Category: Outreach

In a new paper just out in Agricultural and Forest Meteorology, we explore how extended canopy closure in oak and birch forests at Lammi Biological Station in southern Finland affects the growing season for common understorey forbs.

The paper describes an experiment to test the effects of climate warming which may extend the length of time that canopy trees in a forest keep their leaves into the winter. One puzzle associated with climate change is whether plants growing on the forest floor benefit more from the extended warm periods in the spring and autumn, or whether these warm periods mean that canopy trees retain their leaves for longer and thus restrict the light reaching the ground and available there for photosynthesis.

In an experiment comparing stands of oak, birch and spruce, we tested the potential for photosynthesis, retention of chlorophyll, and colouration of understorey plant species on the forest floor throughout autumn and the start of winter. Our main finding was that the increase in light received and change in its spectral composition following canopy leaf fall was the main trigger of senescence in the understorey. Those understorey species able to keep photosynthesizing effectively into late autumn were benefitting the most from warmer temperature and an extended closed canopy period.

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.

We recently traveled to Austria to help set-up our collaborators’ experiments monitoring the effects of UV-B radiation exposure on Pinus cembra pollen in the mountains above Innsbruck.  If we can understand how exposure to UV radiation affects the accumulation of UV-absorbing compounds in pollen today, we may be able to calibrate the concentrations of these compounds found in ice- and sediment cores used in climatic reconstructions. This information potentially will allow palyontologists to understand how UV radiation changed over geological time and what the implications of these changes might have been for the Earth’s ecosystems. By better understanding past climate we will be better prepared to forecast how modern-day changes in UV radiation might affect the Earth’s ecosystems.

Here we take parallel measurements with broadband UV-B sensors and a spectroradiometer next to a specimen pine tree during the period before flowering.

Find up more in last years UNEP update.