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  • 1
    Electronic Resource
    Electronic Resource
    Scientists need back-up by climate organizations (2005)
    [s.l.] : Nature Publishing Group
    Nature 435 (2005), S. 413-413 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sir George Monbiot and the other authors of the Correspondence letter “Time to speak up for climate-change science” (Nature 434, 559; 200510.1038/434559a) call on climate scientists to defend the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/435413a
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  • 2
    Electronic Resource
    Electronic Resource
    In deep shade, elevated CO2 increases the vigor of tropical climbing plants (2002)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 8 (2002), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Climbing plants have profound influences on tropical forest dynamics and may take particular advantage from atmospheric CO2 enrichment, thus potentially enhancing tree turnover. Here we test the effect of a four-step CO2-enrichment on growth of three typical Yucatan (Mexico) climbers, across two low photon flux densities, representing typical understory situations. In pairs of two, species of Gonolobus (Asclepiadaceae), Ceratophytum (Bignoniaceae) and Thinouia (Sapindaceae) were grown on Yucatan forest soil in growth cabinets, which simulated the diurnal climate variation. Biomass increased non-linearly in response to CO2 enrichment from 280 (preindustrial) to 420 ppm and 560 ppm, but then (700 ppm) leveled off. The relative effect of CO2-enrichment between the two lower (280–420 ppm) CO2 concentrations was 63% at low light (LL == 42 µmol m2−2 s2−1), compared to 37% at high light (HL = 87 µmol m2−2 s2−1). This overall response of species pairs was the combined effect of linear and non-linear responses of the individual species across CO2 treatments. Plant biomass was 61% larger in HL compared to LL. The species-specific response depended on the neighbor, a species grew with h, irrespective of plant size. Stem length increased, but not consistently across species and light conditions. Specific stem length (SSL, length per dry mass) declined non-linearly in all three species as CO2 concentration increased (more pronounced at LL than at HL). SLA (leaf area per unit leaf dry mass) became lower as CO2 concentration increased (more pronounced in HL). Enhanced vigor of climbers under elevated CO2 as documented here may accelerate tropical forest dynamics and lead to greater abundance of early succesional tree species. This could reduce forest carbon stocking in the long run.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2002.00533.x
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  • 3
    Electronic Resource
    Electronic Resource
    Thirty years of in situ tree growth under elevated CO2: a model for future forest responses? (1997)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 3 (1997), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Rising concentrations of atmospheric carbon dioxide have been predicted to stimulate the growth of forest trees. However, long-term effects on trees growing to maturity and to canopy closure while exposed to elevated CO2 have never been examined. We compared tree ring chronologies of Mediterranean Quercus ilex which have been continuously exposed to elevated CO2 (around 650 μmol mol–1) since they were seedlings, near two separate natural CO2 springs with those from trees at nearby ambient-CO2‘control’ sites. Trees grown under high CO2 for 30 years (1964–93) showed a 12% greater final radial stem width than those growing at the ambient-CO2 control sites. However, this stimulation was largely due to responses when trees were young. By the time trees were 25–30 y old the annual difference in tree ring width between low and high CO2 grown trees had disappeared. At any given tree age, elevated CO2 had a relatively greater positive effect on tree ring width in years with a dry spring compared to years with more rainfall between April and May. This indicates a beneficial effect of elevated CO2 on tree water relations under drought stress. Our data suggest that the early regeneration phase of forest stands can be accelerated in CO2-enriched atmospheres and that maximum biomass per land area may be reached sooner than under lower CO2 concentrations. In our study, high CO2 grown Q. ilex trees reached the same stem basal area at the age of 26 y as control trees at 29 y, i.e. three years earlier (faster turnover of carbon?). Reliable predictions of the future development of forests need to account for the variable responses of trees over their entire lifetime. Such responses to elevated CO2 can presently only be assessed at such unique field sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1997.00105.x
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  • 4
    Electronic Resource
    Electronic Resource
    System-level adjustments to elevated CO2 in model spruce ecosystems (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Global change biology 2 (1996), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Atmospheric carbon dioxide enrichment and increasing nitrogen deposition are often predicted to increase forest productivity based on currently available data for isolated forest tree seedlings or their leaves. However, it is highly uncertain whether such seedling responses will scale to the stand level. Therefore, we studied the effects of increasing CO2 (280, 420 and 560 μL L-1) and increasing rates of wet N deposition (0, 30 and 90 kg ha-1 y-1) on whole stands of 4-year-old spruce trees (Picea abies). One tree from each of six clones, together with two herbaceous understory species, were established in each of nine 0.7 m2 model ecosystems in nutrient poor forest soil and grown in a simulated montane climate for two years. Shoot level light-saturated net photosynthesis measured at growth CO2 concentrations increased with increasing CO2, as well as with increasing N deposition. However, predawn shoot respiration was unaffected by treatments. When measured at a common CO2 concentration of 420 μL L-1 37% down-regulation of photosynthesis was observed in plants grown at 560 μL CO2 L-1. Length growth of shoots and stem diameter were not affected by CO2 or N deposition. Bud burst was delayed, leaf area index (LAI) was lower, needle litter fall increased and soil CO2 efflux increased with increasing CO2. N deposition had no effect on these traits. At the ecosystem level the rate of net CO2 exchange was not significantly different between CO2 and N treatments. Most of the responses to CO2 studied here were nonlinear with the most significant differences between 280 and 420 μL CO2 L-1 and relatively small changes between 420 and 560 μL CO2 L-1. Our results suggest that the lack of above-ground growth responses to elevated CO2 is due to the combined effects of physiological down-regulation of photosynthesis at the leaf level, allometric adjustment at the canopy level (reduced LAI), and increasing strength of below-ground carbon sinks. The non-linearity of treatment effects further suggests that major responses of coniferous forests to atmospheric CO2 enrichment might already be under way and that future responses may be comparatively smaller.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.1996.tb00088.x
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  • 5
    Electronic Resource
    Electronic Resource
    Seed production and seed quality in a calcareous grassland in elevated CO2 (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: In diverse plant communities the relative contribution of species to community biomass may change considerably in response to elevated CO2. Along with species-specific biomass responses, reproduction is likely to change as well with increasing CO2 and might further accelerate shifts in species composition. Here, we ask if, after 5 years of CO2 exposure, seed production and seed quality in natural nutrient-poor calcareous grassland are affected by elevated CO2 (650 μL L−1 vs 360 μL L−1) and how this might affect long-term community dynamics. The effect of elevated CO2 on the number of flowering shoots (+ 24%, P 〈 0.01) and seeds (+ 29%, P = 0.06) at the community level was similar to above ground biomass responses in this year, suggesting that the overall allocation to sexual reproduction remained unchanged. Compared among functional groups of species we found a 42% increase in seed number (P 〈 0.01) of graminoids, a 33% increase (P = 0.07) in forbs, and no significant change in legumes (− 38%, n.s.) under elevated CO2. Large responses particularly of two graminoid species and smaller responses of many forb species summed up to the significant or marginally significant increase in seed number of graminoids and forbs, respectively. In several species the increase in seed number resulted both from an increase in flowering shoots and an increase in inflorescence size. In most species, seeds tended to be heavier (+ 12%, P 〈 0.01), and N-concentration of seeds was significantly reduced in eight out of 13 species. The fraction of germinating seeds did not differ between seeds produced in ambient and elevated CO2, but time to germination was significantly shortened in two species and prolonged in one species when seeds had been produced in elevated CO2. Results suggest that species specific increases in seed number and changes in seed quality will exert substantial cumulative effects on community composition in the long run.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00581.x
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  • 6
    Electronic Resource
    Electronic Resource
    Complementation cloning identifies CDG-IIc, a new type of congenital disorders of glycosylation, as a GDP-fucose transporter deficiency (2001)
    [s.l.] : Nature Publishing Group
    Nature genetics 28 (2001), S. 73-76 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Congenital disorders of glycosylation (CDG) comprise a rapidly growing group of inherited disorders in which glycosylation of glycoproteins is defective due to mutations in genes required for the assembly of lipid-linked oligosaccharides, their transfer to nascent glycoproteins (CDG-I) or the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/ng0501-73
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  • 7
    Electronic Resource
    Electronic Resource
    A simple method for testing leaf responses of tall tropical forest trees to elevated CO2 (1996)
    Springer
    Oecologia 107 (1996), S. 421-425 
    Details
    ISSN: 1432-1939
    Keywords: Canopy ; Carbohydrates ; Stomata ; Water relations ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of atmospheric CO2 enrichment on mature trees in their natural environment are largely unknown. Here we present a new, and inexpensive technique which can be used in situ to address some key physiological questions related to the CO2 problem. Small, light-weight cups mounted on the lower side of rigid leaves at the top of tall tropical forest trees were supplied with CO2-enriched air derived from a low-technology air mixing device utilizing forest floor CO2 evolution. We present the scientific rationale for such field experiments, technical details, an assessment of potential cup artifacts and first results illustrating effects of elevated CO2 on stomata and carbohydrate accumulation in the canopies of mature trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333930
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  • 8
    Electronic Resource
    Electronic Resource
    Biomass allocation and canopy development in spruce model ecosystems under elevated CO2 and increased N deposition (1997)
    Springer
    Oecologia 113 (1997), S. 104-114 
    Details
    ISSN: 1432-1939
    Keywords: Key words Leaf area index ; Litterfall ; Nitrogen content ; Picea abies ; Productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ecosystem-level experiments on the effects of atmospheric CO2 enrichment and N deposition on forest trees are urgently needed. Here we present data for nine model ecosystems of spruce (Picea abies) on natural nutrient-poor montane forest soil (0.7 m2 of ground and 350 kg weight). Each system was composed of six 7-year-old (at harvest) trees each representing a different genotype, and a herbaceous understory layer (three species). The model ecosystems were exposed to three different CO2 concentrations (280, 420, 560 μl l−1) and three different rates of wet N deposition (0, 30, 90 kg ha−1 year−1) in a simulated annual course of Swiss montane climate for 3 years. The total ecosystem biomass was not affected by CO2 concentration, but increased with increasing N deposition. However, biomass allocation to roots increased with increasing CO2 leading to significantly lower leaf mass ratios (LMRs) and leaf area ratios (LARs) in trees grown at elevated CO2. In contrast to CO2 enrichment, N deposition increased biomass allocation to the aboveground plant parts, and thus LMR and LAR were higher with increasing N deposition. We observed no CO2 ×  N interactions on growth, biomass production, or allocation, and there were also no genotype × treatment interactions. The final leaf area index (LAI) of the spruce canopies was 19% smaller at 420 and 27% smaller at 560 than that measured at 280 μl CO2 l−1, but was not significantly altered by increasing N deposition. Lower LAIs at elevated CO2 largely resulted from shorter branches (less needles per individual tree) and partially from increased needle litterfall. Independently of N deposition, total aboveground N content in the spruce communities declined with increasing CO2 (−18% at 420 and −31% at 560 compared to 280 μl CO2 l−1). N deposition had the opposite effect on total above ground N content (+18% at 30 and +52% at 90 compared to 0 kg N ha−1 year−1). Our results suggest that under competitive conditions on natural forest soil, atmospheric CO2 enrichment may not lead to higher ecosystem biomass production, but N deposition is likely to do so. The reduction in LAI under elevated CO2 suggests allometric down-regulation of photosynthetic carbon uptake at the canopy level. The strong decline in the tree nitrogen mass per unit ground area in response to elevated CO2 may indicate CO2-induced reductions of soil N availability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050358
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of elevated CO2 and phosphorus addition on productivity and community composition of intact monoliths from calcareous grassland (1998)
    Springer
    Oecologia 116 (1998), S. 50-56 
    Details
    ISSN: 1432-1939
    Keywords: Key words Carbon dioxide ; Diversity ; Biomass ; Fertilization ; Legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigated the effects of elevated CO2 (600 μl l−1 vs 350 μl l−1) and phosphorus supply (1 g P m−2 year−1 vs unfertilized) on intact monoliths from species-rich calcareous grassland in a greenhouse. Aboveground community dry mass remained almost unaffected by elevated CO2 in the first year (+6%, n.s.), but was significantly stimulated by CO2 enrichment in year two (+26%, P〈0.01). Among functional groups, only graminoids contributed significantly to this increase. The effect of phosphorus alone on community biomass was small in both years and marginally significant only when analyzed with MANOVA (+6% in year one, +9% in year two, 0.1 ≥P 〉 0.05). Belowground biomass and stubble after two seasons were not different in elevated CO2 and when P was added. The small initial increase in aboveground community biomass under elevated CO2 is explained by the fact that some species, in particular Carex flacca, responded very positively right from the beginning, while others, especially the dominant Bromus erectus, responded negatively to CO2 enrichment. Shifts in community composition towards more responsive species explain the much larger CO2 response in the second year. These shifts, i.e., a decline in xerophytic elements (B. erectus) and an increase in mesophytic grasses and legumes occurred independently of treatments in all monoliths but were accelerated significantly by elevated CO2. The difference in average biomass production at elevated compared to ambient CO2 was higher when P was supplied (at the community level the CO2 response was enhanced from 20% to 33% when P was added, in graminoids from 17% to 27%, in legumes from 4% to 60%, and in C. flacca from 120% to 298% by year two). Based on observations in this and similar studies, we suggest that interactions between CO2 concentration, species presence, and nutrient availability will govern community responses to elevated CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050562
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  • 10
    Electronic Resource
    Electronic Resource
    Nutrient relations in calcareous grassland under elevated CO2 (1998)
    Springer
    Oecologia 116 (1998), S. 67-75 
    Details
    ISSN: 1432-1939
    Keywords: Key words Dinitrogen fixation ; Plant functional types ; legumes ; Nutrient limitation ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant nutrient responses to 4 years of CO2 enrichment were investigated in situ in calcareous grassland. Beginning in year 2, plant aboveground C:N ratios were increased by 9% to 22% at elevated CO2 (P 〈 0.01), depending on year. Total amounts of N removed in biomass harvests during the first 4 years were not affected by elevated CO2 (19.9 ± 1.3 and 21.1 ± 1.3 g N m−2 at ambient and elevated CO2), indicating that the observed plant biomass increases were solely attained by dilution of nutrients. Total aboveground P and tissue N:P ratios also were not altered by CO2 enrichment (12.5 ± 2 g N g−1 P in both treatments). In contrast to non-legumes (〉98% of community aboveground biomass), legume C/N was not reduced at elevated CO2 and legume N:P was slightly increased. We attribute the less reduced N concentration in legumes at elevated CO2 to the fact that virtually all legume N originated from symbiotic N2 fixation (%Ndfa ≈ 90%), and thus legume growth was not limited by soil N. While total plant N was not affected by elevated CO2, microbial N pools increased by +18% under CO2 enrichment (P = 0.04) and plant available soil N decreased. Hence, there was a net increase in the overall biotic N pool, largely due increases in the microbial N pool. In order to assess the effects of legumes for ecosystem CO2 responses and to estimate the degree to which plant growth was P-limited, two greenhouse experiments were conducted, using firstly undisturbed grassland monoliths from the field site, and secondly designed `microcosm' communities on natural soil. Half the microcosms were planted with legumes and half were planted without. Both monoliths and microcosms were exposed to elevated CO2 and P fertilization in a factored design. After two seasons, plant N pools in both unfertilized monoliths and microcosm communities were unaffected by CO2 enrichment, similar to what was found in the field. However, when P was added total plant N pools increased at elevated CO2. This community-level effect originated almost solely from legume stimulation. The results suggest a complex interaction between atmospheric CO2 concentrations, N and P supply. Overall ecosystem productivity is N-limited, whereas CO2 effects on legume growth and their N2 fixation are limited by P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050564
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