摘要:

The spatial pH‐variation is shown to be slightly decreasing when comparing different coniferous stands in northern Sweden with a 200 m2respectively a 2 m2sample plot within a stand. The result indicates that the pH‐variation in the mor layer to a great extent is to be found in a plot <2 m2. The hypothesis of Hesselman (1926) and Bergholm et al. (1985) that few samples should be enough for a reliable pH‐determination of a stand is questioned and critically discussed. The number of samples required to obtain a pH‐determination with an accepted accuracy is discussed. The spatial pH‐variation from the plots in the study suggests that approximately 12 samples are required to get a mean error of 2% at 95% confidence limits. But one should be aware of that, even with 12 samples, the difference between the highest and lowest value in a 2 m2plot will be about 0.6 pH‐units.

ISSN:0282-7581    

DOI:10.1080/02827588909382541

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The quantity and quality of throughfall and soil leachate were measured in 1983–1985 in three Scots pine stands of different age situated in Ilomantsi, eastern Finland. Soil leachate was collected using percolation lysimeters. Free precipitation pH varied from 4.0 to 5.2. Throughfall was more acidic than free precipitation. The closed canopy layer intercepted about 70% of the free precipitation. The canopy acted as a sink for nitrate and ammonium, and as a source for Mn, K, Mg and Ca. The quality of the throughfall and soil leachate varied seasonally. The hydrogen ion input into the soil was greatest at snow melt. The major part of the nitrogen load was deposited during winter. Part of the winter‐time nitrate load was leached through the surface soil. However, during the growing season all the nitrogen was efficiently taken up or immobilized. Basic cations K, Ca and Mg, as well as Mn, Fe and Al, were leached from the upper soil layers. Manganese was leached especially at snow melt. The output of magnesium in the leachate was greater than its input as deposition. The output of K and Ca from the humus and upper mineral soil layers (0–15 cm) was also greater than their input as deposition, but a major part of these nutrients were ≪adsorbed deeper in the profile.

ISSN:0282-7581    

DOI:10.1080/02827588909382542

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of energy forestry on water balance was quantified for a peat bog in central Sweden. An irrigated plantation containing a mixture ofSalve, BetulaandAlnuswas compared over a 3‐year period with a natural bog as a control area. The groundwater level and the soil water storage decreased in the cultivated area relative to the control area. Runoff during June‐August was generally higher in the cultivated area, mainly in response to irrigation and ditching, which altered runoff dynamics. In September the runoff rate at the cultivated area was lower, owing to the deeper groundwater level and to the larger soil water deficit that occurred prior to the autumn rains. At the cultivated area, about 30% more snow was trapped by the stems and the frost depth was 4 cm shallower. Exapotranspiration increased by 70 mm over the period June‐September compared with the undisturbed area.

ISSN:0282-7581    

DOI:10.1080/02827588909382543

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The joint levels of outcrossing and contamination in two young northern Swedish Scots pine (Pinus sylvestrisL.) seed orchards were studied with the aid of allozyme markers. High levels of contamination (21–36%) were estimated and were attributed to the observed low within orchard pollen production. Outcrossing rate estimates were high (0.957–0.961), though they departed significantly from complete outcrossing (t= 1.0) in spite of the observed high contamination levels. These results confirmed reported relationships between outcrossing and contamination levels in open‐pollinated seed orchards. It was concluded that a crop management option relying on supplemental mass‐pollination would be effective in reducing both contamination and inbreeding levels.

ISSN:0282-7581    

DOI:10.1080/02827588909382544

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Standard 14‐cm plastic‐petri dishes were used as root substrate chambers allowing controlled inoculation, regular inspection under the dissecting microscope, and manipulation of root infections with pathogens and mycorrhizal fungi under nonsterile conditions. Roots of young pine seedlings were placed on the root substrate and, especially those growing on the substrate surface under the lid, were very easy to manipulate. Mycorrhizal species and inoculation methods were compared and the infection process followed continuously under various conditions. The air pockets formed between the lid and the substrate favoured mycorrhiza formation. Brief, periodic flooding prevented formation of mycorrhizas in two mycorrhizal species having hydrophobic hyphae but did not prevent it in less hydrophobic species. IAA treatment of roots led to heavy production of mycorrhizas. Fruiting body formation inLacearia laccatawas induced and followed in the dish cultures. Pure mycorrhizal stock cultures were able to be revitalized in the dish cultures and reisolated in pure culture. The infection strategy of a weak root pathogen,Cylindrocarpon destructans, was studied with the same technique, which was also used for investigating treatments predisposing seedlings to pathogen infection.

ISSN:0282-7581    

DOI:10.1080/02827588909382545

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Equipment for testing root cold hardiness of containerized forest tree seedlings is described in the paper. Using this equipment roots of containerized one‐year‐old Norway spruce seedlings were experimentally frozen on December 3. After freezing, lateral roots were divided and cut into young and mature parts. Samples of young and mature roots were then tested for vitality using the triphenyl tetrazolium chloride (TTC) method. In contrast to mature roots, the reduction of TTC decreased as younger roots were exposed to the lowest test temperatures of — 15°C and —20°C, indicating increasing root damage.

ISSN:0282-7581    

DOI:10.1080/02827588909382546

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The magnitude of measurement errors of the specific impedance difference was estimated and a formula to approximate the variance of the estimated frost resistance was derived. The measurements of specific impedance difference include the measurement errors of impedance before and after frost treatment and cross-sectional area. These errors in connection with the population variation cause variation in the estimated frost resistance. The frost resistance is estimated by first expressing the specific impedance difference values as a logistic sigmoid function of the treatment temperature, and then evaluating the inverse function at a given value of the specific impedance difference. The error variance between the estimated and the measured frost resistance was calculated using the estimated parameters, their standard deviations and correlations. In an example the impedance estimated frost resistance (LT.i0Qm) was - 10.9°C and its standard deviation 0.8°C.

ISSN:0282-7581    

DOI:10.1080/02827588909382547

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Four‐year data on spring outplanted black spruce (Picea mariana(Mill.) B.S.P.), white spruce (Picea glauca(Moench) Voss) and jack pine (Pinus banksianaLamb.) were subjected to stepwise multiple linear regression analysis with mixed models containing both continuous and categorical variables. Several treatments had been imposed on two provenances of seedlings of each species, including machine‐ and hand‐planting in furrows, or hand‐planting on untreated ground; and heavy, light, or no NPK fertilization immediately after planting. Furrow depth, initial height, vertically, and direction of lean of each newly planted tree, and first‐ through fourth‐year survival, growth, and condition were recorded. For each species, survival and total height equations are tabulated to show the proportion of variability explained by qualitative variables (site and stock factors), planting stock characters, and plantation age. Age accounted for 13–92% of the total variability in survival and growth. Both planting without site preparation and heavy fertilization were significantly detrimental to survival and growth, but light fertilization was beneficial when significant. Provenance had little or no influence on results.

ISSN:0282-7581    

DOI:10.1080/02827588909382548

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The risk for damage associated with spruce bark beetle attacks on living trees was estimated in 12 forest districts in the Nordic countries during three years. Pheromone‐baited traps and trees were used. Five groups of three traps were deployed annually on fresh spruce clear‐fellings in each district. The mean catches within districts and years ranged from 950 to 46000 beetles per trap group. The standard error averaged 15%of the mean catch. One tree was baited annually at each of five other sites in each district. The mean number of trees colonized byIps typographusin each district and year ranged from 0 to 5 per site. The standard error was high, averaging 44% of the mean. Inventories of tree mortality within the districts yielded values ranging from 0 to 150 killed trees per km of spruce forest edge. There was a strong linear correlation between mean catches in traps and log‐transformed tree mortality (r=0.82). The correlation between colonization success at tree‐baiting sites and tree mortality was weaker (r=0.59), owing to one deviant observation. The results indicate that pheromone traps and baited trees may be used to assess the risk for damage caused by Ips typographus.

ISSN:0282-7581    

DOI:10.1080/02827588909382549

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Display activity and population size of 2 experimentally logged leks were compared with 7 untreated control leks in a coniferous area in southcentral Norway, during 1974–87. Leks were treated by thinnings and small‐scale seed‐tree‐ and clearcuttings. Number of displaying cocks increased on all leks, but the experimental lek populations increased more than the controls. Displaying cocks were either indifferent to or preferred the logged areas, and recruiting cocks established display sites at newly created group selection cuts and at the edge of seed‐tree and clearcuts. The findings indicate that moderate thinnings, leaving >500 stems/ha, and clearcuts <50 m in diameter, are acceptable cutting methods withinT. urogallusleks, with the reservations that lek populations should not be smaller than 5 displaying cocks, and that surrounding habitats should contain >50% old forest.

ISSN:0282-7581    

DOI:10.1080/02827588909382550

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor