It has been a wet couple of days for BIFoR FACE research technician Gael Denny. Yesterday she was checking and clearing out rain gauges, this morning searching a stream for an electrical conductivity probe. Back in the office, away from the chatter, she sits in the equipment storeroom where, surrounded by test tubes, meters, cameras and dried leaf litter, she talks to Carolyne Locher on the subject of A Day in the Working Life, one of an occasional series featuring those working in the industry.

THE equipment storeroom is in the reception office at the Birmingham Institute of Forest Research (BIFoR) Free Air Carbon Dioxide Enrichment (FACE) facility, in Staffordshire. Gael is a research technician here and responsible for, among other things, collecting woodland biome baseline data and ensuring that the bio-geo-chemical monitoring system’s instruments are in working order. These instruments and Gael’s fieldwork provide increasing amounts of data and are helping to predict, years in advance, how trees, woods and forest ecosystems will respond to climate and environmental change (and their resilience to pests and disease) when exposed to the atmospheric composition (higher levels of CO2) expected in northern temperate latitudes from 2050.

Forestry Journal:  Arrays and meteorological mast. Arrays and meteorological mast.

Following in the research footsteps of sister facility EucFACE (run by Western Sydney University, Australia) and years in the planning, BIFoR’s £15 million FACE facility opened its woodland gates in April 2016.

Spread throughout a 19.1 ha unmanaged, mature, temperate oak woodland, leased on a peppercorn rent from Norbury Estate, this facility is essentially an outdoor laboratory of three zones: ‘Fumigated’, ‘Infrastructure Control (Ambient)’, and ‘Non-Infrastructure Control (Ghost)’.

Each zone contains three arrays, with six of nine (total) containing FACE technology, a series of 22- to 27-metre high metal towers forming rough circles 28 metres in circumference and linked to a central tower that measures the wind and CO2 levels. Into three ‘Fumigated’ arrays, the metal towers support black plastic pipes that deliver eCO2 (air enriched with CO2 that will increase the forest patch atmosphere to 550 parts per million, the levels of atmospheric CO2 expected in 2050), delivered from three tanks outside the forest that store the CO2 at -20°C. Into the three ‘Infrastructure Control (Ambient)’ arrays, black plastic pipes deliver fresh air (aCO2, at current atmospheric CO2 levels of 406 parts per million), pumped at the same volume, pressure, temperature and direction as the CO2-enriched plots. The ‘Non-Infrastructure Control (Ghost)’ arrays are a control for the controls, containing monitoring instruments but no FACE infrastructure.

Forestry Journal:  Image taken in the array with hemispherical camera. Image taken in the array with hemispherical camera.

All arrays contain a minimum of six and a maximum of nine mature oak trees (180+ years) with an understorey of hazel, holly, sycamore, hawthorn, minimal wych elm and one or two self-set ash trees. A number of data loggers are spread across the forest floor. A 40-metre-high ‘flux’ tower dwarfs the array structures and supports a number of instruments which collect and record data on the CO2 exchanges between the forest and the atmosphere, and a phenocam which records daily images of the site.

Having joined BIFoR at the FACE facility in April this year, Gael works alongside Kris Hart (facility manager), Nick Harper (facility engineer), Peter Miles (facility technician) and research technician colleague Robert Grzesik. Project coordinator Deanne Brettle and BIFoR director, the University of Birmingham’s Professor of Atmospheric Sciences, Rob MacKenzie, are based on campus in Birmingham.

From Birmingham, Gael, now 43, left school to work as a medical laboratory assistant (MLA) in a medical microbiology lab. With a love of science and encouraged by colleagues, as a mature student she gained a BSc (Hons) in environmental science from Wolverhampton University.  She says: “I found I loved fieldwork; I feel happier and healthier outdoors,” and so decided to pursue a career in that area.

Working as a landfill technician in a geological services department (Cemex), Gael used geotechnical instruments to take measurements, such as an infrared gas analyser for taking gas measurements from boreholes. Working across landfill environments, she learned valuable skills such as driving a 4x4 and how to interact with landowners and work in fields full of livestock. Wanting to work in environmental research, she topped up her qualifications with a two-year field studies course and volunteered alongside ecologists working on protected species surveys in the quarries.

The 2008 recession and redundancy forced Gael in a different direction, taking interim positions as a health & safety administrator and as a concrete plant field technician (quality control). Periodically looking at the University of Birmingham’s website, she came across BIFoR. Applying for the role of research technician three times, Gael finally joined the team in April 2019.

“To finally get here and to work on this ground-breaking climate change project is a dream come true.”

Forestry Journal:  Anna Gardner and Gael in the woods with icepacks during the August heatwave. Anna Gardner and Gael in the woods with icepacks during the August heatwave.

Supervised by colleague Peter, Gael’s first weeks were spent learning the processes of baseline data collection and the procedures and protocols for using the equipment, and completing online H&S courses. For climbing the array and flux tower structures, she completed courses in advanced climbing, tower rescue at height and aerial rigging.

Gael collects woodland baseline data weekly and monthly. “[Weekly], I take leaf canopy images (always from the same location) using a hemispherical camera (SLR camera with fisheye lens) throughout the year. The data is stored and used to calculate the Leaf Area Index (LAI) – per square metre of the leaves in the canopy by square metre of the ground – for the FACE experiment. Rain gauge filters are checked weekly, sometimes more if there is a data blip. [At this time of year], they get clogged with debris – leaves, frass, slugs and worms. Yesterday, we cleaned 25; 20 at ground level, four on the meteorological towers (20 metres up) and one on the flux tower, which I climb in order to carry out the cleaning. As it is an unmanaged woodland, we also use this time to check for any branches that may have come down, ensuring that nothing can cause a problem for the equipment

Monthly, Gael collects precipitation samples. In autumn, she collects a month’s worth of leaf-fall from all arrays, and dries and stores the leaves. Leaf-fall provides information for a number of research projects. Recording the mass, nutrient balance and isotopic composition of the material helps estimate and inform the Leaf Area Index (LAI) and provides material for decomposition experiments, herbivory measurements and nearly every research project concerned with nutrient and carbon cycling.

Gael collects data from below the forest floor.

“There are four minirhizotrons (clear Perspex tubes 1 metre length) buried in soil. Placing a semi-automatic VS1-BARTZ AS-17 minirhizotron camera inside the Perspex tube, I take 360-degree photographs below ground.  I view the images on a laptop, using a non-scientific umbrella to keep it dry. This technique allows data to be analysed with minimal disturbance to the ecosystem. A mathematician at the university then looks at the data¹ to monitor fine root interactions and migration under elevated carbon conditions.”

PhD students (from the University of Birmingham and other universities) carry out the practical fieldwork for their research projects during late spring, summer and early autumn. There are currently more than 52 ongoing research projects (small side projects bring this number closer to 70) and Gael helps out with a variety of tasks, from showing students where certain equipment is stored and carrying conductivity meters into an array to being on hand to make notes or getting more involved.

“This summer we had over twenty students. One, Anna Gardner² is making photosynthesis measurements in the tree canopy using a LI-COR 6800 Portable Photosynthesis System (taking diurnal instantaneous measurements, A/ci curve measurements and chlorophyll content measurements). Checking all is safe beforehand, we attach her (in a Boson’s chair) to a rope-and-pulley system and use a mechanical winch to hoist her up into the canopy, stay with her all day, and then bring her down.” Anna was in the canopy for 36 days this summer, of which 18 days included 12-hour stretches.

Gael prefers working in the woods in slightly cooler weather: “Supporting Anna in the forest canopy during the August heatwave was unbearable. We had to put freezer packs in our pockets to keep cool. Working the hoist, you cannot leave the array for H&S reasons, and I received 40 mosquito bites in three days. My persistent scratching was caught on the camera traps. People found it very amusing.”

Forestry Journal: Image of Array 3 from a drone.Image of Array 3 from a drone.

Gael also responds to queries from PhD researchers when they are not on site. She says: “This morning, Nicolai Brekenfeld³ noticed a blip in the data collected by an electrical conductivity probe in the stream and asked, via email, if I could remove the debris after last night’s heavy rains. Water levels had risen and the current is fast and he wanted help in calculating the morning and afternoon conductivity. When I first went out, I couldn’t find the probe. He was still getting data, so I went back out and after searching for a while, found it. Going to a spot ten metres upriver from the probe, I mixed 1.5 kg of salt with water and poured it into the stream. The probe will pick it up and he is then able to calculate the electrical conductivity.”

Only eight months into her role, Gael has yet to set the wildlife camera traps. Organised group tours of the facility (not including researchers, 1,884 visitors to date) are led by Dr Kris Hart and director Rob MacKenzie. If, for some reason, it were required, in the future she would step in.

“I was an instructor in the Sea Cadets and speaking to groups of students does not phase me. I still have a lot to learn and would not want to let a group down [for lack of information]. We have two volunteers at the moment. One is carrying out a ground flora survey in all the arrays, and this is something I am going to help with.”

In winter, the ‘Fumigated’ array is shut down (it is a deciduous forest). “Maintaining the [eCO2] delivery system is a big job.  Subjected to the elements, things happen over time. We are a small team and we help out, climbing the array towers (latch-way system) and inspecting the black plastic delivery pipes. I enjoy it. It is an opportunity to better understand the whole system. Climbing 40 metres up the flux tower is scary but exhilarating. Seeing the forest canopy spread out in front of you, before, during and after cleaning and checking the instruments, bringing them down and hoisting them back up, you get such a different perspective.”

Forestry Journal: Gael and the Picarro Cavity Ring Down Spectrometer (which measures trace soil gases such as N2O and CH4).Gael and the Picarro Cavity Ring Down Spectrometer (which measures trace soil gases such as N2O and CH4).

With time indoors during the winter months, Gael hopes to learn more about the research that she facilitates.

“I have really enjoyed working with Anna and hope to understand more how the Portable Photosynthesis System works for taking photosynthesis, transpiration and stomatal conductance measurements. In future, one technician may have to take on those measurements and that is something I am interested in.”

Gael has not yet had much interaction with Australian sister facility EucFACE but, while it is still early days, BIFoR FACE is producing similar (early) results.

“What we are seeing [in the eCO2 arrays] is a ramping up in the metabolism of the woodland, or an increase of up to 20 per cent in some instances in its productivity,” says Kris Hart, “Possibly a ‘CO2-fertilisation’ effect?

“The Australian experiment saw similar positive results lasting around four years. When the forest became saturated, they saw a tailing-off back to baseline levels at which the experiment started, caused by a new unknown limiting factor, possibly water or phosphorus or other. One Australian research paper showed that after a period of tailing off, when they treated the forests like crops, adding phosphorus-rich fertilisers – instead of just planting trees and walking away – forest productivity took off again.”

Forestry Journal: Images from flux tower (with various instruments) across the site.Images from flux tower (with various instruments) across the site.

BIFoR has recently won funding for two new research projects, ‘FACE Underground’ (roots and nitrogen-cycling underground) and ‘QUINTUS: Quinquennial (half-decadal) carbon and nutrient dynamics in temperate forests: Implications for carbon sequestration in a high carbon dioxide world’ (a five-year project looking to try and close the carbon cycle in a temperate woodland, by establishing where in the forest system carbon goes and how much stays there rather than being emitted back into the atmosphere).

Kris Hart explains: “Gael does the underpinning collection of all measurements that we cannot get grant funding for, but that we cannot get grant funding without. She collects the core of samples and takes care of the core instruments around the facility. We could not run ‘FACE Underground’ or ‘QUINTUS’ without her work.”

The rain will soon begin again. This afternoon, after labeling the LAI hemispherical photos, Gael will head back out, over the biosecurity ground mats and into the forest to check the data loggers in all arrays. All are subject to the weather and their desiccant needs topping up. She says: “Every day is different, the weather is always different. Being in the woodland, it is healthy and fresh and good for your wellbeing. With all the science going on, you always learn. You do have days where you don’t always want to be out in extreme weather.”

Gael’s remedy?

“Wrap up warm with plenty of layers and go back to the welfare office to have a hot cup of tea.”

Facility manager Dr Kris Hart has been at BIFoR FACE since it opened and shares information on the site’s history and management. He says: “Before BIFoR took on these undermanaged semi-natural woodlands, they housed a pheasant-rearing pen. Aside from the odd bit of ivy management (no brashing, no thinning), these conditions are maintained. AOD was present and ash dieback is now obvious and having an impact. The woodland is monitored for invasive species, for pests and disease and for tree death. All trees are tagged and mapped. A database of branch drop, tree mortality and tree decay is maintained and the team know where the dead, dying and fallen trees are. For H&S, Quantitative Tree Risk Assessments pinpoint very careful management to specific trees and high target areas. Windblow falls and rots naturally. Premature dismantling simulates a tree’s standing condition: nothing touches the ground and all is stacked above ground to maintain a habitat for invertebrates and as a carbon and nutrient store.”


• ¹ Project title: Quantitative modelling of root growth and carbon allocation: bridging theory and experiment. Claire Zieglar – Supervised by Dr Iain Johnston,

• ² Anna Gardner, Supervised by Prof. Rob MacKenzie & Prof. Jeremy Pritchard, Project Title: ‘Ecophysiological responses of oak (Quercus robur) to elevated CO2, in a mature temperate forest.’

• ³ Nicolai Brekenfeld supervised by Prof. Stefan Krause, Project Title: Hyporheic Biogeochemistry and Residence Time Distributions in a 2nd Order Woodland Stream.