Cabot Institute blog

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Wednesday, 17 May 2017

Yangon’s mobility crisis: A governance problem

A mobility crisis has arisen in Yangon, Myanmar, as growth-induced congestion is slowing travel times for the city’s widely used buses, thereby incentivising car ownership and increasing traffic further. The key cause is poor governance, which manifests itself through fragmented planning, low public infrastructure investment, and a ban on motorcycles and bicycles.

Home to more than 5 million people and producing nearly a quarter of Myanmar’s gross domestic product, this metropolis is once again buzzing with activity as it reopens to the world after decades of military rule. But Yangon’s potential to serve as an engine of economic growth for the nation is being severely undermined by a mobility crisis. As the economy speeds up, the city slows down.

Journey times have skyrocketed in the city as the streets become ever more crowded. Some estimates suggest travel speeds at peak times have dropped from 38 km/h in 2007 to 10-15 km/h in 2015. This slowdown matters for several reasons. First, such high congestion places a significant drag on productivity by raising the cost of doing business and generating friction in the greater Yangon labour market. It is harder for workers to commute to the jobs they are qualified for. Second, the worst affected are the poorest. As a group, they spend the highest share of income on transport and the most time in traffic, which impedes poverty reduction efforts and adds to inequality. Third, air pollution has reached dangerous levels. The World Health Organization finds that Myanmar has some of the worst air pollution in the world, due in part to “inefficient modes of transport”.

The proximate causes: liberalisation and economic growth

Yangon’s mobility crisis is a positive indicator insofar as it reflects robust economic growth. Estimating the city’s growth rate is challenging due to a lack of economic data. However, by exploiting satellite images of night-time lights, which can be used as a rough proxy for economic activity, we can get an idea of the pace of growth. Figures 1 and 2 show images of Yangon at night in 2003 and 2013, respectively. Over this period, the level of luminosity nearly tripled, which we estimate translates into an impressive average annual growth rate in output of 8.5%. Growth appears to have been accelerating, given our estimate that the city grew at an average annual rate of 11.2% between 2008 and 2013.

Figure 1: Luminosity in Yangon Region, 2003   

Figure 2: Luminosity in Yangon Region, 2013

Since 2011 this growth has been accompanied by a large expansion of personal automobile usage. It was virtually impossible to import automobiles prior to 2011 due to heavy restrictions imposed by the military. The relaxation of vehicle import restrictions, as part of a wider range of liberalisation reforms in recent years, has revealed extensive pent up vehicle demand and allowed a precipitous decline in car prices. Yangon’s burgeoning middle class has jumped at the opportunity to acquire newly imported vehicles and escape the deteriorating bus system. Official figures indicate that there was a 153% increase in registered vehicles in Yangon between 2011 and 2014 alone.

The congestion incentive spiral

The surge in automobile ownership has set in motion a “congestion incentive spiral” that has exacerbated traffic. Prior to liberalisation, buses were by far the dominant mode of transport. The bus system was run as a competitive cartel with a restricted number of private bus owners competing for passengers on similar routes. This incentivised overcrowding, reckless driving, and under-investment in bus fleet maintenance — all of which contributed to congestion and a poor passenger experience.

For those who can afford a car, abandoning the buses is rational. Cars are more comfortable and always quicker than buses. The ability to go directly from origin to destination without stops or transfers significantly reduces the overall journey time. There remains a dilemma: the more people abandon buses, the worse traffic becomes, and the greater the incentive to use private transport. It is an incentive spiral that can only be broken by dramatically increasing the costs of individual car use or by providing an attractive alternative.


Fragmented governance as a root cause

There is no ready alternative to buses and cars in Yangon due to a legacy of poor planning, low public investment, and the fact that motorcycles and bicycles are banned in the city. In fact, there has been no significant investment in public transport infrastructure since the colonial era when the city’s Circular Railway was built. The railway is running and affordable, but its slow speed and limited coverage mean it attracts only a small fraction of Yangon’s commuters.

The emergence of the dysfunctional private bus cartel was an organic response to the lack of alternatives, which in turn was a consequence of the systematic lack of public investment in transport infrastructure and services. This crisis of governance persists today despite the energetic efforts of the current Chief Minister of Yangon, who has driven an impressive reform of the bus system by breaking the cartel and introducing proper public oversight.

An improved bus system, however, will not be enough to break the congestion incentive spiral now that so many people have purchased cars. What is required is a comprehensive and financially viable transport plan developed and implemented by a public transport authority with a metropolitan remit. Currently, the delivery of city infrastructure and services is fragmented across three tiers of government and dozens of agencies and offices. This fragmentation of governance is the true underlying cause of Yangon’s mobility crisis.

A path forward: governance then infrastructure

It is important to frame the problem as a mobility crisis, not a traffic congestion crisis. People can move through cities in many ways, and all large cities have traffic congestion challenges. More prepared cities do not suffer from mobility crises because other transport options are available: bus rapid transit systems that are insulated from traffic; cycling infrastructure; rail networks; and pedestrian-friendly mixed-used developments that reduce the demand for vehicular travel.

Relatively modest public investment could help Yangon. Nonetheless, a bus rapid transit plan announced in 2014 unfortunately appears to have been shelved. The mostly flat topography of Yangon is conducive to cycling. Relaxing restrictions on the use of bicycles on key arteries and in the city centre, combined with modest investments in cycling infrastructure, could provide an affordable alternative mode of individualised transport in the city.

These initiatives require significant governance reforms to succeed. Yangon is projected to join the ranks of the world’s mega-cities (i.e. cities with 10 million or more inhabitants) by 2030. With this growth comes physical expansion, which alters commuting patterns and transport demand. Without a concerted and sustained intervention by a metropolitan-scale transport authority with a mandate to maximise urban mobility, Yangon’s transit woes will surely worsen and further undermine the city’s enormous potential to support Myanmar’s economic renaissance.

This blog is written by Dr Sean Fox (Political Economy of Development & Urban Geography) and originally hosted on the IGC blog.

Wednesday, 3 May 2017

Environments without Borders

The effects of climate change vary hugely across political borders, and have wide-ranging impacts on different communities and environments. Climate policy responses must recognise this global interconnectedness, and integrate international cooperation with effective local action. This is why global treaties such as the Paris Agreement are so important in the fight against climate change, but individual nations must also do their bit to achieve the objectives set out in the agreement. In Environments without Borders (part of Research Without Borders), a panel debate hosted by Bristol Doctoral College and the Cabot Institute on Wednesday 10th May, we will discuss some of these issues, using examples from our research on particular challenges facing our global ocean and water environments.

Iceberg photo taken on a research trip to Antarctica, by Eric Mackie

Rising Sea Levels

Many climate change impacts require a policy response that balances mitigation with adaptation. Mitigation, by reducing global greenhouse gas emissions to achieve a zero-carbon economy, can drastically reduce some of the worst effects of climate change. However, we are already committed to certain climate change impacts, and these will require humanity to adapt. Sea level rise is a prime example. Global sea level has already risen 20cm since 1900, and the rate of sea level rise is increasing. We know this trend will continue throughout the 21st century and beyond, but the question is, how much will sea level rise, and how fast? Projections of global sea level rise by 2100 range from a further 30cm, assuming drastic mitigation action, to 1m or more in “business-as-usual” scenarios with increasing carbon emissions. Cutting carbon emissions can hugely reduce the number of people at risk of displacement by sea level rise globally, from up to 760 million in a scenario with 4°C of warming, down to 130 million if warming is limited to 2°C in line with the Paris Agreement. Mitigation is therefore essential if we want to avoid the worst effects, but adaptation is also necessary to ensure humanity is resilient to sea level rise that is already locked in.

A coastal scene taken on a research trip in the South Pacific, by Alice Venn


Disappearing Islands

The South Pacific is home to some of the world’s states most vulnerable to climate change impacts. Sea-level rise threatens coastal erosion, the widespread displacement of people and the inundation of the lowest-lying islands in Tuvalu, Kiribati and the Marshall Islands, while oceanic warming and acidification threaten the livelihoods of many remote coastal communities. More intense tropical cyclones, Cyclone Pam in 2015 and Winston in 2016, have recently resulted in tragic losses of life and damages in excess of $449 million and $470 million respectively. The devastation facing Small Island Developing States in the region, when juxtaposed with their negligible contribution to global greenhouse gas emissions which is estimated at just 0.03%, serves to illustrate the need for the international community to urgently step up efforts to provide support. Enhanced financial assistance for adaptation is essential, however this must be accompanied by strengthened legal protection for communities, readily accessible compensation for loss and damage, capacity building and a strengthened role for civil society organisations giving voice to community needs and traditional knowledge in policy-making processes.

The Lion Fish is an example of an aggressive invasive fish in the Caribbean Sea, and has had an impact over native species, ecosystems and local economies.

Invasive Aliens

Biodiversity in water environments can be adversely affected by invasive fish species, which originate from different sources, including marine ballast, fisheries improvements, and aquaculture. Invasive fish species can cause environmental concerns such as changes in the nutrients cycle, transmission of diseases, competence for resources, displacement and extinction of native species. Success in the establishment of invasive species depends on propagule size, physiology of the proper species, and current biotic and abiotic factors in the invaded system. Invasive species represent a global issue, and when combined with climate change their effects can be sharpened. Some limiting abiotic factors are expected to change as the climate changes, favouring new invasions and the spread of established invasive species to new ranges. Milder winters in northern latitude lakes, worldwide flooding and salinisation of coastal freshwater systems will provide suitable thermal conditions, new pathways for escape and dispersion, and the increase in dominance by invasive fish species adapted to brackish water systems. Deficient planning for future responses in water management can also result in favourable conditions for dispersion of undesirable aquatic organisms. For example, this is the case with the Nile tilapia, an invasive species in tropical ecosystems of southern Mexico and Tanzania, where flooding causes its dispersion but alternative management policies could improve the situation. More information see the Invasive Species Specialists Group.

Sustainable Resource Management

Against the backdrop of climate change, which will exacerbate the impact of human activities on natural resources, today’s environmental challenges require above all a strong and consistent commitment by national governments to better implement ambitious environmental policies that they previously adopted. However, traditional decision making approaches often are not equipped to ensure that precious resources are protected, if not enhanced. Sustainable management of natural resources is without doubt complex and creates conflicts between users that compete for access. For instance, there still seems to be too great a divide between the environmental and the business sector and these policy domains are as yet not fully integrated. Nonetheless, there are good examples of governments (and sub-national governments) that were successful in getting all key policy sectors on board when implementing difficult and ambitious environmental policies. For instance, the Scottish Government’s approach in implementing the Water Framework Directive demonstrates that with a strong political commitment, coupled with very proactive efforts in balancing the decision making towards more inclusive and cooperative policy processes, and with an intense and systematic use of evidence to back up policy proposals, it is possible to build trust between sectors and to act upon the barriers to implementation.

It’s clear that each of these challenges requires imminent action, but what are the right approaches, actors, and requirements to make meaningful progress? Whether you’re a member of the public, a policy maker, or someone working in the field, we invite you to join us at the Environments without Borders event on Wednesday 10 May for a lively and provocative debate about the challenges we face and how, collectively, we can spur action for change.

Blog authors (and panel members): Laura De Vito is a postgraduate researcher in the School of Geographical Sciences. Carlos Gracida Juarez is a postgraduate researcher in the School of Biological Sciences. Alice Venn is a postgraduate researcher in the School of Social Sciences and Law. Erik Mackie is a postgraduate researcher in the School of Geographical Sciences, working together with the British Antarctic Survey, and kept up a blog during his recent fieldwork in Antarctica. Blog originally posted on the Policy Bristol Blog.

Tuesday, 25 April 2017

Why cities are crucibles for sustainable development efforts (but so hard to get right)


Figure 1. Rural and urban population trends, 1950-2050.
Fox, S. & Goodfellow, T. (2016) Cities and Development, Second Edition. Routledge.

Sustainable Development Goal 11 outlines a global ambition to ‘make cities and human settlements inclusive, safe, resilient and sustainable’. It is arguably one of the most important of the 17 recently agreed Goals, but we’re unlikely to reach it in most parts of the world by 2030.

The importance of Goal 11 stems from global demographic trends. As Figure 1 illustrates, over 50% of the world’s population already lives in towns and cities, and that percentage is set to rise to 66% by 2050. In fact, nearly all projected population growth between now and 2050 is expected to be absorbed in towns and cities, and the vast majority of this growth will happen in Africa and Asia (see Figure 2).

These trends mean that when it comes to eliminating poverty and hunger, improving health and education services, ensuring universal access to clean water and adequate sanitation, promoting economic growth with decent employment opportunities, and creating ‘responsible consumption and production patterns’ (and achieving many other goals) urban centres are on the front line by default.


Figure 2. Estimated and projected urban population increase by region, 1950/2000 & 2000/2050
Dr Sean Fox, Lecturer in Urban Geography and Global Development, University of Bristol


But cities are complex political arenas prone to the kinds of conflicts that can thwart ambitious visions for transformative development.

To appreciate just how difficult it can be to achieve seemingly obvious and desirable improvements in cities, it is useful to examine some practical challenges. Consider the goal of ensuring access to clean, affordable water for all (Goal 6, Target 1; Goal 11 Target 1). In cities across Africa and Asia, a significant share of households live in informal settlements that lack piped water infrastructure. As a result, most residents rely on water provided by private vendors who sell water by the bucketful from tanker trunks or standpipes that they control. Perversely, the poor often end up paying a significant premium for their water on the open market, while more fortunate residents who are connected to municipal infrastructure pay far less. This perpetuates inequality, both between socioeconomic groups and between men and women (as women generally bear the burden of water collection in such contexts), and it also means that there are groups of people with fairly strong incentives to resist infrastructure investments: the water vendors. And these vendors sometimes take aggressive steps to protect their captive markets and thwart infrastructure development.

A similar dynamic is often at play when it comes to upgrading informal settlements more generally. In many cities poorer households do not have formal (i.e. legally binding) tenure security but rather pay some form of rent to a third party in return for protection against eviction. This form of ‘land racketeering’ is often undertaken by the very politicians and bureaucrats who should be seeking to improve citizens’ lives.

In other words, urban underdevelopment creates profitable opportunities for some, which in turn creates interest groups opposed to change.

But even rich cities, with well-developed physical infrastructure and formal tenure arrangements, often suffer from political gridlock that impedes progress. Consider the city of Bristol in the UK. Bristol was recently voted the best place to live in the UK, yet the city also suffers from dangerous levels of air pollution, which is linked directly to debilitating levels of traffic congestion in the city.
While Bristol’s transport woes have long been recognized, it has proven fiendishly difficult to tackle the underlying problem: a lack of metropolitan-scale transport planning and investment integrated with land use plans. This is due to a legacy of ‘horizontal fragmentation’ and ‘vertical dependence’.

Figure 3. Map of Greater Bristol with council boundaries 

Horizontal fragmentation refers to the fact that Greater Bristol—i.e. the functional area of the city as defined by daily commuter behaviour—is home to over 1 million people spread across four different local government areas, each with its own budget, council, transport planning processes, etc. As Figure 3 clearly shows, the local government boundaries (in red) carve up this functional urban region into four artificial parts). Indeed, in some places, such as north Bristol, local government boundaries run straight through clearly contiguous built-up areas (represented as grey). The challenge of coordinating planning and investment across four councils is compounded by the fact that in the past any major infrastructure investment needed to be approved and funded by the UK central government (i.e. the problem of vertical dependence). This support is not necessarily forthcoming. An ambitious plan tabled around the turn of the millennium to integrate city transport with a tram network, and make the whole system more inclusive for low income residents, was rejected by central government. This is a prime example of how political challenges in wealthy countries impede development progress.

In sum, there are significant political obstacles to progress in poor cities and rich cities alike. But this doesn’t mean that progress is impossible. In fact, recognising and understanding these political complexities is helpful in identifying effective courses of action, whether as citizens, activists or policymakers. I doubt we will fulfil the aspirations of SDG 11 in a convincing manner by 2030, but I am hopeful that progress can be made if we approach the challenge with our eyes wide open to the political dynamics that could undermine our efforts.

Blog by Dr Sean Fox, School of Geographical Sciences. Originally hosted by the Policy Bristol blog.

The views expressed here are personal views and do not reflect the views of the funders of our research.




Thursday, 20 April 2017

Smart Energy Marketplace 2017

The energy market is changing. Although, when I say changing, what I really mean it is moving back to how it was in the beginning, in a manner of speaking. When electricity was first brought to the UK, the generators were placed close to loads to reduce transmission losses. We then moved to a more centralised grid, with a smaller number of large power stations, and energy shipped all over the country through a high voltage transmission network. With the more recent increase in renewable penetration, roof-top solar, small- and large-scale storage, all of which is distributed across the country, we are shifting back to the distributed generation paradigm. Power is not only flowing from the centralised generation facilities, but also from traditional consumers as well. This creates a large number of new problems to solve.

This year’s Smart Energy Marketplace, organised by Regen, discussed this shift from centralised to distributed generation, with panellists and delegates from large industry, technology start-ups, consultancies, national and local government and academia. I was really interested in finding out how local generation was being utilised, what barriers were felt to exist restraining the move to a fully distributed grid and how policies, charging regimes and attitudes in industry were changing and developing.

There were several major barriers that came up during the discussions:
  •  How to balance supply and demand, both of which could potentially be highly volatile, along with the integration of storage;
  • Grid capacity constraints and need for reinforcement when adding distributed generation which can lead to disproportionately high costs for small generators;
  • The roll-out of smart meters to enable variable electricity tariffs for domestic consumers;
  • Automation technology in homes to allow devices to be switched on and off remotely or automatically dependent on energy price;
  • Consumer engagement issues, not willing to move suppliers or change behaviour to save money.

These barriers were identified through a number of different case studies presented, such as the Sunshine Tariff pilot study in Wadebridge, Cornwall. Here consumers were incentivised by reduced energy prices to use power during the day. This local and regional balancing of supply and demand seems to be one of the key ways to reduce energy cost, and prevent the need to reinforce the grid further.

Cornwall seemed to be a real hub for energy market innovation, which may be due to the grid constraint in the county, along with the massive renewable generation opportunities that have continue to be exploited. (The UK’s first wind farm at Delabole has recently celebrated its 25th birthday!) Cornwall County Council together with Regen are developing ideas to improve the local energy market, improving access to local energy, working with community energy groups, housing stock improvements and using the geothermal potential to supply heating needs. All this will support the population living in energy poverty, whilst still maintaining a low carbon future for the county and keeping money within the local economy. The Eden Project has also trialled a peer-to-peer trading platform called Piclo, developed by Open Utility, where it could choose where to buy its electricity from depending on price and availability.

Energy Local presented two of their projects, SWELL and Bethesda, where they developed local energy clubs to buy power from local renewable energy suppliers at lower cost, with the consumers working on a time-of-use tariff to reduce bills. This enables the supplier to earn more from their generation, and consumers to keep their money in the local area. Other local energy groups, such as Plymouth Energy Community, looked at creating their own energy supply, by creating their own customer base and buying the aggregated power from an existing electricity supplier, known as white labelling. This is able to develop local tariffs for the community, and again keep profits in the local economy.

During the day, many presenters and delegates were discussing local energy platforms, in relation to local balancing through micro-aggregation of supplies and loads, private or virtual private wire systems, peer-to-peer trading, and how to engage energy consumers with the benefits of these new technologies – a problem when it may only save them around £150 a year. A major barrier to these ideas were policy, with the current trading market unable to deal with this flexibility. However, through funding being delivered through the Department of Business, Energy and Industrial Strategy, this is beginning to be addressed.

The event concluded with a presentation from a panel of investors and renewable operators, talking about the current market and business opportunities within it. As the UK government has cut back on the feed-in tariff and the renewables obligation, there were many concerns that future renewable installations would collapse. However, there was some cautious optimism from those involved with many thinking that large scale solar has nearly reached grid parity, especially where the grid connection is geographically near, with grid storage parity also possible in the next few years.

What have I taken away from the day? I think there are three main points:
  • There is huge opportunity in local supply and consumption to reduce costs and remove strain from the grid – a real win-win for all involved. Using tools such as peer-to-peer electricity trading and 30 minute electricity pricing tariffs can allow consumers to be fully empowered to control and reduce their spending, and decide when to use power.
  • Policy needs to move forward quickly to catch up with the new market to allow these opportunities to really take off.
  • Consumers must be engaged and empowered into this new energy future to ensure its success. Technology will be required to allow many choices to be carried out automatically, but some users will still want to be interacting with the process.

The full conference presentations from the day can be found here, and those from the talks can be found here.

Blog by Dr Sam Williamson, Faculty of Engineering. Sam is a Lecturer in Electrical Engineering, in the Electrical Energy Management Group, interested in how energy can be provided sustainably and appropriately, both to existing users and those without access.

Tuesday, 28 March 2017

Scaling up probabilities in space

Suppose you have some location or small area, call it location A, and you have decided for this location the 1-in-100 year event for some magnitude in that area is ‘x’. That is to say, the probability of an event with magnitude exceeding ‘x’ in the next year at location A is 1/100. For clarity, I would rather state the exact definition, rather than say ‘1-in-100 year event’.

Now suppose you have a second location, call it location B, and you are worried about an event exceeding ‘x’ in the next year at either location A or location B. For simplicity suppose that ‘x’ is the 1-in-100 year event at location B as well, and suppose also that the magnitude of events at the two locations are probabilistically independent. In this case “an event exceeding ‘x’ in the next year at either A or B” is the logical complement of “no event exceeding ‘x’ in the next year at A, AND no event exceeding ‘x’ in the next year at B”; in logic this is known as De Morgan’s Law. This gives us the result:

Pr(an event exceeding ‘x’ in the next year at either A or B) = 1 – (1 – 1/100) * (1 – 1/100).

This argument generalises to any number of locations. Suppose our locations are numbered from 1 up to n, and let ‘p_i’ be the probability that the magnitude exceeds some threshold ‘x’ in the next year at location i. I will write ‘somewhere’ for ‘somewhere in the union of the n locations’. Then, assuming probabilistic independence as before,

Pr(an event exceeding ‘x’ in the next year somewhere) = 1 – (1 – p_1) * … * (1 – p_n).

If the sum of all of the p_i’s is less than about 0.1, then there is a good approximation to this value, namely

Pr(an event exceeding ‘x’ in the next year somewhere) = p_1 + … + p_n, approximately.

But don’t use this approximation if the result is more than about 0.1, use the proper formula instead.

One thing to remember is that if ‘x’ is the 1-in-100 year event for a single location, it is NOT the 1-in-100 year event for two or more locations.  Suppose that you have ten locations, and x is the 1-in-100 year event for each location, and assume probabilistic independence as before.  Then the probability of an event exceeding ‘x’ in the next year somewhere is 1/10. In other words, ‘x’ is the 1-in-10 year event over the union of the ten locations. Conversely, if you want the 1-in-100 year event over the union of the ten locations then you need to find the 1-in-1000 year event at an individual location.

These calculations all assumed that the magnitudes were probabilistically independent across locations. This was for simplicity: the probability calculus tells us exactly how to compute the probability of an event exceeding ‘x’ in the next year somewhere, for any joint distribution of the magnitudes at the locations. This is more complicated: ask your friendly statistician (who will tell you about the awesome inclusion/exclusion formula). The basic message doesn’t change, though. The probability of exceeding ‘x’ somewhere depends on the number of locations you are considering. Or, in terms of areas, the probability of exceeding ‘x’ somewhere depends on the size of the region you are considering.

Blog post by Prof. Jonathan Rougier, Professor of Statistical Science.

First blog in series here.

Second blog in series here.

Third blog in series here.

Fourth blog in series here.

Thursday, 23 March 2017

What happens when you let PhD students and post-docs organise a meeting?

As plant science PhD students, we feel it is vital to share our research with other scientists to generate new ideas for collaborative projects. For this reason we decided to organise the ‘Innovations in Plant Science to Feed a Changing World’ workshop, which was held in the University of Bristol Biological Sciences department in February 2017. The delegates included early-career scientists from Kyoto University, Heidelberg University and of course the University of Bristol.

Figure 1. The Conference Poster
The University of Bristol has a long-standing partnership with Kyoto University and more recently, Heidelberg University, as our plant science groups share overlapping research areas. The main aim of the workshop was to encourage novel collaboration opportunities between the plant science groups, which would give rise to future projects, publications and ultimately funding.

Last year, Kyoto University hosted a highly engaging and productive workshop (see Sarah Jose’s blog post last year) for early-career scientists from the three universities in this coalition. Following from the success of this workshop, we decided to organise the second workshop, where participants could build upon the partnerships forged at the last meeting, form new links and present their results in a friendly environment. So, for the past six months, a team of PhD students and post-docs has been busy organising the meeting that took place in February.

As it turns out, organizing a three-day conference, even a relatively small one, is quite a lot of work. Getting venues, transfers, catering, accommodation and social activities booked all presented their own particular challenges. However, perhaps the most challenging task was designing the program for the workshop, which was set out into different themes to encompass the participants’ different subject areas.

All the organisation paid off when the visitors arrived, slightly (very) jet lagged from their long flights. Once the workshop had started, we were delighted with how smoothly the sessions ran and how engaging the talks were. Following the talks there were many discussions over coffee, during the poster session and break-out session. We also included a careers talk from Prof Tokitaka Oyama from Kyoto University, who shared his insights on how to succeed as a plant scientist. Another highlight was the keynote talk from Professor Keith Lindsey (University of Durham), who shared his fascinating work on modeling plant developmental biology.

In amongst all the science, we had time for an excursion to the University of Bristol Botanical Gardens where Nick Wray gave a fascinating tour, which was very enjoyable. We also visited the Wills memorial building tower and even had a go at ringing the bell!
Figure 2. Nick Wray (far right) led a fascinating tour of the University’s Botanic Garden for the visitors.
Although organising the workshop was a lot of work, it was definitely worth it. Our organisation, leadership and project management skills were trained and tested in the run-up to the workshop, but in the end, it went very well indeed. All the delegates thoroughly enjoyed their participation and a comment that was heard a few times was that delegates were impressed, not just with the quality of the science being presented, but also the quality of the scientific discussion particularly given that English was not the first language for the majority of the participants.

We hope that the links formed at the workshop will continue to develop into novel collaborative projects. - I (Donald) definitely benefited as the post-doc Massaki Okada even stayed on a few days to teach me some techniques.

We would like to thank our funders, the Bristol Centre for Agricultural Innovation and the New Phytologist Trust for their support. We’d also like to thank the other members of the organising committee whose hard work made this workshop so successful: Fiona Belbin, Deirdre McLachlan, Tsuyoshi Aoyama and Antony Dodd.

Figure 3. Group Photo


Blog post by Donald Fraser & Katie Tomlinson

Monday, 20 March 2017

What is Probability?

The paradox of probability

Probability is a quantification of uncertainty. We use probability words in our everyday discourse: impossible, very unlikely, 50:50, likely, 95% certain, almost certain, certain. This suggests a shared understanding of what probability is, and yet it has proved very hard to operationalise probability in a way that is widely accepted.

Uncertainty is subjective

Uncertainty is a property of the mind, and varies between people, according to their learning and experiences, way of thinking, disposition, and mood. Were we being scrupulous we would always say "my probability" or "your probability" but never "the probability". When we use "the", it is sometimes justified by convention, in situations of symmetry: tossing a coin, rolling a dice, drawing cards from a pack, balls from a lottery machine. This convention is wrong, but useful -- were we to inspect a coin, a dice, a pack of cards, or a lottery machine, we would discover asymmetry.

Agreement about symmetry is an example of a wider phenomenon, namely consensus. If well-informed people agree on a probability, then we might say "the probability". Probabilities in public discourse are often of this form, for example the IPCC's "extremely likely" (at least 95% certain) that human activities are the main cause of global warming since the 1950s. Stated probabilities can never be defended as 'objective', because they are not. They are defensible when they represent a consensus of well-informed people. People wanting to disparage this type of stated probability will attack the notion of consensus amongst well-informed people, often by setting absurdly high standards for what we mean by 'consensus', closer to 'unanimity'.

Abstraction in mathematics

Probability is a very good example of the development of abstraction in mathematics. Early writers on probability in the 17th century based their calculations strongly on their intuition. By the 19th century mathematicians were discovering that intuition was not good guide to the further development of their subject. Into the 20th century mathematics was increasingly defined by mathematicians as 'the manipulation of symbols according to rules', which is the modern definition. What was surprising and gratifying is that mathematical abstraction continued (and continues) to be useful in reasoning about the world. This is known as "the unreasonable effectiveness of mathematics".

The abstract theory of probability was finally defined by the great 20th century mathematician Andrey Kolmogorov, in 1933: the recency of this date showing how difficult this was. Kolmogorov's definition paid no heed at all to what 'probability' meant; only the rules for how probabilities behaved were important. Stripped to their essentials, these rules are:

1. If A is a proposition, then Pr(A) >= 0.
2. If A is certainly true, then Pr(A) = 1.
3. If A and B are mutually exclusive (i.e. they cannot both be true), then Pr(A or B) = Pr(A) + Pr(B).

The formal definition is based on advanced mathematical concepts that you might learn in the final year of a maths degree at a top university.

'Probability theory' is the study of functions 'Pr' which have the three properties listed above. Probability theorists are under no obligations to provide a meaning for 'Pr'. This obligation falls in particular to applied statisticians (also physicists, computer scientists, and philosophers), who would like to use probability to make useful statements about the world.

Probability and betting

There are several interpretations of probability. Out of these, one interpretation has emerged to be both subjective and generic: probability is your fair price for a bet. If A is a proposition, then Pr(A) is the amount you would pay, in £, for a bet which pays £0 if A turns out to be false, and £1 if A turns out to be true. Under this interpretation rules 1 and 2 are implied by the reasonable preference for not losing money. Rule 3 is also implied by the same preference, although the proof is arcane, compared to simple betting. The overall theorem is called the Dutch Book Theorem: if probabilities are your fair prices for bets, then your bookmaker cannot make you a sure loser if and only if your probabilities obey the three rules.

This interpretation is at once liberating and threatening. It is liberating because it avoids the difficulties of other interpretations, and emphasises what we know to be true, that uncertainty is a property of the mind, and varies from person to person. It is threatening because it does not seem very scientific -- betting being rather trivial -- and because it does not conform to the way that scientists often use probabilities, although it does conform quite closely to the vernacular use of probabilities. Many scientists will deny that their probability is their fair price for a bet, although they will be hard-pressed to explain what it is, if not.

Blog post by Prof. Jonathan Rougier, Professor of Statistical Science.

First blog in series here.

Second blog in series here

Third blog in series here.

Wednesday, 1 March 2017

Interests in Aid and Development: a talk with Myles Wickstead

Ever wondered what a career in aid and development is like? Or how the world’s current development programmes came into being? Look no further than this blog on Myles Wickstead who gave a Cabot Institute lecture and short interview on his reflections and experiences on a colourful career in aid and development.

Among Wickstead’s notable achievements are a position as head of British Development Division in Eastern Africa, coordinating a British Government White Paper on eliminating world poverty and now being an advisor to the charity Hand in Hand International.

An audio recording of Myles lecture can be found above. His talk focussed largely on the inception of the building blocks of international development; the UN, the World Bank and the International Monetary fund. He began by turning back time towards the end of the second World War, in which the atmosphere of global reconciliation bred the need for trans-border institutions such as the UN that had the oversight necessary for peace to prevail.


Many years later, the UN decided to introduce development goals with the aim of reducing global poverty within a given time frame. The first of these was the Millennium Development Goals which were drafted in the UN head quarters with little external solicitation. In fact, Wickstead reminisced that environmental goals were almost completely overlooked and only added when a member of the committee ran into the director of the UN environment department on the way to the copier room…

Wickstead went on to add that a large parts of the Millennium goals were generally quite successful although there was still plenty of scope to be more inclusive. He also dwelt on the new Sustainable Development Goals drafted by the UN in 2015 and the Paris climate summit which, Wickstead claims, represent a much more integrated approach to propel international development into the future.

Below is my interview with Myles in which I question him on his talk and ask him about his career in aid and development:

You mentioned a fair bit in your talk about the importance of tying in environment sustainability with aid and development. How do you see that working in practice in a developing country when sustainable practices can be sometimes be quite anti-economic? 

Yes, the two things are brought together in the Global Goals for Sustainable Development agreed in New York in September 2015.  Let’s take an example of a country that’s well-endowed with forest resources. They could get rich quickly by chopping down the trees and selling the wood. You can’t expect those countries to simply say ‘we are not going to chop our forest down’. Firstly you need them to realise that for the long-term sustainability of their country they need to preserve the  forest. But second, because maintaining the forests helps protect us all from climate change they rightly expect some compensation from the international community to do so. There are (albeit imperfect) mechanisms in place for this. Despite this I do, on the whole, think they are being successfully implemented: take Brazil for example.

There are also examples where – often without the consent of the government - indigenous forests are being cut down to make way for palm oil plantations, with devastating consequences not only for the trees but the wildlife.  In these situations, governments need to be encouraged to take firm action against the individuals or  companies concerned, again with support from the international community as and if appropriate.

I work on volcanic hazard in Ethiopia and one of the things I’ve noticed is the more wealthy urban areas are developing fast with an expanding middle class, but the more rural areas are still subject to a lot of extreme poverty. What part should external aid play in helping this wealth filter down?

It’s a very important question and one I touched on when talking about the Millennium Development Goals (MDGs) which were in place from 2000-2015.  That period saw extraordinary progress, including halving the proportion of people living in absolute poverty, but many people (for example, those with disabilities or from ethnic minorities) were left out.  It is also the case that urban areas, with generally better infrastructure and more job opportunities, tended to make faster progress.  A lot of people in rural areas were in very much the same position in 2015 as in 1990. Within Ethiopia, a combination of rapid economic growth – supported both by investment and aid  – and good policies mean that the benefits are now being felt more widely.

The role of Chinese investment in infrastructure, particularly roads, has I think been quite a positive one. The Government of Ethiopia has a very clear five year growth and investment plan and they expect their partners to deliver; I remember one case of former Ethiopian Prime Minister Meles requiring a Chinese company to rebuild a road they had just built as it was not up to standard; I am sure they were equally exacting of other companies from other countries.  Not all African governments have that kind of determination but on the whole I think Chinese engagement has been a good thing.  And the fact that Africa was largely unaffected by the global recession following the crash of 2008 was not only because it was not as connected to the international financial system as other parts of the world, but also because China and other countries in Asia continued to buy its raw materials.

What influenced your decision to have a career in Aid and development?

I had lived and travelled overseas a little.  My father was a marine biologist and as a technical expert worked for the predecessors of DFID and lived and worked overseas in places like Singapore, Tanzania, and Jamaica.  So I probably got some of the wish to live and work overseas from him – though alas didn’t inherit the science gene, which passed me by!

I went through the civil service fast stream process, and having successfully negotiated that had to make a choice about which Department I wanted to join.  It was then the Ministry of Overseas Development; a few years later became the Overseas Development Administration of the FCO; and in 1997 became a fully-fledged Department of State with its own Cabinet Minister. Interestingly, DFID remains the most popular choice of all government departments for fast-steam applicants.

Is there a defining moment in your career you want to mention? 

I have been extraordinarily lucky in the choices that I have made - or have been made for me - in terms of where I was at particular time. To have had the chance to run a regional office in Africa; to have been on the Board of the World Bank; to have worked closely with Ministers both as a Private Secretary and in coordinating the 1997 White Paper (the first in 24 years); and to be Ambassador to Ethiopia and the African Union – it was a huge privilege (and very hard work!) to be given these responsibilities.  I ran the Commission for Africa Secretariat in 2004/5, and I suppose one of the great moments was going to present a copy of the Commission’s Report ‘Our Common Interest’ in 2005 to Nelson Mandela.

Someone asked earlier today- how do you keep positive despite the gloomy state of much of the world? My answer would be that the world has made extraordinary progress over the past quarter of a century in pulling people out of poverty, and that we have a real chance of completing the task, in line with the Sustainable Development Goals, by 2030. Of course there have been setbacks along the way, and there will be more – conflict and environmental challenges to name but two. But with political will, and by maintaining a positive focus, I believe we can aspire to a better world both for ourselves and for future generations.

Blog post by Keri McNamara

Monday, 13 February 2017

Contemporary Eco-Cities: An improvement on previous work?

History offers up many grand ideas for how urban planning and design can be used to improve cities and society to be more sustainable and liveable. These ideas include early urban reforms by David Dale, Robert Owen, and Titus Salt, Benjamin Ward Richardson’s City of Health, Ebenezer Howard’s Garden City and Le Corbusier’s Contemporary City, amongst others. The eco-city, as an idea that initially developed out of the 1960s grassroots environmental movement, should be considered within this long tradition of ideas for the betterment of cities. The construction of ‘eco-cities’ in the recent decade has also been controversial. The aim of this article is to introduce the ideas and practices of contemporary eco-cities and to discuss the extent to which they can be regarded as an improvement on the work of previous urban reformers.

Eco-city concept and development stages of eco-cities

The term ‘eco-city’ was first coined in 1987 by US-based eco-city pioneer Richard Register as ‘an urban environmental system in which input (of resources) and output (of waste) are minimised’. As the eco-city concept began to be used more extensively, it became more broadly defined, ergo, there is no single accepted definition in the literature. Recognising and permeating ideas of nature in the city into the concept of sustainable cities should be considered essential in setting a framework for eco-cities. This idea can be seen as a continuation of planning trends which attempted to reconcile the nature-city relationship, beginning with Howard’s Garden City movement. The approach is also novel, in that it represented a wide range of factors which coalesce around sustainability in the contemporary context of global climate change, environmental degradation and environmental politics.

There are three stages in the development of eco-city. Early initiatives in the 1970s and 1980s were locally-oriented, bottom-up approaches which aimed to improve environmental conditions, with only few examples of practical projects. The period of 1990s to early 2000s marked the emerging stage of eco-city development, when balanced sustainable development was adopted as a principal objective. At this stage, national and municipal governments started to develop eco-cities and eco-towns, most of which were redevelopments or expansions of existing towns and cities as demonstration projects. Successful examples include eco-towns in Japan and small-scale ones in Europe. Since the mid-2000s, a number of ambitious built-from-scratch eco-city masterplans have emerged, aiming to make entire towns and cities highly sustainable. These top-down proposals are occurring predominantly in Asia, including the highly publicised Dongtan Eco-City, Sino-Singapore Tianjin Eco-City and Caofeidian Eco-City in China and the Masdar City which was proposed as a zero-carbon city in the UAE. The latter two stages of eco-cities are the foci in the following discussion, considering the development scale and significance.

General visions and planning of contemporary eco-cities

Contemporary eco-cities and eco-towns are, in general, an improvement on previous ideas and works in terms of their visions, planning and objectives.

Almost all smaller eco-town plans and holistic eco-city blueprints in recent years are emerging as reflections of and responses to the global context of climate change and environmental degradation, with emphasis on cutting-edge technology, clean energy, and circular economy to achieve sustainable living. This indicates that the finiteness of resources as well as the ecosystem itself has been more extensively recognised. This is an improvement from earlier works. Earlier works targeted urban problems including sanitation and personal health in the case of ‘Hygeia, City of Health’ by Richardson in 1876, and poor working and living conditions in the case of Saltaire and New Lanark, but hardly realised the limits of the environment. An example was Howard’s claim in his 1902 book Garden Cities of Tomorrow: ‘…to a more noble use of its infinite treasures. The earth for all practical purposes may be regarded as abiding forever’. Today’s improvement leads to the consideration of intergenerational ecological justice, being an essential principle of the development of eco-cities.

Moreover, there are three forms of eco-city projects identified: new developments, expansions of urban areas, and retrofits where existing cities adopt eco-city principles. Unlike earlier visionaries such as Ebenezer Howard and Le Corbusier who tended to reject the idea of gradual improvements to the conditions of existing cities in favour of comprehensive transformations of the urban environment, the planning of contemporary eco-cities/towns includes various forms of urban development and redevelopment. Whilst the ambitiously proposed built-from-scratch eco-cities in China and the UAE belong to the first type, most examples of smaller-scale ones in Japan, Germany, Scandinavia, and the UK are expansions of urban areas and retrofits, which is an improvement in terms of development forms.

Implementations and outcomes of contemporary eco-cities

The implementations and outcomes of contemporary eco-cities at early stage of the development in the 1990s and early 2000s are an improvement upon early urban reformers in many aspects, while those at current development stage may vary in light of different contexts. It is doubtful that the prospects of these newly-built eco-cities might be an improvement.

At the early stage, contemporary eco-cities and eco-towns were mainly developed in Japan and central and northern Europe, exemplifying the eco-cities in Germany. During this stage, a distinctive characteristic of small-to-moderate-scale developments is that they gave equal weighting to the environmental, economic and social aspects of their design and integrated them well.

The Eco-Town Program was launched in Japan in 1997 through national initiatives and municipal redevelopment planning in order to deal with waste management issues, industrial pollution and to stimulate new industry development during a time of economic stagnation. The Eco-Town concept in Japan originally focused on Industrial Symbiosis—the iconic 3R application of Industrial Ecology which concerns ‘the productivity and environmental impacts of resources in industrial societies’ (McManus 2005). The theory then extended to Urban Symbiosis to become part of the Eco-City concept, focusing on overall urban planning and urban ecosystems, civil society and greening of cities. The implementation of this program and the successful development of 26 eco-towns, which focused mainly on circular economy and environmentally conscious planning, highlight three major aspects of improvement on earlier urban reformers. First, the government put in place a comprehensive legal framework for becoming a recycling-based society. This action provides a legislative foundation, imposes a sense of duty, and reduces the risk for further transition and development in industries and society, which is a practical improvement on the ideas of earlier reformers which were often hard to carry out (in a large scale) without legislative basis. Second, the program emphasised a combination of initiatives from public sector, business sector and, especially, civil society. There were a number of citizen activities emerging during that period and engaging in the program, which stands in contrast to places like Saltaire that were largely paternal. Third, the program was carried out mainly in the form of redevelopment and retrofitting projects, which faced less trouble than those early built-from-scratch ideas because it could take advantages of existing social capital.

There are also two smaller-scale eco-town examples in Freiburg, Germany: Vauban and Rieselfeld. These two district-scale projects are expansion of the city in response to the increasing population. They were carefully planned and developed with foci on public transport, dense but diverse housing, and environmental buildings. A major improvement on earlier works includes the emphasis on public transport, as these two districts were designed to minimise car dependency, given that 35% of residents in Vauban have abstained from driving (Beatley 2012). Le Corbusier’s fetishisation of the automobile in his La Ville Radieuse (1967) is of little relevance considering today’s traffic congestion, the high energy consumption, and air quality concerns associated with automobiles. These two examples successfully demonstrate how public transport can contribute to urban and environmental sustainability.

At the current stage (since mid-2000s), contemporary eco-cities are primarily proposed to be built from scratch, on a grand scale. They would represent highly sustainable, experimental flagships, most of which are promoted by the Chinese national and municipal governments including examples such as the Masdar City in the UAE. The characteristic of these projects is they are predominantly entrepreneurial cities and tend to prioritise economic concerns over environmental ones. In terms of implementation and outcomes, these new cities sometimes fail to demonstrate improvements on previous works, with uncertainty remaining considering that many of them are still under construction.

Due to rapid population influx, emissions pressure and pollution issues, the Chinese state government encourages local governments to experiment the ‘eco-city’ as a flagship project for new technologies and ‘sustainable’ economic and ecological urban development. Highly publicised projects include Dongtan Eco-City on Chongming Island, Shanghai, Sino-Singapore Tianjin Eco-city and Caofeidian Eco-City. The first project, Dongtan Eco-City, has already been stalled due to issues of land quotas. The subsequent Caofeidian Eco-City, claiming to be a renewable energy city, has only completed a few buildings and failed to attract residents, suffering from huge debt and being indefinitely postponed. The only project that has come close to completion is the Sino-Singapore Tianjin Eco-city, which has not been developed without issues and is still of little improvement upon earlier urban reformers. It is being developed according to 26 sustainability indicators (Fig. 1), demonstrating the progressive practices within the Chinese context, although many of them are taken for granted in the West. There are many problems in the construction. The city claimed to promote green transport but the implementation of numerous highways are still the dominant transport structure in the city, accompanied by high-rise residential buildings, which is a strong resemblance of the type of city Le Corbusier imagined for ‘the contemporary city’. There is even less open green space compared with Le Corbusier’s ideas. Additionally, this city has only managed to attract 6000 residents thus far—far less than its objective. There is also hardly any inclusion of social sustainability, where there should be relevant viable attempts, as Caprotti states (2015), ‘the view of sustainability which is concerned purely with a city’s environmental footprint, or with its economic success is severely limited’.

26 Key performance indicators to measure success (Sino-Singapore Tianjin Eco-City Investment and Development Co.,Ltd 2015)
In the case of Masdar City, the so-called ‘carbon-neutral city’ (recently modified to be ‘low- carbon city’) initiatives are just a part in making Abu Dhabi a leader in the industry of renewable energy technologies, which does not include many real actions with reconciliation of the nature-human relationship. An exception to the Asian ambitions of the eco-city is the Eco-town plan in the UK, which may constitute an improvement on earlier works. Those eco-towns proposed by the North West Bicester, which are an expansion of existing urban areas, aim for affordable housing and promoting social justice.

In conclusion, the contemporary eco-cities, from the early emerging stage of the1990s till today, are in general, an improvement upon the work of earlier urban reformers in terms of their ideas and planning. Whilst the early-stage developments such as Eco-towns in Japan demonstrate an improvement in terms of practical implementations and existing outcomes, brand-new built-from-scratch eco-cities may not be sustainable in reality in light of different contexts.  They tend to prioritise economic goals instead of environmental concerns. Whether these newly built eco-cities will be an improvement on those of earlier reformers remains uncertain. The developments which have begun, however, provide lessons for future urban developments which can be introduced to improve future designs and the redevelopment of existing cities.

Blog by Cabot Institute Masters Research Fellow Shiyao (Silvia) Liu.

Further reading

Beatley, T., 2012. Green cities of Europe: global lessons on green urbanism, Washington DC, Island Press.
Caprotti, F., 2015, Eco-Cities and the Transition to Low Carbon Economies, Palgrave.
Howard, E., 1902, Garden Cities of Tomorrow, London: Swan Sonnenschein.
Le Corbusier, 1967, The Radiant City (La Ville Radieuse): Elements of a doctrine of urbanism to be used as the basis of our machine-age civilization, New York, The Orion Press.
McManus, P., 2005, Vortex Cities to Sustainable Cities: Australia’s Urban Challenge, UNSW Press, Sydney.
Register, R., 1987, Ecocity Berkeley: Building Cities for a Healthy Future. Berkeley, CA: North Atlantic Books.
Richardson, B.W., 1876, Hygeia, A city of health. MacMillan & Co., London.
Sino-Singapore Tianjin Eco-City Investment and Development Co.,Ltd. 2015, Tianjin Eco City website,  http://www.tianjineco-city.com/en/index.aspx

Wednesday, 8 February 2017

Model uncertainties in multispecies ecological models

We live in an increasingly uncertain world.  Therefore, when we model environmental processes of interest, it is vital to account for the inherent uncertainties in our analyses and ensure that this information is communicated to relevant parties.  Whilst the use of complex statistical models to estimate quantities of interest is becoming increasingly common in environmental sciences, one aspect of uncertainty that is frequently overlooked is that of model uncertainty.  Much of the research I conduct considers this additional aspect of uncertainty quantification; that is not just uncertainty in the quantities of interest, but also in the models that we use to estimate them.

An example of this is in a paper recently published in Ecology and Evolution (Swallow et al., 2016), which looks at how different species of birds that we commonly see in our gardens respond to the same environmental factors (or covariates).  Some of the species have declined rapidly over the past 40 years, whilst others have remained stable or even increased in number.  Possible drivers of these changes that have been suggested include increases in predators, changes in climate and availability of natural food sources.  Statistically speaking, we try to understand and quantify changes in observed numbers of birds by relating them to changes in measured environmental quantities that the birds will be subjected to, such as numbers of predators, weather variables, habitat quality etc.  Most previous analyses have modelled each of the species observed at many different geographical locations (or monitoring sites) independently of each other, and estimated the quantities of interest completely separately, despite the fact that all these species share the same environment and are subject to the same external influences.  So how do we go about accounting for the fact that similar species may share similar population drivers?

This essentially constitutes a model uncertainty problem – that is, which parameters should be shared across which species in our statistical model and which parameters should be distinct?

If we were to consider two different species and use two different environmental factors to explain changes in those species, say habitat type and average monthly temperature, there are four possible models to consider.  That is,

Model
Habitat type
Temperature
No parameters
1
Shared
Shared
2
2
Distinct
Shared
3
3
Shared
Distinct
3
4
Distinct
Distinct
4

This can easily be extended to a higher number of species and covariates.

There is also inevitably going to be some aspects of variability shown by some of the species that we cannot account for through the quantities we have measured.  We account for this using site-specific random effects, which explain variability that is linked to a specific monitoring site, but which is not accounted for by the environmental covariates in the model.  Again, we would usually assume this is a single quantity representing the discrepancy between what we have accounted for using our measured covariates and what is ‘left over’.  Following on from work of previous authors (Lahoz-Monfort et al., 2011), we again split this unexplained variation into two – unexplained variation that is common to all species and unexplained variation that is specific to a single species.  The ratio of these two quantities can give us a good idea of what measurements we may be missing.  Is it additional environmental factors that are wide-ranging in their effects or is it something relating to the specific ecology of an individual species?

In the paper, we apply our method to a large dataset spanning nearly 40 years, collected as part of the British Trust for Ornithology’s Garden Bird Feeding Survey.  We selected two groups of similar species commonly found in UK gardens during the winter.  For ecological reasons, we would expect the species within the two groups to show similar traits, so they act as ideal study species for detecting synchrony in responses to environmental factors.  Whilst most the results were consistent with those from single-species models (e.g. Swallow et al., 2015), studying the species at an ecosystem level also highlighted some additional relationships that it would be impossible to study under more simplistic models.  The results highlight that there is unsurprisingly a large degree of synchrony across many of these species, and that they share many of the traits and drivers of population change.  The synchronies observed in the results corresponded to both significant positive or negative relationships with covariates, as well as those species that collectively show no strong relationship with a given environmental factor.  There is, however, more to the story and some of the species showed strong differences in how they respond to external factors.  Highlighting these differences may offer important information on how best to halt or reverse population declines.

The results from our analyses showed the importance of considering model uncertainty in statistical analyses of this type, and that by incorporating relevant uncertainties, we can improve our understanding of the environmental processes of interest.  Incorporating more data into the analysis will help in further constraining common or shared parameters and reduce uncertainties in them.  It also allows us to guide and improve future data collection procedures if we can gain a better understanding of what is currently missing from our model.

Blog written by Dr Ben Swallow, a Postdoctoral Research Associate, studying Ecological and environmental statistics in the School of Chemistry.

References

Lahoz-Monfort, J. J., Morgan, B. J. T., Harris, M. P., Wanless, S., & Freeman, S. N. (2011). A capture-recapture model for exploring multi-species synchrony in survival. Methods in Ecology and Evolution, 2(1), 116–124.

Swallow, B., Buckland, S. T., King, R. and Toms, M. P. (2015). Bayesian hierarchical modelling of continuous non-negative longitudinal data with a spike at zero: An application to a study of birds visiting gardens in winter. Biometrical Journal, 58(2), 357–371

Swallow, B., King, R., Buckland, S. T. and Toms, M. P. (2016). Identifying multispecies synchrony in response to environmental covariates. Ecology and Evolution, 6(23), 8515–8525

Figure 1. Blue tits show a highly synchronous response with great tits, and to a lesser degree coal tits, to their surrounding environment.



Figure 2. Male house sparrow feeding on fat balls.  Whilst they show some synchrony in their response to environmental factors, they appear to be subject to a differing ecology to the other two species they were compared with.