应用主成分分析对土壤肥力的评价

以大兴安岭蒙古栎(Quercus mongolica var. mongolica)低质林为研究对象,采用主成分分析法建立不同改造模式下土壤肥力的评价体系,计算各改造样地的综合得分。结果表明:蒙古栎低质林诱导改造后,土壤肥力综合得分最高的是10 m×10 m(G_2),根据评价结果可知林窗改造优于带状改造模式。     

紫金牛光合速率及其生理生态因子日变化研究

利用Li-COR6400便携式光合作用测定系统对紫金牛的光合速率日变化进行研究。结果表明:紫金牛叶片净光合速率日变化呈双峰曲线,最高峰出现8:00,次高峰出现在14:00,有明显的"午休"现象,非气孔因素是导致午休的主要原因。相关分析和回归分析表明,紫金牛光合速率的主要影响因子为气孔导度。紫金牛叶片光能利用率和水分利用效率随着光合有效辐射的增强而降低,说明紫金牛对弱光的利用能力较强。     

麻栎幼林施肥试验

对麻栎幼林开展施肥试验。结果表明:施用微生物有机菌肥与化肥对麻栎树高生长有显著影响,其中施用微生物有机菌肥2kg·株^-1+尿素2kg·株^-1对麻栎树高增长效果最好,施肥1年3个月后树高增长量为2.31m;微生物有机菌肥与化肥施肥量配比对麻栎胸径生长有显著影响,施用微生物有机菌肥1kg·株^-1+复合肥2kg·株^-1和微生物有机菌肥2kg·株^-1+复合肥2kg·株^-11年3个月后,胸径增长量分别为0.99cm和0.89cm,均显著高于施用其它配比肥的。增施复合肥更有利于麻栎的均衡生长,而微生物有机菌肥是缓效性肥料,对改善土壤理化性质和增加土壤活性有益。     

遮荫对弗吉尼亚栎苗木生长及光合-荧光参数的影响

[目的]揭示美国引进树种弗吉尼亚栎幼苗对光照强度的响应特征,为弗吉尼亚栎的引种驯化和高效栽培提供科学依据。[方法]采用人工遮荫法,研究3种光环境下(全光——100%自然光、中度遮荫——50%自然光和强度遮荫——25%自然光)弗吉尼亚栎苗木生长、光合作用以及叶绿素荧光参数的变化。[结果]表明:中度遮荫明显促进弗吉尼亚栎苗高生长(P0.05),但对地径生长影响不明显;而强度遮荫条件下,地径生长受到明显抑制(P0.05),苗高虽有所下降,但与对照相比差异不明显。对弗吉尼亚栎光响应曲线的观测表明:与全光条件相比,中度遮荫条件下,弗吉尼亚栎叶片暗呼吸速率(Rd)、光饱和点(LSP)以及光补偿点(LCP)均明显下降(P0.05),说明适度的遮荫有助于提高弗吉尼亚栎对光的利用效率,促进干物质的积累;而强度遮荫条件下,光补偿点和光饱和点明显上升,暗呼吸速率明显增加(P0.05)。遮荫并未对表观量子效率(α)和最大净光合速率(P_(max))产生明显的影响。进一步对叶绿素荧光参数分析发现,遮荫条件下,PSⅡ最大光化学量子产量(F_v/F_m)和实际光量子产量(Yield)有所增加,但均在正常范围,说明遮荫对PSⅡ活性并未产生胁迫。[结论]弗吉尼亚栎幼苗对遮荫均具有一定的耐受性,中度遮荫有利于苗高生长;而强度遮荫不利于干物质的积累。因此,建议在营林以及人工栽培过程中维持50%以上的自然光照。     

Note: Histology of the midgut and peritrophic membrane inLymantria dispar caterpillars fed on leaves ofQuercus cerris orRobinia pseudoacacia

The structure of the columnar cells, goblet cells and peritrophic membrane was studied in the midgut of gypsy moth (Lymantria dispar L.) caterpillars fed with a suitable (Quercus cerris L.) or an unsuitable (Robinia pseudoacacia L.) host. Columnar cells in the midgut of caterpillars fed onR. pseudoacacia leaves were elongated with small nuclei, partial loss of microvilli and vacuolated cytoplasm. The number and height of goblet cells and their nuclei were greater in caterpillars fed onQ. cerris leaves in comparison with larvae fed onR. pseudoacacia leaves. Peritrophic membranes were thin and delicate in the midgut of caterpillars fed onR. pseudoacacia leaves. http://www.phytoparasitica.org posting Nov. 8, 2005.     

油松与锐齿栎林地土壤微生物生物量初步研究

本文分析秦岭火地塘林区油松,锐齿栎林和草丛壤微生物Cmic,Nmic量及其分布特点,结果表明：（1）油松,锐齿栎林土壤微生物生物量在土壤剖面中从上到下明显的下降趋势,0－20cm土层是土壤微生物生物量集中分布区;（2）土壤微生物生物量与土壤有机质含量,孔隙度,细根（死,活）生的量呈正相关,与土壤容呈负相关;（3）0－30cm土层土壤微生物生物量锐齿栎林,油松林和草丛的Cmic分别为565.87,87,502.64,292.25mg/kg,Nmic分别为89.48,79.34,46.38mg/kg,不同植被土壤微生物生物量排序为：锐齿 栎林＞油松林＞草丛。     

THE WAY OF RESTORING AND REESTABLISHING BROADLEAVED/CONIFEROUS MIXED FOREST ECOSYSTEM FROM SECONDARY FOREST OF MONGOLIAN OAK

The necessity,basis,characteristic and methods of restoring and reestabling broadleaved/coniferous mixed forest ecosystem from the secondary forest of Mongolian oak(Quercus mongolica)are briefly set forth;then several effective methods of restoration and reestablishment are put forward and discussed as follows:openning up effect belt or island to establish horizontal order mixture;replenishing the blank niche to make vertical orderly mix-ture;planting artificial mixed forest to create biological diversity;developing ecological forestry,establishing integrated agroforestry ecosystem;and closing the land for forest and pre-serving some stands considering special conditions and demads.     

复方白毛藤注射液的制备及体外抑菌试验

采用水醇法制备复方白毛藤注射液,用管蝶法进行该制剂的体外抑菌作用试验.结果复方白毛藤中诸药无配伍禁忌,协同作用强,制剂性状稳定.该制剂对金黄色葡萄球菌、链球菌、沙门氏菌均有较强的抑菌作用,其抑菌圈直径(mm)分别为21.7士0.33,20.5土1.13和19±1.17,与烟酸诺氟沙星、洁霉素的抑菌作用比较无显著差异(P＞0.05).     

Phytophthora species in oak ecosystems in Turkey and their association with declining oak trees

From 1999 to 2001, a survey on the occurrence of Phytophthora spp. in the rhizosphere soil of healthy and declining oak trees was conducted in 51 oak stands in Turkey. Seven Phytophthora spp. were recovered from six out of the nine oak species sampled: P .  cinnamomi , P .  citricola , P .  cryptogea , P .  gonapodyides , P .  quercina , Phytophthora sp. 1 and Phytophthora sp. 2. The most frequently isolated species, P .  quercina , was very common on slopes susceptible to drought. It occurred in four different climatic zones and on six Quercus spp., suggesting that it is native to oaks. The second most common species, P .  citricola , was separated into three subgroups: type C was recovered only in Anatolia, whereas A and B occurred only in the European part of Turkey. Phytophthora cinnamomi was recovered at one site only, and may not be involved in oak decline in Turkey. The other four species were recovered sporadically. On affected sites there was a significant association between deteriorating crown status and the presence of Phytophthora spp., particularly P .  quercina . The occurrence of Phytophthora species was significantly influenced by soil pH. Stem inoculation tests on oak seedlings revealed that Q .  petraea was the most susceptible species.     

Comparative aggressiveness of standard and variant hybrid alder phytophthoras, Phytophthora cambivora and other Phytophthora species on bark of Alnus, Quercus and other woody hosts

Pathogenicity tests were carried out on the bark of Alnus glutinosa with 19 isolates of the standard (near-tetraploid) hybrid alder phytophthora, nine isolates representing its known heteroploid variants and 11 isolates of P. cambivora , a probable parent species of the hybrid. Over a 4-year period, 12 experiments were conducted on living alder logs incubated at 20°C. Most isolates of the standard hybrid and those of the 'Dutch variant' were highly aggressive to alder bark. Isolates of the 'Swedish', 'UK' and 'German variants', and of P. cambivora , were only weakly pathogenic. Also, isolates of P. fragariae , P. cinnamomi , P . sp. 'O-group', P. cryptogea , P. megasperma , P. gonapodyides and P. citricola were either weakly or nonpathogenic. Rates of lesion development were greatest on logs cut during July–October, slower on logs cut between November and March and zero on logs cut during April, indicating a strong seasonal effect. Other evidence indicated that lesion development was subject to critical thresholds of host resistance. The standard hybrid was nonpathogenic to the bark of four other hardwood and two conifer species, indicating that it is relatively host specific. In contrast, P. cambivora was an aggressive pathogen on live bark of Quercus and Castanea . The significance of these results is discussed.