Metla Project 8186
Growth of Silver Birch at evelevated levels of carbon dioxide and ozone: Adaptations in photosynthesis, injuries and protection by ascorbate and terpenes
Duration: 1998-2001
Keywords: carbon dioxide, clone, global change
Objectives
Climate change and air pollutants are in future of major importance for growth and success of forest trees. According to growth models, climate change will alter the species distribution of trees in the boreal zone in favour of deciduous trees, and especially birch. From air pollutants particularly the rise in ozone concentration is a risk that together with climate change can alter the responses and species distribution of forest trees in future. According to pot experiments deciduous trees are more susceptible to ozone than conifers, although there is genetic variation in sensitivity also within species. In silver birch the responses to increased ozone may differ markedly the most sensitive individuals reacting rapidly with leaf injuries, early yellowing and decreased growth. Results from experiments with aspen show that elevated carbon dioxide concentration cannot compensate for the injuries caused by ozone.
In the present 3-year study our aim is to study the responses of silver birch to elevated carbon dioxide and ozone concentrations, an approach that has not been conducted with deciduous trees anywhere in Scandinavia. The study will take benefit of a field experiment, established at Suonenjoki Research Station in 1993 on 15 silver birch clones. From this experiment 2 fast-growing clones are selected for this study, one ozone sensitive and one ozone tolerant, according to results from pot experiments. The selected saplings are exposed to the following treatments in open-top chambers: 1) outside control; 2) chamber control; 3) O3 -treatment (2 * background O3); 4) CO2 -treatment (720 ppm) and 5) O3 + CO2 -treatment (2 * background O3 + 720 ppm CO2). In the study the wide experience and expertise of the partners from various research institutions is used to be able to answer the following questions:
1. What is the field performance of photosynthesis and its component reactions under changing environmental conditions? 2. Are the results obtained with potted seedling under elevated O3 comparable to data with established, field-grown birch saplings in open-top chambers? 3. Do the O3-caused injuries also appear under elevated CO2? 4. What is the role of ascorbate and terpenes in protection of oxidative stress in silver birch? 5. How do the changes in the chemical quality of the leaves under elevated CO2 affect the edibility of the leaves and what are the consequences on litter composition and nutrient circulation? 6. Are the present predictions of the growth models sound for silver birch under elevated CO2 and how does O3 interfere with CO2?
The study is supported by a grant from EU (contract no. ERBIC15CT980102) and in realized in collaboration with partners from University of Tartu, Estonia (prof. Agu Laisk), Institute of Ecology, Estonia (prof. Olevi Kull) and Consiglio Nazionale delle Richerche, Rome (Dr. Francesco Loreto). The project works in collaboration with scientists from University of Kuopio (Drs. Toini Holopainen, Jarmo Holopainen and Elina Oksanen) and from University of Joensuu (Drs. Riitta Julkunen-Tiitto and Tapani Repo).
Project leader:
Vapaavuori, Elina
The Finnish Forest Research Institute,
Suonenjoki Office,
Juntintie 154, FI-77600 SUONENJOKI, FINLAND
Phone: +358 29 532 4888
E-mail: elina.vapaavuori@metla.fi
Other researchers:
Peltonen, Petri (1998-2000), Riikonen, Johanna, SU (1998-2000)
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Updated 12.06.2012
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