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  • 1
    ISSN: 1432-2285
    Keywords: Branch cross-sectional area ; Leaf area ; Leaf biomass ; Picea abies ; Sapwood area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationship of leaf biomass and leaf area to the conductive area of stems and branches was investigated in Picea abies. A total of 30 trees were harvested to determine if these relationships were different in different crown zones and in trees growing with and without competition for light. Two methods were compared. In the first, data were accumulated from crown zones situated at the top of trees to the bottom; in the second, data were used from individual crown zones. The results indicated that the latter method is much more sensitive in detecting differences in the relationship of leaf biomass or leaf area to conductive area. The analysis also indicated that ratios such as leaf area/sapwood area are frequently size-dependent. This size-dependency can in some cases result in the differences being abscured, but more often leads to the false impression that the relationship between the variables changes. The relationship between leaf biomass and leaf area and conductive area of stems or branches was different in different crown zones and under different growth conditions. The slopes of these regressions appear to increase with decreasing transpirational demand and decrease with increasing hydraulic conductivity. The intercepts are probably related to the amount of identified sapwood actually involved in water conductance.
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  • 2
    ISSN: 1432-2285
    Keywords: P/V curve ; Picea abies ; Aerial uptake ; Bark permeability ; Mass flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Uptake of water and magnesium chloride solution was investigated through the outer surface of twigs of Picea abies (L.) Karst. Water uptake was determined by using pressure/volume (P/V) curves of the twigs as a basis for calculation to avoid problems of superficial extraneous water. When water was sprayed on bark and needles of 3- to 7-year-old twigs at a xylem water potential of -1.00 MPa, they absorbed as much as 80 mm3 water in 200 min/g twig dry weight as the twig water potential recovered to -0.15 MPa. With fluorescent dyes, pathways for absorption of water and solutes through the twig bark were found, particularly through the radially orientated ray tissue. In addition to uptake by mass flow, magnesium could also diffuse along a concentration gradient from the twig surface into the xylem. In the field, the magnitude of these uptake processes would depend on the concentration of elements deposited by atmospheric precipitation, the concentration gradient between the plant surface and the xylem sap, the xylem water potential and the intensity and duration of each precipitation event.
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  • 3
    ISSN: 1432-1939
    Keywords: Forest decline ; Carbohydrates ; Picea abies ; Growth ; Leaf area index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This is the first in a series of papers on the growth, photosynthetic rate, water and nutrient relations, root distribution and mycorrhizal frequency of two Norway spruce forests at different stages of decline. One of the stands was composed of green trees only while the other included trees ranging in appearance from full green crowns to thin crowns with yellow needles. In this paper we compare the growth and carbohydrate relations of the two stands and examine relationships among growth variables in ten plots. The declining stand produced 65 percent of the wood per ground area compared with the stand in which all trees were green because its foliage produced less wood at any level of leaf area index. The difference in foliage efficiency between the sites could not be explained by differeneces in climate, competition or stand structure. The declining stand appeared to have lower carbon gain as indicated by a smaller increase in reserve carbohydrates before bud break, and weaker sinks for carbohydrates as indicated by less use of the stored carbohydrates than the healthy stand. Thus, growth reduction was probably related to factors which affect both photosynthesis and, even more, the sinks for carbohydrate.
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  • 4
    ISSN: 1432-1939
    Keywords: Forest decline ; Ectomycorrhizas ; Fine roots ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of root tips and apparent ectomycorrhizas was compared in the Fichtelgebirge (FRG) over one growing season in two 30-year-old Picea abies stands, both on soils derived from phyllite but showing varying symptoms of decline. Visual symptoms of tree decline reflected a lower relative and absolute mycorrhizal frequency, a lower number of ectomycorrhizas per m2 leaf area and an uneven vertical distribution of root tips and ectomycorrhizas. The number of apparent ectomycorrhizas per ground area was correlated with the amount of magnesium, calcium, and ammonium, and the pH in the free-drainage soil solution, and with the molar calcium to aluminium ratio in mineral soil extracts. The foliage concentrations of magnesium and calcium were correlated with the numbers of apparent ectomycorrhizas per m2 leaf or ground area. These observations were used to formulate testable hypotheses concerning the role of the root system and the soil environment in forest decline.
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  • 5
    ISSN: 1573-5036
    Keywords: atmospheric deposition ; δ15N ; δ34S ; forest decline ; nitrogen ; Picea abies ; stable isotopes ; sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations and natural isotope abundance of total sulfur and nitrogen as well as sulfate and nitrate concentrations were measured in needles of different age classes and in soil samples of different horizons from a healthy and a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), in order to study the fate of atmospheric depositions of sulfur and nitrogen compounds. The mean δ15N of the needles ranged between −3.7 and −2.1 ‰ and for δ34S a range between −0.4 and +0.9 ‰ was observed. δ34S and sulfur concentrations in the needles of both stands increased continuously with needle age and thus, were closely correlated. The δ15N values of the needles showed an initial decrease followed by an increase with needle age. The healthy stand showed more negative δ15N values in old needles than the declining stand. Nitrogen concentrations decreased with needle age. For soil samples at both sites the mean δ15N and δ34S values increased from −3 ‰ (δ15N) or +0.9 ‰ (δ34S) in the uppermost organic layer to about +4 ‰ (δ15N) or +4.5 ‰ (δ34S) in the mineral soil. This depth-dependent increase in abundance of 15N and 34S was accompanied by a decrease in total nitrogen and sulfur concentrations in the soil. δ15N values and nitrogen concentrations were closely correlated (slope −0.0061 ‰ δ15N per μmol eq N gdw −1), and δ34S values were linearly correlated with sulfur concentrations (slope −0.0576 ‰ δ34S per μmol eq S gdw −1). It follows that in the same soil samples sulfur concentrations were linearly correlated with the nitrogen concentrations (slope 0.0527), and δ34S values were linearly correlated with δ15N values (slope 0.459). A correlation of the sulfur and nitrogen isotope abundances on a Δ basis (which considers the different relative frequencies of 15N and 34S), however, revealed an isotope fractionation that was higher by a factor of 5 for sulfur than for nitrogen (slope 5.292). These correlations indicate a long term synchronous mineralization of organic nitrogen and sulfur compounds in the soil accompanied by element-specific isotope fractionations. Based on different sulfur isotope abundance of the soil (δ34S=0.9 ‰ for total sulfur of the organic layer was assumed to be equivalent to about −1.0 ‰ for soil sulfate) and of the atmospheric SO2 deposition (δ34S=2.0 ‰ at the healthy site and 2.3 ‰ at the declining site) the contribution of atmospheric SO2 to total sulfur of the needles was estimated. This contribution increased from about 20 % in current-year needles to more than 50 % in 3-year-old needles. The proportion of sulfur from atmospheric deposition was equivalent to the age dependent sulfate accumulation in the needles. In contrast to the accumulation of atmospheric sulfur compounds nitrogen compounds from atmospheric deposition were metabolized and were used for growth. The implications of both responses to atmospheric deposition are discussed.
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  • 6
    ISSN: 1432-1939
    Keywords: Picea abies ; Forest decline ; Stomatal response ; Photosynthesis ; Mg-deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary CO2 assimilation rate (A) and leaf conductance (g) were measured in the field on intact branches of 35-year-old Picea abies (L.) Karst. trees, in five plots each in a healthy and a declining stand. The declining site included trees with yellow needles. In order to separate atmospheric effects on gas exchange from effects of nutrient deficiency, direct effects of atmospheric pollutants were studied on green needles of different age classes in plots of trees at different stages of visible decline. The effects of nutrient deficiency on gas exchange were studied on a different group of trees showing needles of various degrees of yellowing. CO2 assimilation of green needles at the same leaf conductance fell somewhat only when needles had reached 5 years of age, the oldest age examined in this study. Leaf conductance decreased with increasing needle age, but green needles in the declining stand had leaf conductances similar to those of needles in the healthy stand. Stomata of needles with different magnesium concentrations responded to light and air humidity in all age classes. Thus, as long as needles were green, no dese effect was detectable up to 5 years of exposure to atmospheric emissions. Since all needles, green and yellow, were exposed to the same pollution levels, differences in gas exchange between green and yellow needles could not be explained simply in terms of long-term direct effects of air pollution. Needle magnesium contents were correlated with needle yellowing. Neither needle color change nor the magnesium concentration were related to g, but CO2 uptake at ambient CO2 levels declined with lower magnesium concentration and greater degrees of needle yellowing.
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  • 7
    ISSN: 1432-1939
    Keywords: Picea abies ; Forest decline ; Xylem flow ; Whole tree transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The water relations of Picea abies in a healthy stand with green trees only and a declining stand with trees showing different stages of needle yellowing were investigated in northern Bavaria. The present study is based on observations of trees differing in their nutritional status but apparently green on both sites in order to identify changes in the response pattern which might be caused by atmospheric concentrations of air pollutants and could lead to the phenomenon of decline. Transpiration was measured as water flow through the hydroactive xylem using an equilibrium mass-flow measurement system. Total tree transpiration was monitored diurnally, from July 1985 until October 1985 at both sites. The relationship between transpiration and meteorological measurements indicated that transpiration was a linear function of the vapor pressure deficit. No differences in transpiration of green trees were observed between the two sites. Canopy transpiration was 57%–68% of total throughfall and 41%–54% of total rainfall. Due to this positive water balance, soil water potential at 10 and 20 cm depths remained close to-0.02 MPa (max.-0.09 MPa) for most of the summer. Soil water potential was correlated with the difference between the weekly precipitation and transpiration. No differences in the water relations of apparently healthy trees in the two P. abies stands were observed. It is concluded that differences between green trees at the two sites in terms of nutrient relations or growth rate cannot be explained by changes in whole-tree transpiration or soil water status.
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  • 8
    ISSN: 1432-1939
    Keywords: Air pollution ; Acid rain ; Photosynthesis ; Nutrition ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Photosynthetic rates and nutrient contents of spruce needles were measured in a region with high levels of air pollution in NE Bavaria, Germany (FRG), and compared to spruce grown under clean air conditions at Craigieburn, in the South Island of New Zealand (NZ). The absolute rates of CO2 uptake, the slope of the CO2 response curve at 240 μl l−1 internal CO2 concentration, and the change of photosynthetic rates with needle age at ambient and saturated CO2 concentrations were virtually identical at both measuring sites. These results confirm an earlier conclusion, that there is no long-term effect of atmospheric pollutants directly on photosynthetic CO2 uptake rates with persistent exposure at the FRG site to high levels of anthropogenic air pollution. Photosynthetic capacity at saturating CO2 concentration was three times higher in the NZ spruce. Needles with high photosynthetic capacity in NZ had lower nitrogen and higher calcium concentrations per unit dry weight but higher concentrations of nitrogen, phosphorus, potassium, magnesium and calcium per unit leaf area, and twice the specific leaf weight.
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  • 9
    ISSN: 1432-1939
    Keywords: δ13C ; δ15N ; Nitrogen assimilation ; Forest decline ; Picea abies ; Stable isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Natural carbon and nitrogen isotope ratios were measured in different compartments (needles and twigs of different ages and crown positions, litter, understorey vegetation, roots and soils of different horizons) on 5 plots of a healthy and on 8 plots of a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), which has recently been described in detail (Oren et al. 1988a; Schulze et al. 1989). The δ13C values of needles did not differ between sites or change consistently with needle age, but did decrease from the sun-to the shade-crown. This result confirms earlier conclusions from gas exchange measurements that gaseous air pollutants did no long-lasting damage in an area where such damage was expected. Twigs (δ13C between-25.3 and-27.8‰) were significantly less depleted in 13C than needles (δ13C between-27.3 and-29.1‰), and δ13C in twigs increased consistently with age. The δ15N values of needles ranged between-2.5 and-4.1‰ and varied according to stand and age. In young needles δ15N decreased with needle age, but remained constant or increased in needles that were 2 or 3 years old. Needles from the healthy site were more depleted in 15N than those from the declining site. The difference between sites was greater in old needles than in young ones. This differentiation presumably reflects an earlier onset of nitrogen reallocation in needles of the declining stand. δ15N values in twigs were more negative than in needles (-3.5 to-5.2‰) and showed age- and stand-dependent trends that were similar to the needles. δ15N values of roots and soil samples increased at both stands with soil depth from-3.5 in the organic layer to +4‰ in the mineral soil. The δ15N values of roots from the mineral soil were different from those of twigs and needles. Roots from the shallower organic layer had values similar to twigs and needles. Thus, the bulk of the assimilated nitrogen was presumably taken up by the roots from the organic layer. The problem of separation of ammonium or nitrate use by roots from different soil horizons is discussed.
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