Труды сотрудников ИЛ им. В.Н. Сукачева СО РАН

[Text] / M. . Slot [et al.] // Tree Physiol. - 2005. - Vol. 25, Is. 9. - P1139-1150. - Cited References: 37 . - 12. - ISSN 0829-318XРУБ Forestry

Аннотация: Regeneration patterns of Pinus sylvestris L. juveniles in central Siberian glades were studied in relation to cold-induced photoinhibition. Spatial distribution of seedlings in different height classes revealed higher seedling densities beneath the canopy than beyond the canopy, and significantly higher densities of seedlings < 50 cm tall on the north side of the trees. These patterns coincided with differences in light conditions. Compared with plants on the north side of canopy trees (north-exposed), photosynthetic photon flux (PPF) received by plants on the south side of canopy trees (south-exposed) was always higher, making south-exposed plants more susceptible to photoinhibition, especially on cool mornings. Chlorophyll fluorescence data revealed lower photochemical efficiency and increased non-photochemical quenching of small (20-50 cm in height), south-exposed seedlings from spring to early autumn, indicating increased excitation pressure on photosynthesis. Maximum rate of oxygen evolution was less in south-exposed plants than in north-exposed plants. Increased pools of xanthophyll cycle pigments and formation of the photoprotective zeaxanthin provided further evidence for the higher susceptibility to photoinhibition of south-exposed seedlings. A linear mixed model analysis explained many of the physiological differences observed in seedlings according to height class and aspect with early morning temperature and PPF as predictors. The link between photoinhibition and differential distribution of seedlings by height class suggests that photoinhibition, together with other environmental stresses, decreases the survival of small, south-exposed P sylvestris seedlings, thereby significantly affecting the regeneration pattern of central Siberian pine glades.

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Держатели документа:
Univ Wageningen & Res Ctr, Forest Ecol & Forest Management Grp, NL-6700 AH Wageningen, Netherlands
Princeton Univ, Dept Ecol & Evolutionary Biol, Princeton, NJ 08544 USA
Russian Acad Sci, Inst Forest, Siberian Branch, Krasnoyarsk 660036, Russia
Max Planck Inst Biogeochem, D-07745 Jena, Germany

Доп.точки доступа:
Slot, M...; Wirth, C...; Schumacher, J...; Mohren, GMJ; Shibistova, O...; Lloyd, J...; Ensminger, I...

[Text] / I. . Ensminger [et al.] // Glob. Change Biol. - 2004. - Vol. 10, Is. 6. - P995-1008, DOI 10.1111/j.1365-2486.2004.00781.x. - Cited References: 57 . - 14. - ISSN 1354-1013РУБ Biodiversity Conservation + Ecology + Environmental Sciences

Аннотация: During winter and early spring, evergreen boreal conifers are severely stressed because light energy cannot be used when photosynthesis is pre-empted by low ambient temperatures. To study photosynthetic performance dynamics in a severe boreal climate, seasonal changes in photosynthetic pigments, chloroplast proteins and photochemical efficiency were studied in a Scots pine forest near Zotino, Central Siberia. In winter, downregulation of photosynthesis involved loss of chlorophylls, a twofold increase in xanthophyll cycle pigments and sustained high levels of the light stress-induced zeaxanthin pigment. The highest levels of xanthophylls and zeaxanthin did not occur during the coldest winter period, but rather in April when light was increasing, indicating an increased capacity for thermal dissipation of excitation energy at that time. Concomitantly, in early spring the D1 protein of the photosystem II (PSII) reaction centre and the light-harvesting complex of PSII dropped to their lowest annual levels. In April and May, recovery of PSII activity, chloroplast protein synthesis and rearrangements of pigments were observed as air temperatures increased above 0degreesC. Nevertheless, severe intermittent low-temperature episodes during this period not only halted but actually reversed the physiological recovery. During these spring low-temperature episodes, protective processes involved a complementary function of the PsbS and early light-induced protein thylakoid proteins. Full recovery of photosynthesis did not occur until the end of May. Our results show that even after winter cold hardening, photosynthetic activity in evergreens responds opportunistically to environmental change throughout the cold season. Therefore, climate change effects potentially improve the sink capacity of boreal forests for atmospheric carbon. However, earlier photosynthesis in spring in response to warmer temperatures is strongly constrained by environmental variation, counteracting the positive effects of an early recovery process.

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Max Planck Inst Biogeochem, D-07701 Jena, Germany
Umea Univ, Dept Plant Physiol, S-90187 Umea, Sweden
Mt Allison Univ, Sackville, NB E4L 1G7, Canada
Umea Univ, Dept Biochem, S-90187 Umea, Sweden
Russian Acad Sci, Inst Forest, Siberian Branch, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Ensminger, I...; Sveshnikov, D...; Campbell, D.A.; Funk, C...; Jansson, S...; Lloyd, J...; Shibistova, O...; Oquist, G...

[Text] / S. . Tanja [et al.] // Glob. Change Biol. - 2003. - Vol. 9, Is. 10. - P1410-1426, DOI 10.1046/j.1365-2486.2003.00597.x. - Cited References: 63 . - 17. - ISSN 1354-1013РУБ Biodiversity Conservation + Ecology + Environmental Sciences

Аннотация: The timing of the commencement of photosynthesis (P-*) in spring is an important determinant of growing-season length and thus of the productivity of boreal forests. Although controlled experiments have shed light on environmental mechanisms triggering release from photoinhibition after winter, quantitative research for trees growing naturally in the field is scarce. In this study, we investigated the environmental cues initiating the spring recovery of boreal coniferous forest ecosystems under field conditions. We used meteorological data and above-canopy eddy covariance measurements of the net ecosystem CO2 exchange (NEE) from five field stations located in northern and southern Finland, northern and southern Sweden, and central Siberia. The within- and intersite variability for P-* was large, 30-60 days. Of the different climate variables examined, air temperature emerged as the best predictor for P-* in spring. We also found that 'soil thaw', defined as the time when near-surface soil temperature rapidly increases above 0degreesC, is not a useful criterion for P-*. In one case, photosynthesis commenced 1.5 months before soil temperatures increased significantly above 0degreesC. At most sites, we were able to determine a threshold for air-temperature-related variables, the exceeding of which was required for P-*. A 5-day running-average temperature (T-5) produced the best predictions, but a developmental-stage model (S) utilizing a modified temperature sum concept also worked well. But for both T-5 and S, the threshold values varied from site to site, perhaps reflecting genetic differences among the stands or climate-induced differences in the physiological state of trees in late winter/early spring. Only at the warmest site, in southern Sweden, could we obtain no threshold values for T-5 or S that could predict P-* reliably. This suggests that although air temperature appears to be a good predictor for P-* at high latitudes, there may be no unifying ecophysiological relationship applicable across the entire boreal zone.

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Держатели документа:
Univ Helsinki, Dept Phys Sci, FIN-00014 Helsinki, Finland
Univ Helsinki, Dept Forest Ecol, FIN-00014 Helsinki, Finland
Dept Systemat & Ecol, FIN-00014 Helsinki, Finland
Finnish Meteorol Inst, FIN-00101 Helsinki, Finland
Swedish Univ Agr Sci, Dept Prod Ecol, SE-75007 Uppsala, Sweden
Lund Univ, Dept Phys Geog, SE-22100 Lund, Sweden
Max Planck Inst Biogeochem, D-07701 Jena, Germany
Russian Acad Sci, Siberian Branch, Inst Forest, Krasnoyarsk, Russia

Доп.точки доступа:
Tanja, S...; Berninger, F...; Vesala, T...; Markkanen, T...; Hari, P...; Makela, A...; Ilvesniemi, H...; Hanninen, H...; Nikinmaa, E...; Huttula, T...; Laurila, T...; Aurela, M...; Grelle, A...; Lindroth, A...; Arneth, A...; Shibistova, O...; Lloyd, J...