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1

Responses to UV-B exposure by saplings of the relict species Davidia involucrata Bill are modified by soil nitrogen availability

Li Y., Gao J., Zhang L., Su Z.

Polish Journal of Ecology

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2014

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Vol. 62, nr 1

101--110

EN

Climate change scenarios suggest that plants will be exposed to increasing levels of ultraviolet radiation in the future. The dove tree, Davidia involucrata Bill (Davidiaceae) is a rare and endangered tree species in China. Its distribution is predicted to become more montane as the climate warms, exposing it to higher levels of UV-B and different soil conditions. We compared the effects of glasshouse ambient (7.08 uW cm-2) and increased (13.93 uW cm-2) UV-B on survivorship, secondary metabolites indicative of radiation damage, and putative defensive responses of Davidia involucrata saplings growing under current and increased nitrogen conditions (5 and 25 g m-2 a-1 N). Mortalities were higher among plants exposed to increased UV-B, but only in soils with high supplementary nitrogen. Increases in compounds associated with defense against radiation were more frequently recorded under high supplementary nitrogen conditions. This rare and localised plant is highly sensitive to elevated UV-B when growing in high nitrogen soils, a combination that is likely to increase in the summer.

2

Variations of the UV-B radiation, ozone and cloudiness at different time scales: A wavelet analysis

Borkowski J.

Acta Geophysica Polonica

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2002

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Vol. 50, nr 1

109-117

EN

Data series of UV-B irradiance, ozone and cloudiness taken at Belsk station are analyzed in order to investigate the interrelation between these variables. Data series are separated into components of different time scales with the use of wavelet multiresolution decomposition. The analysis of the smooth components of UV-B and ozone shows that at the longest time scale, ozone is the main factor affecting the UV-B irradiance. The smooth components of the UV-B and ozone are also used for the long-term trend determination. The detailed components of the ozone and total cloudiness series show remarkable similarity in their structure: they are in phase; positive (negative) deviations of the ozone content are usually associated with the positive (negative) deviations of cloudiness.

3

Altitudinal trends in needle chlorophyll content and chlorophyll fluorescence of Norway spruce (Picea abies Karst.) seedlings exposed to increased ultraviolet-b radiation

Robakowski P., Modrzyński J.

Polish Journal of Ecology

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2000

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Vol. 48, nr 1

49-62

EN

The main purpose of this study was to determine the relation between the altitude of Norway spruce seed origin and seedling response enhanced UV-B irradiation. There were threeUV-B treatments: high UV-B with a dose of 22.76 kJ m^-2 d^-1 UV-B[BE] (biologically effective dose), low UV-B-5.69kJ m^-2 d^-1 UV-B[BE] and control>> ~ 0 kJ m^-2 d^-1 UV-B[BE]. The plants were exposed to enhanced UV-B during 120 days in the greenhouse. Needle chlorophyll content and chlorophyll fluorescence parameters were investigated. The chlorophyll content in irradiated needles was lower relative to control after 30 days of exposure to UV-B, but it was higher after 70 days. All the measured chlorophyll fluorescence parameters including relative vitality indexes were reduced for needles exposed to an increased UV-B radiation. Generally, the needles' chlorophyll content was increased and chlorophyll fluorescence parameters were decreased with altitude of seed origin. The results suggest that the acclimation to higher altitudes may also consist of an increased chlorophyll production. The alterations in chlorophyll concentration among the seedlings originating from different altitudes showed that response of Norway spruce to an enhanced UV-B irradiation depends on the altitude of origin.

4

Impact of ultraviolet-B radiation on two species of forest dwarf shrubs : bilberry (Vaccinium myrtillus L.) and cowberry (Vaccinium vitis-idaea L.)

Robakowski P.

Polish Journal of Ecology

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1999

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Vol. 47, no 1

3-13

EN

Impact of UV-B irradiation on chlorophyll content and chlorophyll fluorescence of two dwarf shrub species: Vaccinium myrtillus L. and Vaccinium vitis-idaea L. was investigated. The plants originating from different latitudes were used. The experiment was carried in the greenhouse. Three variants of ultraviolet-B irradiation were applied = O, lower dose = 11.32 and higher dose = 22.64 kJ m^-2 day^-1 UV-B[BE] (biologically effective dose of UV-B). Measurements of chlorophyll fluorescence and chlorophyll content were carried out. The response of dwarf shrubs to the increased UV-B radiation depended on UV-B dose, species traits and provenance. Vaccinium vitis-idaea was less sensitive to UV-B than Vaccinium myrtillus. The permanent discoloration was observed only on Vaccinium myrtillus leaves. The leaf bud brea of this species was accelerated at high UV-B dose compared to the control. The UV-B radiation influenced its photosynthetic apparatus: the chlorophyll content in leaves was reduced, the maximal and the steady state fluorescence of chlorophyll were diminished. The chlorophyll content in leaves of Vaccinium vitis-idaea did not change significantly but the relative vitality index and the steady state fluorescence were modified under the influence of the radiation.