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81.
WANG Mingyu SHU Lifu TIAN Xiaorui LI JieInstitute of Forest Protection Chinese Academy ofForestrv Forest fire management office. State Forestry Administration 《中国林业科技(英文版)》2003,(4)
Lightning fire is one of natural fires; its mechanism is very complex and difficult to control. Daxing'an Mountain is the main region that lightning fires occur in China. Research on lightning fires indicates that special fuel, dry-storm weather and high altitude form the lightning fire environment. Lightning fires have close relation with lights. When lightning occurs, especially dry-lightning which brings little precipitation with surface temperature growing and fuel dehydrating, these often lead to lightning fires. Lightning fires have characteristics of geography, time and topography. The higher altitude forest region in Daxing'an Mountain, the more lightning fires occur. Valley with altitude above 800 m in the north of 51.N and Larix gmelinii-Pinus pumila, Pinus sylvestris var. mongolica -Pinus pumila forests on the top of mountain are the most concentrating region where lightning fires occur. One serial dry-storming can ignites many lightning fires, the furthest between them is as long as 150 km. 相似文献
82.
83.
本文通过鸡胚接种的方法就蜂胶乙醇浸出物对NDV的灭活作用进行了试验观察,结果表明常温下3分钟,含蜂胶乙醇浸出物0.1mg/ml的95%乙醇稀释液、含蜂胶乙醇浸出物10mg/ml的47.5%乙醇稀释液、含蜂胶乙醇浸出物10mg/ml的生理盐水稀释液;37℃3分钟,含蜂胶乙醇浸出物0.1mg/ml的95%乙醇稀释液、含蜂胶乙醇浸出物0.1mg/ml的47.5%乙醇稀释液、含蜂胶乙醇浸出物10mg/ml的生理盐水稀释液均对ND克隆-30具有完全灭活作用;常温下3分钟,1mg/ml的47.5%乙醇稀释液对ND克隆-30具有灭活作用。 相似文献
84.
杉木不同种源叶养分变异的研究 总被引:1,自引:0,他引:1
研究表明,不同种源杉木的叶养分含量在树液流动期、芽膨期、旺盛生长期(6月,9月)和封顶期有明显的差异。在供试种源分布区范围内,树液流动期和6月旺盛生长期的叶P含量与纬度成显著负相关;N/P值与纬度成显著正相关。产地≥10℃积温与树液流动期的P,K含量,N/P值及6月旺盛生长期的N/P值都有显著负相关关系。产地日照时数仅与芽膨期的叶Mg,Ca,P养分的正偏相关关系明显(α=0.10).用统一的线性模式较难反映变异的规律。但经主成分(PCA)分析,揭示出南岭山地优良种源区种源叶养分(尤其是P,Mg)含量高于一般产地种源的趋势。 相似文献
85.
ZHENG YongqiResearch Institute of Forestry. Chinese Academy of Forestry. Beijing 《中国林业科技(英文版)》2002,(1)
Family outcrossing rates of Pinus caribaea var. caribaea populations that differed in origin and management were estimated by using isozyme markers. The family outcrossing rates were estimated by (1)fixing the probability of pollen gene frequency (p); (2) allowing pollen gene frequency to vary among families. The estimates of family outcrossing rates for all the populations varied widely among families (clones of the seed orchard), ranging from 0.39 to 2.0. The average family outcrossing rates of both methods were greater than the 相似文献
86.
87.
小麦收获前种子发芽敏感性配合力的研究 总被引:10,自引:2,他引:10
选用5个收获前穗发芽敏感性不同的白皮小麦亲本品种,进行双列杂交,研究了发芽敏感性的配合力。结果表明:小麦收获前种子发芽敏感性同时受加性和非加性基因效应影响,而加性基因效应起主导作用;亲本品种发芽敏感性的一般配合力存在极显著差异,杂交组合的特殊配合力和反交效应方差则有时显著,有时不显著;白皮小麦杂交当代种子,以 相似文献
88.
中国科学院南京土壤研究所土壤系统分类课题组 《土壤》2004,36(2):126-131
本文对中国土壤系统分类中的黏化层、雏形层、铁铝层和低活性富铁层的鉴别作进一步讨论。 相似文献
89.
岷江上游23年生油松纯林下凋落物与土壤截留降水的效应 总被引:12,自引:1,他引:12
为了评价人工林下凋落物与土壤截留降水的能力,定位监测和分析了岷江上游23年生人工油松纯林下凋落物层和土壤层对65次降水事件的截留与分配过程。结果表明,65次林外降水总量为400.9 mm,其中208.726mm以穿透雨、33.388 mm以树干茎流进入林地,凋落物层、土壤层分别截留25.695,214.375 mm,截留率分别是6.41%,53.47%。但林外降水量<0.3 mm时,不产生林内降水,凋落物与土壤层不能截留降水。在0.3~10 mm降水范围内,土壤截留量随着降水增大呈增加趋势,而凋落物层截留率先增后减,但降水量>10 mm后,土壤截留率逐渐趋于稳定,呈较小波动(63.46%~73.58%),而凋落物截留率趋于稳定,并略有下降趋势;土壤截留量与林内外降水量、土壤截留量与茎流量均呈显著线性相关关系。综合分析表明,人工油松林凋落物层和土壤层对降水均有一定的拦蓄截留效应,其中:土壤层>凋落物层,土壤层的截留量达同期林外降水量的1/2以上。 相似文献
90.
LI Xue-hua JIANG De-ming ZHOU Quan-lai Institute of Applied Ecology Chinese Academy of Sciences Shenyang P. R. China. LI Xiao-lan XIN Jiang Academy of Agricultural Reclamation Sciences Shihezi P. R. China. 《林业研究》2011,(3):475-479
The effects of various salinities and desalination on seed germination of six annual glycophytes (Artemisia sieversiana, A. scoparia, Chloris virgata, Eragrostis pilosa, Chenopodium acuminatum and Chenopodium glaucum) were studied in Horqin Sandy Land, Inner Mongolia, China. NaCl solutions of five concentrations (0 mM, as the control, and 50, 100, 200 and 300 mM) were used for saline stress and desalination treatments. Increasing salinity significantly reduced germination percentages of A. sieversiana, A. scoparia, Ch.virgata and Ch. acuminatum, but had no effect on the germination percentages of E. pilosa. Lower salinity levels (50 mM) significantly increased germination percentage of Ch. glaucum. High salinity might be a precondition for germi- nation after desalination for five of the six species, excepting E. pilosa at NaCl concentration of 300 mM in comparison with non-primed seeds. Higher salinity (>200 mM) led to some specific ion toxicity and reduced seed viability of A. sieversiana. No specific ion toxicity but an osmotic effect limited the germination of other five species was observed The final germination percentages (salinity stress and desalination) of the six species showed three variations in comparison with the controls, namely, indiscrimination, stimulation, and reduction. Germination responses to salinity and desalination suggested that the six species were separated into three categories. Three species (A. sieversiana, Ch. virgata and Ch. acuminatum) showed similar germination responses to salinity with those of halophyte, but also showed a lower tolerance limit than most halophytes, although this was not always the case. A. scoparia and Ch. glaucum exhibited some ’salt stimulation’ in seed germination percentages after desalination, whereas E. pilosa did not show any obvious responseto salinity. Therefore, salinity usually induces dormancy of seeds with strong germination capacity in fresh water, but has few, or even positive, effects on seeds with strong innate dormancy. 相似文献