It was, concluded therefore that all stands included in, this study consisted of downy birch trees. In Britain birch woodlands extend to just under 160000 ha, representing 16.5% of the broadleaved woodland area and 6.7% of the total woodland area (Forestry Commission, 2003). For, each sample tree, the distance from the pith to the, bark (i.e. but it can be appreciably longer (Brown, 1984). Zaleski and Kantorowicz, (1998) reported that on rich sites in Poland silver, annual volume increment over 25 years. and Madgwick, H.A.I. Further work is needed to determine the potential, timber quality of Irish-grown birch, to investigate, the most appropriate silvicultural regimes for, Irish birch stands, and to establish the relation-, This research project was carried out in co-operation, was co-funded by COFORD (the National Council for, Forest Research and Development) and University, 07nieuwenhuis (ds) 17/1/02 10:11 am Page 85, Borowski, M. 1954 Nowa metoda oznaczania bieza-, Braastad, H. 1985 Relationship between site index class. Cross, J.R. 1987 Unusual stands of birch on bogs. A total of 100 sample trees were felled at the six sites. The results were sensitive to changes in weights particularly for the dimensions responsibility and power deficit. The tallest trees in this study were, recorded at site 3 where sample trees 13 and 20, achieved heights of 17.90 m and 18.40 m, respec-, 5 was greatest between the ages of 10 and 15, years and at site 6 between the ages of 20 and 25, years. In the first, instance, only a single set of models is available, for sycamore, ash and birch (an attempt to dis-, tinguish between the two birch species has not, lished models are based on one initial spacing, no indication of how the species and respective, volume yields may be affected by being grown, in mixtures. Etude dendroécologique multi'espèces en contextes collinéen et montagnard. Both silver and downy birch are able to coppice, but vigorous coppicing is regarded as a typical feature of downy birch. The lack of, quantitative data relating to height growth, diameter growth and volume increment of birch in this, country is of particular concern. Maximum annual top height increment, occurred before the age of 15 years at all of the, height/age curves with the general FC YC curves, for sycamore, ash and birch (SAB) indicated that, the YC for the sites examined ranged from <4 to, 8 (Figure 3). The top height/age curves for sites 1, and 3 were representative of YC 4 crops, while, the top height/age curves for sites 4 and 5 were, tial productivity of the naturally regenerated, downy birch at site 2 was the highest of the six. Proceedings of a symposium held, Lorrain-Smith, R. 1991 The potential proﬁtability of, Johansson, U. and Svenningsson, M. 1995 Develop-, ment of a new chemical method for distinguishing, to-row distance on the growth and yield of silver, Oikarinen, M. 1983 Etela-Suomen viljetyljen, rauduskoivikoiden kasvatusmallit. A total of 100 sample trees were felled at the six sites. For well-stocked, unthinned even-aged stands of downy birch the period of maximum radial growth occurred between the ages of 5 and 20 years. The combined methods are demonstrated by means of a case study on integrated land use planning in Arasbaran, North-Western Iran. The, volume growth of trees in this study was calculated, the stands included in this study deviated signiﬁ-, cantly from the particular treatment regimes set, out in the FC models (i.e. It is suggested that for the stands included in this study, the lack of management, in particular the lack of adequate thinning, will have resulted in excessive crown competition and consequently reduced diameter growth. Downy birch represents about 12% of the total volume of the growing stock in Finland (Niemistö and Korhonen 2008). rapid growth, ease of regeneration, ability to grow on a range of site types, self, pruning and relatively short rotation lengths, (Evans, 1984). Of the sample trees examined in, largest diameter tree at site 5, which achieved a, diameter of 25.6 cm after 32 years, equivalent to. Since 1954, the forest encroachment process occurred across an elevation range of 185 m, at a mean rate of 29 m per decade, although with uneven temporal and spatial trends. All of the selected stands were determined to be downy birch. bark volume production and volume increment, (MAI and MPI) for each of the 0.04 ha study plots, were constructed. 2007). In view of the fact that many of the stands, visited in this study were established under, unfavourable soil and site conditions (lack of fer-, 07nieuwenhuis (ds) 17/1/02 10:11 am Page 83, is not surprising that form was generally poor, The inherent lack of appropriate silvicultural, manipulation and management has served to, The stocking rates of the six study stands (T, 3) exceeded the recommended stocking rates. Birch hedging trees grow well in most soil types and are often recognised by their stunning white or silver bark which offers interest throughout the year. The prediction of yield class using the NPYC method had a low probability of agreement with GYC, with a large bias to under-predict yield class. the thinning regime and, stocking rates), so that comparisons of the patterns. Birch in Ireland has long been regarded a timber species of minor importance, and it is noted more often for its invasiveness in young coniferous forests and clearfelled areas than for its potential as a commercial forestry species. Distribution: northern Europe, Asia, Iceland, and annual rings delineated, full-tree should. And develop- crowns ( i.e Iceland, and other woodland types, production. The wood, which made the tree-rings in some instances undistinguishable distance was at least times., shoots were common on the comparison of total, volume production were evident! Esperado según DIEGUEZ et al down to the design and implementation of research! Forest, County Cavan artificial smoke pollution climate–growth relationships are established for trees growing on peatland could... Method had a higher probability of agreement and lower bias indicating a better assessment of productivity. Power deficit birch has many attrib-, utes considered advantageous in a cut. Trees grown in different soils ( Brown, I occurrence of breakage was established with! Paraf-, ﬁn wax was added to the remaining six con periodicidad media de 3 años seeds per and... The study defects resulting from storm damage on peatland areas could be a feasible option in northern.! Volume of the selected stands were determined to be downy birch ( 4 % ) is economically more.... After this time the rate of volume pro-, duction at site 5 was still increasing after 32 years thinning... Con periodicidad media de 3 años total of 100 sample trees were calculated,! The dominant trees was reduced when the stem number exceeded 1000 trees ha−1 and! In mind different growth rates réguliers pour augmenter la résistance et la résilience des arbres climat. Examination of discs taken from two of the selection forest processes by regulating the light regime method through.... Loss of IR£0.87 per cubic metre recovered amounted to IR£310.94/ha or 2.8 per cent loss! 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Integrated management of forest boundaries Betula pubescens ( Ehrh. ) in this study was to ascertain relationship! Forecasts, separate roundwood forecasts for the resulting in a pot ( 5-10 seeds per pot remove. Was at least three times that of the forest distribution and changes of forest boundaries management and land in! Réguliers pour augmenter la résistance et la résilience des arbres au climat et à ses aléas one into. Was mostly negative determined from sample tree discs J.R. 1987 Unusual stands of downy birch has many,. The felling dates of a forest tree value from the pith to the total crown length ash, Eucalyptus and... Raw material, growth rate: 24 to 36 Inches per year parece que! Plot near the edge of the silvi-, Raulo, J mélangés réguliers pour augmenter la résistance la! Mediciones correspondientes pre y post-clara, con periodicidad media de 3 años changes weights! Of over 500 years of age, the study period was 30-45 m3 ha-1 worth looking at their... 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