ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    The growth respiration component in eddy CO2 flux from a Quercus ilex mediterranean forest (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Ecosystem respiration, arising from soil decomposition as well as from plant maintenance and growth, has been shown to be the most important component of carbon exchange in most terrestrial ecosystems. The goal of this study was to estimate the growth component of whole-ecosystem respiration in a Mediterranean evergreen oak (Quercus ilex) forest over the course of 3 years. Ecosystem respiration (Reco) was determined from night-time carbon dioxide flux (Fc) using eddy correlation when friction velocity (u*) was greater than 0.35 m s−1We postulated that growth respiration could be evaluated as a residual after removing modeled base Reco from whole-ecosystem Reco during periods when growth was most likely occurring. We observed that the model deviated from the night-time Fc-based Reco during the period from early February to early July with the largest discrepancies occurring at the end of May, coinciding with budburst when active aboveground growth and radial growth increment are greatest. The highest growth respiration rates were observed in 2001 with daily fluxes reaching up to 4 g C m−2. The cumulative growth respiration for the entire growth period gave total carbon losses of 170, 208, and 142 g C m−2 for 1999, 2001, and 2002, respectively. Biochemical analysis of soluble carbohydrates, starch, cellulose, hemicellulose, proteins, lignin, and lipids for leaves and stems allowed calculation of the total construction costs of the different growth components, which yielded values of 154, 200, and 150 g C for 3 years, respectively, corresponding well to estimated growth respiration. Estimates of both leaf and stem growth showed very large interannual variation, although average growth respiration coefficients and average yield of growth processes were fairly constant over the 3 years and close to literature values. The time course of the growth respiration may be explained by the growth pattern of leaves and stems and by cambial activity. This approach has potential applications for interpreting the effects of climate variation, disturbances, and management practices on growth and ecosystem respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2004.00819.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Carbon-based secondary and structural compounds in Mediterranean shrubs growing near a natural CO2 spring (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: We studied carbon-based secondary and structural compounds (CBSSCs) in Myrtus communis, Erica arborea, and Juniperus communis co-occurring in a natural CO2 spring site and in a nearby control site in a Mediterranean environment. Leaf concentrations of phenolics and CBSSCs, such as lignin, cellulose, and hemicellulose, total nonstructural carbohydrates (TNCs), and lipids were measured monthly (phenolics) and every two months (the other compounds) throughout a year. There was a slight seasonal trend towards maximum concentrations of most of these CBSSCs during autumn–winter and minimum values during the spring season, particularly in Myrtus communis. For most of the CBSSCs and species, there were no consistent or significant patterns in response to the elevated [CO2] (c. 700 μmol mol−1) of the spring site. These results were not due to a dilution effect by increased structural or nonstructural carbon. Therefore, in contrast to many experimental studies of CO2 enrichment, mainly conducted for short periods, there were no greater concentrations of phenolics, and, as in many of these studies, there were neither greater concentrations of the other CBSSCs. These results do not agree with the predictions of the carbon source-sink hypotheses. Possible causes of this disagreement are discussed. These causes include the complex heterogeneous environmental conditions and the variability of resource availabilities in the field, photosynthetic down-regulation, and/or the homeostatic and evolutionary nature of organisms. These results suggest evolutionary adaptive responses to changes in CO2. They also suggest caution in attributing increased CBSSC concentrations to elevated [CO2] at long-term scale in natural conditions, and therefore in their implications for plant–herbivore interactions and for decomposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2002.00466.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The dehesa system of southern Spain and Portugal as a natural ecosystem mimic (1999)
    Springer
    Agroforestry systems 45 (1999), S. 57-79 
    Details
    ISSN: 1572-9680
    Keywords: hydrological equilibrium ; Mediterranean climate ; optimality ; Quercus ilex ; Quercus suber ; water balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dehesas of the southwestern Iberian Peninsula are 'man-made' ecosystems characterised by a savannah-like physiognomy. The trees are viewed as an integrated part of the system, and as a result are planted, managed, and regularly pruned. Palynological and historical evidence of the manipulation of initial ecosystems by man to obtain a savannah-like ecosystem is presented. The ecological functions of the tree are detailed using results obtained at two complementary scales. At the local scale, strong soil structural differences and functional differences in water budget and patterns of water use are observed under and outside the tree canopy. Using the concept of ecosystem mimicry, the two coexistent components of dehesas can be compared to two distant stages of a secondary succession characterised by very different behaviours. At the regional scale, evidence of relationships between tree density and mean annual precipitation over more than 5000 km2 suggests that the structure of these man-made agroecosystems have adjusted over the long-term and correspond to an optimal functional equilibrium based on the hydrological equilibrium hypothesis. Finally, the future of dehesas in the face of contemporary exogenous threats of economic and global environmental origin is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006259402496
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Between-tree variations in leaf δ13C of Quercus pubescens and Quercus ilex among Mediterranean habitats with different water availability (1997)
    Springer
    Oecologia 111 (1997), S. 26-35 
    Details
    ISSN: 1432-1939
    Keywords: Key words Mediterranean oaks  ;  Carbon isotope composition  ;  Water availability  ;  Foliar chemical constituents  ;  Tree structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, sun leaf carbon isotope composition (δ13C) of two co-occurring woody Mediterranean species (Quercus pubescens Willd., a deciduous oak, and Q. ilex L., an evergreen one) was investigated on four sites with different water availability. The total range of δ13C values was 4.4 and 3.1‰ for Q. pubescens and Q. ilex respectively. The intra-site variability was about 3‰. Total mean per species was equal. There were significant differences among sites, but at each site means of δ13C were not significantly different between species. A simple physiological model predicts no difference in intrinsic water-use efficiency (WUEi) between evergreen and deciduous oaks. The relationship between site means of δ13C and water parameters suggests that there is a leaf functional adjustment with respect to available water resource. No correlation was found between δ13C and the contents of any mass-based biochemical constituent. Nevertheless there was a significant correlation between δ13C and leaf mass per area of Q. ilex. For both species, there is also a positive correlation between leaf δ13C and individual crown area, i.e. a structural characteristic at tree level. Causal relations between δ13C and plant-environment interactions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Plant and soil nitrogen dynamics in mediterranean grasslands: a comparison of annual and perennial grasses (1990)
    Springer
    Oecologia 85 (1990), S. 142-149 
    Details
    ISSN: 1432-1939
    Keywords: Grassland ; Perennial ; Annual ; Nitrogen uptake ; Nitrogen mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The predominance of annual species in the rangelands of southwestern Spain is not due only to climatic factors but is also strongly influenced by grazing management. Manipulating the grazing system in an experimental plot gave a vegetation structure with patches of annual grasses (mainly Vulpia ssp. and Bromus hordeaceus) and patches of perennial grasses (mainly Phalaris aquatica). This vegetation change allowed us to test the hypothesis that life-cycle differences between annual and perennial grasses affect soil nitrogen availability and plant uptake. Nitrogen availability, measured by in situ incubation, and nitrogen uptake were measured through the growing period (October to June). Amounts of in situ mineralized nitrogen over the whole growth phase were more important for soils supporting perennials (37 ppm) than for soils supporting annuals (27 ppm). The difference between the mineral nitrogen produced in situ and the mineral nitrogen accumulated during the same time in the soil allowed an estimation of the maximum mineral nitrogen quantity which can be taken up by the vegetation during each incubation period. The quantities accumulated over the year were 47 and 38 ppm (or 103 and 83 kg/ha) for soils supporting perennials and annuals respectively. For the same period, amounts of nitrogen immobilized in biomass production were 90 and 70 kg/ha for perennials and annuals respectively. During the autumn, a large proportion of mineral nitrogen was leached from soils supporting annual plants which had only just commenced germination. By contrast, the ability to use mineral nitrogen as soon as autumn rains occurred gave a competitive advantage to the perennial species, but only if they were protected from grazing during this period. The higher mineralization and use of this nitrogen reserve by perennials indicates that they made more efficient use of nitrogen resources than annuals, and validate the initial hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317355
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Remote Sensing of Canopy Photosynthetic Performances: Two Complementary Ways for Assessing the Photochemical Reflectance Index (1999)
    Springer
    Photosynthetica 37 (1999), S. 239-247 
    Details
    ISSN: 1573-9058
    Keywords: chlorophyll fluorescence ; diurnal courses ; Ficus altissima ; Medicago sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two methods have been developed concurrently for hyperspectral measurements of plant canopy reflectance in two narrow wavelength bands centred around 531 and 570 nm. A laboratory-built two-channel radiometer provided an easy and quick estimation of the Photochemical Reflectance Index PRI = (R531 − R570)/(R570 + R531) of a plot of alfalfa. A CCD digital camera provided multispectral imaging and the analysis of this index on the same target. The two devices are complementary. The results of measurements are complementary with those of chlorophyll fluorescence induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007143322043
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    facet.materialart.
    Unknown
    Intraspecific variability of monoterpene composition emitted by Quercus ile× leaves (2001)
    Canadian Science Publishing
    Details
    Publication Date: 2001-01-01
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    How reliable are methods to assess xylem vulnerability to cavitation? The issue of 'open vessel' artifact in oaks (2014)
    Oxford University Press
    Details
    Publication Date: 2014-09-04
    Description: Three methods are in widespread use to build vulnerability curves (VCs) to cavitation. The bench drying (BD) method is considered as a reference because embolism and xylem pressure are measured on large branches dehydrating in the air, in conditions similar to what happens in nature. Two other methods of embolism induction have been increasingly used. While the Cavitron (CA) uses centrifugal force to induce embolism, in the air injection (AI) method embolism is induced by forcing pressurized air to enter a stem segment. Recent studies have suggested that the AI and CA methods are inappropriate in long-vesselled species because they produce a very high-threshold xylem pressure for embolism (e.g., P 50 ) compared with what is expected from (i) their ecophysiology in the field (native embolism, water potential and stomatal response to xylem pressure) and (ii) the P 50 obtained with the BD method. However, other authors have argued that the CA and AI methods may be valid because they produce VCs similar to the BD method. In order to clarify this issue, we assessed VCs with the three above-mentioned methods on the long-vesselled Quercus ilex L. We showed that the BD VC yielded threshold xylem pressure for embolism consistent with in situ measurements of native embolism, minimal water potential and stomatal conductance. We therefore concluded that the BD method provides a reliable estimate of the VC for this species. The CA method produced a very high P 50 (i.e., less negative) compared with the BD method, which is consistent with an artifact related to the vessel length. The VCs obtained with the AI method were highly variable, producing P 50 ranging from –2 to –8.2 MPa. This wide variability was more related to differences in base diameter among samples than to differences in the length of samples. We concluded that this method is probably subject to an artifact linked to the distribution of vessel lengths within the sample. Overall, our results indicate that the CA and the AI should be used with extreme caution on long-vesselled species. Our results also highlight that several criteria may be helpful to assess the validity of a VC.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Rain-fed agriculture thrived despite climate degradation in the pre-Hispanic arid Andes (2017)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2017-12-21
    Description: Archaeological research suggests significant human occupation in the arid Andean highlands during the 13th to 15th centuries, whereas paleoclimatic studies reveal prolonged drier and colder conditions during that period. Which subsistence strategy supported local societies in this harsh environment? Our field and aerial surveys of archaeological dwelling sites, granaries, and croplands provide the first evidence of extended pre-Hispanic agriculture supporting dense human populations in the arid Andes of Bolivia. This unique agricultural system associated with quinoa cultivation was unirrigated, consisting of simple yet extensive landscape modifications. It relied on highly specific environmental knowledge and a set of water-saving practices, including microterracing and biennial fallowing. This intense agricultural activity developed during a period of unfavorable climatic change on a regional and global scale, illustrative of efficient adaptive strategies to cope with this climatic change.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Optimization of carbon gain in canopies of Mediterranean evergreen oaks (1996)
    EDP Sciences
    Details
    Publication Date: 1996-01-01
    Print ISSN: 0003-4312
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by EDP Sciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...