桦树桑黄液体发酵培养基优化研究

研究了桦树桑黄液体发酵培养基中不同营养成分对桦树桑黄菌丝生长的影响。采用L9(34)正交设计法对桦树桑黄发酵培养基进行了优化,初步筛选出了桦树桑黄液体发酵的培养基。结果表明,优化培养基为玉米粉1%、麦麸1%、葡萄糖2%、蛋白胨0.5%、酵母膏0.5%、磷酸二氢钾0.1%、硫酸镁0.05%、维生素B1 1 mg.100-1.mL-1。     

红松人工用材林近自然经营技术的研究

以“近自然林业”为指导思想。采用实验生态学的方法,经过６ａ的伐孔实验证实了林隙对红松更新生长的有利作用,确定出树高与林隙孔径比为１：１～４：３时较利于林隙内红松的生长。据此通过理论生态学的方法,得出了５种地位级上单位面积不同白桦高度及白桦－红松经营复合体中白桦株数、林隙个数、林隙孔径、不同直径大小的红松株数及每个林隙中不同大小的红松株数等技术指标,为红松人工用材林的持续经营提供了科学的依据。     

大兴安岭不同演替阶段白桦种群光合生理生态特征

应用LI-6400光合作用测定系统,研究了大兴安岭不同演替阶段白桦光合生理生态学特征。结果表明:无论是最大净光合速率,还是表观最大量子效率,非演替顶极群落中的白桦[(7 79μmol/(m2·s)、0 0698mol/mol)]都大于演替顶极群落中的白桦[(7 59μmol/(m2·s)、0 0457mol/mol)],这表明非演替顶极群落中白桦的实际光合能力和潜在光合能力都大于演替顶极群落中的白桦。2个不同演替阶段中白桦的光饱和点相差不大,但是演替顶极群落中白桦的光补偿点却低于非演替顶极群落,这表明演替顶极群落中白桦的呼吸作用有所下降。此研究结果揭示了大兴安岭顶极群落中白桦退出主林层的生理生态学机制。     

东北林区天然白桦相容性生物量模型

基于东北林区天然白桦实测生物量数据,通过2种方案(以总生物量为基础分级控制和以总生物量为基础直接控制)建立天然白桦一元和二元相容性生物量模型,模型参数估计采用非线性度量误差联立方程组估计方法,并采用加权回归的方法进行异方差的消除。结果表明:2种方案所建立的天然白桦一元、二元相容性生物量模型的确定系数R2=0.800～0.988,模拟效率(EF)=0.80～0.97;2种方案所建立的相容性生物量模型的预测精度大多数在80%以上,树枝和树叶生物量模型的预测精度较差,但也在69%以上;所建立的相容性生物量模型中,总生物量和树干生物量模型效果较好,树根、树叶和树枝生物量模型效果较差。总的来说,2种方案所建立的相容性生物量模型都具有一定的精度,都能对天然白桦生物量进行很好的预估,以总生物量为基础直接控制方案所建立的一元和二元相容性生物量模型好于以总生物量为基础分级控制方案所建立的一元和二元相容性生物量模型,所以在进行天然白桦生物量预估时,建议采用以总生物量为基础直接控制所建立的相容性生物量模型。     

冀北山地杨桦低效林改造的效益分析

[目的]分析研究冀北山地杨桦低效林改造的成果,为该地区的森林健康经营理论提供参考。[方法]采用生态疏伐后人工林下更新的方式进行改造,并以定量计算的方式对改造后样地和未改造对照样地分别从林地生产力、固碳释氧功能、水源涵养功能3方面进行效益分析。[结果]改造后的样地较对应的对照样地在总体效益方面具备很大优势,具体高出值分别为25 008.89和14 802.17元/hm2,增长率分别为16.6%,14.6%。其中林地生产力价值分别高于对照样地44.9%,73.11%;固碳释氧价值分别高出13.4%,9.2%;涵养水源价值分别高出5.4%,2.6%。[结论]对杨桦低效林进行生态疏伐、人工林下更新改造后,林分质量得到显著改善,提高了林地生产力和林分生态功能的同时,带来了经济效益的增长。     

环境湿度对白桦木材尺寸稳定性的影响

对白桦木材在不同环境湿度下的尺寸稳定性进行了试验研究,试验表明:白桦小试件的含水率随环境湿度变化的时间较短,在正常的湿环境中1~2d内就与周围的环境达到平衡;较大尺寸的家具拼板材在干燥的环境中解吸速度较慢,需要较长的时间,同样在潮湿的环境中吸湿较慢,要达到与周围的环境相平衡同样需要比小试件更长的吸湿时间。     

Seasonal changes in contents of root starch and soluble carbohydrates in 4–6‐year old Betula pubescens and Popuius tremula

Roots of 4–6‐year old European aspen and pubescent birch were collected monthly during 1983–87 and 1983–88, and analysed to determine their starch, fructose and glucose concentration. Carbohydrate concentrations in aspen roots fluctuated with low levels in May‐June. Seasonal variation was not as consistent in birch roots as in aspen roots. The drop during May‐June occur as consistently in birch. Total carbohydrate concentrations in roots of birch collected from six latitudes (56–67°N) in Sweden showed similar patterns of variation. There were no significant difference between starch concentrations among roots of different diameters (2–11 mm), nor did concentrations differ between sites at different distances (5–25 cm) from the main stem. It was difficult to visually differentiate between low and medium starch levels. Some practical implications of the results are discussed     

Incidence and severity of dieback in birch plantings associated with Anisogramma virgultorum and Marssonina betulae in Scotland

Betula pendula and B. pubescens were surveyed at nine Scottish Woodland Grant Scheme (WGS) sites in 2004 to assess the incidence and severity of two fungal pathogens, Anisogramma virgultorum and Marssonina betulae , and their association with crown dieback. Of the surveyed trees, 47% had at least 40% crown dieback, with B. pendula more severely affected than B. pubescens at most sites. Overall, 57% of surveyed birch trees had A. virgultorum and 28% had M. betulae , with the incidence of trees infected with both species varying among sites. Incidence and severity of A. virgultorum were greater on B. pubescens than on B. pendula , whereas the reverse was true for M. betulae. The relationship between incidence of M. betulae foliar disease and sunken cankers was significant, with 83% of M. betulae -infected trees having these cankers. The presence of M. betulae foliar disease resulted in a greater percentage of crown dieback compared with non-infected trees in both birch species, whereas the presence of A. virgultorum caused greater crown dieback in B. pubescens only. Across all sites and both birch species, as severity of infection with either A. virgultorum or sunken cankers increased, so did the severity of crown dieback. This study showed that A. virgultorum and M. betulae appear to contribute significantly to birch dieback at the nine sites surveyed.     

The seasonal pattern of soil microbial community structure in mesic low arctic tundra

Soil microorganisms are critical to carbon and nutrient fluxes in terrestrial ecosystems. Understanding the annual pattern of soil microbial community structure and how it corresponds to soil nutrient availability and plant production is a fundamental first step towards being able to predict impacts of environmental change on ecosystem functioning. We investigated the composition, structure and nutrient stoichiometry of the soil microbial community in mesic arctic tundra on 9 sample dates in 6 months from winter to fall using phospholipid fatty acid analysis (PLFA), quantitative polymerase chain reaction (qPCR), epifluorescent microscopy and chloroform-fumigation–extraction (CFE). PLFA analysis indicates that the winter microbial community was fungal-dominated, cold-adapted and associated with high C, N and P in the soil solution and microbial biomass. The microscopy data suggest that both bacteria and fungi were active and growing in soils between −5 °C and 0 °C. A significant shift occurred in the PLFA data, qPCR patterns, microscopy and microbial biogeochemistry after the thaw period, resulting in a distinct community that persisted through our spring, summer and fall sample dates, despite large changes in plant productivity. This shift was characterised by increasing relative abundances of certain bacteria (especially Gram +ves) as well as a decline in fungal biomass, and corresponded with decreasing C, N and P in the soil solution. The summer period of low substrate availability (plant–microbe competition) was associated with microbial indicators of nutritional stress. Overall, our results indicate that tundra microbial communities are clearly differentiated according to the changes in soil nutrient status and environmental conditions that occur between winter and post-thaw, and that those changes reflect functionally important adaptations to those conditions.     

天然杨桦胶合板材用材林的定向培育

采用固定标准地定位观测和临时标准地调查点面结合的方法．研究了天然杨桦林分的经营密度。 确定杨桦林最佳经营密度为０．７０。通过对杨桦林各径级株数分布以及胸径与小头直径相关关系的综合分析．根据 林分平均胸径和平均树高的生长进程规律及林分最佳经营密度模型．提出了天然杨桦胶合板材用材林定向培育的 技术措施。结果表明：采取该项技术．Ⅲ立地级的山杨林和Ⅱ立地级的白桦林单位面积胶合板用材林的总产量可 分别提高 １６． ４１％和 ４． ５５％。