The concept of succession in relation to the spread of sheathing mycorrhizal fungi on inoculated tree seedlings growing in unsterile soils

Summary Repeated annual assessments of the toadstools (fruitbodies) of mycorrhizal fungi associated with a mixed stand ofBetula spp. indicated that they were produced in a pattern ordered in time and space, suggesting a succession with identifiable early-and late-stage fungi. This concept is supported by below-ground observations of mycorrhizas which, however, need to be augmented.Both early- and late-stage mycorrhizal fungi form mycorrhizas on seedlings growing in axenic (aseptic) conditions. In contrast, only early-stage fungi seem able to trigger mycorrhizal formation on seedlings growing in unsterile soils.During axenic propagation, the early-stageHebeloma sacchariolens and the late-stageAmanita muscaria formed similar numbers of mycorrhizas per root system. After being transplanted to a range of unsterile field soils,A. muscaria failed to keep pace with the spread of the developing root system: no moreA. muscaria mycorrhizas were formed. On the other hand the continued development ofH. sacchariolens mycorrhizas precluded, during the first season after transplanting, the development of mycorrhizas by fungi naturally occurring in field soils. In the second season, however, the development ofH. sacchariolens mycorrhizas was restricted in acid peat but not in three other types of soil.The development ofLaccaria mycorrhizas after inoculating Sitka spruce with this fungus was associated, irrespective of soil type, with accelerated tree growth; with heights at the end of the first season being doubled.     

IL-2 secretion by soluble antigen-reactive human T-cell clones

Human tetanus toxoid specific T-cell lines and clones capable of producing IL-2 were established. IL-2 production occurred only when the antigen-specific T cells were cultured with both tetanus toxoid antigen and an autologous, irradiated adherent cell population. The T-cell lines and clones remained strictly dependent on exogenous IL-2 for proliferation at all other times. Phenotypic characterization with monoclonal antibodies recognizing T-cell subsets revealed that the antigen-specific lines and clones bore predominantly OKT3 and OKT4 markers with essentially no OKT8 positive cells present. T-cell clones which were demonstrated to secrete IL-2 activity could also partially deplete media of IL-2 if cultured in the absence of soluble antigen and irradiated adherent cells.     

Schwefel in Waldböden Nordwest-Deutschlands und seine vegetationsabhängige Akkumulation

Summary Amounts of total sulfur and sulfate (NaHCO₃-extractable) were determined in soil samples from 19 representative profiles under forest vegetation in the areas of pleistocene and of the triassic middle range mountains in Germany. The mean total sulfur contents in surface and subsurface samples were 278 and 136 g S/g soil respectively. The total amount of sulfate and its fraction in the total sulfur was low in the surface samples. The subsurface soil samples of pH>5 contained very little sulfate. The difference between total sulfur and NaHCO₃-extractable sulfate described as nonsulfate fraction was mainly constituted by the fraction of organic sulfur. The mean C:N:S ratio (sulfur as nonsulfate) for samples with carbon content more than 2% was 225101.14. Compared with the parent material there was an accumulation of S in the acid brown earths developed from loess. Comparison of the sites with beech and spruce vegetation showed that the amount of nonsulfate-sulfur was of the same magnitude in both sites, but the amount of sulfate was higher in the spruce area. Similar differences between a beech and a spruce site were also observed for soils developed from weathered sandstone. The high amounts of sulfate under spruce are probably the result of higher inputs in the area due to the filtering action of the spruce trees on emitted SO₂.

     

Monoterpenes in sitka spruce: Within tree and seasonal variation

The composition of oils from needles and cortex of Sitka spruce is unique. Cortex oil is essentially all monoterpene hydrocarbons, while needle oil may be up to 50% oxygenated monoterpenes. Very wide seasonal variations in composition occur in needle oil in young tissue. At bud burst, the oil is > 95% myrcene; this drops to about 40% at the end of summer. The oxygenated terpenes camphor and piperitone develop to about 20% each in concentration during the growing season.     

Gibberellin A9 glucosyl ester in needles of Picea sitchensis

A polar gibberellin-like substance present in needles of Picea sitchensis was identified as GA₉-β-d-glucosyl ester on the basis of enzymatic hydrolysis and identification of the aglycone by GC-MS. The biological activity of the synthetic material was tested in two bioassays.     

Aluminium effects on spruce and beech seedlings

Summary Natural spruce seedlings sampled on acid brown soil of the Belgian Ardennes, either on mineral soil, or on the litter layer, show higher Al content in the latter case, where substrate Al content is lower. Absorbing power of the root for Al organic chelates is probably higher than for Al⁺³ ions.Most soluble Al is chelated, especially in the holorganic and hemiorganic layers, under spruce and beech. In the mineral layers pH is above 3.8, and total Al in soil solutions is always found to be less than 2 eq/ml.     

Resource partitioning and tolerance of monoterpenes in four species of spruce aphid

Abstract. The tolerance of four species of aphids to myrcene was assessed by measuring the mortality of aphids exposed to different amounts of this monoterpene.Each species was found to exhibit significantly different levels of tolerance to myrcene.which is explicable in terms of the likely concentration of myrcene at the feeding site of each species.
Tolerance to monoterpenes maybe specific only to those encountered in high concentrations at the feeding site.whereas others are found to be toxic.This suggests that each species has become physiologically adapted to tolerate different levels of the specific monoterpenes that occur in the microhabitats they occupy.     

Microsatellites as DNA markers in Sitka spruce

Nine microsatellite loci were found by screening a genomic DNA library of Sitka spruce (Picea sitchensis) with the four oligonucleotide probes (TG), (CAC), (GATA) and (AT). Pairs of flanking primers were generated for seven microsatellites. Five primer pairs were used to screen up to 58 Sitka spruce clones. The five loci SStg3a, SStg4, SStg4a, SStg4c and SSgataS were found to have 15, 13, 4, 3 and 6 different length alleles respectively, and in using a combination of them almost all 58 Sitka spruce genotypes could be identified. The five primer pairs were successful in amplifying DNA from two other spruce species (Picea albutilia and Picea smithiana), while only one primer pair could amplify DNA from the pine species, Pinus sylvestris and Pinus latifolia. The inheritance of microsatellites in Sitka spruce was co-dominant Mendelian.     

The effects of SO2 and O3 on the foliar nutrition of Scots pine, Norway spruce and Sitka spruce in the Liphook open-air fumigation experiment

Foliar elements were analysed in Scots pine, Sitka spruce and Norway spruce over a 6 year period before and during continuous exposure to SO₂ and O₃ in an open-air fumigation experiment. Sulphur dioxide treatment elevated foliar sulphur concentration in all species, and there were increases in foliar nitrogen in the two spruce species but not in pine. The concentrations of cations were frequently increased by SO₂ treatment, but there was no correlation between the sulphur concentration of needles and their total cation charge. SO₂-related elevations of foliar magnesium were correlated with the concentration of this element in soil solution, but the mechanism by which other cations were enhanced remains unclear. The only consistent effects on nutrient ratios were for SO₂ treatments to increase sulphur/cation ratios.