Surviving on the Edge

We are grateful to a grant  from HiLIFE Grand Challenges, Biological Resilience Seed Funding, allowing us to start work on the project: Surviving on the edge – trait syndromes that facilitate northerly species-range expansion.

This project will allow us to utilise a unique field-trial of Fagus sylvatica (European beech) at the University of Helsinki – far beyond the north-eastern limit of its range. Using such trials, we can compare the traits of populations in  new potentially stressful environments, giving us the tools to forecast how they will respond to climate change and potentially exploit more northerly regions of Europe.

In addition to field data, the project will test how trait information can be inserted into species distribution models. We will bring together experts in the field from Helsinki and beyond, to discuss how best to develop such models to provide informed forecasts of future species distributions. Armed with this knowledge, we will consider how policy makers, foresters, and conservation bodies might utilise this information in their work.

Newly thinned Helsinki beech-provenance trial in May 2020; with four populations covering the European range limits.

How does tree phenology respond to a warmer climate?

In the latest paper published in Agricultural and Forest Meteorology together with our collaborators from Bordeaux we consider the effect of warming on the phenology of European beech.

September, October, November relationships with Leaf senescence
The interactive relationship between leaf senescence and the mean temperature in September, October and November (Tm SON) for (a) the trial and (b) for the provenance.

Using ΔTrait Species Distribution Modelling of a large dataset from provenance trials, we established that not only earlier spring phenology but also delayed leaf senescence in northern populations allowed them to exploit warmer summer temperatures.

Beech is one of those forest trees that utilises a combination of temperature and day-length cues to prompt advancement of its annual growth cycle, meaning the climate warming and associated northerly range shifts have potentially complex outcomes for its phenology.

You can read the full paper open-access for 50 days: Greater capacity to exploit warming temperatures in northern populations of European beech is partly driven by delayed leaf senescence

Homero Gárate-Escamilla, Craig C. Brelsford, Arndt Hampe, T. Matthew Robson, Marta Benito Garzón, (2020) Greater capacity to exploit warming temperatures in northern populations of European beech is partly driven by delayed leaf senescence, Agricultural and Forest Meteorology, Volume 284,

Doctoral Course in Plant Responses to Climate Change

During the 3rd week of October at the University of Helsinki we ran an international course which considered how plant responses to light are mediated by environmental factors and the implications of climate change for plants’ capacity to adjust to their light environment.  The course, organised on behalf of the Doctoral Programme in Plant Sciences (DPPS), was attended by 13 visiting teachers and PhD students from all around Europe, in addition to the local participants from the University of Helsinki.

With the objective of understanding how plants scale their responses across levels of organisation, and respond to light over the appropriate time-scale for their environment, there were plenty of opportunities for students and teachers to develop inter-disciplinary knowledge and collaborations during the course.

We started the week considering photoreceptors and cell-cell signalling, and gradually scaled-up to look at the photosystem and chloroplast responses, physiological and biochemical mechanisms of photoprotection, the use of light in the timing of growth and flowering, and finally, plant traits, ecological and ecosystem levels.  A breadth of expertise was provided by an outstanding team of research leaders both from Helsinki and around Europe, giving really engaging lectures and stimulating discussions among the group.

International teachers and students enjoying the forest at Lammi Biological Station

The international participants rounded off the week with a visit to Lammi Biological Station to experience the Finnish forest, lake and hospitality!


UNEP EEAP panel preparing 2020 update

UNEP have put together a video explaining the work of the UNEP panels that assess ozone depletion, UV-B radiation and their interaction with climate change.

The UNEP Environmental Effects Assessment Panel in New Zealand

In late September, the UNEP Environmental Effects Assessment Panel met in Alexandra, New Zealand, home of Richard McKenzie, for our annual assessment of new research into the environmental effects of ozone depletion, UV radiation, and their implications with respect to climate change.

This year Janet Bornman, Paul Barnes, Carlos Ballaré, Sharon Robinson and myself were particularly tasked with understanding how plant-level effects on biodiversity and key ecological processes scale-up to the ecosystem level.  We also focussed on crosscutting themes affecting not only terrestrial ecosystems, but mankind and the entire global environment.

A traditional Pōwhiri – Māori welcome – for the UNEP panel.

The capacity for us to address ozone depletion through the successful implementation of the Montreal Protocol, which limited the production of ozone depleting chemicals, can be seen as a flagship example of our capacity to address global environmental problems through concerted international action.  In this respect, one of the panel’s responsibilities in future reports will be to provide quantitative comparisons of how our environment differs today from what it would have looked like without the Montreal Protocol.

The World Avoided – Projection of the UV index in March 2065 with (left) and without (right) the implementation of the Montreal Protocol – from Barnes et al., (2019) Nature Sustainability 2, 569–579

Do UV-radiation and blue light have a role in photodegradation affecting decomposition in Finnish forests over winter

The rate of decomposition of leaf litter on the forest floor controls the thickness of the litter layer and nutrient recycling within the ecosystem. Decomposition is well known to depend on moisture and temperature which hasten both the microbial and non-microbial breakdown of leaves following their autumn senescence.

In this paper, just accepted in Plant Physiology and Biochemistry we test the extent to which light plays a role in the decomposition of autumn leaves. Photodegradation, the process by which sunlight accelerates decomposition, has typically been considered important only in dry environments. However, Santa Neimane and Marta Pieristè found in this experiment that it can also participate in decomposition during winter and spring prior to forest canopy closure.

The paper also considers how photodegradation acts on leaves of silver birch and European beech. Using spectrally selective filters over leaf litter in the understorey of different stands in Viikki arboretum and under controlled conditions, the distinct roles of UV radiation and of blue light, which facilitates microbial colonisation could be identified.

The experiment also exploited natural UV filters found in the epidermis of leaves as a means to see whether screening UV-radiation from the mesophyll when leaves are orientated with their upper-face upwards would affect the rate of photodegradation.

This research formed part of Santa Neimane’s undergraduate thesis on Erasmus exchange in Helsinki. It complements the subsequent long-term study of decomposition in a temperate beech forest published this summer, Pieristè et al. 2019, which considers the dynamics of photodegradation in leaves of tree species spanning a continuum of succession.

Read more in the papers:

Pieristè M, Neimane S, Nybakken L, Solanki T, Jones AG, S, Forey E, Chauvat M, Ņečajeva J, Robson TM. (2020) Ultraviolet radiation accelerates photodegradation under controlled conditions but slows the decomposition of leaf litter from forest stands in southern Finland. Accepted in Plant Physiology and Biochemistry. PLAPHY5920.

Pieristè M, Chauvat M, Kotilainen TK, Jones AG, Aubert M, Robson TM, Forey E. (2019) Solar UV-A radiation and blue light enhance tree leaf litter decomposition in a temperate forest by accelerating photodegradation rate. Oecologia, 191(1), 191-203.

Understanding plants’ readiness to grow beneath the snowpack

A quick start to the growing season for plants emerging from the snowpack can provide them with a fitness dividend in locations where the summer is short.

In our latest paper, Transmission of ultraviolet, visible and near-infrared solar radiation to plants within a seasonal snow pack, just out in a Special Issue of PPS devoted to plant UV responses, we measured how much sunlight plants receive under snow and how the properties of the snowpack affect the irradiance spectrum.

Changes in the spectral composition of light under the snowpack may help plants perceive the onset of spring and physiologically prepare for exposure to the full sunlight and cold temperatures they will experience once they emerge.

This field work involved spending some very cold clear days hiding in deep snowpacks! 

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.
  • 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.

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.