摘要:

The persistence of the four herbicides atrazine, hexazinone, lenacil and linuron was studied in forest nursery soils. The adsorption capacities of the soils for the chemicals were described by the distribution coefficientskjandkoc.Due to the low content of organic matter in the soils theka‐values were low, in several cases being <1 for hexazinone. Hexazinone also had the lowestkoc‐value (30) while the other substances hadkoc‐values within the range 200–400. In some cases hexazinone showed great mobility under field conditions. The formulac=co‐kt1/2was used to describe the disappearance of the herbicides from the various soils. The rate of degradation of the four herbicides correlated well with the rate of respiration in the same soils in laboratory experiments, and for linuron reasonably well also in field experiments. In the field experiments the herbicides penetrated the top soil layer. In the subsoil the risk of further transport downward to the drainage system or ground water increased, especially for hexazinone. Linuron as well as the fungicides maneb and tolylfluanid suppressed the decomposition rate of hexazinone in laboratory experiments.

ISSN:0282-7581    

DOI:10.1080/02827589009382628

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Ingestad's concept of relative addition rate was used to grow a range of seedling types, of both black (Picea mariana)(Mill.) B.S.P.), and white spruce(Picea glauca(Moench) Voss). Seedlings were grown for about 18 weeks in styrofoam containers under greenhouse conditions, and fertilized at exponentially increasing rates of either one, two, four or six per cent per day, following a one month pretreatment period. Pretreatment consisted of applying a nutrient solution proportionally low in nitrogen, but that had a relatively high conductivity compared to the initial solutions used in the exponentially increasing fertilizer treatments. Black spruce seedlings grew fastest, had significantly more root development or had a higher efficiency of nitrogen uptake when nutrients were applied at exponentially increasing amounts. In contrast, white spruce grew more rapidly when fertilized with a constant level of fertilizer (control treatment). Biomass allocation and nitrogen concentrations in seedlings of both species varied significantly with treatment, indicating that various levels of nitrogen stress had been achieved. It is suggested that different seedling stock types, which are acclimated to various levels of nutrient stress, can be produced by controlling the rate of nutrient addition.

ISSN:0282-7581    

DOI:10.1080/02827589009382629

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Needle retention in conifers is affected by several environmental factors, e.g. climate, mineral nutrition, other edaphic conditions, and more recently by air pollution. This paper describes a method to determine the history of needle retention in pine stems. In the pines so far investigated, the retention of needles varied from one to four annual needle sets (year classes); and there were significant differences in the variation of retention between individual trees. No descending trend was detected which could have been caused by adverse changes in the environment. Some years with deep troughs in the retention data could be connected with exceptionally cold vegetative periods.

ISSN:0282-7581    

DOI:10.1080/02827589009382630

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Survival, growth, plant structure and insect damage ofin vitro‐derived cuttings from twoSalixclones (5.schweriniiand 5.viminalis)were compared in a field trial with performance of conventional cuttings of the same clones. No obvious morphological abnormalities were induced byin vitrotreatment. The survival rate of in vitro‐derived cuttings of theS. schweriniiclone was much higher than that of conventional cuttings. In the 5.viminalisclone, height growth was slightly but significantly reduced forin vitro‐derived cuttings compared with conventional cuttings although stem basal area and estimated plant dry weight were unaffected. The number of stems per cutting, the number of side shoots per stem and gall midge damage did not appear to be affected by the type of cutting. Electrophoretic analysis of 12 enzyme systems revealed identical isozyme patterns for mvitro‐derivedand conventionally propagated plants.

ISSN:0282-7581    

DOI:10.1080/02827589009382631

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Container‐grownPinus sylvestrisseedlings fertilized at several different levels were inoculated with vegetative mycelium of twelve isolates representing nine different ectomycorrhizal fungi. Eight isolates formed mycorrhizae of whichPiloderma croceumandCenococ‐cum geophilumwere most promising. Mantle thickness and Hartig net/cortex ratio of colonized seedlings exhibited no differences. Although unfertilized seedlings were significantly smaller than those fertilized, they were significantly more colonized by ectomycorrhizal fungi. There were no size differences between low fertilized, standrad fertilized and high fertilized seedlings. A wide array of fungus ecotypes should be tested to find a ground fertilization level at which tolerant strains can produce seedlings of acceptable size for transplantation.

ISSN:0282-7581    

DOI:10.1080/02827589009382632

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Reciprocal families of Scots pine,Pinus sylvestris(L.), from a Swedish seed orchard were artificially freeze tested to ‐10°C at the end of the first growth period. The degree of freezing damage was used as an indication of the cold acclimatization achieved at the time of freeze testing. Both one‐year cold acclimatization and one‐year height were mainly additively inherited. Specific combining ability, reciprocal and maternal effects were small. On the family level, freezing damage was non‐significantly correlated with field survival and field height after ten years. One‐year height was positively correlated with 10‐year field height and negatively correlated with field survival on the family level. Within families, plants from early germinated seeds cold acclimated earlier and were higher at the end of the first growth period than plants from lately germinated seeds. The results indicate that conclusions made from first‐year cold acclimatization studies can be influenced by variation in the rate of seed germination and seedling/germinant development.

ISSN:0282-7581    

DOI:10.1080/02827589009382633

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The volume increment of a single tree can be estimated in different ways. A problem with some of the methods is that the height increment must be estimated. Strand (1968) worked out formulae that can be used to estimate the form height increment per cent. Tests of one of these formulae were made on data from the National Forest Survey of Norway and from the Norwegian Forest Research Institute. The test on forest survey data indicated rather large differences between computed and observed volume increment. A new formula for the volume increment of Norway spruce is given. Data from 10 permanent sample plots were used. Tests of this new formula gave promising results.

ISSN:0282-7581    

DOI:10.1080/02827589009382634

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Differences in development of Scots pine in a European birch shelterwood and on a clear‐felled area in northern Sweden were examined 20 years after the pines were planted. Different light conditions and temperature climate in the two stand types are not the main causes for differences in development of the Scots pine. Hypotheses that competition from the birches in the shelterwood restricts the development of the pine seedlings soon after planting and that competition between trees is strongly related to distance are supported.

ISSN:0282-7581    

DOI:10.1080/02827589009382635

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We compared the degree of browsing by moose on 30 clones of Scots pine with the concentrations of mono‐ and diterpenes in their needles. The pine clones originated from 11 Swedish and one Norwegian locality within the latitudes 61–69° N. They were grown in a nursery in northern Sweden, close to 63° N, and were accidently exposed to moose during one winter. The relative amount of twig biomass removed differed significantly between clones. No statistically significant correlation was found between monoterpene concentrations in the needles and degree of moose browsing. For the diterpene pinifolic acid, however, there was a significant negative correlation.

ISSN:0282-7581    

DOI:10.1080/02827589009382636

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of simulated acid rain on the performance ofNeodiprion sertiferlarvae fed on treated Scots pine needles was tested in a subarctic area with low ambient pollution level. Acid rain treatments (pH 4 and pH 3, both with H2SO4and HNO3) did not significantly affect the relative growth rates or cocoon weights ofN. sertifer2 or 3 years after the start of the treatments. The relative growth rate ofN. sertiferlarvae was slightly (nonsignifi‐cantly) higher on plots receiving only ambient rain than on irrigated control plots. The quality of foliage before the start of the treatments explained a significant proportion of the variation in the performance ofN. sertiferlarvae in the bioassay conducted 3 years later.

ISSN:0282-7581    

DOI:10.1080/02827589009382637

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor