Identification of SSR loci in <Emphasis Type="Italic">Betula luminifera</Emphasis> using birch EST data

Expressed sequence tags(ESTs) are generated from single-pass sequencing of randomly picked cDNA clones and can be used for development of simple sequence repeat(SSR) markers or microsatellites.However,EST databases have been developed for only a small number of species.This paper provides a case study of the utility of freely available birch EST resources for the development of markers necessary for the genetic analysis of Betula luminifera.Based on birch EST data,primers for 80 EST-SSR candidate loci were ...     

2．5cm桦木地板毛坯快速干燥新工艺

用干球温度不变、湿球温度连续降低的干燥新工艺对2．5cm桦木地板毛坯进行快速窑干，使干燥周期较常规窑缩短了40％，干燥质量好，且易于操作。     

Dispersal of microarthropods in forest soil

This experiment was a part of a research on the soil community in anthropogenous birch stands in Finland. In that study it was found that communities of Collembola are similar in birch stands of different origin (cultivated field or spruce forest), while the communities of Oribatida are essentially different. When compared to original spruce forest, the communities of both groups are different.Cultivation eliminates the populations of most microarthropod species, that have to disperse after reforestation from the surrounding areas. The aim of the experiment was to study the ambulatory dispersal of soil microarthropods. It was carried out in plastic boxes filled with an intact block of defaunated surface soil taken from a birch stand that was established ca. 30 years earlier on a cultivated field. A strip of intact spruce forest soil was placed at one end of the boxes to harbour the source populations. At the opposite end we placed a row of pitfall traps. Soil samples were taken every two weeks at increasing distances from the source soil using a metal corer, and animals were extracted in a high gradient apparatus. The pitfalls were also emptied every two weeks. The experiment lasted for ten weeks.Pitfall and soil sample data gave an estimation of the maximum dispersal rate for each species or genus. The distance that the populations could potentially disperse in 30 years (age of the stand) indicated that some, but not all of the species could have actively migrated to the central parts of the birch stand (30 m).     

提高桦木板材性能的研究

本文以提高桦木板材物理、力学性能指标，扩大其使用用途为目的，着重研究了桦木中施加强化剂后对其显微结构，物理、力学性能的影响，为今后扩大其木材利用率提供了一定的依据。     

桦木制浆纤维分离点的研究

实践证明,用桦木制浆很有潜力,研究桦木制浆的纤维分离点,对造纸企业得到最佳经济效益,具有指导意义。树种相同,但工艺不同,纤维分离点也不相同。     

白桦树皮提取物的降血脂作用研究

目的研究白桦树皮提取物（BH）的降血脂作用．方法分正常组、模型组、BH给药组：高（300mg／kg）、中（200mg／kg）、低（100mg／kg）剂量和阳性对照组：脂必妥（300mg／kg）．预防给药7d,末次给药2h后,腹腔注射75％蛋黄乳液制作小鼠高脂血症模型,造模12h后测定不同剂量的BH对小鼠血脂水平的影响．结果白桦树皮提取物能够显著降低小鼠血清中TC,TG,LDL-C浓度,显著升高HDL-C．结论白桦树皮提取物具有明显的降血脂作用．     

Influence of felling season,drying method and within-tree location on the brinell hardness and equilibrium moisture content of wood from 27–35-year-old Betula pendula

The Brinell hardness and equilibrium moisture content (EMC) were measured from thinning-aged silver birch wood. Wood material both from the trees harvested in the first commercial thinning and from trees remaining on site after the thinning was included. The average Brinell hardness was 19.40 MPa. It correlated significantly with the basic density of wood. With respect to the distance from the pith, the Brinell hardness of air-dried wood was higher than that of artificially dried wood. The average EMC of the conditioned (20°C, 65% relative humidity) wood was 12.0%. The EMC of the wood also varied, with the EMC being higher for air-dried wood than for kiln-dried wood. EMC was the highest at a distance of 30–40 mm from the pith, decreasing towards both pith and log surface. Seasonal variation in both the Brinell hardness and the EMC of the wood was found. It was presumed to be a consequence of season-dependent physiological changes in trees.     

Current growth differences of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pendula and Betula pubescens) in different regions in Sweden

Abstract

The choice of species in forestry is important, and a real issue as large areas of wind-damaged forest land in southern Sweden need to be regenerated. To compare the growth potential between the most common tree species in Sweden, ratios between site quality derived from site index values determined with site properties were used. A regression function to determine site index for birch from site properties was used to complement the known relationships between site properties and site index for spruce and pine. In large regions of Sweden the distribution of site quality classes was calculated to compare the special characteristics and demands of the three species. On average, the growth difference for pine compared to spruce was about 60% in southern Sweden and 95% in northern Sweden. Corresponding figures between birch and spruce were 40% and 60%. Birch was expected to produce around 60% of pine in northern Sweden and about 70% in southern Sweden. However, it must be stressed that the comparison is based on survey data encompassing mainly naturally regenerated birch, whereas spruce and pine are mainly planted.     

Browsing by large herbivores on Scots pine (Pinus sylvestris) seedlings in mixture with ash (Fraxinus excelsior) or silver birch (Betula pendula)

Abstract

Food selection by large herbivores occurs at a hierarchy of scales, for example landscape, patch or plant. Several hypotheses regarding food plant selection on patch or plant level have been developed. In this cafeteria-type design field experiment, conducted during one winter immediately after planting, we tested the effect of species mixture on browsing by large herbivores (mainly roe deer) on Scots pine seedlings in mixture with seedlings of ash (highly preferred) or silver birch (less preferred). Browsing on Scots pine was not affected by species mixture, neither in terms of the number of browsed pines nor browsing intensity. Instead, browsed biomass was positively and significantly correlated to the total biomass available for browsing. Also, there were differences due to species, with ash being most browsed (44.6%), followed by Scots pine (18.9%) and silver birch (11.6%). Browsed biomass per browsed seedling, however, was largest for Scots pine. In addition, browsed seedlings were initially taller compared to unbrowsed seedlings for all species. The main management implication in this study is that the species mixture did not influence large herbivore browsing on Scots pine seedlings. Hence, removing or discouraging more (or less) attractive browse species in early stages of pine regeneration activities seems unnecessary from the point of large herbivore browsing.     

Self‐thinning models for even‐aged stands of Pinus sylvestris,Picea abies and Betula pendula

Self‐thinning models were developed to describe the relationship between the stem number and mean diameter of even‐aged and monospecific tree stands undergoing self‐thinning. The models were developed separately for Pinus sylvestris L., Picea abies (L.) Karst. and Betula pendula Roth. stands. Data from 41 unthinned permanent sample plots were used. According to Reineke's equation and the —3/2 power rule of self‐thinning, a log‐log plot of average tree size and stem density will give a straight, self‐thinning line of constant slope. According to this study, the slope of the line consistent with Reineke's equation varies for different tree species. Within tree species, the intercept of the self‐thinning line varies according to site index.