Potential environmental factors that influence the nitrogen concentration and δ(15)N values in the moss Hypnum cupressiforme collected inside and outside canopy drip lines.

Samples of the moss Hypnum cupressiforme were collected at 103 locations in forests of Slovenia. At each location, samples were taken at two types of sites: under tree canopies and in adjacent forest openings. The results show that the moss collected in the forest openings reflects the surrounding land-use characteristics and, consequently, the main N emission sources. For moss sampled under canopies, the characteristics of the forest at the moss-sampling locations are more important than the main emission sources outside the forest. A regression model was used to provide the nitrogen (N) concentration in moss from the forest openings in relation to the N concentration in moss under canopies and other environmental variables. The spatial distribution of the locations of the N concentrations and δ(15)N values in moss collected in the forest openings and under the canopies in relation to main N deposition sources is discussed.

Influence of canopy drip on the indicative N, S and δ(15)N content in moss Hypnum cupressiforme.

Samples of Hypnum cupressiforme were collected at two types of site in forest areas: within the forest stand and within forest openings, and analyzed for N and S concentrations and δ(15)N. Mosses sampled within forest openings reflect the atmospheric N deposition; however, no influence of throughfall N deposition on the N in the moss that was sampled within the forest stand was found, nor was any influence of S deposition on the S in the moss found. For the N and S concentrations in the mosses sampled within forest openings, the within-site variability was comparable to the between-site variability, and for the δ(15)N, the within-site variability was lower than the between-site. The results showed that a short distance (<1 m) between the sampling location and the nearest tree canopy increases the N in the moss, and significantly higher values are found in mosses sampled in areas within the forest stand.

Epiphytic lichen mycota of the virgin forest reserve Rajhenavski Rog (Slovenia).

A list of 128 taxa (127 species) of lichens, 6 species of lichenicolous fungi and 2 non-lichenized fungi traditionally included in lichenological literature from the virgin forest Rajhenavski Rog and its surroundings in the southeastern part of Slovenia is presented. The lichen Gyalecta derivata, the lichenicolous fungus Homostegia piggotii, and the non-lichenized fungus Mycomicrothelia pachnea are new to Slovenia. The lichenized fungi Chaenotheca trichialis, C. xyloxena, Lecanactis abietina, Lecanora thysanophora, Pertusaria ophthalmiza, the lichenicolous fungi Monodictys epilepraria, Tremella hypogymniae, Taeniolella friesii, and the non-lichenized fungus Chaenothecopsis pusilla are new to the Dinaric phytogeographical region of Slovenia.

Arsenic accumulation and thiol status in lichens exposed to As(V) in controlled conditions.

Thalli of epiphytic lichen Hypogymnia physodes (L.) Nyl. and terricolous Cladonia furcata (Huds.) Schrad., collected from an area with background arsenic concentrations, were exposed to 0, 0.1, 1 and 10 microg mL(-1) arsenate (As(V)) solutions for 24 h. After exposure they were kept in the metabolically active state for 0, 24 and 48 h in a growth chamber. In the freeze dried samples glutathione (GSH), glutathione disulphide (GSSG), cysteine (Cys) and cystine were analysed and induction of phytochelatin (PC) synthesis measured by reversed-phase high-performance liquid chromatography in combination with fluorescence detection or UV spectrometry. Total arsenic content in thalli was measured by instrumental neutron activation analysis (INAA). In H. physodes, which contained higher amounts of arsenic compared to C. furcata, total glutathione content significantly decreased in samples exposed to 10 microg mL(-1) As(V), whereas in C. furcata a significant increase was observed. In both species PC synthesis was induced in thalli exposed to 10 microg mL(-1).

Norway spruce needles as bioindicator of air pollution in the area of influence of the Sostanj Thermal Power Plant, Slovenia.

This paper reports the results of total sulphur content, photosynthetic pigments, ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) analysed in current-year needles of Norway spruce (Picea abies (L.) Karst.) in the area influenced by sulphur emissions from the Sostanj Thermal Power Plant (STPP), Slovenia, in the period 1991-2004. Ten differently polluted sampling sites in the emission area of STPP were selected. After desulphurization of emission gases from STPP total sulphur content in needles decreased and vitality parameters of needles increased. Moreover, a strong correlation between the average annual emissions of SO(2) from STPP and average annual sulphur content (increase) or average annual chlorophyll content (decrease) in current-year needles was found. The results showed that spruce needles may be an useful bioindicator for detecting changes in the emission rates of SO(2).

Monitoring air quality with lichens: a comparison between mapping in forest sites and in open areas.

Four different methods of epiphytic lichen mapping were used for the assessment of air quality in the region under the influence of the Sostanj Thermal Power Plant (Salek Valley, Slovenia). Three methods were based on the presence of different lichen species (VDI, EU and ICP-Forest), the fourth on a frequency and coverage assessment of different growth forms of epiphytic lichens, e.g. crustose, foliose and fruticose (SI). A comparison of the results from the assessment of air quality between forest sites (ICP-Forest, SI) and open areas (VDI, EU and SI), obtained by the different methods of epiphytic lichen mapping, is presented in the contribution. Data showed that lichen species richness is worse in forest sites in comparison with open areas. From the data obtained it can be concluded that epiphytic lichen mapping in open areas is a better method for the assessment of air pollution in a given area than mapping in forest sites. The species-based methods in open areas are more powerful and useful for air quality assessment in polluted research areas than the SI and ICP-Forest methods.

Vegetational and mycorrhizal successions at a metal polluted site: Indications for the direction of phytostabilisation?

Plant communities on plots with different metal pollution levels were compared in a field study in order to select the most suitable plant species for the direction of secondary succession toward the targeted grassland vegetation. The vegetational succession showed a gradual increase in plant cover and the number of plant species on the less polluted locations. Two predominant grass species Calamagrostis varia and Sesleria caerulea were selected for phytostabilisation, but a severely reduced seed germination capacity obstructed their use in practice. The mycorrhizal succession showed a gradual replacement of non-mycorrhizal with mycorrhizal plant species. Similar levels of arbuscular mycorrhizal colonisation of a particular plant species may be developed within each growing season regardless of the levels of pollution, with the exception of vesicle/intraradical spore formation. The results suggest that lower overall mycorrhizal colonisation levels and increased vesicle/spore formation may be a part of a mycorrhizal strategy at the most polluted locations.

Biochemical responses in leaves of two apple tree cultivars subjected to progressing drought.

The influence of water deprivation on potted apple trees (Malus domestica Borkh.) was investigated. Biochemical responses including ascorbic acid, glutathione (GSH), tocopherols, chlorophylls, carotenoids, free amino acids, and soluble carbohydrates were measured in leaves of diploid 'Elstar' and triploid 'Jonagold Wilmuta' subjected to progressive drought. Leaf water potential was chosen to be the primary indicator of water stress in tested plants. Time courses of measured biochemical parameters showed that mild drought did not significantly affect the chosen stress indicators. Moderate drought increased the concentrations of ascorbic acid, total GSH, beta-carotene, zeaxanthin and alpha-tocopherol, indicating the adaptation to oxidative stress in apple trees. Moderate drought also increased concentration of soluble carbohydrates, mostly due to increased sorbitol concentration. Severe drought negatively affected vitality of apple trees, and caused a decrease in sorbitol concentration. Severe drought also caused decreases in ascorbic acid, total GSH, beta-carotene, alpha-tocopherol and chlorophyll concentrations, which, together with the increase in oxidised GSH concentration, indicated severe damage due to oxidative stress. Severe drought increased free amino acid concentration, which was probably the result of increased proteolysis. Zeaxanthin concentration remained high even in leaves of apple trees subjected to severe drought stress. The results were similar for both tested apple cultivars.

Biochemical traits of lichens differing in relative desiccation tolerance.

• Oxidative stress arises when desiccation restricts photosynthesis and light energy is transferred from photo-excited pigments onto ground state oxygen. We tested whether a highly desiccation tolerant lichen, Pseudevernia furfuracea, displays better protection against oxidative stress than more sensitive species, Lobaria pulmonaria and Peltigera polydactyla. • We rehydrated lichens after desiccation periods of 2, 7 and 9 weeks and assessed their viability by measuring CO2 exchange using IRGA. During desiccation and rehydration, photosynthetic pigments and the antioxidant α-tocopherol were analysed by HPLC, and peroxidases by spectrophotometry. • Pseudevernia furfuracea contained considerably lower chlorophyll, α-tocopherol and ß-carotene concentrations and peroxidase activity than the two other lichens. However, it recovered photosynthesis rapidly, even after remaining in the desiccated state for 2 months while there was a significant delay in the onset of photosynthesis in L. pulmonaria and P. polydactyla. • We conclude that high antioxidant concentrations do not necessarily indicate better adaptation to desiccation. Rather, the ability to rapidly re-establish the species-specific normal antioxidant concentrations during rehydration, even after longer desiccation times, is a characteristic of well-adapted species.