摘要:

An empirical model is presented to forecast the incidence of root rot at stand level. In addition, the impact of different thinning programmes on the incidence of root rot is evaluated. The model is based on data from 152 permanent forest research plots of purePicea abiesin southern Sweden, within which the incidence of root rot at stump height in thinned trees has been recorded after each thinning since 1950. In total, about 20 000 stumps have been studied. According to simulations with the model, areas previously used as fields or for grazing are particularly susceptible to root rot, while old hardwood sites are less susceptible. Furthermore, simulations with the model imply that the earlier, the harder or more often a stand is thinned, the faster will be the development of root rot.

ISSN:0282-7581    

DOI:10.1080/02827589509382870

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Data from 16 forest stands were used to assess the accuracy of aerial photo interpretation of areas with thin soil cover and bedrock outcrops. Thin soil cover was defined as soil depth less than 10 cm, including outcrops. The portion of the area with thin soil cover within the stands was interpreted by four experienced persons according to a 4 x 4 Graeco‐Latin square design. IR‐color photographs and panchromatic black‐and‐white photographs at the scales 1:15 000 and 1 :22 000 were used.

ISSN:0282-7581    

DOI:10.1080/02827589509382871

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Functions for the prediction of tree species composition category were estimated by means of discriminant function analysis. Five tree species composition categories were defined, and the functions were calibrated using the National Forest Inventory sample plots from two counties in eastern Norway. The independent variables were site index, altitude, and slope, which can all be derived from spatial databases. Tree species composition category was predicted for the calibration data and independent test data. The prediction was based on a deterministic and a probabilistic approach. About 30–60% of the observations were correctly classified. The deterministic approach gave large systematic errors for the individual categories. The probabilistic approach gave no such errors. Tree species composition category can be predicted within a GIS environment for production of small scale thematic maps. Although the classification accuracy was rather low, the functions might be used for map production in the absence of better alternatives.

ISSN:0282-7581    

DOI:10.1080/02827589509382872

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The carbon and nitrogen mineralization dynamics ofPinus sylvestrisL. harvesting residues, when mixed with an acidic, nitrifying fen peat, were studied during aerobic, laboratory incubation at 20°C over 12 weeks. Green needle, brown needle and fine root showed a pattern of curvilinear decline in C mineralization rate with time. The total amounts of C mineralized from those residues, expressed as a percentage of their initial C content, were 52, 41 and 16%. Stem bark and stem wood mineralized more slowly; the value for stem bark was near zero. With the exception of stem bark, the harvesting residues enhanced the mineralization of added14C‐labelled glucose. During the early decomposition of the pine residues, the degree of net N immobilization of mineral N was related to the initial C/N ratio or total N concentration of the residues and net N mineralization was negatively correlated with mineralization of C. The remineralization rate of freshly immobilized N was estimated as seven times faster than the mineralization rate of the more recalcitrant native N from the fen peat. The added pine residues did not influence measurably the nitrification capacity of the fen peat.

ISSN:0282-7581    

DOI:10.1080/02827589509382873

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This synthesis paper presents a model for estimating the buildup of soil organic matter in various types of coniferous forests. The knowledge used was obtained from a well‐studied forest with good Iitterfall data, decomposition information and validation measurements of the soil organic matter layer. By constructing a simple model for litterfall, and the information on maximum decomposition levels for litter, we could estimate the annual increase in soil organic matter and extend this to encompass stand age. The validation measurement and the estimated amount of soil organic matter differed by about 8 or 26% over a 120‐yr period, depending on the litterfall model. The estimated increased storage of soil organic matter as a consequence of climate change was found to be drastic. We thus found that the soil organic matter layer would grow about four times as fast as a result of the needle component only. This estimate was based on a comparison between latitudes with a difference of 17°.

ISSN:0282-7581    

DOI:10.1080/02827589509382874

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Species, provenances and even individual trees are known to differ in stem volume yield capacity, even when grown on the same site. Increased knowledge of the fundamental mechanisms for different productivity is essential for the success of breeding research and for the maximization of yield. Genetically homogeneous tree materials were selected on the basis of expected differences in stem volume yield capacity and trees were sampled and destructively analysed. The hypothesis to be tested was that yield capacity is correlated to certain traits of trees. High correlations with stem volume yield capacity were shown for harvest index, needle‐use efficiency and mineral‐nutrient‐use efficiency. Only weak correlations were shown for needle longevity and nitrogen concentration in needles. Also, indications were found that phenotypic plasticity was correlated positively to stem volume growth capacity. An attempt to correlate the ability to retranslocate nitrogen from dying needles with yield capacity failed.

ISSN:0282-7581    

DOI:10.1080/02827589509382875

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Seedlings ofPinus pinasterfamilies exhibiting monocyclic or polycyclic adult growth patterns, were cultivated in climate chambers during two successive growth periods separated by a period of low temperature to satisfy the chilling requirement. Six treatments combining photoperiod and temperature factors were tested. The morphology of the apex was assessed and height and biomass measured. First season seedlings grown in continuous light varied in apex morphology from the typical juvenile rosette to the adult bud usually found outdoors on 2‐yr‐old plants. It seems possible to distinguish monocyclic and polycyclic populations at an early stage by characters related to development and growth height. The results indicate that special environmental conditions during seedling development may be used as a tool in the search for criteria for early selection.

ISSN:0282-7581    

DOI:10.1080/02827589509382876

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Seeds from open pollination of individual female stroboli on different days in June 1990 in a coastal clone archive ofPinus sylvestris(L.) in northern Sweden (latitude 63°39’ N) were used for a short‐term progeny experiment to study differences over time in the genetic composition of the background pollen. Analysis of progeny growth and cold acclimatization in artificial whole‐plant freezing tests suggested no genetic differences in the fertilizing pollen between pollination days. A clinal variation with the latitude of pollen origin was observed for reference progenies from fertilization with pollen of known geographical origin. Comparisons between open‐pollinated progenies and reference progenies indicate that the pollen cloud originated from approximately 1° latitude (based on height growth) or 1.5° latitude (based on freezing injury) north of the pollination site.

ISSN:0282-7581    

DOI:10.1080/02827589509382877

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In two consecutive years, seedlings of Norway spruce(Picea abies)were planted in a 50‐yr‐old Norway spruce forest in limed (3.8 tons CaCO3ha−1) and control plots. After 6 months they were harvested and the mycorrhizal status of the roots was analysed. Six types of mycorrhiza were distinguished. Three decreased after liming, two increased and one was not affected consistently by the liming. The effects on the total mycorrhizal colonization of the roots were opposite for the two years, indicating that the effects of liming are influenced strongly by other environmental factors. Statistical analysis also revealed pronounced natural variation in space. An inventory of the sporocarp‐producing fungi showed that the number of saprotrophic species producing sporocarps was significantly higher in the limed plots whereas the number of ectomycorrhizal species was lower in the limed plots, compared with the control plots. It is concluded that more information is needed concerning the effects of liming on different soil types before any general conclusions can be made about its effects on mycorrhizal colonization.

ISSN:0282-7581    

DOI:10.1080/02827589509382878

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The influence of irradiance and light quality onin vitrocultures was studied at the rooting stage, and subsequently as it affected the field performance of birch(Betula pendulaRoth.). Forty‐five μmol m−2s−1during the rooting stage reduced the rooting time compared with 30μmolm−2s−1. The light quality treatments of the cultures, from which the microcuttings were harvested, had a larger effect on the rooting than the treatments during the rooting stage. The fastest rooting was observed in microcuttings pre‐treated with blue light (6 days), and the slowest rooting after treatments with red light (12 days), which also, respectively, gave the highest (5.1) and lowest (3.5) mean number of roots per microcutting. The largest growth rate in the field was observed in plantlets harvested from cultures subjected to blue and cool white light.

ISSN:0282-7581    

DOI:10.1080/02827589509382879

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor