Papers by Toini Holopainen
Plant and Soil, 2007
Two field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elev... more Two field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO 2 and O 3 for three growing seasons (1999)(2000)(2001). The phenolic compounds of naturally abscised leaf litter were analyzed in order to determine the possible CO 2 -and O 3 -induced changes in the litter quality. The potential litter-mediated CO 2 and O 3 effects on litter-feeding soil macrofauna (detritivore) performance were assessed in microcosm experiments, i.e., the relative growth rates (RGR) of Lumbricus terrestris and Porcellio scaber, the relative consumption rates (RCR) of P. scaber, and mortality of the test animals were measured. The leaf litter grown under elevated CO 2 had increased concentrations (weight per mass unit) and contents (weight per leaf) of phenolic acids, flavonol glycosides, condensed tannins and total measured phenolics. Elevated O 3 increased the concentrations of 3,4'-dihydroxypropiophenone 3-b-D-glucoside (DHPPG) and flavonoid aglycones but only under ambient CO 2 . However, elevated O 3 effects on the content of some lowmolecular-weight phenolic (LMWP) compounds (i.e. phenolic acids, DHPPG, flavonoid aglycones) and total LMWP changed over time emphasizing the importance of conducting longterm (>3 years) exposure studies. In general, RGR of young L. terrestris was affected by the litter quality changes induced by elevated CO 2 and O 3 , as the animal growth rates were reduced when they were fed with CO 2 -and O 3 -exposed leaf litter of clone 80 in Experiment 1. P. scaber RCR or RGR responses to CO 2 -and O 3 -induced changes in litter quality were more variable and inconsistent, and neither were there any littermediated CO 2 and O 3 effects on animal mortality in these microcosm experiments. In conclusion, elevated CO 2 has the potential to alter silver birch leaf litter quality, but the possible O 3 effects on phenolic compounds and litter-mediated CO 2 and O 3 effects on detritivores are more difficult to validate.
Global Change Biology, 2005
We assessed the effects of ambient solar ultraviolet (UV) radiation on below-ground parameters in... more We assessed the effects of ambient solar ultraviolet (UV) radiation on below-ground parameters in an arctic heath in north-eastern Greenland. We hypothesized that the current UV fluxes would reduce root biomass and mycorrhizal colonization and that these changes would lead to lower soil microbial biomass and altered microbial community composition. These hypotheses were tested on cored soil samples from a UV reduction experiment with three filter treatments (Mylar, 60% UV-B reduction; Lexan, up to 90% UV-B reduction 1 UV-A reduction; UV transparent Teflon, filter control) and an open control treatment in two study sites after 3 years' manipulation. Reduction of both UV-A and UV-B radiation caused over 30% increase in the root biomass of Vaccinium uliginosum, which was the dominant plant species. UV reduction had contrasting effects on ericoid mycorrhizal colonization of V. uliginosum roots in the two sites, while it had no clear effects on fungal (ergosterol) or microbial biomass (measured both with fumigation-extraction and quantitative lipid biomarker analysis) in soil. However, principal component analysis of lipid biomarkers (phospholipid and glycolipid fatty acid profiles) showed that microbial community composition was altered by UV reduction. Although the UV responses were slight considering the large dose difference between the treatments (from near-ambient to up to 90% UV-B reduction), we cannot rule out the possibility that the recovery of ozone layer would change the below-ground functioning of arctic ecosystems.
Scandinavian Journal of Clinical and Laboratory Investigation, Feb 1, 1965
Electrical Engineering, 2005
Eccentric rotor motion of an electric motor induces an unbalanced magnetic pull. This eccentricit... more Eccentric rotor motion of an electric motor induces an unbalanced magnetic pull. This eccentricity force can be described using a simple parametric model with physical parameters. This model allows an arbitrary rotor motion and transient operation. This paper presents an effective method to estimate the parameters from simulation results of electromagnetic fields. Further, the numerical results verify the form of the proposed parametric model in steady-state operation.
Open-top chamber fumigation of cloned silver birch (Betula pendula Roth) trees to elevated CO 2 a... more Open-top chamber fumigation of cloned silver birch (Betula pendula Roth) trees to elevated CO 2 and ozone: description of the fumigation system and the experimental site. Metsäntutkimuslaitoksen tiedonantoja 838. The Finnish Forest Research Institute, Research Papers 838. 28 p. An open-top chamber (OTC) system was designed and constructed at Suonenjoki Research Station, Finland (62°05'N, 27°00'E, 130 m asl) in order to study the responses of silver birch (Betula pendula Roth) trees to elevated CO 2 and O 3 alone and in combination. The aim was to provide a facility to study long-term responses of the trees in projected future climate. The facility enabled us to assess the responses on following parameters: growth, allocation, crown and leaf structure, gas exchange, biochemical and chemical properties of the leaves, herbivores and palatability of the leaves, leaf pathogens, and soil systems including root and mycorrhizal growth, soil respiration and litter decomposition. The treatments from 1999 to 2001 were: 1) outside control; 2) chamber control; 3) 2 * background CO 2 ; 4) 2 * background O 3 ; and 5) 2 * background ppm CO 2 + 2 * background O 3 . Two birch clones with different ozone-sensitivity were included in the study and both clones were represented as four replicates in each treatment. Thus, the experiment included altogether 40 trees, 32 being enclosed in cylindrical open top chambers and 8 serving as outside controls. The experiment was organised as a randomised incomplete blocks -design to eliminate the site differences between the blocks. The mixture of fumigation gases and air was blown at the speed of 0.1-0.6 m 3 s -1 at the bottom of the chamber using a computer-controlled blower. The CO 2 and O 3 dispensing and monitoring system was computer-controlled and compared the measured gas concentration to the chosen target concentration and adjusted the gas fl ow into the chambers. In the present paper we describe the experimental design, site conditions, the OTC system and principles of the measuring/regulation system as well as the measured values for air temperature, light and gas composition in the chambers. The daily mean temperature in the chambers was on an average 1.7, 2.3 and 2.4 °C higher than the daily mean temperature of the ambient air in 1999, 2000 and 2001, respectively. Temperature sums (above +5 °C) were 189 dd (in 1999) to 400 dd (2001) higher in chambers than outside. In 2000 and 2001 the doubled target concentrations of O 3 and CO 2 were reached during nearly most of the fumigation period, while in 1999 the concentrations were slightly lower than the targets. Ozone exposure during the growing seasons 1999, 2000 and 2001, calculated as AOT40values (accumulated over a threshold of 40 ppb), was 18, 22 and 29 ppm.h greater in the elevated ozone treatments than in ambient air.
Tree Physiology, 2015
Climate warming is having an impact on distribution, acclimation and defence capability of plants... more Climate warming is having an impact on distribution, acclimation and defence capability of plants. We compared the emission rate and composition of volatile organic compounds (VOCs) from silver birch (Betula pendula (Roth)) provenances along a latitudinal gradient in a common garden experiment over the years 2012 and 2013. Micropropagated silver birch saplings from three provenances were acquired along a gradient of 7° latitude and planted at central (Joensuu 62°N) and northern (Kolari 67°N) sites. We collected VOCs emitted by shoots and assessed levels of herbivore damage of three genotypes of each provenance on three occasions at the central site and four occasions at the northern site. In 2012, trees of all provenances growing at the central site had higher total VOC emission rates than the same provenances growing at the northern site; in 2013 the reverse was true, thus indicating a variable effect of latitude. Trees of the southern provenance had lower VOC emission rates than trees of the central and northern provenances during both sampling years. However, northward or southward translocation itself had no significant effect on the total VOC emission rates, and no clear effect on insect herbivore damage. When VOC blend composition was studied, trees of all provenances usually emitted more green leaf volatiles at the northern site and more sesquiterpenes at the central site. The monoterpene composition of emissions from trees of the central provenance was distinct from that of the other provenances. In summary, provenance translocation did not have a clear effect in the short-term on VOC emissions and herbivory was not usually intense at the lower latitude. Our data did not support the hypothesis that trees growing at lower latitudes would experience more intense herbivory, and therefore allocate resources to chemical defence in the form of inducible VOC emissions.
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Papers by Toini Holopainen