Tuesday, 14 April 2015

CEH science at EGU 2015

CEH scientists are among those presenting research updates to the European Geosciences Union General Assembly in Vienna this week (12-17 April 2015). The meeting brings together scientists from all over the world to discuss aspects of Earth, planetary and space sciences.

Abstracts of oral and poster presentations led by CEH scientists and students can be found below:
Additionally, Dr Eiko Nemitz is a convenor of two sessions on Biosphere-atmosphere exchanges while Bob Moore is convening a PICO session on hydrological forecasting.

On Thursday, Prof Christel Prudhomme is one of the panel of experts taking part in the Young Hydrologic Society's session on Meet the expert in hydrology - The mystery of evaporation.

Good luck to everyone taking part!

Dr Paul Scholefield is one of the CEH scientists presenting at EGU2015 this week:

Below, poster presentation by Christine Braban and colleagues in the Natural Hazards session on Atmosphere emissions from volcanoes and their dispersion:

Effusive Eruption Modelling project: Assessing UK impacts of trace species and sulphur deposition

EGU 2015 is taking place at the Austria Center Vienna. Photo: CC BY-SA 3.0 BambooBeast

Related links

European Geosciences Union General Assembly 2015

CEH Biosphere-Atmosphere Interactions science area

CEH Natural Hazards science area

Friday, 27 March 2015

What ails our horse chestnut trees and can we save them?

A guest blog from pupils of La Sainte Union School, Camden, London.

Dr Michael Pocock, an ecologist at CEH, is one of the scientists behind Conker Tree Science. Thanks to a Royal Society partnership grant, he recently shared some of his knowledge and skills with students at a school in London.
One pupil’s scientific drawing of the tiny leaf-miner larva

Michael writes, “Over the past few months I have been visiting Dr Pari Collis and her pupils at La Sainte Union school in Camden, London as part of a Royal Society partnership grant. Based on my experience with Conker Tree Science, I helped the girls begin a project on the horse-chestnut leaf miner, but with their teacher they took it so much further than I thought they would.

"Not only did they undertake careful ecological studies, but they also covered biochemistry and environmental ethics, mixed with a little bit of German, maths and art! My final visit to the school was last week when they gave an excellent presentation of their project in front of an audience of teachers and parents.
"It has been a privilege to work with Dr Collis and the girls over the past year and share moments of scientific discovery and excitement with them. I would highly recommend using the Royal Society partnership grants for any scientist to link with a local secondary school."

The pupils at La Sainte Union school have written up their project and submitted it for peer review at the Young Scientists Journal. Below is an abridged version of their full article:

"Horse chestnut trees are ornamental trees and were largely planted for their attractive shape and beautiful flowers which make them really desirable in parks and village greens. We noticed that there was extensive early browning of the horse chestnut trees in our school grounds, which we found was caused by the horse-chestnut leaf-miner, Cameraria ohridella. Both the horse chestnut tree and the Cameraria ohridella are invasive species but we consider the moths to be pests because they harm the trees that we chose to plant.

We worked in groups to visually estimate the number of horse chestnut leaf miner in one tree. We counted the number of the leaf miners in a small section of the tree and then scaled up to estimate that there were 250,000 – 500,000 leaf miners per tree.

Making careful observations of  horse-chestnut leaves
The common horse chestnut Aesculus hippocastanum is very susceptible to infestation by the leaf miner, but we found that the red-flowering hybrid (Aesculus x carnea) is very resistant. The mass of the red flowered horse chestnut tree leaves was approximately twice that of the white flowered trees (0.02 compared to 0.01 g per cm2). The caterpillars seem unable to feed successfully on these leaves.

We wanted to find out if anything could be done to stop the moths. We investigated the following possibilities of control:

  • Natural predators (parasitoid wasp and blue tit);
  • Pheromone traps that attract and kill male moths;
  • Collecting and burning or burying fallen leaves in autumn to destroy the overwintering pupae.

Natural pest controllers: Leaves from an infected horse chestnut tree were collected and stored in zip-lock bags for two weeks on a cool and dark shelf. We then recorded the number of adult Cameraria ohridella moths and parasitoid pest controllers. There were 171 wasps altogether (19% of the total) which means 171 horse chestnut tree leaf miner larvae were killed by the larvae of the parasitic wasps.

Pupils ready for the big sweep to 
collect fallen horse chestnut leaves

Blue tits have discovered that horse chestnut trees are absolutely loaded with caterpillars. Caterpillars are an important food source for blue tits, which feed them to their young. If blue tits were to start eating a substantial amount of the caterpillars it would help the horse chestnut tree. We examined the leaves for v-shaped tears as evidence of ‘bird attack’ and found 0 to 57 bird attacks per leaf.

Pheromone traps: The main component of the sex attractant (pheromone) released by the females of the horse chestnut leaf miner has been identified as E,Z-8,10-Tetradecadienal12. We used pheromone traps to catch male moths which reduces mating and therefore egg laying. We weighed the content of the trap and estimated that 30,000 moths had been captured over a period of two months. This is about a tenth of the number we had estimated on each tree in July after the 1st generation.

Clearing leaf litter: Early in the season (July), we noticed that the browning of the leaves is more prominent at the base of the tree. This is consistent with the moths emerging from the fallen leaves and spreading upwards first to the lower leaves. We collected fallen leaves from under the horse chestnut tree and found an average of 100 pupae per leaf. If we estimate that there could be at least 100 fallen leaves in the vicinity of the tree, then 10,000 moths could emerge. If half of these are females, which lay 30 eggs each, we could expect 150,000 moths at the end of the first generation and 2,250,000 eggs at the end of the second generation. In reality the number will be smaller because not all pupae, moths or eggs will survive. Nonetheless the number of potential moths is formidable bearing in mind that the calculation is based on just 100 leaves.

It may be time for the UK to follow Berlin’s example where there is a programme encouraging everyone to take part in raking up and clearing every single horse chestnut tree leaf. It is considered to be every citizen’s civic duty to participate in the clearing of the leaves. Involving the community in this way may have many social benefits encouraging social interaction, interest and responsibility for the environment."

Michael Pocock and several of the students
By: Tito A, Ursula A, Elisabeth A, Sharon B, Ariane F, Grace G, Catriona G, Zoe H, Oghogho I, Dea L, Mia O, Lara R, Hannah S and Ellie T (La Sainte Union School, London).

Dr Pari Collis is the science teacher at La Sainte Union school who invited Michael to visit and she concludes:  We really enjoyed working with Dr Michael Pocock.  Michael’s enthusiasm was absolutely infectious and it kept everyone on board. The girls did outdoor science, learnt how to be observant and use scientific method.  They improved their communication skills, worked as a team and showed commitment to the project. Under Dr Pocock’s guidance they also learnt to read original scientific papers for themselves. Most importantly they took an interest in their surroundings, seeing them in a different light, and in particular have become extremely fond of horse chestnut trees and conkers.  They discussed the project and shared their enthusiasm with their friends and family. It has been a great pleasure to have worked with Michael and to share and discuss our findings with him.  

Additional information

Michael has also recently written about his life in science for Catalyst magazine, which is produced to inspire secondary school pupils about science.

Royal Society Partnership Grants

Conker Tree Science

Staff page of Dr Michael Pocock

Thursday, 12 March 2015

Retirement beckons for voice of UK hydrological reporting

As many of our regular readers will know, the UK hydrological summary is a monthly update from scientists within the Centre for Ecology & Hydrology working with colleagues from the British Geological Survey. Every month, under the National Hydrological Monitoring Programme, they collate, quality check and analyse various data with regard to river flows, reservoirs and groundwater, placing them in historical context and identifying hydrological trends. The team produces regular updates and occasional reports into events such as the summer floods of 2007 and the recent 2010-2012 drought to flood transformation.

For several decades, a mainstay of the NHMP has been our own Terry Marsh, leader of the programme since 1982. This month, March 2015, is Terry's last before retirement so it is fitting that he authored the summary issued this month (analysing water resources in February 2015), bringing the total he has authored to an incredible 286. This "special souvenir edition" contains a tribute to Terry from his colleagues.

So, download the latest summary (PDF) and, after taking in the assessment of the UK's hydrological conditions, browse to page 3 for a tribute to Terry Marsh, the eloquent voice of UK hydrological reporting over the last three decades. As Terry is always one for a turn of phrase, it is certainly an appropriately written tribute. Although as colleagues note, it’s perhaps ironic that Terry signs off with a month notable for its normality!

A word cloud based on hydrological summaries authored by Terry Marsh

Related links

Staff page of Terry Marsh, CEH

National Hydrological Monitoring Programme

Hydrological Summaries of the UK

Blog posts relating to the National Hydrological Monitoring Programme

Wednesday, 11 March 2015

The Entomological Club: Celebrating entomology through the centuries

Dr Helen Roy, an ecological entomologist at CEH, was recently invited to become a member of the Entomological Club. She writes more about the honour:

Founded in 1826, the Entomological Club is the oldest entomological society in the world. It has an amazing history encompassing many entomological heroes. The membership is restricted to just eight people at any one time, but it would be impossible to estimate the extensive global outreach of the Club. I have personally benefited from the generous mentoring, encouragement and guidance provided by the members over the years.

So imagine my delight, and utter surprise, when I received an invitation to become a member of the Entomological Club. I have the honour of being only the second female member, following (with intimidation) the incredible Miriam Rothschild.

The current membership includes Professor Jeremy Thomas, Professor Helmut van Emden, Professor Paul Brakefield, Professor Simon Leather, Dr Chris Lyal, Dr Richard Lane and Clive Farrell. They have all made unique and inspiring contributions to entomology but perhaps even more importantly they have shared their enthusiasm with diverse audiences in many different ways. It is unsurprising then that I reflect, with a slight sense of awe, at the incredible achievements of the Entomological Club but I am looking forward to being a small part of its long history.

Helen (centre) with Phd students Sandra Viglasova (left)
and Katie Murray (right) at the 2015 Verrall Supper.

The Entomological Club awards small grants, organises meetings and generally works to advance entomology. Within the entomological community it is best known for organising the Verrall Supper, an annual event in which hundreds of entomologists meet Рit is hard to avoid the clich̩ that the atmosphere simply buzzes! Last week (4 March 2015) I attended the Verrall Supper as the newest member of the Entomological Club and it was wonderful to celebrate the legacy of entomology with so many people.

I had the pleasure of accompanying a few of my students and enjoyed many varied discussions (admittedly slightly skewed to ladybirds, but with more than a brief mention of parasitic wasps and fungi!).

I am sure all the discussions around the room were as lively and exciting as they have been over the centuries and I look forward to many more in the future.

Helen Roy

Related links

Staff page of Dr Helen Roy

The Entomological Club

Tuesday, 24 February 2015

CEH lakes research presented at 2015 Aquatic Sciences Meeting

A number of CEH's lake researchers are in attendance at the 2015 Aquatic Sciences Meeting taking place this week in Granada, Spain (22-27 February). See below for details of oral and poster presentations. You can follow updates from the meeting on Twitter with #ASLO2015.

Photo: CEH scientists carrying out restoration research at a lake in Scotland


Related links

2015 ASLO Aquatic Sciences Meeting

UK Lake Restoration research at CEH

Lake Ecosystems research at CEH

Wednesday, 18 February 2015

New dataset released: Integrated Hydrological Units of the United Kingdom

Our colleagues in the National River Flow Archive (NRFA) have released a new, freely available dataset of spatial reference units for hydrological purposes, called "Integrated Hydrological Units of the United Kingdom". Filip Kral explains more:

"This dataset will aid hydrological analysis and water management in the UK by providing a consistent, nationwide framework for segregating river catchments into component parts. It also serves as a reference list of major river names and, by indicating which units are connected, it can be used to trace the flow of rivers across the country.

The Integrated Hydrological Units (IHU) of the United Kingdom (UK) define spatial geographical reference units for hydrological purposes

Researchers and organisations working to improve catchment management have already expressed interest in the dataset which we believe will become popular in the water industry and wider hydrological science community, thanks also to its open data license.

Integrated Hydrological Units (IHU) of the United Kingdom (UK) consists of four polygon layers: Hydrometric Areas, Groups, Sections, and Catchments. Each layer represents a different level of spatial detail.

  • The coarsest level, Hydrometric Areas, consists of more than 100 polygons corresponding to the spatial units used to organise river flow measurement and hydrometric data collection in the UK (for example, HA023 represents the Tyne in Northumberland). 
  • Each Hydrometric Area consists of one or more Groups (405 in total), which carry names derived from the major rivers flowing through, in, and out of each group, for example HA023G03 is Tyne (North Tyne to tidal limits) Northumberland. 
  • Each Group consists of even smaller units – Sections (more than 500,000 in total). A Section is the drainage area of a watercourse between two confluences, for example HA023G03S0024 is Tyne (Devil’s Water to March Burn). 
  • Each Section is associated with one Catchment representing the compound catchment upstream of the Section outflow point.
Tyne Bridge, Newcastle

Historically, Hydrometric Areas were the primary reference units used by the NRFA to manage hydrometric data in the UK. IHU is a new release of the Hydrometric Area definition supplemented with finer scale units, all derived using the CEH Integrated Hydrological Terrain Model. Plans are being developed to utilise the IHU to help users explore other datasets produced by the NRFA and CEH’s Environmental Information Data Centre."

The dataset is available on the EIDC Hub.

Filip Kral

Related links

National River Flow Archive


Wednesday, 4 February 2015

Plant hormone signals and climate models, plus a mathematical surprise

A new study examining the links between soil moisture and leaf stomata should be of interest to both plant physiologists and climate modellers. It was published in the journal Ecological Modelling (27 January 2015, Ecological Modelling 300 (2015) 81–88), and is open access, so freely accessible. Below the lead author, Dr Chris Huntingford of the Centre for Ecology & Hydrology (CEH), explains what they did and how the analysis reveals an unexpected mathematical twist:

“A small team of us have just published a paper on assessing how the equations link together that describe ABA (abscisic acid) messaging in plant systems. Possibly more than most pieces of mathematical analysis, our study turned into a bit of an adventure, including an unexpected outcome.

ABA is a hormone which passes through vegetation, and provides a signal to leaf stomata regarding the amount of soil moisture available. Stomata control both evaporation and photosynthesis and, if soil moisture is depleted, then generally plants close such pores as a protection mechanism during periods of drought.

Climate models are designed to estimate adjustments in near-surface temperature and humidity (amongst many other quantities) in response to raised atmospheric greenhouse gas concentrations. However the land surface is a fully coupled part of the climate system, not simply responding to any imposed adjustment to weather conditions, but also affecting them. This can be through multiple feedbacks, one of which is how rain water is returned to the atmosphere via evaporation. In addition, any better understanding of transpiration losses by vegetation can aid impacts planning of viable crops for future perturbations to the climate system.

Despite this need, many land surface descriptions within climate models contain only an empirical semi-linear response to soil stress. This varies from no effect at a critical moisture level, down to complete shut-down at a prescribed soil moisture wilting point.

Detailed laboratory and field measurements of ABA concentration at the leaf level reveal a strong dependence on both soil moisture and the actual transpiration rate. Concentration levels then influence the amount to which stomata open. This allows the opportunity of building more accurate, chemically-based descriptions into the functioning of the terrestrial part of climate models, with performance verifiable against ecological data. Hence the first role of the paper is to describe the equations in full, and in that context.

Figure 2 of the paper, providing a schematic of the main equations analysed
At the same time, where climate models frequently do excel is in non-water stressed representation of photosynthetic response, including the impact of temperature and light effects. But these descriptions are not included in models of ABA control on stomata, giving the opportunity to merge both. We are not the first to suggest this (see earlier paper, Dewar, 2002) but here, as we unite equation sets, we fully analyse their projections of such a common model to soil moisture, light, temperature, CO2 concentration and surface humidity – our Figure 1 within the paper. This can be important to check as such linking can create odd cross-effects between model components. Fortunately we find this more ABA-based combined model does reproduce the salient features of expected stomata response across a range of imposed environmental conditions. We offer this as a possible future candidate for inclusion in climate models.

There is, however, also a mathematical surprise!

Despite our linking together in a common framework, which generally makes models more complex, we find that equation re-arrangement may actually simplify things. Stomatal response can be re-written as a function of soil moisture, evaporative flux, atmospheric CO2 concentration and photosynthetic flux only. We are not suggesting that this is necessarily what the stomata “see” to guide their responses (eg with drivers such as temperature occurring instead of via influence on photosynthesis). But the ability to write the equations in this form links to a long-term “store” of the hydrological cycle, ie soil moisture, and to a more instantaneous flux, ie transpiration, the latter fluctuating more with weather conditions.  And, in a symmetry for the carbon cycle, links to the “store” of atmospheric CO2 concentration, and again to more immediate fluctuations of photosynthetic uptake.

Could plants therefore respond to the more slowly changing stores in the carbon and water cycles, but using fluxes to provide time-evolving corrections dependent on the precise passing meteorological conditions?

Although our priority is to try and contribute towards improving process representation in land surface models, we really hope that other authors might investigate further the “stores-fluxes” concept that the equations of this model hint at.”

Dr Chris Huntingford

Additional links

Chris Huntingford, D Mark Smith, William J Davies, Richard Falk, Stephen Sitch, Lina M Mercado. Combining the [ABA] and net photosynthesis-based model equations of stomatal conductance. 2015. Ecological Modelling. doi: 10.1016/j.ecolmodel.2015.01.005

The full paper is open access and can be read by anyone. The work was carried out by scientists from CEH, Exeter University, Lancaster University and the IUCN.

Staff page of Dr Chris Huntingford