Effects of elevated CO2 on chloroplast pigments of spruce (Picea abies) and beech (Fagus sylvatica) in model ecosystems as modified by provenance, soil type, and nitrogen supply

Young beech (Fagus sylvatica L.) and spruce (Picea abies [L,] Karst.) trees, each from two different provenances, were grown in competition in model ecosystems in open-top chambers for four years. The treatments consisted of elevated concentrations of CO, (370 μL L-1 versus 590 μL L-1), increased wet deposition of nitrogen (7 versus 70 kg N ha-1 y-1) and two different forest soils (acidic versus calcareous). Chloroplast pigments in dark- and light-adapted leaf material sampled in the last year of the experiment were analysed. Differences in pigment composition between provenances were observed only in beech trees. Soil type significantly affected the pigment composition in both species. Trees grown under calcareous conditions had higher contents of chlorophylls, whereas acidic soil conditions caused significantly enhanced levels of ß-carotene and xanthophylls as well as increased values of the xanthophyll de-epoxidation status. For both tree species light-adapted samples had higher carotenoid concentrations and de-epoxidation state values than dark-adapted foliage, whereas neither C02 nor N-treatment affected these parameters. Elevated CO, application induced decreased concentrations of total chlorophyll contents in both species. Nitrogen deposition had no effects on pigment composition neither for spruce nor for beech trees. Interactions between CO, and nitrogen application were not observed for both tree species

Impacts of Air Pollution and Climate Change on Forest Ecosystems — Emerging Research Needs

Outcomes from the 22nd meeting for Specialists in Air Pollution Effects on Forest Ecosystems “Forests under Anthropogenic Pressure Effects of Air Pollution, Climate Change and Urban Development”, September 1016, 2006, Riverside, CA, are summarized. Tropospheric or ground-level ozone (O3) is still the phytotoxic air pollutant of major interest. Challenging issues are how to make O3 standards or critical levels more biologically based and at the same time practical for wide use; quantification of plant detoxification processes in flux modeling; inclusion of multiple environmental stresses in critical load determinations; new concept development for nitrogen saturation; interactions between air pollution, climate, and forest pests; effects of forest fire on air quality; the capacity of forests to sequester carbon under changing climatic conditions and coexposure to elevated levels of air pollutants; enhanced linkage between molecular biology, biochemistry, physiology, and morphological traits

Seasonal growth, δ13C in leaves and stem, and phloem structure of birch (Betula pendula) under low ozone concentrations

The growth of potted birch cuttings (one clone of Betula pendula) was studied under low O3 concentrations (0, 0.050, 0.075, 0.100 μl l-1) throughout an entire growing season. With increasing O3 dose, 20–50% of all leaves formed were prematurely shed, while 40–70% of the remaining foliage displayed advanced discoloration by the end of the season. Ozonation affected the S, P and N concentration of leaves and increased δ13C in leaves and stem, while the CO2 assimilation rate declined with increasing CO2 concentration in mesophyll intercellulars. While whole-plant production correlated negatively with the O3 dose, ozone increased the specific leaf weight (i.e. leaf weight/leaf area, SLW) but decreased the ratios of stem weight/stem length and root/shoot biomass. Neither the latter ratio nor SLW changed in experimentally defoliated control plants, whereas in ozonated plants starch accumulated along leaf veins and phloem tissue was deformed in the leaf petioles and the stem. Only in early summer was the relative growth rate higher in the ozonated than in the control plants. The ratio of whole-plant biomass production versus total foliage area formed was lowered under O3 stress. However, when relating biomass to the actual foliage area present due to leaf loss, this ratio did not differ between treatments. Similarly the ratio of actual foliage area versus basal stem area in cross-section did not differ. Overall, whole-plant production was strongly determined by O3-caused changes in crown structure and began to be limited at O3 doses (approximately 180 μl l-1 h) similar to those of rural sites in Central Europe

Responses to Airborne Ozone and Soilborne Metal Pollution in Afforestation Plants with Different Life Forms

With the current increases in environmental stress, understanding species-specific responses to multiple stress agents is needed. This science is especially important for managing ecosystems that are already confronted with considerable pollution. In this study, responses to ozone (O3, ambient daily course values + 20 ppb) and mixed metal contamination in soils (MC, cadmium/copper/lead/zinc = 25/1100/2500/1600 mg kg−1), separately and in combination, were evaluated for three plant species (Picea abies, Acer pseudoplatanus, Tanacetum vulgare) with different life forms and ecological strategies. The two treatments elicited similar stress reactions, as shown by leaf functional traits, gas exchange, tannin, and nutrient markers, irrespective of the plant species and life form, whereas the reactions to the treatments differed in magnitude. Visible and microscopic injuries at the organ or cell level appeared along the penetration route of ozone and metal contamination. At the whole plant level, the MC treatment caused more severe injuries than the O3 treatment and few interactions were observed between the two stress factors. Picea trees, with a slow-return strategy, showed the highest stress tolerance in apparent relation to an enhancement of conservative traits and an exclusion of stress agents. The ruderal and more acquisitive Tanacetum forbs translocated large amounts of contaminants above ground, which may be of concern in a phytostabilisation context. The deciduous Acer trees—also with an acquisitive strategy—were most sensitive to both stress factors. Hence, species with slow-return strategies may be of particular interest for managing metal-polluted sites in the current context of multiple stressors and for safely confining soil contaminants below ground

Effects of elevated CO2 on chloroplast pigments of spruce (Picea abies) and beech (Fagus sylvatica) in model ecosystems as modified by provenance, soil type, and nitrogen supply

Young beech (Fagus sylvatica L.) and spruce (Picea abies [L,] Karst.) trees, each from two different provenances, were grown in competition in model ecosystems in open-top chambers for four years. The treatments consisted of elevated concentrations of CO, (370 μL L-1 versus 590 μL L-1), increased wet deposition of nitrogen (7 versus 70 kg N ha-1 y-1) and two different forest soils (acidic versus calcareous). Chloroplast pigments in dark- and light-adapted leaf material sampled in the last year of the experiment were analysed. Differences in pigment composition between provenances were observed only in beech trees. Soil type significantly affected the pigment composition in both species. Trees grown under calcareous conditions had higher contents of chlorophylls, whereas acidic soil conditions caused significantly enhanced levels of ß-carotene and xanthophylls as well as increased values of the xanthophyll de-epoxidation status. For both tree species light-adapted samples had higher carotenoid concentrations and de-epoxidation state values than dark-adapted foliage, whereas neither C02 nor N-treatment affected these parameters. Elevated CO, application induced decreased concentrations of total chlorophyll contents in both species. Nitrogen deposition had no effects on pigment composition neither for spruce nor for beech trees. Interactions between CO, and nitrogen application were not observed for both tree species

Effects of heavy metal soil pollution and acid rain on growth and water use efficiency of a young model forest ecosystem

ISSN:0032-079XISSN:1573-503