摘要:

The degree of moose damage was estimated for 32 Finnish pine progenies grown in two field trials in Central Finland. In both trials, the browsing intensity correlated negatively with the increasing geographical latitude of the progeny origin. The lower susceptibility of northern pine progenies to moose was associated with the higher dry matter content of current and 1‐year‐old needles of these progenies.

ISSN:0282-7581    

DOI:10.1080/02827588909382561

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The accuracy of two distant‐independent diameter growth functions for individual trees ofPicea abiesL. (Karst.) are tested on plots older than 55 years b.h., and with relatively few trees per hectare. Both functions (I1 and I2) have site index, stand basal area, and individual tree basal area as explanatory variables; in addition age at breast height is used in Function I1. Relative to mean measured increment, Functions I1 and I2 underestimate the growth of the test plots by 4.4% and 10.9% respectively; Function I1 shows a root mean squared deviation of 29.2% for single plot predictions, and 5.4% for mean of all plots. Function II predicts the growth as well as some stand functions frequently in use in Norway. Function I2 is unacceptable because age is not an independent variable.

ISSN:0282-7581    

DOI:10.1080/02827588909382562

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Private small forest owners’ cutting decisions are analyzed using decision theory and by focusing on their goals. The need for the study arose because of low cutting intensity among certain groups of small forest owners. This phenomenon is apparent for example in France, the Federal Republic of Germany, the Nordic countries and the USA. My research strategy has been to increase the understanding of the decision situation and decision processes of private small forest owners. This will make it possible for the government and the wood buyers to find effective measures for increasing cutting intensity. The results show that most small forest owners, regardless of owner category, have a long time perspective. In all owner categories we found a strong desire to hold the estate in trust and hand it onto the next generation. Most owners looked upon the estate as an inheritance from the grandparents and a loan from the children. However, the operational goal profile is quite different for various owner categories. If there is a goal conflict between the strategic and operational goals the latter usually prevail. Compared with farmers, many non‐farmers have less economic and financial inducements to cut. For many non‐farmers letting the forest grow is a fair and easy investment alternative. Interesting investment alternatives are needed. Forest bonds are put forward as an idea.

ISSN:0282-7581    

DOI:10.1080/02827588909382563

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A theoretical analysis shows that the influence of tree dimension on production capacity differs between, but also within, different delimbing principles. Some multi‐stem delimbing methods seem to be the most promising for upholding productivity in a situation with declining tree dimensions. There are a few machines available today which work according to these methods. However, some multi‐stem delimbers are as sensitive to tree dimension as single‐stem delimbers, although they may have a higher rate of production. Further research and development are required to solve the problems of future harvestings

ISSN:0282-7581    

DOI:10.1080/02827588909382564

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Six‐week‐old Pinus sylvestris seedlings were exposed separately and simultaneously to sulphur dioxide and simulated sulphuric acid irrigation applied through the growth medium. At the end of experiments the growth of seedlings and the sulphur content of the needles were measured and the structural changes in the primary needles and growing long root tips at the light and electron microscope level were observed. Seedlings exposed to sulphur dioxide showed an increase in needle sulphur content without visible alterations or changes in the growth of seedlings. In needle mesophyll cell chloroplasts thylakoid swelling and decrease in size of starch grains were observed. Combined sulphur dioxide and simulated sulphuric acid irrigation caused greater ultrastructural alterations in needles than sulphur dioxide alone. Acid irrigation alone did not have any effect on the needles, but it caused injuries in the root cortical cell ultrastructure, whereas sulphur dioxide alone did not cause any observable structural effects on the roots.

ISSN:0282-7581    

DOI:10.1080/02827588909382565

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Shoots were induced at a very high frequency (85.6%) from dormant axillary buds ofPopulus tremulaL. Exogenous phytohormones were not necessary for shoot induction but an addition of BAP (benzylaminopurine) in media increased somewhat the number of regenerating buds. Effects on shoot regeneration of the vitamin content of the media as well as of the season of bud collection were confirmed. Micropropagating coefficient values in regenerated aspen shoots varied from 6.6 to 23.8 depending on clonal variations and cultural conditions. 96.0% of cultured shoots differentiated roots within 10 days and the rooted plantlets were easily transplanted to the greenhouse.

ISSN:0282-7581    

DOI:10.1080/02827588909382566

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Gene dispersion within a population was studied in a 2‐hectare stand of 74 seed trees and 1100 seedlings. Isozyme markers were used to determine the genetic relationships among parental trees, embryos and seedling progenies. Paternity exclusion analyses were used to study multilocus progeny genotypes from certain parents. Results demonstrate large variation between trees in their capacity to contribute their genes through natural regeneration. The proportion of all genes dispersed into a specific distance interval from the source was estimated. The estimation procedure took into account the background of seedlings where parenthood was not excluded, but where the seedlings turned out to be unrelated. We found little evidence for clusters of progeny seedlings surrounding their parental tree. Within 15 m from a tree, approximately 5 % of the genes originated from that tree and 95%originated from other trees. We found no evidence for an increase in levels of inbreeding, or genetic substructuring in the seedling progeny stand relative to the parental seed trees. A mathematical model for pollen distribution was developed. According to this model, 90% of pollen was distributed more than 15 m from the source. It is concluded that the marker seed trees had a surprisingly low detectable genetic contribution to the regeneration. It seems likely that a considerable part of the new seedlings have parents among felled trees or from surrounding stands.

ISSN:0282-7581    

DOI:10.1080/02827588909382567

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The average stump and below‐ground biomass of pine was 1464 g/m2; 4% as fine roots (Ø<1 mm), 18% small roots (Ø=1–10 mm), 49% large roots (Ø>10 mm), and 29% stumps), which comprised 35% of the total biomass in the Scots pine stands. The average root length of pine was 728 m/m2: 71 % of this length was fine roots, 29% was small roots, and less than 1 % was large roots. Most of the fine pine roots (80%) were in the 0–10 cm peat layer. The root biomass of the field layer was 548 g/m2, which comprised 47 % of the total field layer biomass. Characteristic features of the root systems were: high below‐ground/above‐ground ratios, rather low amounts of root biomass, shallow rooting, and relatively thin roots. Hummocks tended to have less roots in the 0–10 cm layer and more roots in the 10–20 cm layer than the hollows.

ISSN:0282-7581    

DOI:10.1080/02827588909382568

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Results are presented from artificial freezing tests comparing young controlled crossed progenies from the southern seed orchard at Lyngdal (58° N) with open‐pollinated progenies from the same mother trees standing in the northern natural forest (63°‐66°N). The seed orchard material was more damaged by frost during cold acclimation. This effect was persistent for more than one growing season. Different photoperiodic treatments imposed on the progenies the first year did not affect the hardiness level in the same material three years later. The results imply that the seed orchard material has been genetically altered to perform like more southern ecotypes than the progenies form the forest. Possible causes of the present results are discussed in relation to four alternative hypotheses. In two of these it is postulated that the parental environment in the seed orchard could alter the genotypic performance of the progenies.

ISSN:0282-7581    

DOI:10.1080/02827588909382569

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Results are presented from three different field trials comparing controlled crossed materials of Norway spruce from the southern seed orchard at Lyngdal (58° N) with open‐pollinated progenies from the same mother trees standing in the northern natural forest (63–66° N). The seed orchard progenies flushed consistently later in the spring, terminated leader shoot growth later in the summer, had higher frequencies of lammas shoots, were delayed in lignification during autumn, and were 15% taller at age seven years from seed. The difference between the orchard‐ and the natural stand material appeared to be permanent from age four to age seven. It is suspected that the non‐native environment in the seed orchard could affect the genotypic performance of the seed orchard progenies.

ISSN:0282-7581    

DOI:10.1080/02827588909382570

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor