华北低丘山区栓皮栎人工林冠层CO2浓度和δ13C变化及其影响因素

采用离轴积分腔输出光谱技术测定华北低丘山区栓皮栎人工林冠层上缘(11 m)和下部(6 m)大气CO₂浓度和δ¹³C值,在小时尺度上分析冠层CO₂浓度和δ¹³C变化及其影响因素.结果表明： 冠层CO₂浓度呈先高后低再升高的日变化趋势,而δ¹³C值没有明显一致的日变化规律.白天大气不稳定状态出现的频率为70.2%,在光合作用和林内湍流的共同作用下,栓皮栎冠层下部CO₂浓度高于冠层上缘约1.70 μmol·mol^-1,而δ¹³C值低于冠层上缘约0.81‰.晚上大气稳定状态出现的频率为76.2%,湍流弱,冠层叶片呼出的CO₂不易流动,导致冠层下部CO₂浓度高于上缘约1.24 μmol·mol^-1,δ¹³C值低于冠层上缘约0.58‰.白天和晚上冠层上下缘的CO₂浓度差值与δ¹³C差值均呈显著的相关关系.逐步回归分析表明,白天太阳辐射和相对湿度是影响冠层CO₂浓度和δ¹³C值差异的主要环境因子,晚上温度显著影响冠层下部与上缘δ¹³C值的变化,这些环境因子通过增强或减弱光合和呼吸作用来影响冠层大气中CO₂浓度和δ¹³C值的变化.     

广西落叶栎林的分类研究

广西的落叶栎林属亚热带落叶阔叶林的一个群系组, 常见有栓皮栎林、麻栎林和白栎林３ 个群系。主要论述其类型划分和生境特点, 为其经营管理和合理利用提供基本材料和依据。     

Responses of Amblyomma americanum and Dermacentor variabilis to odorants that attract haematophagous insects

Carbon dioxide (CO₂), 1‐octen‐3‐ol, acetone, ammonium hydroxide, L‐lactic‐acid, dimethyl trisulphide and isobutyric acid were tested as attractants for two tick species, Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae), in dose–response bioassays using Y‐tube olfactometers. Only CO₂, acetone, 1‐octen‐3‐ol and ammonium hydroxide elicited significant preferences from adult A. americanum, and only CO₂ was attractive to adult D. variabilis. Acetone, 1‐octen‐3‐ol and ammonium hydroxide were separately evaluated at three doses against CO₂ (from dry ice) at a field site supporting a natural population of A. americanum nymphs and adults. Carbon dioxide consistently attracted the highest number of host‐seeking ticks. However, for the first time, acetone, 1‐octen‐3‐ol and ammonium hydroxide were shown to attract high numbers of A. americanum. Further research is needed to determine the utility of these semiochemicals as attractants in tick surveillance and area‐wide management programmes.     

Phosphorylation and nitrogenase activity in isolated heterocysts from Anabaena variabilis (ATCC 29413)

Adenylate-pool composition, energy charge, and nitrogenase activity were examined in isolated heterocysts from Anabaena variabilis (ATCC 29413). ATP formation was detected as a light- or oxygen-induced increase in ATP concentration. No cofactors or substrates had to be added for photophosphorylation to occur, whereas oxidative phosphorylation was dependent on hydrogen and oxygen (Knallgas reaction). The increase in ATP concentration was reflected by a decrease in AMP concentration, accompanied by small changes in ADP levels. Thus, a regulation of the adenylate pool by a myokinase (adenylate kinase) has to be assumed. Upon dark-light transitions, the energy charge in heterocysts increased from values below 0.4 to values approaching 0.8. High energy-charge values, reached in the light only, allowed for high rates of acetylene reduction in the presence of hydrogen. The increase in the energy charge in the dark to approx. 0.64 by addition of oxygen (5% ($\text{v}\text{v}$) in the presence of hydrogen) resulted in low nitrogenase activities, generally not exceeding 1–3% of the light-induced rates. In the dark, oxygen concentrations above 10% were inhibitory to both ATP formation and acetylene reduction. Increasing light intensities led to a steep increase in energy charge followed by an increase in nitrogenase activity. Plotting enzyme activity versus energy charge, a nonlinear, asymptotic relationship was observed.     

陕西不同地区栓皮栎种群增长模拟与预测预报的研究

时间序列分析可以通过差分、周期的方法,对植物种群的增长进行模拟与预测。在陕西的秦岭、汉中、黄龙地区选择林相整齐、有代表性的地段作为标准地,设置样方40个,对各样方内的林木进行每木检尺,通过优势木解析的方法,测得栓皮栎种群胸径的实际生长量,运用起伏型时间序列分析,建立了栓皮栎种群个体年龄与胸径生长的时间序列模型,四个模型所得的各个样地栓皮栎胸径生长的模拟值与实际值进行比较,其模拟平均误差都在1．5％以内,平均精度达到97．8％,模拟效果较好。经检验,该模型预测胸径的生长量具有较好的可靠性和精度高等优点,从而丰富和发展了种群增长模拟与预测预报的方法。     

中国美登木属的新分类群

本文拟定中国美登木属4新种1新等级,它们是:广南美登木M. guangnanensis H.Shao,蒙自美登木M. mengziensis H.Shao,易门美登木M. yimenensis H.Shao,树状美登木M. arboreus H.Shao和疏刺刺茶M. variabilis(Hemsl.)C.Y.Cheng var.inermis(C.Y.Cheng et W.L.Sha)H.Shao。     

宝天曼落叶阔叶林样地栓皮栎种群空间格局

种群空间格局分析有利于更好地理解格局形成的潜在生态过程.本研究在温带-亚热带过渡区的宝天曼自然保护区内选择两个1 ha固定监测样地,以栓皮栎(Quercus variabilis)为研究对象,采用单变量和双变量g(r)函数分析了两个典型样地中栓皮栎种群空间分布格局、4个不同生长阶段的空间分布格局和空间关联性,以及栓皮栎活立木与残干间的空间关联性.结果表明:(1)栓皮栎种群分布格局以聚集为主,样地Ⅰ的聚集性更强,而样地Ⅱ则表现出较大的随机性;(2)在两个样地中,早期阶段的个体均表现为聚集分布格局,而后期阶段的个体则表现为随机分布格局;(3)样地Ⅰ中栓皮栎种群不同生长阶段均表现为空间正相关,样地Ⅱ中栓皮栎种群的早期阶段与其后的两个阶段间均表现为空间负相关;(4)样地Ⅰ中栓皮栎活立木与残干之间为空间正相互作用,样地Ⅱ中栓皮栎活立木与残干之间无空间关联性.宝天曼自然保护区栓皮栎种群空间分布格局可能受环境异质性的作用,并对自身的天然更新产生影响.     

栓皮栎茎段离体培养的研究

以4～6个月的实生苗茎段为外植体,研究了离体条件下培养基及激素对栓皮栎器官发生和植株再生的影响。结果表明:初代培养选用低盐培养基WPM、BTM和GD,附加0.2mg·L-16-BA,丛生芽较多,茎粗壮,生长势健壮,均好于高盐培养基MS。继代培养时,以BTM为基本培养基,添加0.2～0.6mg·L-16-BA有利于茎芽增殖和生长,当6-BA浓度为0.8～1.0mg·L-1时,不利于茎芽伸长。以WPM为基本培养基,附加NAA0.1mg·L-1和IBA0.25mg·L-1时,生根率高,根系发育好。     

PHYSIOLOGICAL RESPONSES OF ANABAENA VARIABILIS (CYANOPHYCEAE) TO INSTANTANEOUS EXPOSURE TO VARIOUS COMBINATIONS OF LIGHT INTENSITY AND TEMPERATURE1

Light intensity and temperature interactions have a complex effect on the physiological process rates of the filamentous bluegreen alga Anabaena variabilis Kütz. The optimum temperature for photosynthesis increased with increasing light intensity from 10°C at 42 μE·m^?2·s^?1 to 35°C at 562 μE·m^?2·s^?1. The light saturation parameter, I_K, increased with increasing temperatures. The maximum photosynthetic rate (2.0 g C·g dry wt.^?1·d^?1) occurred at 35°C and 564 μE·m^?2·s^?1. At 15°C, the maximum rate was 1.25 g C·g dry wt.^?1·d^?1 at 332 μE·m^?2·s^?1. The dark respiration rate increased exponentially with temperature. Under favorable conditions of light intensity and temperature the percent of extracellular release of dissolved organic carbon was less than 5% of the total C fixed. This release increased to nearly 40% under combinations of low light intensity and high temperature. A mathematical model was developed to simulate the interaction of light intensity and temperature on photosynthetic rate. The interactive effects were represented by making the light-saturation parameters a function of temperature.