Table of Content

10 October 1997, Volume 16 Issue 05

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Effect of Water Deficit on Net Photosynthesis Rate of Winter Wheat

Wang Hui

1997, (5):  1-6. 

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On the basis of the calculation models of crop water deficit index (CWDI) and canopy net photosynthesis rate (P_n), field observation items were chosen according to the parameters used in models. Comparisons of the conditions of water deficit,stomata activities,net photosynthesis rate and matter production were made between two typical experiment plots, one plot was well watered while the other was never watered artificially. Results indicated that: (1) Stomata activity was the key link relating to water deficit and net photosynthesis. The stomata under dry treatment responded to water deficit more sensitively. Increase of stomata resistance caused by water deficit could markedly reduce net photosynthesis rate . (2) There was a positive linear correlation between the crop water deficit index (CWDI) and the crop hunger index (CHI). According to this, the influenced degree of net photosynthesis rate can be estimated. (3) Water deficit influenced on crop photosynthesis frequently and complexly. The final results of water deficit was to obviously reduce the leaf area, number of stem (or spike) and economic yield of the wheat.

Intra_ and Interspecific Competition among the Adults of Three Grasshoppers (Orthoptera: Acrididae) on a Desert Grassland

He Dahan, Fang Cheng, Zheng Zhemin

1997, (5):  7-13. 

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By means of artificial field_cage expriments, both intra_ and interspecific competition among the adults of three common, mixed grass_feeding grasshoppers, Sphingonotus ningsianus Zheng et Gow, Compsorhipis davidiana (Sauss), Pseudotmethis alashanicus B. Bienko on the desert grassland of the east side of Helan mountains in Ningxia was detected. The results of daily capacity for eating, high mortality and low fecundity showed that strong intraspecific compesition among species at higher densities existed. Interspecific competition was weaker than intraspecific competition. The interspecific competition was complex in its effects. The species with large size had higher mortality but without distinctive difference in reproduction from the species of smaller size. The intraspecific competition was mainly effected by food limitation, while the interspecific competition was effected by the factors of food limitation and self_adaptation to the environments.

The Accumulation and Biological Cycling of Nitrogen in the Alder and Cypress Mixed Forest

Shi Peili, Yang Xiu, Zhong Zhangcheng

1997, (5):  14-18,37. 

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The accumulation and biological cycling of nitrogen of the 16 year old alder and cypress mixed forest have been studid in Yanting county,Sichuan province.The results showed that the amount of nitrogen in the standing biomass of the community was 533.98 kg穐a^-1 of which the amounts of aboveground and underground parts were 468.48 kg穐a^-1 and 55.50kg穐a^-1 respectivly.With regard to the biological cycling of nitrogen in the community,the value of annual uptake was 110.36kg穐a^-1 of which its retention was 23.45kg穐a^-1 and the return was 86.91 kg穐a^-1 per year.The turnover period was 6 years.The nitrogen cycling of the community was charaterized by large uptaking much returning and rapid turnover.

The Studies of Seed Bank of Kobresia huilis Meadow in Qing_Zang Plateau

Deng Zifa, Zhou Xingmin, Wang Qiji

1997, (5):  19-23. 

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The seed bank of Kobresia humilis meadow in Qing_Zang Plateau was preliminaryly studied and the relationships among seed bank, seed rain and above_ground vegetation were compared and analysed.The results showed that there were 23 species in the seed bank in both of green up and withering stage.In species composition of the seed bank,Ranunculaceae and Leguminosae were dominant,while the percentage of Cyperaceae and Gramineae were lower. The percentage of K.humilis seeds was relatively lower with 0.97% in green up stage and 1.97% in withering stage.The species composition of the seed bank correlated with that of the seed rain(r=0.7505,P <0.01),and there were 18 common species which was 78.3% of species of the seed bank. Only 41.81% of above_ground vegetation species presented in the seed bank. The seed numbers of the dominant plant species in vegetation were smaller, with lower percentage in the seed bank. Therefore, the dominant vegetation of K. humilis et al.mainly depended on vegetative reproduction to maintain and strengthen.From vegetation to the seed bank in green up stage,the species diversity decreased by 9.94%. It implied that the seed bank was the source of vegetation regeneration,but also a mechanism of preserving species diversity of the plants.

The Identification of a Mechanism Model of the Zooplankton Density Dynamics in the Dapeng Bay, South China Sea

Guo Yuanqiong, Huang Weijian, Han Boping, Qi Yuzao

1997, (5):  24-27. 

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A mechanism model simulated density dynamics of the zooplankton population in Dapeng Bay was described. The data were based on the samples taken 2 days intervals from April 2 to June 22,1990. The factors including phytoplankton, temperature, salinity, dissolved oxygen(DO), pH,dissolved inorganic phos phate(DIP), dissolved inorganic nitrogen(DIN) (NO₂_N, NO₃_N), Si(OH)₄, Fe and Mn were measured. It was identified that phytoplankton and temperature were the controlling parameters on the growth of zooplankton. By using hierachy to the reciprocation and introducing into the model identification, three non_linear regression models were established.

Effect of HF on the Activities of Superoxide Dismutase and Cellulase in Plum (Prunus mume) Leaves

Meng Fanping, Wu Fangzheng, Pan Xiaomin

1997, (5):  28-31. 

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By means of treatment with the artifical smoke, the activities of Superoxide dismutase and Cellulase in Plum (Prunus mume) leaves and the irrelation with HF were studied. Based on experimental results, the possible mechanism of senescence caused by fluoride and the future reseach objectives were proposed.

Exergy Theory: A New Method For Ecosystem Research

Sun Pingyue, Lu Jianjian

1997, (5):  32-37. 

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The properties of exergy theory, the relationship between exergy theory and ecosystem research and the application of exergy theory in ecosystem research were reviewed and discussed. Some new prospects of exergy theory used in ecosystem research were also put forward.

Variations of Distribution and Population Quantity of Mongolian Gazelle in the World

Jin Kun, Gao Zhongxin, Guan Dongming, Bao Xinkang, Bai Lijun, Wang Kewei

1997, (5):  38-42. 

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In history, Mongolian gazelle (Procapra gutturosa) had once been distributed in a large area. The most western and eastern occurring areas were the southeast Quyl grassland or Altay mountains in Russia and the eastern grasslands in Mongolia, Hulunbuir grassland in China. To the north Mongolian gazelle reached to Mongolian grasslands belt, to the south of Tuwa and external Baikal in Russia, even in Dawuli grassland. The southeast occurring area was near the north of Yellow River. At present, Mongolian gazelle in distributed only ib the eastern grasslands in Mongolia and Hulunbuir, Xilingele, Ulanchabu districts in China, especially concentrates in the bordering area between two countries.In the 40's of this century, about 1.5 millions of Mongolian gazelle existed in the world. But now, The population of Mongolia gazelle is only about 400 thousands in Mongolia and less than 300 thousands in China.The distribution and population quantity of Mongolian gazelle, an important economic species, have been reduced constantly. There is an urgent need to strengthen the conservation and research of Mongolian gazelle.

Effect of Dry_fruit Eating Birds to Seed Dispersal

Lu changhu, Yuan Li

1997, (5):  43-46,66. 

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Frugivorous birds can be divided into two groups:fleshy_fruit eating birds and dry_fruit eating birds (including pine_nut eating birds). Many dry_fruit birds store a lot of seeds for future use and scatter hoarders have an effect to seed dispersal. This is coadaption between hoarding birds and plants. Corvidae are the most important dispersers. Seed dispersal contain three steps:seed selection, transportation and caching. Caching behavior affects the dispersal efficiency greatly. Death ratio of seeds is very high during seed dispersal period. Owing to hoarders' recovery and reforaging and only a few seeds can survive. However regeneration of many species of plants with big and edible seeds depend on birds and other animals' caching. These plants include conifers with big and wingless seeds and broadleaved trees with nuts.

Eco_hydrological Functions of Tropical Forest,China

Zhou Guangyi

1997, (5):  47-50,56. 

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The present papeer analysed comprehensively the main ecohydrological functions of tropical forest ecosystem of China. The results in the paper were useful for various government department (Minstry of Forestry and Environment Protection Bureau,for example) to formulati a reasonable policy of environmental protection and to work out a rational management plan of tropical forest.

Study of the Ecological Strategies of the Landscape in the Lower Huaihe Valley

Yan Chuanhai, Song Yongchang

1997, (5):  51-56. 

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Based on the studies on climate,geomorphology,soil and vegetation, the landscape ecological classification system for the lower Huaihe valley was established. The system included 10 landscape types and 35 landscape subtypes. The landscape type was divided by vegetation (vegetation type or cultivated vegetation type), while landscape subtype was classified according to topography and vegetation (formation group or cultivated vegetation group). Using the soil map (1:1000000) of the region as base map, landscape subtype as mapping unit and several kinds of maps related to the area (landsat images, regetation maps, landuse maps and geomorphological maps), The map of landscape ecological types of the lower Huaihe valley (1:1000000) was compiled. On the map the areas of landscape types and landscape subtypes were measured. The ecological problems of the main landscape types in the lower Huaihe valley were analysed in detail and the corresponding strategies were put forward.

Study of Phosphorus Biological Availability in the Soil_plant Rhizosphere

Li Fayun, Gao Ziqin

1997, (5):  57-60. 

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Phosphorus bio_availability in the soil_plant rhizosphere system was discussed in this paper. Four aspects including rhizosphere biomass, phosphatase, root exudates and method of rhizosphere phosphorus study were expounded. According to present situation of phosphorus study in this field, much more attention should be paid to the phosphorus biological and ecological process in rhizophere micro_system。

Study on the Fate of Nitrogenous Fertilizer in the Black Soil

Wang Jianguo, Han Xiaozeng, Liu Hongxiang

1997, (5):  61-63. 

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By means of 15 N experiments,the fate of nitrogenous fertilizer of maize and soybean and wheat in the farmland was studied. The results showed that in the black soil farmland of Songnen Plain,wheat's N fertilizer use efficiency was 33%-40% with average of 37%,the soil residual 12%-16% with average of 14% and the gaseous loss 47%-50%, with average of 48.6%. Maize's N fertilizer use efficiency,the soil residual and gaseous loss was 37%,14% and 49% respectively. Sweet clover's N fertilizer use efficiency,soil residual and gaseous loss was 9%,30% and about 60% respectively. And soybean's N fertilizer use efficiency was 33%-40% with average of 37%,the soil residual 25%-50% with average of 31% and the gaseous loss 15%-35% with average of 27%.

A Method of Rearing House-fly Larva with Liquid Feed

Ying Huabao, Wang Kuiren, Xu Rumei

1997, (5):  64-66. 

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The study of rearing house-fly with the liquid feed and inventing a new rearing equipment of style of many layers,circulatory and spray were carried out. The results showed that the mew method with many advantage including quickly seperating speed,saving time and high efficiency might be suitable for industrial production.

Agruments about the Concept of Ecological Equilibrium

Huang Fuxiang, Liu Xuyang

1997, (5):  67-71. 

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Equilibrium is a very important concept in ecology. It had been considered as a scientific paradigm in ecology in the past.However, the equilibrium also has been an argumentative issue. In the past decade, the traditional equilibrium theory was rejected completely. Some major researches in this field were introduced and the authars' opinions were given in this paper.

Wetland Conservation and Advances Derived from the fifth International Wetlands Conference

Wang Renqing, Liu Chunhui, Chao Min

1997, (5):  72-76. 

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The main contents of the 5th International Wetlands Conference were compendiously introduced, and the updated advances in wetland conservation and research were formulized in the paper. Some suggestions about how wetland conservation and research should be carried on in China were put forward.