摘要:

Medium‐term plans give prescriptions for individual stands in each of three to five years. The long range plan, on the other hand, is based on aggregated data in the form of timber classes, and multi‐year periods. Three treatment indices for stands are developed as linkages between these plans. Several model studies are performed where the prioritizing of thinning and fertilization according to index are compared with the solution to a model based on disaggregated data. The index that is based on reduced costs computed on stand data shows the best correspondence. The index that shows the poorest results transfers the treatment assigned to the timber classes to the stand via the kinship of the initial state of the stands with that of the timber classes. It is not evident that the use of this index would perform better than a mere random selection. The third index has reduced costs computed on timber class data which are transferred to the stands via the kinship between them and the timber classes. This index is not as reliable as the first but should be preferred to the second in cases where necessary stand data is lacking.

ISSN:0282-7581    

DOI:10.1080/02827588709382461

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A method for forecasting the log‐class distribution resulting from harvesting forest stands is investigated. The diameter distribution of a stand is approximated by a two‐parameter Weibull density function, the parameters of which are recovered from stand level characteristics. Theoretical bucking is performed for actual and simulated distributions and the resulting log yields are compared. An application to 40 stands indicates that an accurate prognosis can be expected, given a good approximation of the diameter distribution. For cases with multimodal diameter distributions or many small trees, the prognosis is unreliable.

ISSN:0282-7581    

DOI:10.1080/02827588709382462

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Exchangeable Al and acidity of Swedish beech(Fagus sylvaticaL.) forest soils are documented and discussed on the basis of known changes in soil chemical properties during recent decades. It is concluded that the pH and base saturation decrease, which has occurred in most forest soils of the region, has been accompanied by increases in the amount of exchangeable and soil solution Al and a greater decrease of the Ca: AI ratio, particularly in the B horizon. An adverse nutritional state now seems to prevail in most beech forest B horizons. Conditions are more favourable in the topsoil due to the formation of Al‐humus complexes which are less available to plant uptake, and in the case of very acid mor layers, a low Al content. However, in A (mull) horizons of intermediate acidity with a rather high clay content and low in humus, conditions approaching those of the B horizon may be found.

ISSN:0282-7581    

DOI:10.1080/02827588709382463

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A provenance trial of lodgepole pine(Pinus contortavar.latifolia)planted in 1969 at Matrand, Eidskog, Norway was apparently attacked byGremmeniella abietinain 1984/85. In late autumn the damage was recorded separately on the lower and upper halves of the trees. The material ranged in latitude from 40.25°N to 56.28°N, and in altitude from 2 850 to 450 m a.s.l., highest in interior western United States and lowest in western Canada. The most heavily attacked sources were those from southern latitudes and from high elevations. The attack frequency changed gradually from south to north. In order to avoid attack byG. abietina, only well‐adapted provenances should be used.

ISSN:0282-7581    

DOI:10.1080/02827588709382464

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Inbreeding depression after selfing was estimated in two field trialsof Pinus sylvestris, age 11 and 14 years, respectively, by comparing stem volume and height after selfing and outcrossing. For the majority of trees, inbreeding caused a statistically significant reduction in stem volume. The average inbreeding depression for stem volume was 46% and 66% for the two trials, respectively, with a large variation among trees. For one of the trials, the inbreeding depression for height remained at a constant level between age 6 to 14 years, while the inbreeding depression increased between age 6 to 11 years for the other trial. Inbreeding depression was not found to be correlated with the GCA for stem volume of the individual trees. The relative phenotypic within‐family variance was found to be higher in progenies after selfing as compared to outcrossing.

ISSN:0282-7581    

DOI:10.1080/02827588709382465

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A simple model for willow forest growth during the growing season is presented. The model is based on nitrogen productivity, expressed as the daily above‐ground biomass growth per the amounts of nitrogen in foliage and leaf litter. It is shown that the nitrogen productivity can be expressed as a linear function of the amounts of leaves produced. The model, which also includes allocation of biomass between stem and leaf biomass as well as between foliage and leaf litter biomass, is tested against accurate measurements of the seasonal growth of willow of four different plots. Simulated and measured biomass of stem, foliage, leaf litter and the total above‐ground biomass agreed well for all four plots. The model concept should be useful in nitrogen flux models and as a tool to describe the actual growth of a willow stand, knowing only the annual leaf production and the nitrogen concentrations of foliage during the growing season.

ISSN:0282-7581    

DOI:10.1080/02827588709382466

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In a combined population‐progeny experimental plantationof Pinus sylvestrisat Nordanås, lat. 64°19’ long. 18°12’ alt. 400 m, a few growth characters and around 25 quality characters were meaured or assessed at age 34 from seed. The populations under study originated from latitudes 63–67. The experimental design is a split‐plot with three replications. Each population is represented by 10–20 open pollinated progenies planted in 15‐tree row plots at a spacing of 2.5x2.5 m. All growth and most quality characters showed significant population differences. Family differences were noted for approximately half of the quality characters. The family repeatability for growth and quality characters varied much between the populations in a non‐consistent way. Thanks to the strong genetic correlations between breast height diameter and stem volume, as well as between tree height and stem volume those two characters could be used to estimate stem volume.

ISSN:0282-7581    

DOI:10.1080/02827588709382467

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

If low absolute pressure is first applied to and then released from seeds ofPinus sylvestrisL. lying in water, the seeds with mechanical damage, i.e. with seed coat cracked, with part of seed coat missing or with part of seed coat and gametophyte missing, quickly lose their buoyancy and sink and can thus be separated from the floating undamaged seeds (PREVAC method). The most crucial of the tested physical properties was the level of pressure. The time of treatment (1–20 min) was of less importance, and the water temperature (5–40°C) was unimportant. Treatment at approximately 97 kPa below atmospheric pressure (3–5 kPa absolute pressure) for 1 up to 20 min resulted in removal of almost all mechanically damaged seeds in the four studied seed lots (containing up to 26% damaged seeds). In total, less than5%undamaged seeds of the whole seed lots were removed. The germination percentage of the fractions remaining after separation increased with increasing number of damaged seeds in the seed lots and vice versa for the removed fractions.

ISSN:0282-7581    

DOI:10.1080/02827588709382468

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Simple techniques are described and illustrated for fitting four common diameter distribution models: Beta, Gamma, Lognormal, and Weibull. A visual goodness of fit test is illustrated using typical plot data. Programs by the authors are available which allow all necessary computations to be easily performed on a hand‐held, programmable calculator.

ISSN:0282-7581    

DOI:10.1080/02827588709382469

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Seedlings of Norway spruce (Picea abies(L.)) were grown at 335 and 1000 μl CO21−1for 118 days in growth rooms at different irradiance levels. Photon flux density ranging from 8.6 to 34.6 mol m−2day−t(PAR) was given either as constant light or as alternating levels in intervals of two or six hours. CO2enrichment increased the plant dry weight from 36% to 105% by increasing photon flux density from 8.6 to 25.9 mol m−2day−1. At constant light the dry weight apparently reached its maximum at a photon flux density of 25.9 mol m−2day−t. At the lower radiation levels alternating in CO2enriched air gave slightly higher dry weights compared to constant light levels. At the highest radiations the effect on dry weight was the opposite. High CO2concentration and 300 μmol m−2s−1constant light (25.9 mol m−2day−1) gave the best growth and quality of plants. Top, root, stem and foliage weight were proportionally affected. Shoot length was enhanced by CO2enrichment. Shoot weight per cm was substantially increased both by CO2enrichment and increasing photon flux density.

ISSN:0282-7581    

DOI:10.1080/02827588709382470

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor