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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 https://www.nature.com/articles/s41893-019-0314-2
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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. https://doi.org/10.1016/j.plaphy.2019.11.005

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. https://doi.org/10.1007/s00442-019-04478-x

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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! 
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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)

 

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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
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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.

 

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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

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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

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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.