, for example, or plant reproductive ecology, may learn something new about topics adjacent to their specialisms. I certainly learned a lot from writing the book.”
The book is about 100,000 words in length, lots of illustrations, and there will be an index. My copy editor reckons there’s 450 references cited, though I haven’t counted. I do know that they run to 28 pages in the manuscript, and that’s with 11pt text. All going well it will be published before Christmas.
As I near completion of the copy-editing phase of my forthcoming book it’s frustrating to see all of the great research that’s been produced in recent weeks that I probably won’t be able to cite! Here’s a few things that caught my eye:
In the journal New Phytologist, Rhiannon Dalrymple and colleagues, including Angela Moles who hosted me during my recent stay in Australia, have a great study entitled Macroecological patterns in ﬂower colour are shaped by both biotic and abiotic factors. The title pretty much sums it up: in order to fully understand how flowers evolve we need to consider more than just their interactions with pollinators. It’s another demonstration of how we must look beyond simplistic ideas about pollination syndromes to fully understand the complexities of the relationship between flowering plants and pollinators…..
…..talking of which, again in New Phytologist, Agnes Dellinger asks: Pollinationsyndromes in the 21st century: where do we stand and where may we go? It’s an insightful and far-reaching review of a topic that has intrigued me for more than 25 years. There are still a lot of questions that need to be asked about a conceptual framework that, up until the 1990s, most people in ecology and biology accepted rather uncritically. One of the main unanswered questions for me is how further study of largely unexplored floras will reveal the existence of new pollination systems/syndromes. Which leads nicely to….
…..an amazing paper in Nature this week by Rodrigo Cámara-Leret etal. showing that New Guinea has the world’s richest island flora. The described flora includes 13,634 plant species, 68% of which are endemic to New Guinea! And the description of new species each year is not leveling off, there’s still more to be discovered. A commentary on the paper by Vojtech Novotny and Kenneth Molem sets some wider context to the work, and quite a number of media outlets have covered the story. Why is this relevant to pollinators and pollination? Well, we actually know very little about this critical aspect of the ecology of the island: there’s only a handful of published studies of plant-pollinator interactions from New Guinea, mostly focused on figs, bird-flower interactions, and a couple of crops. For such a biodiverse part of the world that’s a big gap in our understanding.
Finally, James Reilly, Rachael Winfree and colleagues have a paper in Proceedings of the Royal Society series B showing that: Crop production in the USA is frequently limited by a lack of pollinators. Most significant findings to me were that of the seven crops studied, five of them have their yields limited by lack of pollinators, and that even in areas of highly intensive farming, wild bees provided as much pollination service as honeybees.
That’s a few of the things that I spotted this week; what have you seen that’s excited or intrigued you? Feel free to comment.
In the next few months my new book Pollinators & Pollination: Nature and Society will be published. As you can imagine, I’m very excited! The book is currently available to pre-order: you can find full details here at the Pelagic Publishing website. If you do pre-order it you can claim a 30% discount by using the pre-publication offer code POLLINATOR.
As with my blog, the book is aimed at a very broad audience including the interested public, gardeners, conservationists, and scientists working in the various sub-fields of pollinator and pollination research. The chapter titles are as follows:
Preface and Acknowledgements
1. The importance of pollinators and pollination
2. More than just bees: the diversity of pollinators
3. To be a flower
4. Fidelity and promiscuity in Darwin’s entangled bank
5. The evolution of pollination strategies
6. A matter of time: from daily cycles to climate change
7. Agricultural perspectives
8. Urban environments
9. The significance of gardens
10. Shifting fates of pollinators
11. New bees on the block
12. Managing, restoring and connecting habitats
13. The politics of pollination
14. Studying pollinators and pollination
In the past couple of weeks I’ve delivered two presentations at virtual conferences. The first was at a Global Sustainability Summit run by Amity University, one of our partner institutions in India. The second was at the University of Northampton’s own internal research conference. Both of these focused on pollinators, as you might imagine, but they also referred to the United Nations’ Sustainable Development Goals (SDGs). The 17 SDGs are being increasingly used as a framework for promoting the importance of biodiversity to human societies across the globe, and I’m seeing them referred to more and more often in studies and reports about pollinator conservation. That’s great, and I’m all in favour of the SDGs being promoted in this way. However I wanted to highlight a couple of aspects of the SDGs that I think are missing from recent discussions.
The first is that pollinators, and their interactions with plants, are often seen as contributing mainly to those SDGs that are directly related to agriculture and biodiversity. Here’s an example. Last week the European Commission’s Science for Environment Policy released a “Future Brief” report entitled: “Pollinators: importance for nature and human well-being, drivers of decline and the need for monitoring“. It’s a really interesting summary of current threats to pollinator populations, how we can monitor them, and why it’s important. I recommend you follow that link and take a look. However, in the section about relevant, global-level policies, the report highlights “the UN Sustainable Development Goals (SDGs) – especially regarding food security (‘zero hunger’) and biodiversity (‘life on land’).
I think this is under-selling pollinators and pollination, and here’s why. First of all, as we pointed out in our 2011 paper “How many flowering plants are pollinated by animals?”, approaching 90% of terrestrial plants use insects and vertebrates as agents of their reproduction and hence their long-term survival. As we showed in that paper, and a follow up entitled “The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability“, the proportion of animal-pollinated plants in a community varies predictably with latitude, typically from 40 to 50 % in temperate areas up to 90 to 100% in tropical habitats. Now, flowering plants dominate most terrestrial habitats and form the basis of most terrestrial food chains. So the long-term viability and sustainability of much the Earth’s biodiversity can be linked back, directly or indirectly, to pollinators. That’s even true of coastal marine biomes, which receive a significant input of energy and nutrients from terrestrial habitats.
Biodiversity itself underpins, or directly or indirectly links to, most of the 17 SDGS; those that don’t have an obvious link have been faded out in this graphic:
The underpinning role of biodiversity, and in particular plant-pollinator interactions, on the SDGs needs to be stated more often and with greater emphasis than it is currently.
The second way in which I think that some writers and researchers in this area have misconstrued the SDGs is that they seem to think that it only applies to “developing” countries. But that’s certainly not the way that the UN intended them. ALL countries, everywhere, are (or should be) “developing” and trying to become more sustainable. To quote the UN’s SDG website:
“the 17 Sustainable Development Goals (SDGs)….are an urgent call for action by all countries – developed and developing – in a global partnership.”
“the SDGs are a call for action by all countries – poor, rich and middle-income – to promote prosperity while protecting the environment.”
I interpret this as meaning that “developed” countries need to consider their own future development, not that they only have to give a helping hand to “developing” countries (though that’s important too). Just to drive this home, here’s a recent case study by Elizabeth Nicholls, Dave Goulson and others that uses Brighton and Hove to show how small-scale urban food production can contribute to the SDGs. I like this because it goes beyond just considering the agricultural and food-related SDGs, and also because by any measure, Brighton and Hove is a fairly affluent part of England.
I’m going to be talking about all of this and discussing it with the audience during an online Cafe Scientifique on Thursday 25th June – details are here. I’m also going to be exploring more of these ideas in my forthcoming book Pollinators & Pollination: Nature and Society, which is due for publication later this year. The manuscript is submitted and is about to be copy-edited. The PowerPoint slide which heads this post uses a graphic from that book that sums up how I feel about biodiversity, plant-pollinator interactions, and the UN’s Sustainable Development Goals.
UPDATE: turns out the figure I cited for number of bee species is out of date so I’ve corrected it below. Thanks to John Ascher for pointing this out.
Publication of my book Pollinators & Pollination: Nature and Society by Pelagic Publishing has been pushed back until the end of this year or early in 2021. The current pandemic has created problems for the printing and distribution sectors, as it has for so many industries. Therefore, to celebrate World Bee Day, here’s a preview of the bee section from Chapter 2 which is entitled (ironically enough) “More than just bees – the diversity of pollinators”.
2.3 Bees, wasps and sawflies (Hymenoptera)
The bees and their relatives rank only third in terms of overall pollinator diversity. Within this taxonomic Order, bees are not especially species rich (17,000 or so described species, perhaps 20,000 in total) – over 20,400 (see: https://www.catalogueoflife.org/col/details/database/id/67) compared with the other 50,000 social and solitary wasps, sawflies, and so forth. But what they lack in diversity the bees make up for in importance as pollinators of both wild and agricultural plants, and in their cultural significance. The general notion of what a bee is, and how it behaves, looks to the honeybee (Apis mellifera) as a model: social, with a hierarchy, a queen, and a large nest (termed a hive for colonies in captivity). In fact, this view of bee-ness, though long embedded within our psyche, is far removed from the biology of the average bee: most of them have no social structure at all, and a fair proportion of those are parasitic. In Britain we have about 270 species of bees, give or take (Falk 2015) though there have been extinctions and additions to this fauna (see Chapters 10 and 11). These species provide a reasonable sample of the different lifestyles adopted by bees globally. They can be divided into four broad groups.
Honeybees include several highly social species and subspecies of Apis, of which the ubiquitous western honeybee (A. mellifera) is the most familiar. Most colonies are found in managed hives, though persistent feral colonies can be found in hollow trees, wall cavities, and other suitable spaces. They are widely introduced into parts of the world where they are not native (e.g. the Americas, Australia, New Zealand) and there is some debate as to whether they are truly native to Britain and northern Europe, with supporting evidence and arguments on both sides. Colonies can be enormous and contain thousands of individuals, mostly female workers, with a single queen. Unmated queens and males (drones) are produced by the colony later in the season.
Bumblebees (Bombus spp.) are typically also social, though their nests are much smaller (tens to hundreds of individuals). Depending upon the species these nests can be in long grass, rodent holes, or cavities in buildings and trees. Twenty-seven of the more than 250 species have been recorded in the UK, but six of these are not strictly social; they are parasitic and belong to the subgenus Psithyrus which will be described below.
The so-called solitary bees are by far the largest group in Britain (about 170 species) and worldwide (more than 90% of all species). In the UK they belong to 15 genera, including Andrena, Anthophora, Osmia, Megachile, etc. The females of most of these bees, once they have mated, construct nests that they alone provision with pollen for their developing young. Nesting sites can be genus- or species-specific, and include soil, cavities in stone or wood, and snail shells. Some species are not strictly solitary at all and may produce colonies with varying levels of social structure, though without a queen or a strict caste system; we term them “primitively eusocial”. In fact sociality has evolved and been lost numerous times in the bees and in the rest of the Hymenoptera (Danforth 2002, Hughes et al. 2008, Danforth et al. 2019). It’s also been lost in some groups that have reverted back to a solitary lifestyle, and even within a single genus it can vary; for example in the carpenter bee genus Ceratina (Apidae: Xylocopinae) tropical species are more often social than temperate species (Groom & Rehan 2018).
The final group is termed the cuckoo bees and, like their avian namesake, they parasitise the nests of both social and solitary bees (though never, interestingly, honeybees). There are about 70 species in 7 genera, including the bumblebee subgenus, Psithyrus. Other genera include Melecta, Nomada and Sphecodes. In some cases the parasitic species are closely related evolutionarily to their hosts and may resemble them, for example some Psithyrus species. In other cases they may be only distantly related and in fact look more like wasps, e.g. Nomada species. Some genera of cuckoo bees are restricted to parasitising only a single genus of bees, others are parasites of a range of genera (Figure 2.4).
Although we often think of bees, overall, as being the most important pollinators, in fact species vary hugely in their importance. Pollinating ability depends upon factors such as abundance, hairiness, behaviour, body size, and visitation rate to flowers (Figure 2.1). Size is especially important for three reasons. First of all, larger animals can pick up more pollen on their bodies, all other things being equal. Secondly, in order to bridge the gap between picking up pollen and depositing it, flower visitors must be at least as large as the distance between anthers and stigma, unless they visit the stigma for other reasons. Finally, larger bee species tend to forage over longer distances on average (Greenleaf et al. 2007) thus increasing the movement of pollen between plants. However, most of the world’s bees are relatively small as we can see from the analysis of British bees in Figure 2.5. Many species have a maximum forewing length of only 4 or 5 mm, and the majority of species are smaller than honeybees. Remember also that these are maximum sizes measured from a sample; individual bees can vary a lot within populations and even (in the case of Bombus spp.) within nests (Goulson et al. 2002). So the assumption that all bees are good pollinators needs to be tempered by an acknowledgement that some are much better than others.
Figure 2.5: The sizes of British bees. Forewing length is a good measure of overall body size and the data are maximum lengths recorded for species, except for the social bumblebees and honeybee I have used maximum size of workers (queens are often much larger). The blue line indicates the honeybee (Apis mellifera). The biggest bee in this data set is the Violet Carpenter Bee (Xylocopa violacea) which, whilst not generally considered a native species (yet), has bred in Britain in the past. Data taken from Falk (2015).