Beurteilung des Kalkbedarfes von Waldb?den im mittelfr?nkischen Keupergebiete

Ohne Zusammenfassung     

Formation and use of microbial residues after adding sugarcane sucrose to a heated soil devoid of soil organic matter

A 67-day incubation experiment was carried out with a soil initially devoid of any organic matter due to heating, which was amended with sugarcane sucrose (C₄-sucrose with a δ¹³C value of ?10.5‰), inorganic N and an inoculum for recolonisation and subsequently at day 33 with C₃-cellulose (δ¹³C value of ?23.4‰). In this soil, all organic matter is in the microbial biomass or in freshly formed residues, which makes it possible to analyse more clearly the role of microbial residues for decomposition of N-poor substrates. The average δ¹³C value over the whole incubation period was ?10.7‰ in soil total C in the treatments without C₃-cellulose addition. In the CO₂ evolved, the δ¹³C values decreased from ?13.4‰ to ?15.4‰ during incubation. In the microbial biomass, the δ¹³C values increased from ?11.5‰ to ?10.1‰ at days 33 and 38. At day 67, 36% of the C₄-sucrose was left in the treatment without a second amendment. The addition of C₃-cellulose resulted in a further 7% decrease, but 4% of the C₃-cellulose was lost during the second incubation period. Total microbial biomass C declined from 200 μg g^?1 soil at day 5 to 70 μg g^?1 soil at day 67. Fungal ergosterol increased to 1.5 μg g^?1 soil at day 12 and declined more or less linearly to 0.4 μg g^?1 soil at day 67. Bacterial muramic acid declined from a maximum of 35 μg g^?1 soil at day 5 to a constant level of around 16 μg g^?1 soil. Glucosamine showed a peak value at day 12. Galactosamine remained constant throughout the incubation. The fungal C/bacterial C ratio increased more or less linearly from 0.38 at day 5 to 1.1 at day 67 indicating a shift in the microbial community from bacteria to fungi during the incubation. The addition of C₃-cellulose led to a small increase in C₃-derived microbial biomass C, but to a strong increase in C₄-derived microbial biomass C. At days 45 and 67, the addition of N-free C₃-cellulose significantly decreased the C/N ratio of the microbial residues, suggesting that this fraction did not serve as an N-source, but as an energy source.     

Einfluß von Mg- und Ca-Mangel auf Mg- und Ca-Gehalte,Chlorophyllgehalt und Chlorophyllfluoreszenz von Fichtennadeln sowie auf die Mikromorphologie und Benetzbarkeit ihrer epicuticulären Wachse

The influence of Mg- and Ca-deficiency on the micromorphology of epicuticular waxes and on the wettability of spruce needles The influence of Mg- and Ca-deficiency in nutrient solution on epicuticular waxes of needles of Norway spruce (Picea abies [L.] Karst.) was investigated in greenhouse experiments. Spruce clones were cultivated in sand and supplied with nutrient solution. For two vegetation periods, plants of the treatment groups -Mg, -Ca and -Mg/-Ca were provided with only 15 % of the respective mineral element of the control. At the end of the second vegetation period, the nutrient deficiency was documented by reduced Mg- and/or Ca-content of the needles and changes in chlorophyll fluorescence. No effect on micromorphology of epicuticular waxes and wettability of needles of any age was observed following deficient Mg and/or Ca supply.     

Differences in the chemical composition of dissolved organic matter from waste material of different sources

The chemical composition of waste-material-derived dissolved organic matter (DOM) was characterized by chemolytic analyses and ¹H, ¹³C and ³¹P nuclear magnetic resonance (NMR) spectroscopy. Dissolved organic matter was extracted by water from an aerobic fermented urban waste compost, a sewage sludge and a pig slurry and then fractionated using the XAD-8 method. The amount of water-extractable dissolved organic carbon (DOC) ranged from 3% in the sewage sludge to 22% in the pig slurry. Dissolved organic matter isolated from pig slurry was equally distributed between hydrophilic and hydrophobic DOC, whereas in the sewage-sludge-derived material the hydrophobic fraction was predominant. Dissolved organic C from the urban waste compost was mainly within the hydrophilic fraction. Wet-chemical analysis and ¹H- and ¹³C-NMR spectra showed that both DOM fractions from the urban waste compost were low in neutral, acidic and amino sugars as well as in lignin-derived compounds. In turn, the materials were rich in low-molecular-weight aliphatic compounds. The chemical structure of both fractions is probably the result of the intensive transformation of urban waste compost during its fermentation. The hydrophilic fractions of DOM from sewage sludge and pig slurry contained considerable amounts of carbohydrates but were also rich in low-molecular-weight aliphatics. The respective hydrophobic fractions had the largest contents of CuO-extractable phenols which may in part derive from sources other than lignin. By contrast with the other materials, the hydrophobic fraction from the pig slurry seemed to contain polymeric rather than low-molecular-weight material. The ³¹P-NMR spectrum of the hydrophilic DOM fraction from urban waste compost did not show signals of inorganic or organic P compounds while the spectrum of the hydrophobic fraction revealed traces of monoester P, diester P, and orthophosphate. ³¹P-NMR spectroscopy suggested that both the hydrophobic and hydrophilic fractions from pig slurry did not contain organic P. The hydrophilic DOM fraction from sewage sludge contained orthophosphate, organic monoester P and a little pyrophosphate. The hydrophobic fraction contained mainly organic diester P and smaller amounts of teichoic acids and organic monoester P. Considering that water-soluble fractions of urban waste compost contained no easily plant-available P and a low content of labile organics, we conclude that this material contains less labile nutrients and is more refractory than the soluble constituents of pig slurry and sewage sludge.     

How to consider history in landscape ecology: patterns,processes, and pathways

Landscape Ecology - Landscape ecology early on developed the awareness that central objects of investigation are not stable over time and therefore the historical dimension must be included, or at...