Table of Content

25 May 1997, Volume 8 Issue 3

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Articles

Effect of human activities on atmospheric CO₂ concentration in subtropical forests and carbohydrate content of two species of woody plants

Peng Changlian, Lin Zhifang, Lin Guizhu, Wei Caimiao, Kong Guohui, Liu Hongxian

1997, 8(3):  225-230. 

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This paper dealt with the effect of human activities including tourism, religion activity, and industrial waste gas on atmospheric CO₂ concentration of subtropical forests and carbohydrate content of two species of woody plants: Schima superba and Pinus massoniana. The results show that human activities not only changed the daily variation, but also the vertical distribution of CO₂ within forests. Comparing to control site (core area of Biosphere Reserve),the CO₂ concentration in disturbed sites is increased 4～11 μl·L^-1.The total contents of soluble sugars and non structural carbohydrate in leaves of two woody plants are decreased with increasing intensity of human activities, and the trends of decrease are consistent with increasing CO₂ concentration. The contents of soluble sugars and starch are more sensitive to human activities in upper canopy than in lower canopy. On the other hand, human activities show little influence on the content of cellulose in leaves of forest trees. The different response of carbohydrate metabolism to human activities was observed between Schima superba and Pinus massoniana.

Simulation of diameter distribution of Pinus sylvestris var. mongolica plantations on sandy soil

Zeng Dehui, Jiang Fengqi

1997, 8(3):  231-234. 

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Through the use of reverse Weibull function, this article simulated the diameter distribution of Pinus sylvestris var. mongolica plantations on Zhanggutai Sandy Land, which shows that for this simulation, reverse Weibull function had the characteristics of high precision and strong adaptation. Correlation equations of three parameters of reverse Weibull function and stand age and density, and regression equation of diameter distribution and these three parameters were established, which could be used to predict the stand yield and timber grade, and to appraise the management effects.

Role of nitrogen-fixing trees in mixed forest Ⅱ. Seasonal variation patterns of N and P contents in leaves of nitrogen-fixing trees

He Xingyuan, Zhang Chenggang, Yang Sihe, Chen Wei, Zhang Yue, Liu Huichang, Su Daoyan

1997, 8(3):  235-239. 

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The seasonal variation and export rate of N and P contents in leaves and the export course of N and P in decrepit leaves of 23 nitrogen-fixing and non nitrogen-fixing tree species were studied. The results showed that in the leaves of all tested trees, there was an obvious seasonal variation of N and P contents,their average variation rate was 21～23%,and the maximum appeared at decrepit stage. During this stage, the dynamic character of N and P in leaves was different between nitrogen-fixing and non nitrogen-fixing trees. The former displayed a low export rate, and the N content in their fallen leaves was 1.6～3.7 times higher than the later. The N content in the leaves of nitrogen-fixing trees was about 2.5% in growing seasons.

Effect of sea dike on the quantity, community characteristics and restoration of mangrove forest along Guangxi coast

Fan Hangqing, Li Guangzhao

1997, 8(3):  240-244. 

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63% of the coastline of Guangxi mainland are margined by 498 sets of sea dikes, which destroyed the pristine mangrove forests, with a remain of 5654 hm². About 85% of the remain are dike fringed mangrove forests. The dike discontinued the natural geomorphological profile of mangrove flat.Consequently, Rhizophora stylosa and Bruguira gymnorrhiza are sharply decreased, Lumnitzera racemosa is endangered and Ceriops tagal is disappeared. Excoecaria agallocha and other most landward species can only grow on dike slopes. In contrast, the pioneer species of Avicennia marina and Agiceras corniculatum dominate the present day mangrove forests.The restoration of sea dike fringed mangrove forests are strongly interfered by human's maintenance of sea dikes. The tidal flats edged by sea dikes are not the optimal habitats for mangrove forest development, due to relatively low elevation above mean sea level.It seems that the survival rate of afforestation and the restoration speed of secondary mangrove forests may greatly depend on the sedimentation rate of habitats.

Environmental and vegetation studies of the gaps of secondary forests on Zijin Mountain

An Shuqing, Hong Bigong, Li Zhaoyang, Zhang Ya, Liu Zhili

1997, 8(3):  245-249. 

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This paper studied the development, distribution, vegetation and environment of the gaps of secondary forests on Zijing Mountain. The gaps are mainly produced by logging of Pinus massoniana, and they distribute randomly. 53 woody species are found in the gaps, Liquidambar formosana having the highest frequency (100%),and Kalopanax pictus, Quercus fabri, Pistacia chinensis and Quercus variabilis being very frequent species. 1283 individuals are recorded, of which, 18.75% is Liquidambar formosana., and Dalbergia hupeana, Quercus fabri, Kalopanax pictus and Quercus variabilis are 10.9, 8.7,5.5 and 5.3%, respectively. 7 woody species and 190 individuals per 100 m² are found in the gaps. According to variance analysis, the density distributions of major species such as Liquidambar formosana, Dalbergia hupeana, Quercus fabri and Quercus variabilis are significantly different from Poison, showing that their distributions are nonrandom. In the gaps, individuals under 2 cm of basal circumferennce account for 59.0% of the total. The higher the basal circumference, the less the number of individuals. The number of individuals is decreased by 70.5% from 2 cm to 4 cm of basal circumference, and by 96.2% from 2 cm to 10 cm of it. The temporal distributions of light intensity, air humidity and air temperature in the gaps are similar to those on open lands, but their spatial patterns are more complicated.

Numerical simulation of winter wheat growth in a regular windbredk system

Wang Hanjie

1997, 8(3):  250-256. 

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An ecological model simulating the process of winter wheat growth is established, and used to do numerical simulation on its growth process with and without the protection of windbreaks. The outputs of the model include the eco-physiological factors which are closely associated with crop growth, such as leaf area index, biomass of various plant organs(root, leaves, stems, and storage organs),dynamics of soil water content, water utilization efficiency, photosynthesis efficiency, respiration efficiency, and so on. The results show that due to the improved microclimate in the windbreaks, the agro forestry mixed system in windbreak areas has a stronger drought resistance than the monoculture system. In the droughty year of 1994, the simulated yield in windbreak areas is about 11.6% higher than that under monoculture conditions, and the simulated above ground yield fits quite well with the field growth monitoring data.

Simulation of winter wheat and summer maize production under optimum conditions

Zhou Yunhua, Xiang Yueqin, Li Jun, Lin Zhonghui, Zhou Zhiquan

1997, 8(3):  257-262. 

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By means of simulation models, the dynamic change of dry matter production by winter wheat and summer maize at production level 1 is obtained. The results show that the simulated values match well with the measured ones in 1990/1991 and 1991/1992. The grain yield 1000 kg·mu^-1 ·yr^-1 can be considered as a target yield for winter wheat followed by summer maize in the Huanghuaihai Plain without intercropping at the production level 1. If winter wheat followed by intercropped medium maturity summer maize is adapted, instead of the winter wheat followed by early maturity summer maize without intercropping, the total grain yield of the both crops is increased by more than 10%. The simulations for various LAIs show that the dry matter production and the grain yield of the two crops within a year without intercropping can reach up to 46 and 19.1 t·hm^-2, respectively.

Diurnal change of water use efficiency of spring wheat and its physioecological basis

Huang Zhanbin, Shan Lun

1997, 8(3):  263-269. 

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Using a ratio of photosynthetic rate (Pn) and transpiration rate (Tr) to express water use efficiency (WUE), the WUE of two varieties of spring wheat and its physioecological affecting factors under different water treatments are analyzed . It is found that the WUE of both varieties is higher in the morning, with a peak at 8～10 am than in the afternoon.The change of WUE is determined by non symmetry and contrary characteristics of Pn and Tr, i.e.,Pn is higher in the morning than in the afternoon, but Tr is on the contrary.The Pn and Tr values are all lower under water stress condition, but the WUE of different varieties is not the same. The results indicate that some physiological factors, such as leaf water potential(ψ_w) and stomatal resistance (Rs), and some ecological factors, such as relative air humidity (RH), solar radiation (Q) and canopy temperature(Tc), are significantly correlated with WUE , although both physiological and ecological factors have different effects on it. 40% of RH is an important threshold value to WUE change.

Relationship bwtween CH₄ and N₂O emissions from rice field and its microbiological mechanism and impacting factors

Hou Aixin, Chen Guanxiong, Wu Jie

1997, 8(3):  270-274. 

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The CH₄ and N₂O emissions from rice field in northern China were measured in situ by chamber technique from March to December 1995～1996,and their relationship was discussed.Soil temperature,pH,moisture and Eh in the rice field were also determined.The results showed that there was a significant teade off between CH₄ and N₂O emissions(R²=-0.494).During the period of monitoring,soil temperature,pHand Eh varied between 0 and 24℃,6.87 and 7.02,adn 415 and 300mv,respectively.Soil moisture was 38～72% FC during the non-flooding period.Among these impacting factors,soil Eh was very important functionally on CH₄ and N₂Oemissions.Six related bacteria groups in this rice field,fermenters,H₂ producing acetogens,methanogens,methanotrophs,nitrifiers and denitrifiers,were obsered,All of them had their own dynamic patterns in their numbers and enzyme activities during the period of observation.The trade off between CH₄ and N₂O emissions from rice field could be controlled by the dynamics of the numbers and enzyme activities of these related microorgamisms.

CH₄ and N₂O fluxes from late-rice fields in Guangzhou region and their affecting factors

Lu Weisheng, Zhang Jianguo, Liao Zongwen

1997, 8(3):  275-278. 

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CH₄ and N₂O fluxes from late-rice fileds in Guangzhou region were measured simultaneously by closed chamber method.The results show that the mean CH₄ fluxes are respectively 17.63,2.84 and 0.36mg·m^-2·h^-1 from the treatments of continuous flooding ,routine succession cropping and rice-vegetabele rotation,and the mean N₂O fluxes are 6.74,11.69 and 55.07 μg N₂O-N·m^-2·h^-1 correspondingly,which indicates that continuous floodin can greatly increase CH₄ emission,while sinnificantly reduce N₂O emission.Rice vegetable rotation is the reverse.There exists a trade off between CH₄ and N₂O emission.The factors affectin CH₄ and N₂O emssion are discussed,and the contribution of CH₄ and N₂O to global warming is preliminarily alalysed.

Action mechanism of a durably efficacious ammonium bicarbonate and its enviromental effect

Cui Hongbo, Zhang Zhiming, Zhang Chenggang, Bi Suchun

1997, 8(3):  279-282. 

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In this paper, the general equation for volatilization losses of the ammonia was established based on the analysis for the dominant factors affecting the extent ammonia volatilization. The hydrogen bonds between DCD presented in DEAB and free state ammonia dissociated from AB are probably formed and are well documented by the spectra and properties of DEAB. This interaction force could drop the ammonia apparent concentration and lower pH 0.2～0.4 during ammonia volatilization. As compared with AB, DEAB could delay the formation of nitrogen as nitrate species, reduce the loss of nitrogen by leaching and increase NH₄⁺-N inventory in soil. Thus, DEAB can regulate the nutrient accommodation in form, time and amount, reduce pollution of ground and surface water by fertilizer-derived.

Soil and water loss control in hilly regions of western Liaoning province through constructing horizontal troughs

Lu Changai, Liang Jilu, Wang Hong

1997, 8(3):  283-286. 

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Field investigation, fixed location experiment and laboratory analysis show that in comparison with fish scaled pit, horizontal trough could intercept more runoff, increase its infiltration into soil and prolong its infiltration duration. Constructing horizontal trough combined with planting trees and grasses could decrease water evaporation from soil.In the horizontal trough, organic and inorganic matters carried by run off could be deposited, which participated in the further development of soil and improved the local agro ecological environment.

Aggregated distribution of Anser indicus nest in Bayinbuluke of Tianshan Mountains and its breeding ecology

Ma Ming, Cai Dai

1997, 8(3):  287-290. 

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From 1992 to 1994, stationary obesrvations were taken on the breeding ecology of Anser indicus in Bayinbuluke Swan Lake of Tianshan Mountains. The results show that its nest density is 0.59 nest ·m^-2 or 33～55 nests on each island, and the nests are unevenly distributed. For 184 nests observed, the average number of clutches in each nest is 4.47±2.19 eggs. The climax of egg laying period comes in early or middle May, and that of incubation period is reached in middle June.The goslings can fly 55～65 days after hatching in early August.The reproductive period is 10～20 days later than that in Qinghai region.

Effect of sex pheromone on behaviors of adult Heliothis armigera and its field control

Ge Shaokui, Li Dianmo, Xie Baoyu, Ma Zufei

1997, 8(3):  291-294. 

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Field experiment with cotton shows that sex pheromone can not only affect the courting and copulation of adult Helicoverpa armigera, but also disturb its flying behaviors in the course of feeding, dispersal and concealment. Awide area pheromone trap experiment indicates that after using sex pheromone, the male population is reduced by half, the copulation of each female is reduced 0.6 times, and the incubation rate in room and in field is reduced 19 and 13.5%, respectively.

Functional features of preserving natural enemies to control insect pests in intercropped cotton field ecosystems

Ge Feng, Ding Yanqin

1997, 8(3):  295-298. 

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The population dynamics of insect pests and their natural enemies in single and intercropped cotton field ecosystems are analyzed, and the controlling effects of natural enemies in these ecosystems are compared. The results show that the population densities of cotton seedling aphids (Aphis gossypii) and 2nd generation cotton bollworm (Helicoverpa armigeria) are lower in intercropped than in single cotton field ecosystem, but those of summer aphids and 3rd generation cotton bollworms as well as the energy production of natural enemies (especially that of predacious spiders) are converse. From the viewpoint of function, the preservation effect on natural enemies is greater in intercropped than in single cotton field ecosystem, but the controlling effect of natural enemies on insect pests is converse.

A preliminary study on the feeding of bohai seaLabidocera euchaeta

Yang Jiming, Li Hongling

1997, 8(3):  299-303. 

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Eight hundred Labidocera euchaeta specimens with food in their alimentary canal were collected from the Bohai Sea, and the analysis of their alimentary canal contents shows that Labidocera euchaeta is microplanktonivorous, and feeds mainly on micro copepods, occupying 76.4% in its food composition, in which, Paracalanus parvus is the main prey (74.7%), and others occupy a less portion on diatom (23.0%), dinoflagellates(1.1%), chrysophytes(<0.1%) and ciliates (1.5%). The food composition of this species has an obvious seasonal variation.The mean replacement rate of food group in four seasons is 30.7%, and that of food species reaches to 40.3%, showing that the diatom in its food is increased gradually from spring to winter, and on the contrary, the copepods is decreased, its feeding intensity is increased in the order of spring>autumn>summer>winter.

Allelopathy of Ageratum conyzoides Ⅰ.Allelopathy of Ageratum conyzoides aqueous extract and isolation and identification of its allelochemicals

Hu Fei, Kong Chuihua

1997, 8(3):  304-308. 

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Studies on the allelopathy of Ageratum conyzoides aqueous extract showed that the aqueous extract significantly inhibited seed germination and seedling growth of all tested plants at 0.25 g FW·ml^-1 ,but the inhibition disappeared at 0.10 g FW·ml^-1 . The allelopathic potential of aqueous extract from different organs of A.conyzoides and from its different development stages, especially from different habitats, was different. Ageratum conyzoides growing in adverse habitat showed a stronger allelopathic potential.Three allelochemicals from aqueous extract,e.g. precocene Ⅰ,precocene Ⅱ and stigmast 5,22-diene-3βol,were isolated and identified.

Ecological risk and background warning values of water pollution from rural urbanization

Zhou Qixing, Wang Rusong

1997, 8(3):  309-313. 

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In this paper,the ecological risk of water pollution from rural urbanization at the southern parts of the lower reaches of the Changjiang River was quantitatively evaluated and correlatively analyzed. The results indicate that there exist markedly monolinear correlations between BOD₅, NO₃^--N, phenol, surface activator of surface water, pH, Pb, NO₂^--N, phenol of precipitation, NO₃^--N of groundwater and the total population.Markedly exponential correlations between chloride, total bacteria, detergent of groundwater, CODCr of surface water and total population, and markedly monolinear correlations between BOD₅, phenol, surface activator of surface water, NO₃^--N, chloride, total bacteria, detergent of groundwater, pH, phenol, Pb of precipitation and population density as well as, markedly exponential correlations between NO₂^--N of precipitation and the population density in small towns are also found. The background limit values and maximum allowable background densities of population in small towns of the area were calculated.

Analysis of major constraints on plant colonization at Fankou Pb/Zn mine tallings

Shu Wensheng, Lan Chongyu, Zhang Zhiquan

1997, 8(3):  314-318. 

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Through greenhouse cultivation and field investigation, the major constraints on plant colonization at Fankou Pb/Zn mine tailings are analysed.The results show that total Pb, Zn, Cu and Cd contents in the tailings are 34300,36500,215 and 82.6 mg·kg^-1 ,while their available contents are 1.5, 1963,0.71 and 8.03 mg·kg^-1 respectively.Greenhouse cultivation reveals that the toxicity of heavy metals significantly inhibits the root vitality of Stylosanthes guianensis, prevents plant from absorbing inorganic nutrient, and leads to evident chlorosis, which significantly affects grass growth. Both greenhouse cultivation and field investigation demonstrate that available Zn and Cd contents in tailings are negatively correlated with plant growth.Heavy metal toxicity, especially the toxicity of available Zn and Cd is the major constraint on plant colonization at Fankou Pb/Zn mine tailings, and the extreme infertility is another major constraint on plant growth.

On urban rural development from ecological view

Han Jinchun

1997, 8(3):  319-324. 

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This paper described the significance of urban rural development and its faced three issues on human population, environment and resources. In order to make the urban rural development on scientific basis, it is necessary to utilize the natural resources rationally, to protect the ecological environment well, and to balance the benefit/cost, structure and function of urban rural ecosystem.Such a system should be really constructed at a place, where its functions are full, environment is beautiful, production is growing, and life is comfortable.

Interactions among host plants, phytophagous insects and natural enemies and relevant research methods

Lou Yonggen, Cheng Jiaan

1997, 8(3):  325-331. 

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Based on the latest researches all over the world, the direct and indirect interactions among host plants, phytophagous insects and their natural enemies mediated by chemical and physical factors, including allelochemicals, host plant's nutrients, toxins, morphological characters, density, diversity and distribution, are reviewed, and the central role of host plants in these interactions is revealed. The present general research methods in this area are also introduced.

Relationship between canopy temperature and water condition of winter wheat farmland ecosystem

Shi Peihua, Mei Xurong, Leng Shilin, Du Baohua

1997, 8(3):  332-334. 

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Based on field experiments and using the temperature difference between canopy and air as well as the canopy temperature difference between wet and dry fields as main parameters, the models for soil moisture monitoring were established.According to the response of winter wheat, water diagnostic indices were also obtained. The study shows that canopy temperature difference between wet and dry fields can exclude the effect of atmosphere, and comparing with the temperature difference between canopy and air, it is a better of farmland water conditions.

Preference of Thrips palmi to different color sticky cards and trapping effect of blue one

Chen Huaping, Bei Yawei, Gu Xiuhui, Gao Chunxian

1997, 8(3):  335-337. 

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The test on the preference of Thrips palmi to eight color sticky cards was carried out in an eggplant field. The thrip had the strongest preference to blue sticky card (P<0.01), and its preference order to the other 7 color cards was as follows: blue, turguoise, yellow, deep blue, green, orange, red and black. Results on the trapping effect of blue sticky card from east, south, west and north directions show that most thrips were trapped from the north,which existed a significant difference with those from the other three directions (P<0.05). Five blue sticky cards were set up at the heights of 73.9,101.7,129.5,157.3 and 185.1 cm above the ground to trap thrips, when the average height of eggplant was approximately 70 cm. More thrips were trapped of 73.9 and 101.7 cm height, which existed significant difference with those at the other three heights. During 5 continuous 3 hour spans from 5 am to 8 pm, the numbers of female, male and total adult thrips trapped were not significantly different.