POST DOC IN PLANT–ATMOSPHERE MODELLING AND CANOPY PROCESSES

We are offering a four-year post-doctoral position from September 2019 in our CanSEE research group at the University of Helsinki. The successful candidate will assess canopy photosynthesis under diffuse vs. direct sunlight, as part of a project considering how climate change, and its potential solutions involving climate manipulations e.g. aerosol geoengineering, will affect the ratio of diffuse to direct solar radiation thereby altering photosynthesis at the plant-canopy level.

Potential future increases in the diffuse radiation are predicted to enhance worldwide photosynthesis by up-to 10%. These estimates are based on the deeper penetration of diffuse than direct radiation into plant canopies. However, practical field measurements are required to validate such models. This information will substantially improve our ability to forecast the environmental effects of climate change; and by improving our knowledge of canopy processes will also have ecological and agricultural applications.

The position will involve: planning and coordinating experiments to assess photosynthesis in plant canopies under controlled conditions, and applying field measurements to validate radiative transfer models of canopy photosynthesis.

Applicants should demonstrate aptitude in:

  • Understanding of plant ecophysiology (gas exchange, chlorophyll fluorescence, and associated ecosystem processes).
  • Having strong quantitative and modelling skills and proven capacity to process large datasets.
  • Ability to write and publish timely high-quality research papers.

The successful candidate should have good inter-personal skills and will be integrated into an international research team of experts in plant ecophysiology and biophysical atmospheric processes. They should be prepared to participate in mobility exchanges to receive training in radiative transfer modelling, including to the US National Centre for Atmospheric Research in Colorado.

The salary will be based on level 5 of the demands level chart for teaching and research personnel in the salary system of Finnish universities. In addition, the appointee will be paid a salary component based on personal performance with the overall starting salary amount being about 3200 – 3500 euros/month. A six-month trial period will be applied.

Applications should include (preferable in a single pdf-file):
(1) a one-page expression of motivation and interest in the position,
(2) a CV (no more than 4 pages),
(3) a list of their publications with the 3-5 most-relevant highlighted, and
(4) details of two referees who can be contacted to give academic references.

Further information about the position and research group should be obtained from Matthew Robson (matthew.robson(at)Helsinki.fi).

Please submit your application using the University of Helsinki Recruitment System via the link Apply for the position. Applicants who are employees of the University of Helsinki are requested to leave their application via the SAP HR portal. ). Applications should be submitted by July 29th 2019.

Long-Term Ecological Research into plant UV adaptation high in the French Alps

Santa Neimane and Twinkle Solanki recording diurnal patterns in leaf optical properties of alpine plants under UV filters

We spent the last two weeks of May 2019 at the Station Alpin du Lautaret in the French Alps, which has been designated a Research Platform for long-term ecological studies under the framework of Horizon 2020 Transnational Access – who funded our research visit through the French National Centre for Scientific Research, CNRS.

 

Pedro J Aphalo measures solar radiation; to better understand how reflection from the snow pack affects exposure of plants in the environment.

 

 

Our team of researchers, collaborating with José Ignacio García Plazaola and Beatriz Fernandez-Marin from the University of the Basque-Country, to study how plants response to the steep increases in UV radiation that they receive on emergence from under snow cover in spring.

By characterising the patterns of response to UV radiation in terms of the photoprotection and UV-screening of plants across a diversity of species, we hope to better understand how and why these response evolved and what environmental cues underpin their induction.

Canopy photosynthesis in diffuse vs direct sunlight: implications under future climates

We’re delighted that the Academy of Finland has funded a new 4-year project from our group to study, Canopy level photosynthesis under conditions of diffuse and direct sunlight and its implications for light use efficiency by plants under future climates.

Both climate change and it potential solutions involving climate manipulations cause shifts in direct and diffuse sunlight that plant canopies receive (e.g. under clouds or aerosols). Photosynthesis at the whole-canopy scale is more efficient under diffuse than direct light; as diffuse radiation penetrates further into the canopy. But we lack knowledge of how canopies adjust to receiving diffuse radiation and the mechanisms as allow greater efficiency in light use.

Knowledge of canopy-level light use efficiency are of both ecological and practical value: these data provide input to models of global carbon assimilation and can be useful in crop improvement.

We will develop this project with collaborators:
Titta Kotilainen (LUKE senior scientist)
Pedro Aphalo  (OEB, University of Helsinki)
Anders Lindfors and Anu Heikkilä (FMI)
Sasha Madronich (National Center for Atmospheric Research, USA)
Otmar Urban (CzechGlobe)
Alexey Shapiguzov (OEB, University of Helsinki)
Sharon Robinson (University of Wollongong, Australia)
Erik Murchie (Nottingham Univ., UK)
Twinkle Solanki & Jon Atherton (University of Helsinki)

 

Effective supplementation of the sunlight available to plants in greenhouses

Large seasonal changes in sunlight and its spectral composition are challenging for greenhouse growers in commercial horticulture. This is particularly true for growers at high latitudes like Finland.

Better informing growers of the light environment within greenhouses throughout the year and how the of use of lamps with bespoke spectra, and output optimised for specific crop species, allows efficiency saving to be made.

Blue:green (B:G) ratio in sunlight , in a polytunnel and glass greenhouse in Raleigh, North Carolina, USA.

At GreenSys 2019 in Anger, France 16-20 June 2019, Titta Kotilainen will present our research showing how greenhouse lighting subjects plants to different light spectra for photosynthesis depending on the time of year and location of greenhouses.

Titta Kotilainen will discuss how better selection and management of the light environment, through greenhouse materials, shade screens and insect nets, and appropriate lighting, improves crop yield and reduces energy costs.

  • Robson TM, Kotilainen TK. (2018) Transmittance of spectral irradiance by climate screens and nets used in horticulture and agriculture (Version 1.1.1) [Data set]. Zenodo. http://doi.org/10.5281/zenodo.1561317
  • Kotilainen TK, Robson TM, Hernández R. (2018) Light quality characterization under climate screens and shade nets for controlled-environment agriculture. PLoS ONE 13(6): e0199628. https://doi.org/10.1371/journal.pone.0199628

Range‐wide variation in local adaptation and phenotypic plasticity of fitness‐related traits

Last year, we published a database of traits from European beech provenance trials; the most extensive set of such data to be collected (Robson, Benito-Garzon et al, 2018 Scientific Data), and earlier this year provided a road map of how to use these sort of trait data in Species Distribution Model to predict responses to climate change (Benito-Garzon et al., 2019 New Phytologist). So it’s fitting that Homero Garate, working with Marta Benito-Garzon in Bordeaux in collaboration with us, should give a practical illustration of the application of these models to this data set, presented here in a new paper just out in Global Ecology and Biogeography.

Spatial projections of vertical growth (cm) for (a) vertical‐radial growth model and (b) vertical growth‐leaf flushing models

The paper entitled, Range‐wide variation in local adaptation and phenotypic plasticity of fitness‐related traits in Fagus sylvatica and their implications under climate change, quantifies local adaptation and phenotypic plasticity of vertical and radial growth, leaf flushing and survival across the species range to estimate the contribution of each trait towards explaining occurrence.

 

The place of spectral composition among cues controlling tree phenology

In this review, just out in Tree Physiology, we assess the literature researching how the composition of UV, blue, and red/far-red regions of the spectrum affect bud burst and leaf senescence  phenology.

The role of plant photoreceptors in detecting diurnal shifts in spectral composition

The effect of climate change on phenology is a strong determinant of fitness. But shifts in the timing of annual events and the polewards displacement of species ranges both have the potential to interfere with the interactive control of phenology by temperature and photoreceptor-mediate processes.  This dictates that to anticipate plant responses to climate changes, we must gain an understanding the mechanisms underlying the role of spectral composition in phenology.

These ideas and more are explored in the Tree Physiology review article, Brelsford et al., 2019: The influence of spectral composition on spring and autumn phenology in trees. https://doi.org/10.1093/treephys/tpz026

Moving Forward in Plant-UV Research

Our new and comprehensive review and perspective on the future of plant-UV research assimilates the knowledge and insight across the breadth of plant science from researchers in UV4Plants Association. We hope that it will inspire researchers in their attempts to better understand plant responses to UV radiation and to put this knowledge to practical use.

Let us know what you think! Photochemical & Photobiological Sciences, 2019, DOI: 10.1039/C8PP00526E

How can we track long-term trends in solar UV-B irradiance?

Is there potential to apply our knowledge that  plant phenolic compounds respond to UV-B radiation to infer past changes in global solar UV-B irradiance?  This is the possibility that we explore in a Perspective paper just out in Photobiological & Photochemical Sciences.

Our collaborators from the University of Bergen in Norway and University of Innsbruck intend to test the potential for us to use fossilised pollen grains to do just that. By testing whether the UV-screening phenolics in the pollen of trees growing today tracks their exposure to UV-B radiation they will try to establish a mechanistic link that will allow past UV irradiances to be revealed in cores of fossilised pollen.

In this perspective piece we formulate a model for how this approach might be put into practice.

How can we compare solar spectra with each other?

Assessing differences in spectral irradiance is at the heart of our research group’s work, and yet considering entire spectra at once is not something that is straight-forward to do. Traditionally, most research has broken-down spectra into their component regions in order to compare one light environment with another, but looking at the whole spectrum has the potential to yield much more detailed information.

Our open-access paper just out in Ecology & Evolution considers ways to quantitatively assess differences between entire solar spectrum. This approach is illustrated by tracking changes in the forest canopy through the spring and amongst stands dominated by different tree species.

The method we used, called thick pen transform, involves redrawing our spectra of interest with increasingly thick lines and then comparing their similarity. This allows the coarse and fine features of spectra to be compared, and a “Thick Pen Measure of Association” to be calculated to quantify their similarity, as illustrated above.

Using this technique, we were able to trace differences in the spectral irradiance at ground level between forest stands of birch, oak, and spruce at Lammi Biological Station in central Finland. This is the first time such fine-scale differences in the light environment due to the species, phenology, height and leaf-optical properties of canopies have been distinguished. By better understanding how light environments in forests differ we can start to better explain the factors that control species composition and ecosystem functioning in these environments.

As well as detailing the theory and methodology behind this research, the paper gives a comprehensive protocol of how to maximise the information obtained from hemispherical photos of the forest canopy. These are used to assess leaf area index and the sunlight reaching the floor throughout the year.

Read the full text at Hartikainen SM, Jach A, Grané A, Robson TM. Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance. Ecol Evol. 2018;00:1–13. https://doi.org/10.1002/ece3.4496