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  • Storage  (3)
  • Canopy conductance  (2)
  • Drosera  (2)
  • Heterosis  (2)
  • Hydraulic lift
  • Biomes
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Trees 1 (1987), S. 219-224 
    ISSN: 1432-2285
    Keywords: Larix ; Heterosis ; Photosynthesis ; Stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Individual 33-year-old forest trees of the deciduous conifer speciesLarix decidua, Larix leptolepis andLarix decidua x leptolepis were investigated with respect to the phenomenon of stem heterosis in hybrid larch; the first part of this study compares the gas exchange responses of leaves. CO2 assimilation per leaf area was similar in the three larch species, but on a dry weight basis the nitrogen content of the needles and maximum CO2 assimilation rate (Amax) were slightly higher in the hybrid. This increase was accompanied by a higher protein content than in the Japanese and a lower specific leaf weight than in the European larch. All three species were similar in terms of the photosynthetic “nitrogen use” and stomatal conductance atA max. The similar slopes of the area-related steady-state responses of gas exchange against irradiance, evaporative demand and internal CO2 concentration led to similar rates of CO2 uptake under ambient conditions. The natural combinations and variability of the environmental factors also reduced the small dry weight-related difference inA max between hybrid larch and the parent species, such that all trees achieved similar daily carbon gains. Thus, the ecological significance of small interspecific differences in the metabolism of leaves has very little effect under the natural habitat conditions of a temperate climate. The second part of the study will investigate the effect of growth characteristics on the heterosis of hybrid larch.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Trees 1 (1987), S. 225-231 
    ISSN: 1432-2285
    Keywords: Larix ; Heterosis ; Growth ; Branching pattern ; Needle density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Among 33-year-old forest trees ofLarix decidua, L. leptolepis andL. decidua x leptolepis, the hybrid possessed an above-ground biomass which was three times greater, although all larches displayed similar relative distributions of biomass. At a “relative growth rate” slightly lower than in the parent species, hybrid larch achieved twice the annual carbon gain, increment in stem length and above-ground production, and its foliage-related stem growth was higher than in European (L. decidua) but similar to Japanese (L. leptolepis) larch. A similar “relative growth efficiency” and foliage-related total above-ground production in all trees did reflect the similarity of photosynthetic capacity of the hybrid found at the leaf level. While the lengths of lateral twigs on hybrid branches were intermediate between the European larch with short, and the Japanese larch with large, twigs the hybrid possessed the longest branches with the highest needle biomass. This resulted in a crown structure of the hybrid crown similar to the Japanese larch together with a high needle density on branches as in the European larch. In total, the foliage biomass per crown length was about 30% higher in hybrid larch than in both of the parent species. Thus, the high carbon input for the stem heterosis was based on a “complementation principle” of advantageous parent features at the crown level. Similar slopes of foliage against sapwood area of stem and branches did not indicate a special need for a thick hybrid stem with respect to water transport.
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  • 3
    ISSN: 1432-1939
    Keywords: Key words Water transport ; Grass roots ; Hydraulic lift ; Deserts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Downward transport of water in roots, in the following termed “inverse hydraulic lift,” has previously been shown with heat flux techniques. But water flow into deeper soil layers was demonstrated in this study for the first time when investigating several perennial grass species of the Kalahari Desert under field conditions. Deuterium labelling was used to show that water acquired by roots from moist sand in the upper profile was transported through the root system to roots deeper in the profile and released into the dry sand at these depths. Inverse hydraulic lift may serve as an important mechanism to facilitate root growth through the dry soil layers underlaying the upper profile where precipitation penetrates. This may allow roots to reach deep sources of moisture in water-limited ecosystems such as the Kalahari Desert.
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  • 4
    ISSN: 1432-1939
    Keywords: Deep roots function ; Terrestrial vegetation ; Biomes ; Plant forms ; Root depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The depth at which plants are able to grow roots has important implications for the whole ecosystem hydrological balance, as well as for carbon and nutrient cycling. Here we summarize what we know about the maximum rooting depth of species belonging to the major terrestrial biomes. We found 290 observations of maximum rooting depth in the literature which covered 253 woody and herbaceous species. Maximum rooting depth ranged from 0.3 m for some tundra species to 68 m for Boscia albitrunca in the central Kalahari; 194 species had roots at least 2 m deep, 50 species had roots at a depth of 5 m or more, and 22 species had roots as deep as 10 m or more. The average for the globe was 4.6±0.5 m. Maximum rooting depth by biome was 2.0±0.3 m for boreal forest. 2.1±0.2 m for cropland, 9.5±2.4 m for desert, 5.2±0.8 m for sclerophyllous shrubland and forest, 3.9±0.4 m for temperate coniferous forest, 2.9±0.2 m for temperate deciduous forest, 2.6±0.2 m for temperate grassland, 3.7±0.5 m for tropical deciduous forest, 7.3±2.8 m for tropical evergreen forest, 15.0±5.4 m for tropical grassland/savanna, and 0.5±0.1 m for tundra. Grouping all the species across biomes (except croplands) by three basic functional groups: trees, shrubs, and herbaceous plants, the maximum rooting depth was 7.0±1.2 m for trees, 5.1±0.8 m for shrubs, and 2.6±0.1 m for herbaceous plants. These data show that deep root habits are quite common in woody and herbaceous species across most of the terrestrial biomes, far deeper than the traditional view has held up to now. This finding has important implications for a better understanding of ecosystem function and its application in developing ecosystem models.
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  • 5
    ISSN: 1432-1939
    Keywords: Carbohydrate ; Growth ; Nitrogen ; Phaseolus lunatus ; Storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth, photosynthesis, and storage of nitrogen (N) and total non-structural carbohydrates (TNC) of a perennial wild type and an annual cultivar of lima bean (Phaseolus lunatus) were examined at different light intensities and N supplies. Relative growth rate and photosynthesis increased with light and N availability. N limitation enhanced biomass allocation into root rather than into shoot, while light limitation enhanced growth of leaf area. The TNC concentrations increased with light intensity and thus with photosynthesis, while the concentrations of organic N and nitrate decreased. Increasing N supply had the opposite effect. Therefore, TNC and organic N concentrations were negatively correlated (r=−0.90). Pool size of N or TNC increased with N and light availability when either resource was non-limiting, but increased little or remained constant when either resource was limiting. Storage reached a minimum when both resources were supplied at an equal rate.
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  • 6
    ISSN: 1432-1939
    Keywords: Storage ; Accumulation ; Reserve formation ; Storage structure ; Biennial plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four biennial species (Arctium tomentosum, Cirsium vulgare, Dipsacus sylvester and Daucus carota) which originate from habitats of different nutrient availability were investigated in a 2-year experiment in a twofactorial structured block design varying light (natural daylight versus shading) and fertilizer addition. The experiment was designed to study storage as reserve formation (competing with growth) or as accumulation (see Chapin et al. 1990). We show that (i) the previous definitions of storage excluded an important process, namely the formation of storage tissue. Depending on species, storage tissue and the filling process can be either a process of reserve formation, or a process of accumulation. (ii) In species representing low-resource habitats, the formation of a storage structure competes with other growth processes. Growth of storage tissue and filling with storage products is an accumulation process only in the high-resource plant Arctium tomentosum. We interpret the structural growth of low-resource plants in terms of the evolutionary history of these species, which have closely related woody species in the Mediterranean area. (iii) The use of storage products for early leaf growth determines the biomass development in the second season and the competitive ability of this species during growth with perennial species. (iv) The high-resource plant Arctium has higher biomass development under all conditions, i.e. plants of low-resource habitats are not superior under low-resource conditions. The main difference between high- and low-resource plants is that low-resource plants initiate flowering at a lower total plant internal pool size of available resources.
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  • 7
    ISSN: 1432-1939
    Keywords: Canopy conductance ; Canopy transpiration ; Xylem sap flow ; Humidity response of stomatal ; Nothofagus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tree transpiration was determined by xylem sap flow and eddy correlation measurements in a temperate broad-leaved forest of Nothofagus in New Zealand (tree height: up to 36 m, one-sided leaf area index: 7). Measurements were carried out on a plot which had similar stem circumference and basal area per ground area as the stand. Plot sap flux density agreed with tree canopy transpiration rate determined by the difference between above-canopy eddy correlation and forest floor lysimeter evaporation measurements. Daily sap flux varied by an order of magnitude among trees (2 to 87 kg day−1 tree−1). Over 50% of plot sap flux density originated from 3 of 14 trees which emerged 2 to 5 m above the canopy. Maximum tree transpiration rate was significantly correlated with tree height, stem sapwood area, and stem circumference. Use of water stored in the trees was minimal. It is estimated that during growth and crown development, Nothofagus allocates about 0.06 m of circumference of main tree trunk or 0.01 m2 of sapwood per kg of water transpired over one hour. Maximum total conductance for water vapour transfer (including canopy and aerodynamic conductance) of emergent trees, calculated from sap flux density and humidity measurements, was 9.5 mm s−1 that is equivalent to 112 mmol m−2 s−1 at the scale of the leaf. Artificially illuminated shoots measured in the stand with gas exchange chambers had maximum stomatal conductances of 280 mmol m−2 s−1 at the top and 150 mmol m−2 s−1 at the bottom of the canopy. The difference between canopy and leaf-level measurements is discussed with respect to effects of transpiration on humidity within the canopy. Maximum total conductance was significantly correlated with leaf nitrogen content. Mean carbon isotope ratio was −27.76±0.27‰ (average ±s.e.) indicating a moist environment. The effects of interactions between the canopy and the atmosphere on forest water use dynamics are shown by a fourfold variation in coupling of the tree canopy air saturation deficit to that of the overhead atmosphere on a typical fine day due to changes in stomatal conductance.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 70 (1986), S. 466-474 
    ISSN: 1432-1939
    Keywords: Biennial plants ; Carbon partitioning ; Nitrogen partitioning ; Storage ; Harvest index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Growth and nitrogen partitioning were investigated in the biennial monocarp Arctium tomentosum in the field, in plants growing at natural light conditions, in plants in which approximately half the leaf area was removed and in plants growing under 20% of incident irradiation. Growth quantities were derived from splined cubic polynomial exponential functions fitted to dry matter, leaf area and nitrogen data. Main emphasis was made to understanding of the significance of carbohydrate and nitrogen storage of a large tuber during a 2-years' life cycle, especially the effect of storage on biomass and seed yield in the second season. Biomass partitioning favours growth of leaves in the first year rosette stage. Roots store carbohydrates at a constant rate and increase storage of carbohydrates and nitrogen when the leaves decay at the end of the first season. In the second season the reallocation of carbohydrates from storage is relatively small, but reallocation of nitrogen is very large. Carbohydrate storage just primes the growth of the first leaves in the early growing season, nitrogen storage contributes 20% to the total nitrogen requirement during the 2nd season. The efficiency of carbohydrate storage for conversion into new biomass is about 40%. Nitrogen is reallocated 3 times in the second year, namely from the tuber to rosette leaves and further to flower stem leaves and eventually into seeds. The harvest index for nitrogen is 0.73, whereas for biomass it is only 0.19.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 95 (1993), S. 153-163 
    ISSN: 1432-1939
    Keywords: Evaporation ; Aerodynamic conductance ; Canopy conductance ; Humidity response ; Soil water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Canopy-scale evaporation rate (E) and derived surface and aerodynamic conductances for the transfer of water vapour (gs and ga, respectively) are reviewed for coniferous forests and grasslands. Despite the extremes of canopy structure, the two vegetation types have similar maximum hourly evaporation rates (E max) and maximum surface conductances (gsmax) (medians = 0.46 mm h-1 and 22 mm s-1). However, on a daily basis, median E max of coniferous forest (4.0 mm d-1) is significantly lower than that of grassland (4.6 mm d-1). Additionally, a representative value of ga for coniferous forest (200 mm s-1) is an order of magnitude more than the corresponding value for grassland (25 mm s-1). The proportional sensitivity of E, calculated by the Penman-Monteith equation, to changes in gs is 〉0.7 for coniferous forest, but as low as 0.3 for grassland. The proportional sensitivity of E to changes in ga is generally ±0.15 or less. Boundary-line relationships between gs and light and air saturation deficit (D) vary considerably. Attainment of gsmax occurs at a much lower irradiance for coniferous forest than for grassland (15 versus about 45% of full sunlight). Relationships between gs and D measured above the canopy appear to be fairly uniform for coniferous forest, but are variable for grassland. More uniform relationships may be found for surfaces with relatively small ga, like grassland, by using D at the evaporating surface (D0) as the independent variable rather than D at a reference point above the surface. An analytical expression is given for determining D0 from measurable quantities. Evaporation rate also depends on the availability of water in the root zone. Below a critical value of soil water storage, the ratio of evaporation rate to the available energy tends to decrease sharply and linearly with decreasing soil water content. At the lowest value of soil water content, this ratio declines by up to a factor of 4 from the non-soil-water-limiting plateau. Knowledge about functional rooting depth of different plant species remains rather limited. Ignorance of this important variable makes it generally difficult to obtain accurate estimates of seasonal evaporation from terrestrial ecosystems.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 82 (1990), S. 427-429 
    ISSN: 1432-1939
    Keywords: Insectivorous plants ; Insect capture ; Leaf growth ; Nitrogen storage ; Drosera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rates of insect capture increased with leaf area in the insectivorous plant Drosera rotundifolia, and growth of new leaves was related to insect capture. However, increased leaf growth was counterbalanced by leaf abscission which was in turn related to insect capture and leaf growth. Leaf loss equaled leaf growth in plants having natural rate of insect capture. A large proportion of the nitrogen gain from prey was stored in the hypocotyl; it was estimated from feeding experiments that about 24% to 30% of the nitrogen stored in the hypocotyl after winter originated from insect capture in the previous season. The effect of insect capture is discussed in relation to the life cycle of Drosera.
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