Articles containing the keyword 'CO2'

The present study is the first attempt to carry out an inventory of greenhouse gas (GHG) fluxes in the forests of Estonia. The emission and uptake of CO₂ as a result of forest management, forest conversion and abandonment of cultivated lands in Estonia was estimated. The removal of GHG by Estonian forests in 1990 exceeded the release about 3.3 times. Changes in the species composition and productivity of forest sites under various simulated climate change scenarios have been predicted by using the Forest Gap Model for the central and coastal areas of Estonia. The computational examples showed that the changes in forest community would be essential.

• Mandre, E-mail: mm@mm.unknown
• Klõseiko, E-mail: jk@mm.unknown
• Reisner, E-mail: vr@mm.unknown
• Tullus, E-mail: ht@mm.unknown

Willows (Salix phylicifolia) were grown for four months in organic rich soil at four nutrient levels (fertilization with a micronutrient-macronutrient mixture of 0, 100, 500 and 1,000 kg ha^-1 per month) and four CO₂ concentrations (300, 500, 700 and 1,000 ppm). Nitrogen and phosphorus concentration of the willows were reduced at CO₂ enhancement, the decrease being larger in the leave and roots than in the stems. Nitrogen content of the willows plus extractable nitrate-N in the soil coincided well with the doses of nitrogen supplied, but the corresponding sum of phosphorus in the plants and soil were smaller. The total nitrogen content of willows grown in unfertilized soil was nearly two times higher than the sum of the extractable nitrate-N in soil and N content of the cutting at the beginning of the experiment. The contents of nitrogen and phosphorus of the unfertilized willows were independent of CO₂ concentration, suggesting that CO₂ concentration did not affect through increased mineralization the availability of those nutrients to the willows.

• Silvola, E-mail: js@mm.unknown
• Ahlholm, E-mail: ua@mm.unknown

The effects of realistically elevated O₃ and CO₂ concentrations on the needle ultrastructure and photosynthesis of ca. 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied during one growth period in open-top field chambers situated on a natural pine heath at Mekrijärvi, in eastern Finland. The experiment included six different treatments: chamberless control, filtered air, ambient air and elevated O₃, CO₂ and O₃ + CO₂. Significant increases in the size of chloroplast and starch grains were recorded in the current-year needles of the saplings exposed to elevated CO₂ These responses were especially clear in the saplings exposed to elevated O₃ + CO₂ concentrations. These treatments also delayed the winter hardening process in cells. In the shoots treated with O₃, CO₂ and combined O₃ + CO₂ the P_max was decreased on average by 50% (ambient CO₂) and 40% (700 ppm CO₂). Photosynthetic efficiency was decreased by 60% in all the treated shoots measured under ambient condition and by 30% in the CO₂ and O₃ + CO₂ treated shoots under 700 ppm. The effect of all the treatments on photosynthesis was depressive which was probably related to evident accumulation of starch in the chloroplasts of the pines treated with CO₂ and combined O₃ + CO₂. But in O₃ treated pines, which did not accumulate starch in comparison to pines subjected to ambient air conditions, some injuries may be already present in the photosynthetic machinery.

• Palomäki, E-mail: vp@mm.unknown
• Holopainen, E-mail: th@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown
• Laitinen, E-mail: kl@mm.unknown

The eddy covariance technique is a novel micrometeorological method that enables the determination of the atmosphere-biosphere exchange rate of gases such as ozone and carbon dioxide on an ecosystem scale. This paper describes the technique and presents results from the first direct measurements of turbulent fluxes of O₃, CO₂ and H₂O above a forest in Finland. The measurements were performed during 15 July-5 August 1994 above a Scots pine (Pinus sylvestris L.) stand near the Mekrijärvi research station in Eastern Finland.

The expected diurnal cycles were observed in the atmospheric fluxes of O₃, CO₂ and H₂O. The data analysis includes interpretation of the O₃ flux in terms of the dry deposition velocity and evaluation the dependency of the net CO₂ flux on radiation. The eddy covariance method and the established measurement system has proved suitable for providing high-resolution data for studying ozone deposition to a forest as well as the net carbon balance and related physiological processes of an ecosystem.

• Aurela, E-mail: ma@mm.unknown
• Laurila, E-mail: tl@mm.unknown
• Tuovinen, E-mail: jt@mm.unknown

A third generation of forest tree gas exchange measuring system design for the use in the field is described. The system is designed to produce data for determining the dependence of the rate of tree photosynthesis, respiration and transpiration on environmental factors. The system consists of eight cuvettes, a tubing system, two infrared gas analysers, an air flow controller, a data logger, and a computer. The measuring cuvette is a clap type, i.e. it is mostly open, only closing during measurement. CO₂ exchange is measured as the change in the cuvette concentration of CO₂, and, transpiration is measured as the increase in water vapour concentration while the cuvette is closed. The environmental factors measured are temperature, irradiance and air pressure. The system was planned in 1987 and constructed in 1988. It worked reliably in late summer 1988 and the quality of data seems to be satisfactory. 

The PDF includes an abstract in Finnish.

• Hari, E-mail: ph@mm.unknown
• Korpilahti, E-mail: eeva.korpilahti@luke.fi
• Pohja, E-mail: tp@mm.unknown
• Räsänen, E-mail: pr@mm.unknown

The interactive effects of water stress and temperature on the CO₂ response of photosynthesis was studied in Salix sp. cv. Aquatica using the closed IRGA system. A semi-empirical model was used to describe the CO₂ response of photosynthesis. The interactive effect of water stress and temperature was divided into two components: the change in CO₂ conductance and the change in the photosynthetic capacity. The CO₂ conductance was not dependent on the temperature when the willow plant was well watered, but during water stress it decreased as the temperature increased. The photosynthetic capacity of the willow plant increased along with an increase in temperature when well-watered, but during water stress temperature had quite opposite effect.

The PDF includes a summary in Finnish.

• Smolander, E-mail: hs@mm.unknown
• Lappi, E-mail: jl@mm.unknown

The study was an attempt to assess, from a theoretical viewpoint and with the techniques of measurement in mind, the usability respiration and cumulative respiration in the observation of the progress of seed germination in Norway spruce (Picea abies (L.) H. Karst.), as well as the influence of air temperature substrate moisture and the stage of physiological development of seeds on respiration. Furthermore, the reserve nutrient consumption and the possible uptake of mineral nutrients were kept under observation during the 9–11 days after seeding.

The results showed that the stage of physiological development of the seeds can be rather well described by the means of cumulative CO₂ release. There was a strong interaction in the CO₂ release between the moisture of the substrate and the air temperature. It seems to be to great extent due to differences in the rate of development in the early phases of germination. The CO₂ release from seeds showed a close correlation with percentage germinated seeds.

The PDF includes a summary in English.

• Hari, E-mail: ph@mm.unknown
• Lehtiniemi, E-mail: tl@mm.unknown

In the literature review the current status of information on the genetic variation of CO₂ exchange and some reviews and investigations on this subject are listed. Photorespiration is separately discussed and unpublished data of an electron microscope study of poplar leaf microbodies are presented.

Considerable genetic inter- and intraspecific variation is found in several characteristics that affect CO₂ exchange in trees. Photosynthesis in young trees does not correlate well with growth through the whole rotation cycle. A special interest has been shown to marginal environmental conditions (e.g. water deficit, low temperature, and low light intensity), as opposed to optimal conditions often employed in laboratory studies of CO₂ exchange in trees.

In an unpublished poplar studies by the author et.al. a preliminary experiment with poplar clones showed variation in the CO₂ competition point. This variation was negatively correlated with the photosynthesis efficiency of these clones.

The PDF includes a summary in English.

• Luukkanen, E-mail: ol@mm.unknown

• Huttunen, Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: liisa.huttunen@utu.fi
• Ayres, Biological Sciences, Dartmouth College, Hanover, NH 03755, USA E-mail: matt.ayres@dartmouth.edu
• Niemelä, Section of Biodiversity and Environmental Science, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: pekka.niemela@utu.fi
• Heiska, The Finnish Forest Research Institute, Punkaharju Unit, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail: susanne.heiska@metla.fi
• Tegelberg, Digitarium - Digitization Centre of the Finnish Museum of Natural History and the University of Eastern Finland, Joensuu Science Park, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: riitta.tegelberg@helsinki.fi
• Rousi, The Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: matti.rousi@metla.fi
• Kellomäki, Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: seppo.kellomaki@uef.fi

• Raymer, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432 Ås, Norway E-mail: akr@nn.no
• Gobakken, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432 Ås, Norway E-mail: terje.gobakken@umb.no
• Solberg, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, N-1432 Ås, Norway E-mail: bs@nn.no

• Eriksson, SLU, Dept of Bioenergy, P.O. Box 7061, SE-750 07 Uppsala, Sweden E-mail: ee@nn.se
• Johansson, SLU, Dept of Bioenergy, P.O. Box 7061, SE-750 07 Uppsala, Sweden E-mail: tj@nn.se

• Aalto, Finnish Meteorological Institute, Air Quality Research, Sahaajankatu 20 E, FIN-00810 Helsinki, Finland E-mail: tuula.aalto@fmi.fi
• Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: ph@nn.fi
• Vesala, University of Helsinki, Dept. of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland E-mail: tv@nn.fi

• Aalto, Department of Physics, P.O. Box 9, FIN-00014 University of Helsinki, Finland E-mail: tuula.aalto@helsinki.fi

• Palomäki, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: virpi.palomaki@uku.fi
• Hassinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ah@nn.fi
• Lemettinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ml@nn.fi
• Oksanen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: to@nn.fi
• Helmisaari, Finnish Forest Research Institute, Department of Forest Ecology, P.O.Box 18, FIN-01301 Vantaa, Finland E-mail: hsh@nn.fi
• Holopainen, Agricultural Research Centre, FIN-31600 Jokioinen, Finland E-mail: jh@nn.fi
• Kellomäki, University of Joensuu, Faculty of Forestry, P.O.Box 111, FIN-80101 Joensuu, Finland E-mail: sk@nn.fi
• Holopainen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: th@nn.fi

• Nilsen, The Research Council of Norway, P.O. Box 2700, St. Hanshaugen, N-0131 Oslo, Norway E-mail: pn@rcn.no
• Strand, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway E-mail: line.strand@umb.no