Biodiversity Net Gain is generating a lot of attention in the UK at the moment, some of it positive*:
“when designed and delivered well, BNG can secure benefits for nature, people and places, and for the economy”
“[BNG is] a game-changer for health and wellbeing”
And some of it extremely negative*:
“Biodiversity Net Gain is a lie but most people without enough ecological knowledge cannot see this & are fooled by the lie”
“[BNG is] a horrible legalistic contrivance, and it means nothing”
Regardless of how you feel about BNG, it’s here to stay, at least for the foreseeable future, and so we need to explore it and understand how (or whether) it can positively improve the state of nature in Britain.
Although I don’t pretend to be an expert on BNG**, I have thought a lot about how it might impact the group that I do have some expertise in, pollinators, and the implications for the pollination services that they provide to wild and crop plants.
Last October I produced a short report that considered the implications of BNG for insect pollinators – you can download a copy from the original blog post, though do be aware that some of the dates I mentioned were later revised by the then government and I have yet to revise the document.
As a follow up to this I have been invited by the Biological Recording Company to lead a one-hour webinar discussing this topic on Monday 28th October at 1pm. It’s free to attend and you can book a ticket by following this link. There’ll be a short presentation (30 minutes or so) followed by a live Q&A.
I hope that some of you can join me!
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*Real quotes, culled from reports and social media.
**Indeed, it’s such a new approach to development and nature conservation, can anybody consider themselves an expert?
Just after I arrived in Northampton in 1995, I set about looking for suitable local sites for conducting pollination ecology field work for myself and students. The campus on which we were situated at the time was adjacent to an urban park – Bradlaugh* Fields – parts of which were designated as local nature reserves. In the intervening years, data from that area have made their way into a wide range of published studies, including:
I still have data collected during that time that have never been published, but good data are hard won and they may see the light of day at some point. Case in point is that we’ve just published a paper based on data from Bradlaugh Fields, the first of which were collected in 2001!
In this paper we’ve tested how effective hoverflies, butterflies and bumblebees are at pollinating the flowers of a common generalist grassland plant, colloquially called Field Scabious (Knautia arvensis). The expectation was that bumblebees, being generally larger, hairier and more flower-focused than the other groups, would be the most effective at transferring pollen to stigmas. To our surprise, they were not: hoverflies and butterflies performed just as well! In fact we argue that butterflies may be MORE important as pollinators of this plant because they fly further distances between individual plants, rather than hopping between the inflorescences of the same plants, as bumblebees tend to do.
Crucially, the importance of these different groups of pollinators varies enormously as the relative abundance of the insects visiting the flowers differs between seasons. In some years butterflies dominate as pollinators, in other years bumblebees or hoverflies. This is driven, we think, both by fluctuations in the populations of these insects and by the availability of other, more preferred flowers that may bloom at the same time.
The paper is part of a special issue of the Journal of Applied Entomology devoted to The Neglected Pollinators. It’s open access and you can download a copy by following the link in this reference:
Plant-pollinator interactions exist along a continuum from complete specialisation to highly generalised, that may vary in time and space. A long-held assumption is that large bees are usually the most effective pollinators of generalist plants. We tested this by studying the relative importance of different groups of pollinators of Knautia arvensis (L.) Coult. (Caprifoliaceae: Dipsacoideae). This plant is suitable for such a study because it attracts a diversity of flower visitors, belonging to different functional groups. We asked whether all functional groups of pollinators are equally effective, or if one group is most effective, which has been documented in other species with apparently generalised pollination systems. We studied two subpopulations of K. arvensis, one at low and one at high density in Northampton, UK. To assess pollinator importance we exposed unvisited inflorescences to single visits by different groups of pollinators (butterflies, bumblebees, hoverflies and others) and assessed the proportion of pollinated stigmas. We then multiplied the effectiveness of each pollinator group with their proportional visitation frequency in five different years. For each group we also compared time spent on flowers and flight distance between visits. The relative importance of each pollinator group varied between years, as did their flight distances between flower visits. Butterflies were the best pollinators on a per visit basis (in terms of the proportion of stigmas pollinated) and flew further after visiting an inflorescence. Different measures and proxies of pollinator effectiveness varied between taxa, subpopulations, and years, and no one group of pollinators was consistently more effective than the others. Our results demonstrate the adaptive value of generalised pollination strategies when variation in relative abundance of different types of pollinators is considered. Such strategies may have buffered the ability of plants to reproduce during past periods of environmental change and may do so in the future.
The latest paper from Muzafar Sirohi‘s PhD work on urban solitary bees has just been published in the journal Zoodiversity, a publication of the National Academy of Sciences of Ukraine. In this paper we looked at how the flight periods of urban populations of bees differ from those in surrounding nature reserves and other “natural” settings. One of the most interesting findings is that urban bees tend to emerge earlier, and be active longer, than their rural counterparts. The quote the study:
“We observed a substantial effect of urban microclimate on bee flight periods. A total of 153 individuals of nine bee species were recorded one to nine weeks before or after their expected flight periods. In contrast, only 14 individuals of four species were seen at unusual flight periods in nature sites.”
In my book Pollinators & Pollination: Nature and Society I discussed the importance of towns and cities for supporting pollinator populations, and conversely how important those populations are for urban food production. Likewise, in Birds and Flowers: An Intimate 50 Million Year Relationship I have a chapter entitled “Urban flowers for urban birds”. The relationship between our built environment and pollinators is a fascinating topic, but there’s still much we don’t understand about how these insects and vertebrates respond behaviorally to urbanisation. Are they adapting in an evolutionary sense, or simply responding flexibly to the different conditions that cities impose on their biologies? Will future climate change make towns and cities uninhabitable for these animals? Hopefully our paper will stimulate further work on these and other topics.
Here’s the full reference with a link to the paper (which is open access):
Solitary and primitively eusocial bees, an important group of pollinators, have declined in the past few decades. In view of the recent focus on safeguarding pollinating insects, it is vital to understand the basic ecology of species for their conservation, for example their phenologies. We observed the flight periods of solitary and primitively eusocial bees in both the urban core of a large British town and nearby nature conservation areas. The bee surveys were conducted with standardised methods, on warm sunny days from the first appearance of bees in March 2012 and continued until October 2012. This study confirmed that a high number of species are active in the spring season. The emergence dates of species in urban areas and nature sites varied; about 26 of the 35 species were recorded at least one week earlier in urban areas; in contrast, only four species were seen earlier in nature conservation sites. When comparing this with the expected flight periods recorded (largely in nature sites) in the literature, many species were recorded at their expected time. However, a few individuals were recorded after their usual flight activity time, suggesting that the populations were possibly affected by the microclimate in urban areas. More urban phenological data are needed to understand the phenological trends in bees in urban habitats.
Is it too early to talk about Christmas? Not if you’re interested in pollinators and pollination! The mid-winter festival has featured quite a number of times on my blog over the years, especially in relation to the iconic plants that represent this time of year in Northern Europe, and what one might describe as the ‘cultural biodiversity‘ of Christmas. The final plant that I included in that last post was the poinsettia (Euphorbia pulcherrima) – this is how I described it:
In many ways this is an unusual plant to have such a strong cultural association with Christmas: it’s a mildly toxic species of spurge from tropical Mexico that was introduced to North America in the 19th century, then subsequently to Europe. However its festive connotations date back to the earliest period of Spanish colonisation in the 16th century, so it’s older than some…other Christmasy traditions…
Just occasionally one sees a bird-pollinated tree planted in a city. The most common in my experience are various banksias in Australia, and the Royal Poinciana (from Madagascar) and the African Tulip Tree in the urban tropics and subtropics elsewhere in the world. I’ve also occasionally encountered large specimens of Poinsettia: when they are given free rein they are a much more impressive plant than their Christmas cousins. The vivid red bracts that surround the clusters of flowers suggest that they may be hummingbird-pollinated in their native Central America, but as far as I know their pollination ecology has not been studied.
Here at the Kunming Botanic Garden there’s several quite large specimens of poinsettia that, as I write, are in full flower, their red bracts a signal to pollinators that can be seen for quite a distance. However we’ve not seen any of the local sunbirds or white-eyes visit the flowers, and, as I said in the book, as far as I know the pollination ecology of poinsettia has never been studied in the wild. Close inspection of the flowers in the garden revealed that almost all of the nectaries had at least one nectar-collecting ant sticking out from it, their prominent backsides a deterrent to the Asian Honey Bees (Apis cerana) that also wanted a piece of the action.
Based on the position of the nectaries in relation to the stamens, if the plant is hummingbird-pollinated then the pollen is likely to end up under the chin of the bird. That’s certainly been described in other plant-bird pollination systems. But it does not have to be birds that move the pollen around – red flowers are also associated with other kinds of pollinators, for example butterflies and beetles. But until someone in Mexico does the necessary field work, we’ll just have to speculate.
During the 2020 lockdown caused by the COVID-19 pandemic, I coordinated an international network of pollination ecologists who used standardised methods to collect data in their gardens. I blogged about it at the time – see here and here for instance – and also put up a post when the data paper from that work was published.
Several research groups are now working with that huge data set and interrogating it for answers to a wide range of questions. The first group to actually publish a paper from the data is a largely Chinese set of researchers from the Key Laboratory of Plant Resources, Conservation and Sustainable Utilization, at the South China Botanical Garden in Guangzhou, assisted by Kit Prendergast and myself.
In this paper we’ve considered how robust these plant-pollinator networks are to simulated extinctions of species, and how this is affected by the elevation, latitude, and plant species diversity of the network.
Here’s the full reference with a link to the study:
If you can’t access it and need a PDF, please send me a request via my Contact page.
Here’s the abstract:
Plant-pollinator interactions play a vital role in the maintenance of biodiversity and ecosystem function. Geographical variation in environmental factors can influence the diversity of pollinators and thus, affect the structure of pollination networks. Given the current global climate change, understanding the variation of pollination network structure along environmental gradients is vital to predict how global change will affect the ecological interaction processes. Here, we used a global plant-pollinator interaction data collection by the same sampling method at the same period to explore the effects of elevation, latitude, and plant richness on the structure and robustness of pollination networks. We analyzed a total of 87 networks of plant-pollinator interactions on 47 sites from 14 countries. We conducted a piecewise structural equation model to examine the direct and indirect effects of elevation, latitude, and plant richness on the network robustness and analyzed the function of network structure in elucidating the relationship between robustness and these gradients. We found that plant richness had both positive effects on robustness under random and specialist-first scenarios. Elevation, latitude, and plant richness affected network connectance and modularity, and ultimately affected network robustness which were mediated by nestedness under specialist-first and random scenarios, and by connectance under the generalist-first scenario. This study reveals the indirect effects of elevation, latitude, and plant richness on pollination network robustness were mediated by nestedness or connectance depended on the order of species extinctions, implying that communities with different pollination network structures can resist different extinction scenarios.
Biodiversity Net Gain (or BNG) promises to transform the way that we approach nature conservation in the UK. I’ve been giving a lot of thought to what this might mean for insect pollinators and have produced a new report that summarises the opportunities that BNG presents and how we can make the most of them. You can download a copy of that report by following this link.
This is meant to be a working document and as BNG progresses, and our understanding of its impacts on pollinators increases, I will update it. In the meantime, please do feel free to comment.
Last year I posted about the work that I’ve been doing on railways and biodiversity with UIC – the International Union of Railways – and the UK Centre for Ecology & Hydrology. That work is now complete and the second of our two reports called UIC Guidelines on Managing Railway Assets for Biodiversity is now out.
UKCEH has produced a press release and I’m copying it verbatim below:
New guidelines for the management of Europe’s railway network to protect and enhance biodiversity have been published.
The UK Centre for Ecology & Hydrology (UKCEH) has worked with the International Union of Railways (UIC), the professional association representing rail companies across the world, to provide technical recommendations and key design features for incorporating and enhancing habitats within the existing European network and new line upgrades, providing examples of best practice.
The UIC European region comprises 118-member companies from 39 countries, amounting to 350,000 kilometres of rail network.
Professor Richard Pywell, Head of Biodiversity at UKCEH who is one of the lead authors of the report, said: “We worked closely with railway companies across Europe to distil the best available knowledge on managing railway assets to benefit nature. For each asset, we considered the most effective measures to protect and restore biodiversity, and how to monitor the outcomes of these interventions.”
Another report author, independent consultant Professor Jeff Ollerton, added: “Working with UIC on this project has revealed just how important the land managed by Europe’s railway companies is for nature. The next step is to better understand how nature supports Europe’s economy, and the health and wellbeing of its people.”
The authors used the widely-adopted mitigation hierarchy approach which guides, developers on protecting existing habitats and ecosystems where possible.
The new UIC Guidelines for Managing Railway Assets for Biodiversity have been drawn up as part of the REVERSE project, in which UIC has worked with its members and UKCEH to formulate a collective vision for protecting and enhancing biodiversity across the European rail network. They now form part of the European Railways: Strategy and Action Guide to ensure management for biodiversity is embedded at every level of the railway business, alongside safety, performance and sustainability. The adoption of the guidelines by member companies will be promoted through various UIC meetings and online events.
The REVERSE project comprises more than 20 European rail companies including Network Rail and SNCF as well as WWF (Worldwide Fund for Nature).
In 2021, UKCEH worked with Network Rail to draw up the rail company’s Biodiversity Action Plan to inform lineside habitat management across the UK. This involved using high-resolution imagery from satellites and aircraft to produce a detailed national map of all the habitats alongside the rail network.
I’m excited to announce that in March 2024 I will teach a week-long, Master’s-level residential course entitled “Pollination as an Ecosystem Service” at the University of Pavia in Italy. It will be taught in English. Here’s a summary of the course and a brief description of the the syllabus, which is broadly accurate but subject to change as it develops:
POLLINATION AS AN ECOSYSTEM SERVICE
A 3 credit Master’s course for the University of Pavia
Overview
The pollination of crops by bees, flies, birds, bats and other animals, is an ecosystem service that increases crop yields and quality. This is valued at hundreds of billions of Euros each year to European and global agriculture. In addition, these same animals pollinate around 90% of the world’s wild plants which in turn provide us with ecosystem services such as wild food, flood alleviation, microclimate modification, and carbon capture.
In this course, students will explore pollination as an ecosystem service from its first principles and historical roots through to the latest research findings around the consequences of pollinator decline and climate change. The emphasis of the course is on the students learning by actively participating during classes. Each day has a particular theme and will be a mix of interactive lectures, short video clips to illustrate particular points, discussion seminars (for which they will be expected to do some guided reading) and local excursions.
At the end of the course the students will have a developed a deep understanding of the diversity of pollinators, the ecological nature of their interactions with flowers, and the importance of these relationships to nature and to society.
Assessment
At the end of the course, the students will be asked to give a 10 minute presentation based on one of the topics covered in the course, and posed as a question such as “What is….?”, “Why does….?”, “What would happen if….?”, and so forth. The questions will be agreed with me in advance. Presentations will take place on the final day of the course and at the end of each presentation the students will have 5 minutes to answer questions posed by their peers and myself.
Syllabus
Day 1
Theme: Pollinators and pollination – first principles; including historical perspectives, the diversity of pollinators and flowers, and the biology of pollination. Introducing the course assessment.
Excursion: a walk around the local area to observe flowers and pollinators in action.
Day 2
Theme: Pollination as an ecosystem service; including the types of crops that are animal pollinated, how we calculate the value of pollination, and going beyond agriculture to look at the other ecosystem services provided by pollinators; approaches to studying pollinators and pollination.
Day 3
Theme: Pollinator conservation: including reasons for pollinator decline, impacts of climate change, the “politics of pollination”, the consequences of that decline for crop and wild plant pollination, how we can manage and restore habitats for pollinators.
Day 4
Theme: Urban pollinators: understanding the importance of pollinators in an urban setting and in gardens, and how towns and cities support pollinators. Excursion: How is the city of Pavia supporting pollinator populations and what could be improved?
Day 5
Theme: Summing up what we’ve learned, followed by assessed student presentations.
It’s been a rather nomadic couple of years. After Karin and I sold our house in Northampton, we travelled around in the UK and then in Denmark, renting places as we needed them, plus we spent a month in Kenya. We’ve now become more settled in Sjælland and, after some deliberation about whether to buy a house or continue renting, we’ve reached a compromise and bought into an andelsbolig, one of the many Danish cooperative housing schemes – see this article in The Guardianfor more details.
The development of twenty-eight small properties has been newly built to the highest standards of insulation and is plugged into the district heating system which uses a combination of solar warming and gas (in part using methane generated from food waste).
It’s nice to have a garden again. I hadn’t realised how much I’d missed having a space in which to plant and potter. All gardens present challenges, of course, and this one is no exception. Until about 600 years ago the area was under the shallow Kattegat sea. It’s now above sea level due to post-glacial rebound and in fact this whole region of Odsherred is a UNESCO Global Geopark because of the postglacial landscape.
What this means for us is that we are gardening on “soil” which has a very high sand content and is filled with stones, large and small.
Added to that, we’re in one of the driest parts of Denmark (certainly this year) and a persistent coastal wind rapidly strips the moisture from the soil. So as we dig up or find large stones we are using them around plants to retain water and mulching with the smaller stones that we find in abundance. As yet we don’t have any rain water butts so we’re using the kitchen water from washing up to supplement the hosepipe.
It’s not easy gardening here, but we like a challenge and we’re calling in favours from friends and family to provide us with cuttings and divisions of plants from their own gardens, which should mean that they are better adapted to the local conditions than most of the shop-bought plants. We’ve also started a small vegetable and fruit patch and planted apples and pears around a paved patio that over time we will train as self-supporting espaliers.
Gradually we’ll fill up the space and move things around as needed. But for now I’m also interested in seeing what plants come up spontaneously, especially the annual species that are benefitting from the disturbance. I don’t use the term “weed” to refer to these: weeds are just plants in the wrong place at the wrong time. Many such plants are ecologically important, especially as nectar and pollen sources for bees and other insects. This includes Common Bugloss (Anchusa officinalis) with its richly purple, velvet-textured flowers.
Another plant that we are tolerating is a fast-growing relative of spinach that’s variously called Goosefoot or Fat Hen (Chenopodium album). I’d long known that it was edible (it’s grown as a crop in parts of Asia) but until last night I’d not cooked with it.
In fact it’s delicious! I threw some roughly chopped leaves and stems into a mushroom omelette and I have to say that it was better than any commercial spinach I’ve bought or grown. In particular, the texture is much nicer as the leaves are very water-repellant which mean that they don’t absorb as much moisture during cooking. Highly recommended as an alternative to spinach but make sure you correctly identify the plant before you try it – there’s some good advice on this website: https://www.wildfooduk.com/edible-wild-plants/fat-hen/.
As well as Fat Hen we also have the close relative Tree Spinach (Chenopodium giganteum), with it’s beautiful magenta-tinged leaves, coming up in the garden. I’m looking forward to trying that too:
I’ll try to post more as the garden progresses, if I have time. But as I mentioned yesterday, even though the manuscript is complete and submitted to the publisher, there’s still lots to do on my next book! Have a good weekend.
It’s been a couple of years since I last did a talk or workshop for the Wildlife Trust for Bedfordshire, Cambridgeshire & Northamptonshire. But I’m pleased to say that they’ve invited me back and you can join me tomorrow evening for an online introductory talk about pollinators and pollination in the UK.
The talk starts at 7pm UK time and full details of how to sign up are in the link below:
Prof. Jeff Ollerton - ecological scientist and author 