摘要:

The aim of the study was to develop methods for estimating the taper curves for trees tallied in a forest inventory. The average stem form in a stand was described by the principal components of the stand effects in the stem dimensions measured in the polar coordinate system. Measurements of diameter at breast height, diameter at a height of 6 meters, and height taken from trees on the sample tree plots were used for determining the first four principal components. Regression models were derived to predict the principal components from the site and growing stock variables. These models were used to estimate the taper curves of the tallied trees. Use of the principal components estimated by the regression models gave less reliable results than use of the principal component estimates based on measurement of the height of one randomly chosen tree on the sample plot. The best result was found with combined use of the principal component estimates and one height measurement per sample plot.

ISSN:0282-7581    

DOI:10.1080/02827588709382451

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Soil water and temperature measurements were made at a clearcutting in Jädraås, central Sweden, to give appropriate information for nutrient flow calculations and soil biological research. Compared to uncovered plots, slash‐covered plots were 1–2°C colder and had 3–6 volume percent higher water content in the 5 cm thick humus‐layer during the growing season following cutting. Relative to air, soil temperatures became warmer at both treatments during the second season and differences between uncovered and covered plots decreased. Tension dynamics in the mineral soil was most pronounced in uncovered plots, especially during the first dry growing season. The physically based model, SOIL, was used to analyse these observations and to estimate the effects of clearcutting. Simulated snow and frost depths, soil temperatures, water contents and tensions as well as ground water table were compared with measured data during a period of one to four years. Physical parameter values were estimated from independent measurements and by subjective optimization. Simulated soil water dynamics revealed the importance of hysteresis and vapour flows in sandy forest soils. The hydrological clearcutting effect as estimated from mature Scots pine evapotranspiration properties showed a 50% reduction of evapotranspiration, an increased soil water storage (0–1 m) of up to 120 mm and an increased percolation of 125 mm per year.

ISSN:0282-7581    

DOI:10.1080/02827588709382452

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Flooding of soil, tilting of stems, and application of ethrel to stems variously influenced growth, stem anatomy and ethylene production of 12‐month‐oldAcer platanoidesL. seedlings. Flooding greatly suppressed height growth, stem diameter growth, and the rate of dry weight increase of leaves, stems, and roots, with root growth suppressed most. Flooding also increased bark thickness above the level of submergence, reduced the xylem increment, and stimulated ethylene production of stems and ACC accumulation in the roots. Tilting of stems inhibited height growth somewhat, increased diameter growth and fiber production on the upper side of the leaning stem, increased ethylene production somewhat on both the upper and lower side of the stem, and induced formation of tension wood on the upper side of the stem. Tilting did not affect dry weight increase of leaves, stems, or roots. Application of ethrel to upright stems increased xylem increment around the stem; in tilted, ethrel‐treated seedlings xylem increment was increased on the upper side of the stem only. Ethrel applied around the stem increased bark thickness in both upright and tilted seedlings. Local applications of ethrel to tilted seedlings increased xylem increment near the site of application. Ethrel also stimulated formation of axial parenchyma cells and increased the width of the xylem rays as well as the number of cells per ray. The following lines of evidence indicated that ethylene had no direct role in inducing formation of tension wood: (1) ethylene production of stems was stimulated more by flooding of soil than by tilting of stems, but only tilting induced formation of tension wood, (2) the increase in ethylene content of tilted seedlings was as great or greater on the lower side than on the upper side of the stem, but tension wood formed only on the upper side, (3) application of ethrel to upright stems did not cause formation of tension wood, and (4) application of ethrel to tilted stems blocked formation of tension wood.

ISSN:0282-7581    

DOI:10.1080/02827588709382453

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Carbon dioxide uptake response to light intensity of detached shoots of open‐ and forest‐grown Norway spruces was investigated in controlled standard conditions. The initial slope of the CO2uptake light response curve, calculated on leaf area basis and the internal conductance, calculated on leaf weight basis were almost constant for shoots from different positions in the forest canopy. In open‐grown trees the maximum photosynthesis and internal conductance (on leaf weight basis) decreased in relation to the tree age, so that in the 8‐year‐old tree it was about two times of that in the 66‐year‐old tree. These results suggest that 1) the enhanced efficiency of “shade” shoots is caused by morphologic adaptation, i.e. the more sparsely packed photosynthetic apparatus in needles and shoots, and 2) adaptational possibilities of Norway spruce photosynthetic apparatus, its ecological plasticity diminish during tree ontogenesis.

ISSN:0282-7581    

DOI:10.1080/02827588709382454

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Seedlings ofPinus sylvestris(L.) andPicea abies(L.) Karst, were lifted on different occasions in autumn and cold‐stored throughout winter. In spring, in connection with planting, needle conductance (gn), plant water conductance(Gp)and needle water potential (ψn) of a sample of seedlings were measured under controlled climatic conditions in a growth chamber. It was found that measurements ofgnandGpmade after 4 days in the growth chamber correlated with the relative number of severely damaged or dead seedlings after one summer in the field.ψn. however, had little prognostic value. It is proposed that the measurements ofgnandGpmay be suitable as a means of assessing seedling quality and of predicting field performance.

ISSN:0282-7581    

DOI:10.1080/02827588709382455

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Logs of fresh‐felled Norway spruce were stored close to the south‐facing edges of clear‐cuts from the previous winter and treated with controlled release formulation of: 1. The pheromone components verbenone and ipsenol, which act as antiaggregative pheromone inIps typographus. 2. Turpentine, a by‐product derived from pulp mills. The experiments were conducted in 3 locations in South‐Norway during a 3‐year period. All experiments show that treatments with a combination of verbenone and ipsenol released from laminated structure dispensers significantly reduced the attack density ofI. typographus, whereas turpentine treatment had no effect on the rate of beetle infestations.

ISSN:0282-7581    

DOI:10.1080/02827588709382456

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Two Norway spruce stands with heavy infections ofHeterobasidion annosumwere clear‐cut in 1957 and 1959 in Sweden. The stumps were extracted, the soil sifted to remove most of the roots, and young Norway spruce were planted. After 25 and 28 years,H. annosumhad infected 1 % and 2% of trees on plots where stumps had been removed and 17%and 12% of the trees on control plots, respectively. Several of theH. annosumclones fruiting on old‐growth stumps were also detected in decayed, standing trees. The same fungal clone was found to be infecting adjacent trees from several old‐growth stumps. In addition to old stumps, stumps from recent thinnings and diseased living trees were traced as infection sources. Their relative importance in spreading disease was estimated. Disease risk predictions based on the distance of a tree from various infection sources correlated well with observed frequencies of rot.

ISSN:0282-7581    

DOI:10.1080/02827588709382457

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A method for trapping walkingHylobius abietis(L.) (Coleoptera: Curculionidae) was developed and evaluated. Synergism between α‐pinene and ethanol in attractingH. abietiswas confirmed. The effects of varying release rates of these substances and of adding other host terpenes were studied. A simple bait was developed containing α‐pinene and ethanol released from separate vials. The correlation between trap catch and seedling damage was estimated during May, June, and August on 1‐, 2‐, and 3‐year‐old clear‐cuttings. In May and June, population levels were relatively high on all clear‐cuttings and no significant correlations were found. The August experiment showed a strong positive correlation between catch and damage. The percentage damaged seedlings per captured weevil was considerably higher in August than in May or June. Possibilities for developing a system for forecasting seedling damage using this trapping method are discussed.

ISSN:0282-7581    

DOI:10.1080/02827588709382458

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A general model for comparing the profitability of natural regeneration in beech(Fagus sylvaticaL.) with planting of Norway spruce(Picea abiesL.) is developed. The model is basically a method of comparing a series of net present values. An example of using the model is given: BEECH (90–110) denotes a cyclic regime in which regeneration is initiated at age 90 of a stand, and the canopy trees are cleared at age 110. This regime is compared with the alternative of planting Norway spruce. Economic data used for the comparison are representative of the southeastern regions of Denmark. The conclusion of the comparison is as follows: BEECH (90–110) is superior to planting of Norway spruce for required real rates of return up to 3–4%. For higher required rates of return planting of Norway spruce is preferable.

ISSN:0282-7581    

DOI:10.1080/02827588709382459

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In 1981 a storm caused windthrow of 3 million cubic meters of softwood in Denmark, equal to the normal removals of three years. The object of the present analysis is to determine the way in which the probability of windthrow depends on parameters that can be affected by forest management, viz. rotation age, thinning programme, choice of species, spatial distribution of stands and drainage. An empirical data set from 612 stands is used in the estimations. It is found that the windthrow probability is negatively affected by tree diameter, drainage, the time since last thinning and the protection from other stands. The probability increases with tree height, age and relative thinning volume in the latest thinning. Picea is more stable than Abies and Pseudotsuga.

ISSN:0282-7581    

DOI:10.1080/02827588709382460

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor