Table of Content

25 July 1991, Volume 2 Issue 3

Previous Issue    Next Issue

Articles

Study on random error of shelterbelt porosity estimated by measuring photo with the help of digitized photographic silhouettes

Zhou Xinhua, Jiang Fengqi, Zhu Jiaojun

1991, 2(3):  193-200. 

Asbtract ( 1990 )   PDF (2861KB) ( 422 )  

Error resources of shelterbelt porosity estimated by measuring shelterbelt photo with digitized photographic silhouettes were analyzed, of which, the random error is studied. Results show that the bigger random error variance of crown and trunk porosities is the upper limit of whole variance, that the random errors of crown, trunk, and whole porosities in each typical shelterbelts studied distribute in accordance with normal distribution, that the random error variance of whole porosity is irrelevant to tree species and patterns of the shelterbelts, and that the random error variances between crown and trunk porosities of the shelterbelts, which are composed of Populus×beijingensis or P.×xiaozhuanica or other hybrid popular arranged by rectangle or triangle, have no significant difference, however, for local popular, the random error variance of trunk porosity is signifieantly bigger than that of crown. The random error limits of generalactual porosity estimated from average value of measuring photo with digitized photographic silhouettes were defined, and the idea of applying the limits for calculating the number of observation and delimiting range to be measured were also discussed. Finally, available way for establishing the perfect method such as "estimation of shelterbelt porosity by measuring photo with the help of digitized photographic silhcuettes" is advanced. The available way is that both random error and error from both projective aberration and contractive aberration in the porosity respectively, is restricted by increasing the number of samples from different parts of the same belt, and is emended by calculating with their model.

Anatomical structure and stomatal activity of tea leaves in a pine-tea interplantation

Tang Rongnan, Tang Xinglu

1991, 2(3):  201-206. 

Asbtract ( 3210 )   PDF (507KB) ( 321 )  

In this paper, stomatal conductance of leaves and anatomical structure of leaf surface in a pine-tea interplantation and a pure tea plantation are studied using MK-3 Antomatical Porometer. The results show that in pine-tea interplantation, the thickness of upper epidermis, palisade tissue and whole leaf are smaller than those in pure tea plantation, and are 82.7%, 78.2% and 67.2% of the latter respectively; the leaf is tender and the stomatal conductance is smaller; the productivity of spring shoots, the average daily shoot growth, and the hundred-shoot weight of tea are 34.8%, 30.4% and 9.4% of the pure planted tea respectively. The stomatal conductance of tender leaf is greater than that of old leaf. For a common shoot with 5 leaves, the stomatal conductance of the 3rd leaf is the greatest and those of 2nd and 4th leaves are greater than those of 1st and 5th leaves. Vertically, the leaves in the toppest part of canopy (0—5cm) have the largest value of stomatal conductance, and the leaves in the middle part (10—15cm) have larger value than those in the lowest part (about 30cm). It is concluded that the stomatal conductance of tea leaf is affected not only by common ecological factors, but also by some physiological mechanisms related to leaf age, leaf position etc.

Seasonal absorbed features of mineral elements and their relationships in needles of planted Larix leptolepis

Li Peizhi, Fan Shihua, Zhang Songyun

1991, 2(3):  207-213. 

Asbtract ( 1580 )   PDF (553KB) ( 412 )  

Contents of nine mineral elements (N, P, K, Ca, Mg, Cu, Zn, Fe and Mn) in needles of planted Larix leptolepis were analysed, and variation patterns of these elements in growing season were investigated. The results show that modified exponential curves are suitable to describe the seasonal variation of elements in L.leptolpeis needles. The relationship between absorbed macroelement contents and chemical factors effecting the distribution of elements in needles is discussed, and that between contents N, Pand Kis also discussed.

Studies on management model of population life system of brown planthopper

Qi Lizheng, Huang Fangneng, Huang Jianyi, Li Ruduo

1991, 2(3):  214-220. 

Asbtract ( 1379 )   PDF (593KB) ( 466 )  

According to the survey data of the population dynamics of brown planthopper (BPH) (Nilaparvata lugens Stl) in single late rice fields in Tanhu Lake district of Jiangsu province, the simulating model of population dynamics of BPHwas obtained with the frame of boxcar train model presented by Goudriaan (1973). Further, based on the population dynamic model, economic losses of rice and cost of control, the management model of BPHwas established with the Bellman dynamic programming method. Simulation results show that the models can well describe the population dynamic process according to the verification with observations of BPHin Chuansha county from 1984 to 1989. The error and average error of accumulative, population are 1.4%—16.3% and 11.4% respectively. Because of the difference of standards in judgement, the results of two methods are different between experimental and optimal decisions.

Community structure of macroinvertebrates and trophic level of several small lakes in Beijing city

Ren Shuzhi

1991, 2(3):  221-225. 

Asbtract ( 1646 )   PDF (426KB) ( 343 )  

The characteristics of species, abundance and biomass of benthic macroinvertebrates of 6 small connected lakes in Beijing city were investigated from January to December in1987. The results indicate that mollusca, oligochaete and chironomid larvae are dominant groups of macroinvertebrates in the first 3 lakes, and in the other 3 ones, there are oligochaete and chironomid larvae only. Among them, Bellamya putificata only occur in the first 3 lakes, and Pelopia sp. larvae in the other 3 ones. The Shannon species diversity indices (H') show the simitar tendency. It shows that the first 3 lakes belong to mesotrophic, and the other 3 ones to meso-eutrophic. The Shannon species diversity indices(H′) are well corretated with concentrations of BOD, COD, TPand TNin the water. It is possible to evaluate shallow lake trophic level, using diversity index(H′) combined with species indicator of macroinvertebrates.

Cycling utilization of Azolla potassium in rice-Azolla-fish symbiotic system

Zhang Zhongxian, Liu Zhongzhu, Song Yongkang, He Guangzhe

1991, 2(3):  226-231. 

Asbtract ( 1784 )   PDF (489KB) ( 373 )  

Transportation and utilization of Azolla potassium in rice-Azolla-fish symbiotic system were researched by using ⁸⁶Rb as tracer. The experiment showed that the utilization rate of Azolla potassium by Ctenopharynodon idellus and Tilapia wore 39% and 31% respectively. With the prolongation of feeding time to Tilapia, the utilization rate of Azolla potassium is reduced. It's because of the overplus of potassium in the body fluid of fish be excreted by urine. Excrement sunken on the soil surface would released its potassium to the water in1—2 days, and then, the potassium would gradually penetrate to the soil layer. In30 days, about 83% of the potassium from excrements released to the soil and its penetrating depth was only about 10 cm. The utilization rate of Azolla potassium by early and late rices was 14.1% and 17.6% respectively. In our view, there exists an available problem of excrement potassium to rice plant in space and time. The cycling transportation and distribution model for Azolla potassium in rice-Azolla-fish system was laid down. On the basis of the analysis on the structure and function of this system, advantages and problems of the rice-Azolla-fish symbiotic system were commented.

Status of Si, Fe, Mn and Al in rhizosphere and its effect on rice (Oryza sativa L.) growth

Wang Jianlin, Liao Zhongwen, Liu Zhiyu

1991, 2(3):  232-237. 

Asbtract ( 1652 )   PDF (539KB) ( 434 )  

The present research investigated the status of Si, Fe, Mn and Al in rhizosphere of two red earths and two paddy soils after planting rice and its effect on rice growth and element absorption with the combination of rhizobox and pot cultivation experiment. The results show that active Fe and Al are accumulated in the rhizosphere of red earths after rice planting, active Mn is less in the rhizosphere, while active Si is not conspicuous deficient and accumulated on occasion. In paddy soils, after growing rice, active Fe and Al in the rhizosphere has a definite depletion, active Mn has a high depletion, while active Si is depleted very obviously. These differences result in the decrease of element absorption, such as Si, Pand Mn during the rice growing period in two red earths. At the same time, Fe and Al are accumulated in both roots and shoots, and the element absorption and rice growth are hindered. All these findings should help to understand material cycling in rhizosphere microecosystem.

A fertilizer practice improving the ecological impact of nitrogen in paddy field

Zou Bangji, He Rongzhen, Yang Yulan

1991, 2(3):  238-243. 

Asbtract ( 1511 )   PDF (522KB) ( 366 )  

An improved fertilizer practice (IFP) suggested, which increases the Nuse efficiency by 20—30% and rice yield by 400-1004kg/ha, as compared with the conventional one(CFP). Based on the results of field experiment, the ecological impact of the improved fertilizer practice was discussed in respects of reducing atmospheric and water pollution, increasing soil Nfertility and benefiting people and society.

Chemical forms of Pb, Cd and Cu in crops

Xu Jialin, Bao Ziping, Yang Jurong, Liu Hong, Song Wenchang

1991, 2(3):  244-248. 

Asbtract ( 2339 )   PDF (559KB) ( 461 )  

In order to study the chemical forms of heavy metals in crops growing on polluted soil, sequential extraction method has been applied to analyze the roots and leaves of both wheat and rice growing in pots. The results revealed that acetic acid extractable Pb and HCl extractable Pb are the main forms in roots whereas the latter is the main form in leaves as well. Moreover, NaCl extractable Cd predominates in both crops, whereas ethanol extractable Cu and water extractable Cu predominates in roots and leaves respectively. Chemical forms significantly influence the characteristics of migration and accumulation as well as the degree of toxicity of these elements in plants. Pb is generally concentrated and fixed in roots which results in relatively weak accumulation in grains and insignificant retardation effect on the growth of plants. Cd may combine with protein and disturb the activity of enzymes. The existence of low molecular organic complex of Cu results in relatively high accumulation in grain and retardation effect on plant growth when the content is high.

Behaviours of Cs-137 and Cs-134 in artificial marine microhabitat

Cai Fulong, Chen Ying, Xu pian

1991, 2(3):  249-257. 

Asbtract ( 1538 )   PDF (680KB) ( 413 )  

The behaviours of Cs-137 and Cs-134 were comprehensively studied in a marine microhabitat in the presence of Zn-65, Co-60, Fe-59 and Mn-54 by applying artificial modelling. The results showed that after getting into sea water, Cs-137 and Cs-134 were behaving similarly in term of physiology and ecology. They were slowly adsorbed by suspensate and phytoplankton, and existed mainly in ionic form in the sea water; the concentration coefficients of the sediment were very low. The distribution of Cs-137 and Cs-134 in marine animals and some biochemical materials was studied at the same time. The critical organ of concentrating Cs-137, Cs-134 was not distinct. Both Cs-137 and Cs-134 in biochemical materials could be detected. At the end of excretion experiment, the loss of Cs-137 and Cs-134 in stomach-intestine and liver(or digestive-gland) was marked. Their residual rates were in the range of 0—30%. The gill and muscle in individual animal underwent a reabsorption of Cs-137 and Cs-134. The nuclides in the nuclear acid of Tilapia mossambica were dif icult to excret with a residual rate of 50%. The sediments had a process of deabsorption-readsorption.

A further report on the study of climate-ecological prevention way of cucumber downy mildew: the relationship of high-temperature controlling with disease damage and yield and its prevention indices

Ma Shuqing, Ma Jixiang, Liang Honghai

1991, 2(3):  258-263. 

Asbtract ( 1503 )   PDF (537KB) ( 351 )  

Based on field experiment data and with statistical method, this paper analyzed the relationship of range, time and frequency of high-temperature controlling with periods of development and prevailing of cucumber downy mildew, its damage degree and cucumber yield. Relative models were established and technic indices of high-temperature controlling method were defined. Three main indices (maximum temperature, period of hightemperature controlling and controlling frequency) relate closely to damage degree and cucumber yield. If the maximum temperature raises by 1℃, periods of disease development and prevailing will delay by 3—5 days, percentage of damaged leaf will decrease by 13—15% and cucumber yield will increase by 10% or so. Within a definite range, longer controlling period and higher controlling frequency will induce a later disease development and prevailing period, lower damage degree and higher cucumber yield. It is proved that high-temperature controlling method is an effective ecological prevention way, which has a definite climate-ecological basis.

Application of canonical analysis in ordination of coastal solonchalk vegetation of Jiangsu Province

Xia Bing, Liu Fangxun, Huang Zhiyuan

1991, 2(3):  264-268. 

Asbtract ( 1508 )   PDF (420KB) ( 375 )  

Canonical analysis (CA) was applied to the plot ordination of Jiangsu coastal solonchalk vegetation distributed in a precious birds conservation area. The effects of the ordinations by using different canonical variables on revealing the continuum and environmental factors of the community distribution were compared, according to the studies for the coastal vegetation by others.

Effect of three main environmental factors on virulence of NPV from tea geometrid

Ye Gongyin, Hu Cui

1991, 2(3):  269-274. 

Asbtract ( 1576 )   PDF (535KB) ( 350 )  

In this paper, the effect of temperature, ultraviolet radiation and tea dew on the virulence of nuclear polyhedrosis virus from tea geometrid is investigated. Results show that it is suitable for the virus to infect the host larvae of every instar at 18—26℃. The mortality of the larvae fed with virus at the beginning of every instar all reached 100%. But at 30 or 34℃, except the mortality of the larvae fed with NPVat the beginning of the first instar being100%, the mortality, pupation and emergence rate are significantly decreased or increased. When the larvae fed with virus at or after the beginning of the 3rd instar, more than74% larvae pupated and more than89% pupae emerged. The NPVin vitro is distinctly inactivited as exposured to 45℃ for two or more days. The virus in vitro is not inactivited as exposured to ultraviolet radiation for 2—8 minutes and significantly inactivited as exposured for 16 or more minutes. In addition, the effect of UVradiation on the virulence of EoNPVis related to the temperature and the concentration of the virus. Tea dew has a pHof 6.43—6.92 and can't result in an obvious loss in viral activity of the NPVin vitro.

An optimal method of parametr estimation for Logistic and Cui-Lawson equations

Yan Xiaodong, Zhao Shidong

1991, 2(3):  275-279. 

Asbtract ( 1520 )   PDF (455KB) ( 302 )  

This paper develops a method of parameter estimation for some differential dynamic systems in ecology. This method combines simplex method for optimizing a function with Gill-method of numeric solution of a differential equation, The results of parameter estimation of Logistic and Cui-Lawson equations shows a good adaptation of this method.

Application of remote ensing in urban ecosystem research

Yu Guangming

1991, 2(3):  280-285. 

Asbtract ( 1643 )   PDF (548KB) ( 369 )  

In this paper, the integral programme of urban ecosystem research and remote sensing application, and its main research fields and methodology are put forward and discussed. The authors hold that it is possible to solve two difficult problems of collecting multidimensional data and handling a mass of informations by using remote sensing as a means gathering data, analysing data with the theory of large scale dynamic system, and handling and managing data in terms of expert system and geographic information system(GIS). The unmeasurable variables from space sensor are expressed as a function of measurable ones with the intermediate variables. The research field of remote sensing application is expanded with the aid of expert system and GIS.