Seasonal and inter-annual variation in the chlorophyll content of three co-existing Sphagnum species exceeds the effect of solar UV reduction in a subarctic peatland.

We measured chlorophyll (chl) concentration and chl a/b ratio in Sphagnum balticum, S. jensenii, and S. lindbergii, sampled after 7 and 8 years of ultraviolet-B (UVB) and temperature manipulation in an open field experiment in Finnish Lapland (68°N). We used plastic filters with different transmittance of UVB radiation to manipulate the environmental conditions. The plants were exposed to (1) attenuated UVB and increased temperature, (2) ambient UVB and increased temperature and (3) ambient conditions. Chlorophyll was extracted from the capitula of the mosses and the content and a/b ratio were measured spectrophotometrically. Seasonal variation of chlorophyll concentration in the mosses was species specific. Temperature increase to 0.5-1 °C and/or attenuation of solar UVB radiation to ca. one fifth of the ambient (on average 12 vs. 59 uW/cm(2)) had little effect on the chlorophyll concentration or its seasonal variation. In the dominant S. lindbergii, UVB attenuation under increased temperature led to a transient decrease in chlorophyll concentration. Altogether, species-specific patterns of seasonal chlorophyll variation in the studied Sphagna were more pronounced than temperature and UVB treatment effects.

Triterpenoid content of berries and leaves of bilberry Vaccinium myrtillus from Finland and Poland.

Triterpenoid compounds found in free and ester forms in extracts of entire fruits and leaves and in fruit and leaf cuticular waxes of bilberry (Vaccinium myrtillus L.) collected in Finland and Poland were identified and quantitated by gas chromatography-mass spectrometry coupled to a flame ionization detector (GC-MS/FID). The main bilberry triterpenoid profile consisted of α- and ß-amyrin, α- and ß-amyrenone, campesterol, cholesterol, citrostadienol (in berries), cycloartanol, erythrodiol, lupeol, 24-methylenecycloartanol, sitosterol, sitostanol, stigmasterol, stigmasta-3,5-dien-7-one, uvaol, oleanolic and ursolic aldehydes, and oleanolic, ursolic, 2α-hydroxyoleanolic, and 2α-hydroxyursolic acids. Friedelin and D:A-friedooleanan-3ß-ol were found only in Finnish plants, whereas D:C-friedours-7-en-3ß-ol and taraxasterol were found only in Polish plants. To our knowledge, this is the first thorough description of triterpenoid compounds in this species. The presented results revealed that the triterpenoid profile of bilberry varied considerably between different organs of the plant, regardless of the plant origin, as well as between plant samples obtained from the two geographical locations.

Comparison of the triterpenoid content of berries and leaves of lingonberry Vaccinium vitis-idaea from Finland and Poland.

Triterpenoid compounds extracted from fruits and leaves of lingonberry ( Vaccinium vitis-idaea L.) collected in Finland and Poland were identified and quantitated by GC-MS/FID. The main lingonberry triterpenoid profile consisted of α-amyrin, ß-amyrin, betulin, campesterol, cycloartanol, erythrodiol, fern-7-en-3ß-ol, friedelin, lupeol, sitosterol, stigmasterol, stigmasta-3,5-dien-7-one, swert-9(11)-en-3ß-ol, taraxasterol, urs-12-en-29-al, uvaol, oleanolic acid, and ursolic acid. To our knowledge, this is the first thorough description of triterpenoid compounds in this species. Ursolic acid was identified as a principal triterpene in lingonberry fruit. The influence of geographical origin on the level of individual triterpenoid compounds was examined, and considerable variations in triterpenoid profile between berries and leaves obtained from the two locations were observed. The most striking difference concerned the occurrence of fernenol and taraxasterol, which were found to be the major triterpenol in lingonberry leaves of Finnish and Polish origin, respectively.

Decreased frost hardiness of Vaccinium vitis-idaea in reponse to UV-A radiation.

The aim of this study was to investigate plant frost hardiness responses to ultraviolet (UV) radiation, since the few results reported are largely contradictory. It was hypothesized that functional adaptation of life forms could explain these contradictions. Dwarf shrubs and tree seedlings, representing both evergreen and deciduous forms, were tested (Vaccinium vitis-idaea, Vaccinium myrtillus, Pinus sylvestris, Betula pubescens and its red form f. rubra). The research was performed in Sodankylä, Northern Finland (67°N), with enhanced UV-B- and UV-A-radiation treatments between 2002 and 2009. Plant frost hardiness was determined using the freeze-induced electrolyte leakage method in early autumn, during the onset of the frost hardening process. Additional physiological variables (malondialdehyde, glutathione, total phenols, C and N contents) were analyzed in V. vitis-idaea to explain the possible responses. These variables did not respond significantly to UV-radiation treatments, but explained the frost hardiness well (r² = 0.678). The main finding was that frost hardiness decreased in the evergreen shrub V. vitis-idaea, particularly with enhanced UV-A radiation. No significant responses were observed with the other plants. Therefore, this study does not support the idea that enhanced UV radiation could increase plant frost hardiness.

Seasonal acclimation of the moss Polytrichum juniperinum Hedw. to natural and enhanced ultraviolet radiation.

Short- and long-term changes in the methanol-extractable UV-absorbing compounds and biomass of the pioneer moss Polytrichum juniperinum in response to natural and enhanced UV radiation were studied. Under natural conditions, the compounds were found to fluctuate seasonally. In summer these compounds correlated negatively with irradiation. The concentration was low in July after a period of simultaneous heat, drought and high irradiation. Transient positive correlation between daily concentration and UV was seen in June. The concentration increased towards autumn and was relatively high under snow. Two enhanced UV experiments were performed. Seasonality in the compounds was again observed, with negative correlations with irradiation. During the first weeks, a transient inhibition of compound production was observed after the daily UV-B treatment. After six years of modulated UV-treatment in situ, photosynthesizing biomass decreased under UV-B and increased under UV-A. A larger variation in the UV-absorbing compounds was observed under UV-B treatment.

Retrospective bioindication of stratospheric ozone and ultraviolet radiation using hydroxycinnamic acid derivatives of herbarium samples of an aquatic liverwort.

We analyzed bulk UV absorbance of methanolic extracts and levels of five UV-absorbing compounds (hydroxycinnamic acid derivatives) in 135 herbarium samples of the liverwort Jungermannia exsertifolia subsp. cordifolia from northern Europe. Samples had been collected in 1850-2006 (96% in June-August). Both UV absorbance and compound levels were correlated positively with collection year. p-Coumaroylmalic acid (C1) was the only compound showing a significant (and negative) correlation with stratospheric ozone and UV irradiance in the period that real data of these variables existed. Stratospheric ozone reconstruction (1850-2006) based on C1 showed higher values in June than in July and August, which coincides with the normal monthly variation of ozone. Combining all the data, there was no long-term temporal trend from 1850 to 2006. Reconstructed UV showed higher values in June-July than in August, but again no temporal trend was detected in 1918-2006 using the joint data. This agrees with previous UV reconstructions.

Northern plants and ozone.

Forests in northern Fennoscandia are mainly composed of the O3-sensitive species--Scots pine and downy, mountain, and silver birches. Seminatural vegetation also contributes to biodiversity, carbon cycling, and ecosystem services as a part of forests, mires, meadows, and road verges. Fumigation experiments show that current O3 concentrations of 30-50 ppb reduce plant biomass production and reproduction. Visible foliar injury is attributable to peak O3 concentrations and relates to fast phenological development and high growth rate. Trees can acclimate to O3-induced water stress by producing more xeromorphic leaves or needles. The direct effects of O3 on grassland vegetation also translate to changes in the structure and size of the soil microbial community, and ecosystem N cycling. It is necessary to reduce the emission of O3 precursors and maintain high biodiversity to protect northern ecosystems. Regular, systematic, countrywide monitoring and validation as well as quantification of the effects of O3 on plants in the Nordic countries are also necessary.

Long-term evaluation of the needle surface wax condition of Pinus sylvestris around different industries in Lithuania.

The aim of our study was to evaluate the annual dynamics of needle surface wax erosion and wettability in Scots pines exposed to a gradient of industrial pollutants emitted from the main factories of Lithuania: a nitrogen fertilizer factory, an oil refinery and a cement factory. Decreased emissions (in the case of the oil refinery and the cement factory) were reflected in the increased structural surface area (SSA, i.e. area covered by tubular waxes) on the needles. The nearly constant amount of emissions from the nitrogen fertilizer factory within the 1994-2000 period corresponded to negligible annual differences in SSA. Annual changes in the hydrophobicity of needles on the investigated transects were small. Despite the decreased pollution within the 7-year period, industrial emissions are still causing significantly accelerated wax erosion and increased wettability in needles sampled from the stands most heavily affected by pollutants.

Relations between Scots pine needle element concentrations and decreased needle longevity along pollution gradients.

Scots pine (Pinus sylvestris L.) shoots were sampled along transects near one urban pollution source and two smelters. Needle Mg, P and K concentrations decreased from the second to the fourth age class linearly with needle survival along the urban pollution gradient. Still, over 80% of the average concentration of these nutrients remained in the fourth needle age class. Decreased needle longevity was closely related to the increased heavy metal concentrations near the smelters. Near the urban pollution source, it was related to the increased annual needle mass and the increased needle nutrient concentrations. Decreased Mn accumulation along with needle age was detected near all pollution sources. Leaching of Mn from needles and especially from soil as a cause of decreased needle concentrations is discussed.

Total vs. internal element concentrations in Scots pine needles along a sulphur and metal pollution gradient.

Analysis of foliar elements is a commonly used method for studying tree nutrition and for monitoring the impacts of air pollutants on forest ecosystems. Interpretations based on the results of foliar element analysis may, however, be different in nutrition vs. monitoring studies. We studied the impacts of severe sulphur and metal (mainly Cu and Ni) pollution on the element concentrations (Al, Ca, Cu, Fe, K, Mg, Mn, Ni, P, Pb, S and Zn) in Scots pine (Pinus sylvestris L.) foliage along an airborne sulphur and metal pollution gradient. Emphasis was put on determining the contribution of air-borne particles that have accumulated on needle surfaces to the total foliage concentrations. A comparison of two soil extraction methods was carried out in order to obtain a reliable estimate of plant-available element concentrations in the soil. Element concentrations in the soil showed only a weak relationship with internal foliar concentrations. There were no clear differences between the total and internal needle S concentrations along the gradient, whereas at the plot closest to the metal smelter complex the total Cu concentrations in the youngest needles were 1.3-fold and Ni concentrations over 1.6-fold higher than the internal needle concentrations. Chloroform-extracted surface wax was found to have Ni and Cu concentrations of as high as 3000 and 600 microg/g of wax, respectively. Our results suggest that bioindicator studies (e.g. monitoring studies) may require different foliar analysis techniques from those used in studies on the nutritional status of trees.

Ozone-induced free polyamine response in scots pine in northern Finland.

The study aimed to assess the ozone-induced response in Scots pine (Pinus sylvestris L.) needles by measuring free polyamine concentrations. An open-top chamber experiment with realistically elevated ozone concentrations was carried out in northern Finland. A carry-over effect was detected: the concentrations of free polyamines, especially putrescine, were decreased at the beginning of the next growing season in the ozone-exposed trees. This indicates that the free polyamine pathway was not activated by ozone stress in Scots pines in northern conditions.