Size structure analysis of Quercus wutaishanica (Liaodong oak) forest in a mountainous area of Beijing city indicates that while the oak forest is rather stable its regeneration mainly relies on stem base sprouting. The size structure of populations of Acer mono,Ulmus macrocarpa, and Fraxinus rhynchophylla ,the main associated species in the oak forests,indicate that these are also able to co exist the oak. The phenomenon of sprouting from the bases of the oak stems is very common in these forests. In addition to sprouting from stumps and bases of dead and aged individuals,new stems of seedlings and saplings also usually sprout basally. The size structure of the oak populations shows a clear bottleneck at the sapling stage (size class 2) during forest regeneration. However,through its sprouting ability,the number of stump sprouting,size class 3 individuals is large enough to make up the shortage of saplings and complete the regeneration of populations. It is as a result of this resprouting process that the forest is able to maintain its stability. On the other hand,the cohort of seedlings,though limited in size,has ecological significance through its role in maintaining genetic diversity,the vigor of the oak population as whole and the stability of the communities in which it occurs as well as improving the oak's adapting ability to the environmental changes.
Starting from how to realize the goals of decoration project, this paper analyzes the relations among the owner, designer, constructor and supervisor and the functions of each site, and points out that seeking the integrity in the operation of decoration project is an effective shortcut for realizing the goals.
‘Ehuang No.3’ is a new cucumber cultivar developed by crossing 27-11 as female parent with 03-13-1 as male parent. It is extremely early-maturing and able to tolerate low temperature. It bears fruits mainly in main stem. Fruits are straight with 30 cm in length, 5 cm in diameter, 280 gram in single fruit, with podgy fruit caput, green-white skin, few small knobs and spines, delicious, crisp and have aroma fresh. It is suitable for cultivation in green house in spring (67.5 t/hm2) and autumn (52.5 t/hm2).
The effects of rodents to forest dynamics are highlighted in many ecological researches.In 2002 and 2003,a series of experiments were conducted to investigate the predating behavior of rodents to acorns of Quercus aliena var.acuteserrata under 12 different treatments respectively: burnt fully,enwrapped in plastic tapes,dyed with black carbon ink,buried in soil surface,set on different colors of papers,attached with strings,cut into halves and in control.The count numbers of acorns that were left intact,predated in or removed away were examined and documented in detail,as well as the ratios of acorns with infestation before and after.It was found that:(1) the ratios of acorns with infestation before and after were significantly different(p0.05),suggesting that rodents could detect the infestation of acorns.(2) the effects of rodents to acorns could be classified into 4 classes: ① acorns that were simply buried,or set on black paper were not distinguishable from the control,suggesting that rodents don't respond to the small changes of odor concentration resulted from burying and might be more adapted to the black other than else background.② Acorns attached with strings,dyed with black ink,cut into halves or set on white/green/red papers were predated in with decreased rate and removed away with the same rate in the first day of observation when compared with those of the control,but the removal lasted longer time.The final ratio of removal was increased,and that of in was decreased,and none was left intact.This might suggest that rodents have higher predating risk expectation to acorns under the change of their status,colors,completeness or background,and adopted a kind of in situ strategy.③ Acorns burnt fully were neither predated in nor removed in the first day,but both rates were increased to the peak in the forth or fifth day,and then begun to decline.Consequently,the final ratio of in and removal decreased greatly with 50% acorns left intact.This suggests that rodents use the predation or activities strategy to respond to substantial change of acorn odor concentration,and,as a result,much more acorns were remained intact.④ Acorns enwrapped were rarely predated in situ,but the removal remained unchanged at the beginning,then reduced to near zero in the second day,and kept increasing after that until reaching the peak at the fourth day;the final ratio of in was lower than 5% with none left intact,and therefore,the removal was greatly increased.It is supposed that rodents take the in situ strategy under the condition of substantial change in both odor and states of acorns,since the dual change might indicates higher risk and causes rodents to predate less in situ.As is proved here that the detection to the risk was critical to rodents' behavior,it is reasonable to suppose that the eyes of rodents could play a much more important role in rodents' predating behavior than previously expected.
This paper studied the method which determined the contents of pyruvate in broth by HPLC. The optimal chromatographic conditions was established, which consisted of chromatographic column SCR101H, temperature 20 ℃, flow phage perchloric acid liquor, flow rate 0.8 ml/min, pH3.8. It was proved that HPLC was fit for the determination of pyruvate in broth because of its accuracy and speediness by the tests of reproductivity and recovery rate.
The combination of the new technology of the efficient mixed-flow pump with the model experiment changes the specific property of the circulating pump equipped in the Datong No.2 Electric power Plant, transfers its efficient area to large flow,improves its work efficiency,and solves the problem of the high power consumption and inefficient operation of the circulating pump. But there still is something to be improves in the economic dispatch of the circulating pump.
The method and characteristic of cost management under the bill of quantity are presented and compared with that of traditional cost management. The reformative actions of quantity bill to the cost management are analyzed, and the necessary responses are proposed for the construction business.
The Raunkiear's plant lifeform system was revised, according to the features of the forest plants in the warmtemperate zone of China, and based on the revised system, the lifeform spectrum analysis has shown that the hemicryptophytes are the dominant lifeform, accounted for 33.9% of all the forest vascular plants, followed by the geocryptophytes, which cover 19.7%, and all of the phanerophytes make up 27.5%. There are only few macrophanerophytes, being higher than 25 m, because of human activties as well as the inadequate water and temperature supply in this area. The general spectrum of the warmtemperate zone of China could basically represent the characteristics of middle latitude climate that is rainy and warm in summer, and frigid and dry in winter.
In order to make the follow-on experiment successful and efficient,using P.hysterophorus as the experimental materials,the SRAP-PCR reaction system was optimized by the orthogonal experiment design L16(4)with three factors,including template DNA,dNTPs concentration,primers concentration,and the annealing temperature was also optimized.The results show that the optimal SRAP-PCR reaction system is as follows:total volume 25μL,containing template DNA 60 ng,0.4μmol/L primers,0.25mmol/L dNTPs,Mg2+2.5μmol/L,2.5UTaq DNA polymerase,the annealing temperature is 50℃.From that,the effect of dNTPs concentration is the greatest,the primers and the template are less.17primer pairs were screened out from 100primer pairs combinations based on their distinct and abundant bands by utilizing this reaction system.
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