Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Tree root and soil heterotrophic respiration as revealed by girdling of boreal Scots pine forest: extending observations beyond the first year (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Limitations in available techniques to separate autotrophic (root) and soil heterotrophic respiration have hampered the understanding of forest C cycling. The former is here defined as respiration by roots, their associated mycorrhizal fungi and other micro-organisms in the rhizosphere directly dependent on labile C compounds leaked from roots. In order to separate the autotrophic and heterotrophic components of soil respiration, all Scots pine trees in 900 m2 plots were girdled to instantaneously terminate the supply of current photosynthates from the tree canopy to roots. Högberg et al. (Nature 411, 789–792, 2001) reported that autotrophic activity contributed up to 56% of total soil respiration during the first summer of this experiment. They also found that mobilization of stored starch (and likely also sugars) in roots after girdling caused an increased apparent heterotrophic respiration on girdled plots. Herein a transient increase in the δ13C of soil CO2 efflux after girdling, thought to be due to decomposition of 13C-enriched ectomycorrhizal mycelium and root starch and sugar reserves, is reported. In the second year after girdling, when starch reserves of girdled tree roots were exhausted, calculated root respiration increased up to 65% of total soil CO2 efflux. It is suggested that this estimate of its contribution to soil respiration is more precise than the previous based on one year of observation. Heterotrophic respiration declined in response to a 20-day-long 6 °C decline in soil temperature during the second summer, whereas root respiration did not decline. This did not support the idea that root respiration should be more sensitive to variations in soil temperature. It is suggested that above-ground photosynthetic activity and allocation patterns of recent photosynthates to roots should be considered in models of responses of forest C balances to global climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.01053.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Nitrate nutrition ofDeschampsia flexuosa (L.) Trin. in relation to nitrogen deposition in Sweden (1991)
    Springer
    Oecologia 87 (1991), S. 488-494 
    Details
    ISSN: 1432-1939
    Keywords: Deschampsia flexuosa ; Nitrate ; Nitrate reductase ; Nitrogen deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Current and maximally induced nitrate reductase activity (NRA), total-N, nitrate, K, P, Ca, Mg, Mo and sucrose in leaves ofDeschampsia flexuosa was measured three times during the vegetation period in forests along a deposition gradient (150 km) in south Sweden, in north Sweden where the nitrogen deposition is considerably lower, and at heavily N-fertilized plots. In addition, the interaction between nitrogen nutrition and light was studied along transects from clearings into forest in both south and north Sweden. Plants from sites with high nitrogen deposition had elevated current NRA compared to plants from less polluted sites, indicating high levels of available soil nitrate at the former. Current NRA and total N concentration in grass from sites with high deposition resembled those found at heavily N-fertilized plots. Under such circumstances, the ratio current NRA: maximally induced NRA as well as the concentration of nitrate was high, while the concentration of sucrose was low. This suggests that the grass at these sites was already utilizing a large portion of its capacity to assimilate nitrate. Light was found to play an important role in the assimilation of nitrate; leaf concentration of sucrose was found to be negatively correlated with both nitrate and total N. Consequently, grass growing under dense canopies in south Sweden is not able to dilute N by increasing growth. The diminished capacity of the grass to assimilate nitrate will increase leaching losses of N from forests approaching N saturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Tree fallows: A comparison between five tropical tree species (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 50-56 
    Details
    ISSN: 1432-0789
    Keywords: Agroforestry ; 15N ; Nitrogen fixation ; Phenolics ; 13C ; Tree fallows
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The natural abundance of 15N and 13C, conventional soil analyses, and biomass production by maize were used to study the influence of five tropical tree species on soils and their fertility. The experiment was conducted in Morogoro, Tanzania, to compare Cassia (Senna) siamea, Eucalyptus camaldulensis, E. tereticornis (all non-N2-fixing), Leucaena leucocephala, Prosopis chilensis (both N2-fixing), and a grass fallow. Maize biomass production, which was correlated with N uptake (P=0.001), was higher on soils from plots with 5-year-old Leucaena and Prosopis spp. compared to the grass fallow, while other tree species had less favourable effects on maize growth. The per cent N was higher in soil and δ15N of soil total N was lower under Prosopis sp. compared to soil under other tree species, which suggests an input from N2 fixation by Prosopis sp. A transfer of fixed N to maize or to understorey grass species was, however, not indicated by the 15N natural abundance. Prosopis sp. contributed more C to the soil than the other four tree species; the difference in δ13C between soils from Prosopis sp. plots and from grass fallow plots showed that the tree contributed 11% to the total C of the soil over a period of 8 years. The leaves of the N2-fixing species had a low ratio of lignin+phenols to N, and maize growth was negatively correlated with this parameter. The Eucalyptus spp. had leaves with a high lignin+phenols to N ratio, contributed very little C to the soil, and lowered the soil pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335818
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Tree fallows: A comparison between five tropical tree species (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 50-56 
    Details
    ISSN: 1432-0789
    Keywords: Key words Agroforestry ; 15N ; Nitrogen fixation ; Phenolics ; 13C ; Tree fallows
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The natural abundance of 15N and 13C, conventional soil analyses, and biomass production by maize were used to study the influence of five tropical tree species on soils and their fertility. The experiment was conducted in Morogoro, Tanzania, to compare Cassia (Senna) siamea, Eucalyptus camaldulensis, E. tereticornis (all non-N2-fixing), Leucaena leucocephala, Prosopis chilensis (both N2-fixing), and a grass fallow. Maize biomass production, which was correlated with N uptake (P=0.001), was higher on soils from plots with 5-year-old Leucaena and Prosopis spp. compared to the grass fallow, while other tree species had less favourable effects on maize growth. The per cent N was higher in soil and δ15N of soil total N was lower under Prosopis sp. compared to soil under other tree species, which suggests an input from N2 fixation by Prosopis sp. A transfer of fixed N to maize or to understorey grass species was, however, not indicated by the 15N natural abundance. Prosopis sp. contributed more C to the soil than the other four tree species; the difference in δ13C between soils from Prosopis sp. plots and from grass fallow plots showed that the tree contributed 11% to the total C of the soil over a period of 8 years. The leaves of the N2-fixing species had a low ratio of lignin+phenols to N, and maize growth was negatively correlated with this parameter. The Eucalyptus spp. had leaves with a high lignin+phenols to N ratio, contributed very little C to the soil, and lowered the soil pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335818
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Steady-state, O2-deficit and O2-debt at severe work (1950)
    Springer
    European journal of applied physiology 14 (1950), S. 251-254 
    Details
    ISSN: 1439-6327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The O2-uptake during running at different speed between 10 and 20 km/hour on a horizontal treadmill has been compared. A straight lined increase in O2-uptake with increasing speed was found. Determinations of O2-deficit and O2-debt showed, however, that the total energy output did not follow that line. At high speed the energy output showed a steep increase. The explanation for this is apparently that at high speed a significant part of energy has to be delivered by anaerobic processes involving low efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00933842
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The efficiency of anaerobical work (1950)
    Springer
    European journal of applied physiology 14 (1950), S. 249-250 
    Details
    ISSN: 1439-6327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The efficiency of severe work of different length has been studied. The results show that the efficiency of anaerobic work is only 50 p. c. of the efficiency of aerobic work. The consequences as far as professional work and athletic performances are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00933841
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Physiology of skiing (1950)
    Springer
    European journal of applied physiology 14 (1950), S. 292-303 
    Details
    ISSN: 1439-6327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During skiing a maximum O2-uptake of 5,2l/min was recorded with a trained student as a subject; with two other élite skiers 5 liters O2 per minute was found. A trained female subject showed an O2-intake of 4,17l/min and an other female subject had an O2-intake of 64,5 cc/min/kg body weight, presumably the highest values ever recorded in women. In connection with ski competitions youngsters had often pulse values above 250 beats per minute. The maximum values recorded were as high as 270. Proteinuria occurred practically in all subjects and erythrocytes were found in 28% of the urines of trained skiers after competitions. Skiing is the most economical and fastest way of transportation on snow, but even at a relatively low speed the energy output is high. We want to express our sincere thanks to the Swedish Sport Association (Riksidrottsförbundet) for financial support and to every body who assisted us during the experiments, especially the skiers, who acted as subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00933847
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Variations in 15N abundance in a forest fertilization trial: Critical loads of N, N saturation, contamination and effects of revitalization fertilization (1992)
    Springer
    Plant and soil 142 (1992), S. 211-219 
    Details
    ISSN: 1573-5036
    Keywords: 15N ; forest decline ; nitrogen deposition ; revitalization fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 15N abundances of current needles of Norway spruce collected during 23 yrs of a forest fertilization experiment were studied in order to follow ecosystem gains and losses of N. Unlabelled ammonium nitrate at four rates (N0–N3), phosphorus at three rates (P0–P2), and potassium plus other elements including micronutrients at two rates (K0–K1), had been applied to plots in a complete factorial design. Nitrogen had been applied annually at average rates of 0, 34, 68 and 102 kg N ha-1 yr-1. Tree growth had responded positively to additions of N, but the response was remarkably more positive to the N2P2K1 treatment. In N1 treatments, δ15N (‰) declined over time. This was consistent with an earlier study, and should reflect a change in 15N abundance towards that of fertilizer N (minus discrimination during uptake), which in turn means accretion of most of the N added. As in the earlier study, in which N3 plots lost most of the N added, the present N3 plots showed an increasing δ15N (‰). This pattern was not significantly affected by additions of P and K plus other elements, although a weak negative effect of P on N accretion was indicated, i.e. there was a tendency δ15N (‰) to be higher when P was added. This, and another recent result based on an N budget, shows that so-called revitalization fertilization may well increase growth of trees, but also promotes losses of N from the ecosystem. As in the previous study, a decline in δ15N (‰) on control plots provided evidence of contamination. Given a removal of 100 kg N ha-1 at stem harvest and a leaching of 2 kg N ha-1 yr-1, our data on 15N suggest that a load of 9 kg N ha-1 yr-1 would saturate the ecosystem after 100 years. This load is only about twice the annual deposition at the site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010967
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Retention of Nitrogen by a Nitrogen-Loaded Scotch Pine Forest (1999)
    Springer
    Soil Science Society of America journal 63 (1999), S. 383-389 
    Details
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Pinus sylvestris L.) forest that had received two decades of annual additions of N as NH4NO3 at four rates (N0-N3, equivalent to 0, 36, 72, and 108 kg N ha-1 yr-1), with and without supplementary additions of P and K. The highest N treatment (N3) was suspended three years before this study. Leaching of inorganic N was measured beneath lysimeters with and without living tree roots inside them, and the fate of 15N injected into the mor layer was traced by sampling understory vegetation, soil to 20-cm depth, and leachates. Leaching of inorganic N increased with increasing N dose and was dominated by NO- 3on plots to which N had been added. In the suspended N3 treatment, leaching of N was lower than in the N2 treatment. The presence of tree roots greatly reduced leaching of N. the occurrence of labeled NO- 3 under lysimeter to which labeled NH+ 4 had been added showed that nitrification was important in treatment N2, but not in N1, suggesting that additions of 〉 30 kg N ha-1 yr-1 are needed to induce larger net nitrification at this site. Our data showed (i) that trees were an important sink for N, (ii) that additions of P and K had a marginal positive effect on N retention, and (iii) that leaching from previously N-loaded forest rapidly decreased when the N load was removed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The vertical distribution of fine roots of five tree species and maize in Morogoro, Tanzania (1988)
    Springer
    Agroforestry systems 6 (1988), S. 63-69 
    Details
    ISSN: 1572-9680
    Keywords: agroforestry ; fine root biomass ; root competition ; root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to assess the possibility of root competition in agroforestry, the vertical distribution of fine roots (〈 2 mm in diameter) of five tree species in pure two-year-old stands was compared to that of mature maize.Cassia siamea, Eucalyptus tereticornis, Leucaena leucocephala andProsopis chilensis had a rooting pattern similar to that of maize, i.e. a slow decline in fine root mass from 0–100 cm soil depth.Eucalyptus camaldulensis had its roots evenly distributed down to 100 cm. On an average, the fine root biomass of the tree species was roughly twice as that of the maize. We conclude that the studied tree species are likely to compete with maize and other crops with a similar rooting pattern for nutrients and water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...