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《Scandinavian Journal of Forest Research》2012,27(6):529-537
This study demonstrates the correlation between stem form and compression wood content in 36 sampled trees from a 6-yr-old container grown Scots pine ( Pinus sylvestris L.) plantation in central Sweden. Root analyses were carried out to examine causes for the high incidences of basal sweep. On the sampled trees basal sweep, stem sweep and maximum bow-height were measured. Discs were cut at different heights and the compression wood content was analysed using digital image analysis. Pith eccentricity and out-of-roundness were calculated for each disc as well as per stem. Compression wood and pith eccentricity was most pronounced near the stem base, where sweep tends to be high. In general, pith eccentricity increased with degree of basal sweep. As a conclusion, expression of basal sweep can be used to predict compression wood content in young Scots pine trees. This study also shows the importance of anchoring of a tree to prevent basal sweep formation due to instability. 相似文献
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Florence Renou Úna Scallan Michael Keane E. P. Farrell 《European Journal of Forest Research》2007,126(4):545-554
The poor reputation of birch in Ireland is gradually changing, and the interest shown in it by foresters is growing, as is
the recognition of the many advantages that this genus offers, especially from an afforestation and ecosystem development
point of view. The potential of native birch species was investigated on industrial cutaway peatlands in the Irish midlands.
Field experiments were established to evaluate differences (in terms of survival, growth attributes and form) between B. pendula and B. pubescens, between bare-root and container planting, and between small and medium size seedlings. After five growing seasons, B. pendula was found to be the superior species especially on well drained and shallow peat sites. Bare-root B. pendula will grow faster with reasonable form but containerised birch may be favoured on more difficult sites (with deeper and wetter
peat). Larger seedlings performed better, regardless of species. This study demonstrated good growth potential for planted
birch on cutaway peatlands and that this species should be integrated in further planting programmes. 相似文献
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The objective of this study was to compare the survival and volume of conifer stands at 26 years of age with their status
at planting. Survival, growth and damage were studied in eight clear felled stands regenerated in 1972. Five of the areas
were planted with Norway spruce (Picea abies (L.) Karst.) and three with Scots pine (Pinus sylvestris L.). The plantings were examined in 1972 and 1974. In 1974, the number of living undamaged planted seedlings was low (10–15%).
However, the number of undamaged seedlings was supplemented by naturally regenerated conifer and birch seedlings. The total
number of undamaged seedling in 1974 was equivalent to 20–30% of the number of seedlings planted. In 1998, the main species
in three stands had changed from Norway spruce to Scots pine, and in one stand from Norway spruce to birches. Actual volume
in 1998 for the stands was compared to stand volume generate according to five scenarios based on recommended and actual seedling
number in 1972 and 1974. The actual volume was 64% of that expected if the recommended number of trees had been planted. Naturally
regenerated Scots pine and Norway spruce increased stand density in 1998. The actual volume was 37% higher than the average
volume in the surrounding county. On average, 36% of the trees were damaged. More than 50% of the total damage was caused
by moose (Alces alces L.). For Scots pine, moose or other browsing animals damaged 30% of the trees. The results of this study indicate that the
1998 volume was higher than expected, considering the low number of undamaged seedlings in 1974. This was mainly due to the
large amount of naturally regenerated plants. In addition, the results indicate that the volume could have been higher if
the initial conditions had been better. Despite the low number of undamaged seedlings in 1974, seven of the eight studied
stands produced a higher volume than the average stand for the region. In practise, high numbers of seedlings should be planted
on scarified areas. In most cases there will be a supply of naturally regenerated seedlings. 相似文献
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