Table of Content

15 April 2002, Volume 13 Issue 4

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Bamboo rhizome system of mixed forest of Sassafras tsumu and Phyllostachys pubescens

LIU Guihua, LI Hongkai

2002, (4):  385-389. 

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By the method of fixed plots, the bamboo rhizome system structure and nutrient content in rhizome from mixed Sassafras tsumu and Phyllostachys pubescens, which were established in1983-1984 by planting S. tsumu on new-planted bamboo forests (3-4 years old), were investigated. The results showed that the mixtures with rational density of S. tsumu were suitable for optimizing the bamboo rhizome structure and increasing the nutrient content in rhizome. The total length and weight of rhizome, the diameter of rhizome and its evenness indices, the annual growth of new rhizome, the proportion of healthy rhizomes and buds, and the volume of rhizome system in the mixed bamboo forests with the density of 420～615 S. tsumu trees per hectare were higher than those in pure bamboo forest, respectively. The indexes mentioned above in mixed bamboo forests with the density of S. tsumu more than735 trees per hectare were lower than those in pure bamboo forest, respectively, but the frequency of rhizome branch per unit length of rhizome was obviously higher than that in pure bamboo forest. The results of regression analysis showed that there were close relationships between S. tsumu density and total length of rhizome, the length between two joints, the growth of new rhizome, the diameter of rhizome and its evenness indices, and the frequency of rhizome branch per unit length of rhizome. The content of N, P, K, Ca, and Mg in the rhizome from mixed bamboo forests were higher than those in pure bamboo forest, respectively. For example, the content of Nin rhizomes from mixtures was increased by 7.6-11.6% averagely.

Microclimatic effect and soil moisture change of poplar-wheat intercropping systems in Huaibei Plain

LI Junxiang, WAN Zhihu

2002, (4):  390-394. 

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In this paper, the microclimatic effect and the soil moisture of poplar-wheat intercropping systems were studied. The results indicated that the strip intercropping, comparing with the contrast, could increase the relative humidity by 2～8%, decrease the surface temperature by 1～7℃, and reduce wind speed. The illumination hours were decreased with the time and the distance between the rows, and the varying range was within4. 1～15.3%. In shelterbelt network, the relative humidity was increased by 6.4～11.6%, and the illumination hours were decreased by 8.5～11.7%. In strip intercropping, the intercropping systems could improve soil moisture, which was varied with the intensity of tree, and generally, the increase of soil moisture was about in a range of 0.67～3.87%. In shelterbelt network, the soil moisture was related to the orientation and the distance from the shelterbelt, and there existed negative correlation between the soil moisture and the distance in all orientations.

Physiological characteristics of resistance of different plum varieties to artificial adverse environments

ZHU Liwu, LI Shaowen, LIU Jiafa, WANG Jian, ZHANG Ling

2002, (4):  395-398. 

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The relative electric conductivity, soluble sugar content in leaf, and PODactivity of 17 plum varieties, which belong to six species and one genera, were measured under artificial adverse environments. The results showed that there were extreme significant negative correlation (α=0.01) between soluble sugar content and membrane freezing damage, and significant negative correlation (α=0.05) between POD activity in bark and leaf cell heat damage. According to Fuzzy synthetic evaluation, the comprehensive resistances of different plum varieties to adverse circumstances were discussed in this paper.

Architectural plasticity of the stoloniferous herb, Duchesnea indica in response to different elevation

LUO Xuegang, DONG Ming

2002, (4):  399-402. 

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Architectural plasticity of clonal plant may modify its ways of utilization of resources through clonal growth and be of ecologically importance. The plasticity of clonal architecture in response to ecological conditions at different altitudes in a stoloniferous herb, Duchesnea indica, was investigated in an experiment with different elevations of 400, 800, 1200, and 1600 m. The results showed that the change patterns of spacer length, ramet density, branching intensity, and branching angle of Duchesnea indica were in a quadratic curve when the elevation increased. The architectural plasticity of D. indica was simulated through dynamic Logistic model, and the imitative effect was statistically preferable. Combining with the resources utilization of Duchesnea indica under different environments, the architectural plasticity was also discussed in this paper.

Landscape structure of the farming-pastoral zone based on Landsat-TM Data-A case study of Xinghe County, Inner Mongolia

JIANG Yuan, GAO Qingzhu, HE Lihuan, WANG Jiaji

2002, (4):  403-408. 

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Xinghe County, Inner Mongolia, belongs to the typical region of farming-pastoral zone in northern China and is chosen as a case study area in this paper. Based on the interpretation of the Landsat-TM data (with two digital images taken in1989 and 2000, respectively), the landscape structure was studied by analyzing patch-size, spatial pattern, and other index to show the changing feature of landscape pattern. The results showed that farmlands and grasslands were the main landscape types in plain and hilly land of the County, and different landscape types had different scales of landscape patch-size. The patch-sizes of farmland and grassland had been apparently expanded from 1989 to 2000, while those of the forestland and waters had been shrunk. The landscape pattern had an obvious trend of fragmentation due to human activities.

Seeping irrigation effect in sunlight greenhouse

LIU Zuoxin, DU Yaodong, CAI Chongguang, WANG Jian

2002, (4):  409-412. 

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The differences of soil and air environments, crop growth, development and diseases, and water use efficiency of seeping irrigation from furrow irrigation were studied. Results indicated that compared with furrow irrigation, seeping irrigation could increase soil waterstable granular by 81.4%, soil porosity by 29.0% and soil temperature by 1.1～1.71℃ respectively, decrease bulk density by 21.2% and relative air humidity by 13.4% respectively, and save irrigation water by 36.7%. In addition, seeping irrigation could also accelerate crop maturity and increase yield, reduce crop diseases and production cost. Therefore, seeping irrigation was an ideal irrigation technique in sunlight greenhouse at present.

Effect of clipping at seedling stage on growth and yield of spring wheat

YUAN Baozhong, WANG Jing, ZHANG Rong, ZHAO Songling, SUN Jie

2002, (4):  413-416. 

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The compensation for spring wheat (Triticum aestivum) under simulated herbivory stress by clipping was examined in a semi-arid region of Gansu province in1996. The results showed that clipping at seedling stage reduced spring wheat growth under two irrigation conditions. The yield of spring wheat generally under-compensated the clipping effect. Heavy clipping (cutting all leaves above the ground, T0, T₁) resulted in a more serious reduction in yield, compared with light clipping cutting half of the leaves, H0, H₁). The yields of all treatments were lower than controls(CK₀,CK₁),i.e., CK₀>H0>T0>CK₁ >H₁ >T₁. Irrigation for once right after clipping increased wheat growth and its compensatory ability, although they were still under-compensation.

Dynamics of β-glucan content during kernel development and its relationship with meteorological factors

CHEN Jinxing, ZHANG Guoping

2002, (4):  417-420. 

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The dynamics of β-glucan content of two barley varieties during kernel development phase and the effect of some meteorological factors on (β-glucan content were studied. The results showed that β-glucan content in kernel is both dominated by genotype and influenced by meteorological factors. The model of dynamic during kernel development phase is very similar in both barley varieties, but differs in years greatly. It is showed that the dynamic of β-glucan content during kernel development phase is completely consistent with those of kernel-weight increase and protein accumulation per grain. The dynamic of β-glucan content in barley kernel is significantly influenced by meteorological factors, and there is significantly negative relationship between accumulated temperature during kernel development phase and β-glucan content in kernel.

Comparison of morphology, physiology and mineral element contents among genotypes of sesame with different tolerance to waterlogging under anaerobic condition

WANG Wenquan, ZHANG Fusuo, ZHENG Yongzhan, MEI Hongxian

2002, (4):  421-424. 

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The morphological and physiological indexes and the mineral element contents in different organs of 4 genotypes of sesame were examined under controlled oxygen supply. The number of adventitious roots of flooding tolerant varieties, Wild No.7 and Yuzhi No. 1, increased 4～5 fold, the activity of ADHenhanced about twice, but the net photosynthetic rate (Pn) decreased slightly. There were significant increase in Ca and Pand little decrease in Kin roots, and decrease in other elements in roots and 8 elements in stems and leaves. As for less flooding-tolerant genotypes, Danbackaggce and Suiping Xiaozhihuang, however, the number of adventitious roots increased little, the activity of ADHenhanced 5～9 folds, and Pn decreased by 50～60%. An increase in Ca and P, and a significant reduction in Kwas found in roots. It was concluded that the waterlogging tolerance of sesame depended firstly on the structural adaptation, then on the anoxia metabolism, and that Ca and Pmay play an important role in the metabolic adaptation to the anaerobic environment for plant survival.

Characteristics of functional and nutritious soilless culture substrate for vegetables

ZHU Shidong, XU Wenjuan, ZHAO Guorong

2002, (4):  425-428. 

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Afunctional and nutritious substrate for soilless culture, which consists of peant shell, sawdust, vermiculite, chicken manure, coal cinder, etc, was used to grow cucumbers, tomatoes and peppers in this experiment. The results showed that the substrate was rich in organic matter, N, available Pand K, in which the nutrients were basically in balance for three vegetables. High content of microorganisms and high activity of soil enzymes were propitious to the transformation of organic components in the substrate. The yields of cucumber, tomato and pepper increased by 23.83%, 27.34% and 32.98%, respectively. The production value of peppers increased by 180.85%, and its net income increased by 109.69%. The qualities of three vegetables were coincident with 'harmless vegetable' standards.

Ecophysiological effects of CO₂ enrichment on bottle gour in plastic house

ZHU Shidong, XU Wenjuan

2002, (4):  429-432. 

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In vegetable growing under protection, lack of carbon dioxide is one of the most important factors limiting photosynthesis. The application of 600～1200 μmol·mol^-1 CO₂ in the plastic house increased photosyntheitc rates and ratio of C/N, promoted both vegetative and reproductive growth of bottle gourd plants. Plant height, stem diameter, leaf thickness and leaf area increased by 3.90～19.48%, 11.58～27.37%, 38.46～69.23% and 26.09～49.38%, respectively. Average single fruit weight and yield were 4.05～19.62% and 8.65～19.47% higher than that in normal air. Primary female flower position was lowered by 2.6～4.0. Net photosyntheitc rate and the carboxylase activity of RuBP were greatest under CO₂ 1000μmol· mol^-1. The optimal concentration of CO₂ applied to bottle gourd in spring was about 1000 μmol·mol^-1.

Effect of mutual interference and spatial heterogeneity on predation of adult Chrysopa septempunctata

LI Guiting, ZOU Yunding, ZHOU Xiazhi, LIU Tongwen

2002, (4):  433-434. 

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The more wheat stalks the adult Chrysopa septempunctata encountered, the more interference was met during the predation of C. septempunctata, which means that the predation efficiency was low when the spatial heterogeneity was complex. The coefficient of mutual interference within C. septempunctata was 0.9390, and that between C. septempunctata and Propylaea japonica was 0.8722. The frontier was greater than the latter. The correlation of competition strength(I) and the number of natural enemy (P) could be described as I=0.0640+1.11271gP.

Effects of cumulative parthenogenetic generation and age of amictic female on the reproduction of rotifer Bra-chionus calyciflorus

XI Yilong, HU Haoyuan, GENG Hong, JIN Hongjun, HUANG Xiangfei

2002, (4):  435-438. 

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Effects of cumulative parthenogenetic generation and age of amictic female on mictic female production and fecundity of the rotifer Brachionus calyciflorus were studied by means of individual culture. The results showed that percentage of total mictic females produced by the parental females in each of four generations increased with the increasing generations. More mictic females were produced from younger maternal amictic females. Amictic offspring from older mothers produced more mictic daughters. There was no significant effect of the cumulative parthenogenetic generation on the mean number of eggs produced by amictic females per life cycle, and no significant effect of the age of amictic female on the mean number of eggs produced by the offspring of amictic female.

Variation in the viability and the metabolism of internally reserved nutrients of Beauveria bassiana conidia during storage at different regimes of water content and temperature

FENG Mingguang, YING Shenghua

2002, (4):  439-443. 

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While the fresh powder (with water content of 58.9 ± 1.6%) and vacuum-freeze dried (VFD) one (with water content of 7.4±0.9%) of Beauveria bassiana SGBB8702 conidia were stored at 4℃ and 20℃, their viability and contents of internally reserved saccharides and proteins were examined at 5 days intervals. It was found during one-month storage that the water content and temperature interactively affected the levels of conidia viability and the contents of the reserved saccharides and proteins, which in turn correlated considerably well to the viability. Stored at 4℃ and 20℃, the VFDconidia lost content of saccharides by 13.4% and 14.1%, content of proteins by 39.2% and 38. 2%, and viability by 32. 0% and 55. 8% when germinating in water only and 6.7% and 10.4% when germinating in2% glucose solution plus 0. 5% peptone, respectively. In contrast, the four estimates of the fresh conidia stored at 4℃ and 20℃ decreased by 42. 4% and 43. 2%, 66. 3% and 65. 4%, 96.4% and 99.4%, and 9.9% and 98.4%, respectively. Thus, water content of B. bassiana conidia affected variation ranges of the viability and the internally reserved nutrients whereas storage temperature influenced their variation rates. However, depletion of the internally reserved nutrients did not necessarily inactivate the conidia. Instead, such conidia may germinate at relatively high level during a period of time as long as being supplied with sufficient nutrients. In another experiment, the powder of VFDconidia with water content being reduced to 4.0 ±0.9% were half-monthly examined for viability during one-year storage. The viability only decreased slightly from 99.0% to 90.2% at 4℃ by the end of one year. Stored at 20℃, the viability also declined slowly during the first 165 days but dramatically decreased afterwards with little being detected on day 240. Amodeling analysis showed that the time for the VFDconidia to lose 50% viability was 1006 days at 4℃ and 197 days at 20℃, respectively. Conclusively, the B. bassiana conidia powder, even though its water content was controlled below 5%, can be safely stored for one year or longer at low temperature only but for no longer than6 months at ambient temperature.

Integrated control of maind diseases and insects of Dendranthema morifolium

WANG Jie, HU Huilu, ZHANG Chenglin, HU Yibing, LIU Mingfang

2002, (4):  444-448. 

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The main virus diseases, downy mildew, leaf spot, leaf-injuring insects and aphid' s natural enemies in Den-dranthema morifolicum were investigated and identified, and the development laws of pests and natural enemies were studied respectively. The effectiveness of integrated control of stem-tip culture, film covering, interplating with tall stalk crops, micronutrient application, terminal bud excising, and use of natural enemies were evaluated. The results showed that after the application of above integrated control measures, the virus-free rate and the yield-increasing rate of the seedlings from stem-tip culture were about 60% and over 50%, respectively. The incidence of downy mildew and leaf-spot decreased by 28% to 30%. The injurious insect density reduced by 40%. The detection of pesticides residue indicated that three pyrethroids insecticides such as cypermethrin, fenvalter-ate, and deltamthrin were applied one month before harvest, the residues in Dendranthema morifolium after harvest were 0.017,0.058 and 0.019mol稬^-1, respectively, and all lower than the relevant tolerance values.

Spatial heterogeneity of grassland pattern under grazing and forage condition

XIN Xiaoping, LI Xianglin, YANG Guixia, XU Bin

2002, (4):  449-453. 

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Spatial heterogeneity and spatial autocorrelation of grassland pattern under grazing and forage condition were studied using semivariance analysis and fractal method. The results indicate that vegetation patterns are scale-dependent. Spatial heterogeneity and spatial autocorrelation of foraged grassland are more complex than grazed grassland and have more scale regions which determined by different fractal characteristics. Spatial autocorrelation of species diversity on foraged grassland was weaker, in another word, gradient of species diversity(β-diversity) was smaller. Spatial heterogeneity of grazed grassland was simplified by grazing, because topographical variation was partly wiped out.

Difference between two wheat cultivars in Cd and mineral nutrient uptake under different Cd levels

ZHANG Guoping, Motohiro Fukami, Hitoshi Sekimoto

2002, (4):  454-458. 

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Cadmium pollution in soil not only affects growth and yield formation of crop plants, but also develops a potential risk to food health. The experiment was conducted to study growth and Cd and mineral nutrient uptake of two wheat cultivars differed in agronomic performance in seedling stage under 5 Cd levels ranged from 0 to 1.0mg? kg^-1 Cd. The results showed that the growth and dry matter accumulation were stimulated in low Cd concentration (0. 03mg穔g^-1) for both cultivars, while inhibited significantly under high concentration (>0.3mg? kg^-1). The inhibited extension was dependence on cultivars and Genguo 534 had higher tolerance to Cd toxicity in comparison with E18513. There was the significant interaction between Cd level and cultivar in the influence of Cd treatment on Cd content in both root and shoot in that Genguo 534 had higher Cd content in lower Cd levels and E81513 showed more rapid increase in higher Cd levels. Cd treatment had significant influence on mineral nutrient uptake and two cultivars showed different response. In the treatment of 0. 1mg穔g^-1 Cd, the contents of five macro-nutrients were significant lower for E81513 in comparison with those in control, while Genguo remained little changed.

Eco-toxicology of heavy metals on the inhibition of seed germination and root elongation of wheat in soils

SONG Yufang, ZHOU Qixing, XU Huaxia, REN Liping, GONG Ping

2002, (4):  459-462. 

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The eco-toxicity of Cu, Zn, Pb, and Cd in the single form was tested with four types of soils(red loam soils, meadow brown soils, chestnut soils, and dark brown soik) and their combined effect was determined with meadow brown soils. The results showed that with the same content of heavy metals, the root elongation was strongly inhabited than the seed germination, and it indicated that root was more sensitive to heavy metals pollution. The inhibition rate of heavy metals pollution on the root elongation (IRHMRE) of wheat was significantly related with the contents of organic matter (OR) and Kjedahl-nitrogen (K-N) in soils (R_OR²=0.91, R_K-N²=0.92). However, IRHMRE was not significantly related with soil pH as did with OR and K-N, so does the content of CEC (R_pH²= 0.62, R_CEC²=0.60). Whether under the low concentration of Cu, Zn, Pb, and Cd resulted in an irritated effect in root elongation, or under high concentration resulted in an inhibition effect in the single form, an synergistic effect occurred in the combined form.

Sewage sludge as fertilizer for grassland

CHEN Tao, WANG Xin, LIANG Renlu

2002, (4):  463-466. 

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The experiment of sewage sludge composted as fertilizer for Zoysia japonica was conducted, and the results showed that Cd content in soil was lower than0.3mg穔g^-1 under the condition of the fertilizer application lower than45t穐m^-2(dry weight)and the pHvalue of soil lower than6.5 (Cd as the limiting factor for the amount of fertilizer application). NO₃^- -Ncontent of groundwater was lower than the standard of the first class groundwater (10mg穔g^-1).The contents of organic matter, available N, total N, and total Pwere higher than those under control by 16%, 78%, 61%, and 140%, respectively. The biomass of Zoysia japonica was increased two times a-gainst the control. Therefore, sewage sludge utilized as fertilizer for grassland might be a valuable approach.

Changes of chemical and biological properties during composting sewage sludge by using forced aerated static pile model

ZHANG Xueyin, ZHOU Lixiang, SHEN Qirong, ZONG Lianggang, ZHAN Xinhua, WU Qitang, LIAO Xinti, W. C. Wong

2002, (4):  467-470. 

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Municipal sewage sludge was composted for 53 days with Chinese medical herb residues as bulking agent through forced aerated static pile model. The temperature of the pile could quickly rise to more than55℃ after the second day after composting. Furthermore, the temperature of more than 55℃ maintained as long as 8 days, which was helpful in inactivation of pathogens in compost. The cress seed germination index (GI) and the ratio of wa-ter-soluble organic carbon to organic nitrogen (soluble C/N-organic), used as indicators of phytotoxicity and maturation of compost, exhibited that the sludge compost was almost stabilized and matured near the 40^th day of composting, when 80% of GI and 6.4 of soluble C/N-organic were obtained. The content of total N, P, Cu, Zn and Cd in compost increased as the composting time elapsed, while volatile solids, solid and water soluble organic carbons, pH, and NH₄⁺-Ndecreased. F. coli, as a common indicator of pathogens in sludge, was reduced greatly from 1.41×10⁵ to 2.32×10¹ in the final examination of the compost.

Toxicity effect of substituted benzenes in oilfield wastewater by molecular orbital method

JI Guodong, SUN Tiehang, SUI Xin

2002, (4):  471-475. 

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The quantum parameters of energy of highest occupied molecular orbital (E_HOMO), energy of lowest unoccupied molecular orbital (ELUMO), energy of next highest occupied molecular orbital (E_NHOMO), energy of next lowest unoccupied molecular orbital (E_NLUMO), heat of molecular formation(△Hf₀) and dipole moment (μ) of 55 substituted benzenes are calculated based on MOPACsoftware of molecular orbital AM1 method. The QSAR model of multiple descriptors was established by the above parameters and the parameters of first-order valence-corrected molecular connectivity index (¹X^v), octanol-water partition coefficient (logP), observed 30 min-EC₅₀ values of photobacteria. The QSAR model of 55 substituted benzenes was also established by two parameters of ¹X^vand E_HOMO. The toxicity mechanism of different substitutions was discussed. Results showed that the combination of quantum and physio-chemical parameters was very useful in predicting biological activity of substituted benzenes in oilfield wastewater. The quantum parameters were ideal parameters in describing the toxicity of organic compounds in oilfield wastewater.

Problems and trends of long-term ecological research

FU Bojie, LIU Shiliang

2002, (4):  476-480. 

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Long-Term Fcological Research (LTER) has been focused on the monitoring and controlling the factors that influence the ecological process in a long period. The results are also the basis for the ecological assessment and management. Referring to the experiences of long-term research in international perspectives, this paper attempts to elucidate the problems, research contents, research trends and solutions of LTER with the expansion of temporal and spatial scales. It also has an instructive role in the long-term research, the construction of ecological research network and the terrestrial assessment in China.

Land-use strategy in riverine area

PENG Zhenhua, WANG Cheng

2002, (4):  481-485. 

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The land near river is one kind of land zone that is inseparably related to the ecological process of river and lake, and directly affected or endangered by flood. Combined with ecological principles and the theory of forest eco-network system in China, the landscape security, the principles and directional thoughts, the theoretical basis and strategy were comprehensively studied in this paper. The landscape security should include three aspects of ecological benefit security, economical benefit security, and social benefit security. The land-use principles should be to find the best uniting section and ensure integration of the three principles together. The directional thoughts should be to combine management and development together, strengthen the landscape security by various measures, and carry out the near natural land-use and managing strategy by increasing the proportion of forest. Different development models should be selected in different rivers and regions. According to the risk grades of flood disturbance and spatial differentiation of lands near river, the different managing strategy with different disturbance degree should be carried out in different reach in upstream, midstream, and downstream based on the spatial differentiation of river and lands nearby in longitudinal direction, while based on the spatial differentiation and security during flood in cross direction, the utilization strategy should be classified and aimed at fragile use zone, stable use zone, and elastic use zone, respectively.

Assessment method of ecosystem health

KONG Hongmei, ZHAO Jingzhu, JI Lanzhou, LU Zhaohua, DENG Hongbing, MA Keming, ZHANG Ping

2002, (4):  486-490. 

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Ecosystem is the basic unit to maintain human environment. Ecosystem function mainly includes two aspects:e-cosystem service function and goods function. These two functions are the basis for human living and development. Ecosystem health is the presupposition of ecosystem function. The completeness (structure and function), resilience, stabilty, and sustainability are the characteristics of ecosystem health. Ecosystem health assessment selects the indicator based on the ecosystem structure and function, including completeness, suitability, and effectiveness of ecosystem. Ecosystem health assessment mainly has two methods :one is indicator species assessment, and the other is structure and function index assessment which includes single index assessment, complex index assessment, and index system assessment which includes natural index system assessment and social-economic-natural index system assessment. In this paper, different assessment methods on ecosystem health are compared, and different health assessment method for different ecosystem types are also expatiated.

Bamboo rhizome system of mixed forest of Sassafras tsumu and Phyllostachys pubescens

LIU Guihua, LI Hongkai

2002, (4):  385-389. 

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By the method of fixed plots, the bamboo rhizome system structure and nutrient content in rhizome from mixed Sassafras tsumu and Phyllostachys pubescens, which were established in1983-1984 by planting S. tsumu on new-planted bamboo forests (3-4 years old), were investigated. The results showed that the mixtures with rational density of S. tsumu were suitable for optimizing the bamboo rhizome structure and increasing the nutrient content in rhizome. The total length and weight of rhizome, the diameter of rhizome and its evenness indices, the annual growth of new rhizome, the proportion of healthy rhizomes and buds, and the volume of rhizome system in the mixed bamboo forests with the density of 420～615 S. tsumu trees per hectare were higher than those in pure bamboo forest, respectively. The indexes mentioned above in mixed bamboo forests with the density of S. tsumu more than735 trees per hectare were lower than those in pure bamboo forest, respectively, but the frequency of rhizome branch per unit length of rhizome was obviously higher than that in pure bamboo forest. The results of regression analysis showed that there were close relationships between S. tsumu density and total length of rhizome, the length between two joints, the growth of new rhizome, the diameter of rhizome and its evenness indices, and the frequency of rhizome branch per unit length of rhizome. The content of N, P, K, Ca, and Mg in the rhizome from mixed bamboo forests were higher than those in pure bamboo forest, respectively. For example, the content of Nin rhizomes from mixtures was increased by 7.6-11.6% averagely.

Microclimatic effect and soil moisture change of poplar-wheat intercropping systems in Huaibei Plain

LI Junxiang, WAN Zhihu

2002, (4):  390-394. 

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In this paper, the microclimatic effect and the soil moisture of poplar-wheat intercropping systems were studied. The results indicated that the strip intercropping, comparing with the contrast, could increase the relative humidity by 2～8%, decrease the surface temperature by 1～7℃, and reduce wind speed. The illumination hours were decreased with the time and the distance between the rows, and the varying range was within4. 1～15.3%. In shelterbelt network, the relative humidity was increased by 6.4～11.6%, and the illumination hours were decreased by 8.5～11.7%. In strip intercropping, the intercropping systems could improve soil moisture, which was varied with the intensity of tree, and generally, the increase of soil moisture was about in a range of 0.67～3.87%. In shelterbelt network, the soil moisture was related to the orientation and the distance from the shelterbelt, and there existed negative correlation between the soil moisture and the distance in all orientations.

Physiological characteristics of resistance of different plum varieties to artificial adverse environments

ZHU Liwu, LI Shaowen, LIU Jiafa, WANG Jian, ZHANG Ling

2002, (4):  395-398. 

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The relative electric conductivity, soluble sugar content in leaf, and PODactivity of 17 plum varieties, which belong to six species and one genera, were measured under artificial adverse environments. The results showed that there were extreme significant negative correlation (α=0.01) between soluble sugar content and membrane freezing damage, and significant negative correlation (α=0.05) between POD activity in bark and leaf cell heat damage. According to Fuzzy synthetic evaluation, the comprehensive resistances of different plum varieties to adverse circumstances were discussed in this paper.

Architectural plasticity of the stoloniferous herb, Duchesnea indica in response to different elevation

LUO Xuegang, DONG Ming

2002, (4):  399-402. 

Asbtract ( 994 )   PDF (572KB) ( 309 )  

Architectural plasticity of clonal plant may modify its ways of utilization of resources through clonal growth and be of ecologically importance. The plasticity of clonal architecture in response to ecological conditions at different altitudes in a stoloniferous herb, Duchesnea indica, was investigated in an experiment with different elevations of 400, 800, 1200, and 1600 m. The results showed that the change patterns of spacer length, ramet density, branching intensity, and branching angle of Duchesnea indica were in a quadratic curve when the elevation increased. The architectural plasticity of D. indica was simulated through dynamic Logistic model, and the imitative effect was statistically preferable. Combining with the resources utilization of Duchesnea indica under different environments, the architectural plasticity was also discussed in this paper.

Landscape structure of the farming-pastoral zone based on Landsat-TM Data-A case study of Xinghe County, Inner Mongolia

JIANG Yuan, GAO Qingzhu, HE Lihuan, WANG Jiaji

2002, (4):  403-408. 

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Xinghe County, Inner Mongolia, belongs to the typical region of farming-pastoral zone in northern China and is chosen as a case study area in this paper. Based on the interpretation of the Landsat-TM data (with two digital images taken in1989 and 2000, respectively), the landscape structure was studied by analyzing patch-size, spatial pattern, and other index to show the changing feature of landscape pattern. The results showed that farmlands and grasslands were the main landscape types in plain and hilly land of the County, and different landscape types had different scales of landscape patch-size. The patch-sizes of farmland and grassland had been apparently expanded from 1989 to 2000, while those of the forestland and waters had been shrunk. The landscape pattern had an obvious trend of fragmentation due to human activities.

Seeping irrigation effect in sunlight greenhouse

LIU Zuoxin, DU Yaodong, CAI Chongguang, WANG Jian

2002, (4):  409-412. 

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The differences of soil and air environments, crop growth, development and diseases, and water use efficiency of seeping irrigation from furrow irrigation were studied. Results indicated that compared with furrow irrigation, seeping irrigation could increase soil waterstable granular by 81.4%, soil porosity by 29.0% and soil temperature by 1.1～1.71℃ respectively, decrease bulk density by 21.2% and relative air humidity by 13.4% respectively, and save irrigation water by 36.7%. In addition, seeping irrigation could also accelerate crop maturity and increase yield, reduce crop diseases and production cost. Therefore, seeping irrigation was an ideal irrigation technique in sunlight greenhouse at present.

Effect of clipping at seedling stage on growth and yield of spring wheat

YUAN Baozhong, WANG Jing, ZHANG Rong, ZHAO Songling, SUN Jie

2002, (4):  413-416. 

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The compensation for spring wheat (Triticum aestivum) under simulated herbivory stress by clipping was examined in a semi-arid region of Gansu province in1996. The results showed that clipping at seedling stage reduced spring wheat growth under two irrigation conditions. The yield of spring wheat generally under-compensated the clipping effect. Heavy clipping (cutting all leaves above the ground, T0, T₁) resulted in a more serious reduction in yield, compared with light clipping cutting half of the leaves, H0, H₁). The yields of all treatments were lower than controls(CK₀,CK₁),i.e., CK₀>H0>T0>CK₁ >H₁ >T₁. Irrigation for once right after clipping increased wheat growth and its compensatory ability, although they were still under-compensation.

Dynamics of β-glucan content during kernel development and its relationship with meteorological factors

CHEN Jinxing, ZHANG Guoping

2002, (4):  417-420. 

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The dynamics of β-glucan content of two barley varieties during kernel development phase and the effect of some meteorological factors on (β-glucan content were studied. The results showed that β-glucan content in kernel is both dominated by genotype and influenced by meteorological factors. The model of dynamic during kernel development phase is very similar in both barley varieties, but differs in years greatly. It is showed that the dynamic of β-glucan content during kernel development phase is completely consistent with those of kernel-weight increase and protein accumulation per grain. The dynamic of β-glucan content in barley kernel is significantly influenced by meteorological factors, and there is significantly negative relationship between accumulated temperature during kernel development phase and β-glucan content in kernel.

Comparison of morphology, physiology and mineral element contents among genotypes of sesame with different tolerance to waterlogging under anaerobic condition

WANG Wenquan, ZHANG Fusuo, ZHENG Yongzhan, MEI Hongxian

2002, (4):  421-424. 

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The morphological and physiological indexes and the mineral element contents in different organs of 4 genotypes of sesame were examined under controlled oxygen supply. The number of adventitious roots of flooding tolerant varieties, Wild No.7 and Yuzhi No. 1, increased 4～5 fold, the activity of ADHenhanced about twice, but the net photosynthetic rate (Pn) decreased slightly. There were significant increase in Ca and Pand little decrease in Kin roots, and decrease in other elements in roots and 8 elements in stems and leaves. As for less flooding-tolerant genotypes, Danbackaggce and Suiping Xiaozhihuang, however, the number of adventitious roots increased little, the activity of ADHenhanced 5～9 folds, and Pn decreased by 50～60%. An increase in Ca and P, and a significant reduction in Kwas found in roots. It was concluded that the waterlogging tolerance of sesame depended firstly on the structural adaptation, then on the anoxia metabolism, and that Ca and Pmay play an important role in the metabolic adaptation to the anaerobic environment for plant survival.

Characteristics of functional and nutritious soilless culture substrate for vegetables

ZHU Shidong, XU Wenjuan, ZHAO Guorong

2002, (4):  425-428. 

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Afunctional and nutritious substrate for soilless culture, which consists of peant shell, sawdust, vermiculite, chicken manure, coal cinder, etc, was used to grow cucumbers, tomatoes and peppers in this experiment. The results showed that the substrate was rich in organic matter, N, available Pand K, in which the nutrients were basically in balance for three vegetables. High content of microorganisms and high activity of soil enzymes were propitious to the transformation of organic components in the substrate. The yields of cucumber, tomato and pepper increased by 23.83%, 27.34% and 32.98%, respectively. The production value of peppers increased by 180.85%, and its net income increased by 109.69%. The qualities of three vegetables were coincident with 'harmless vegetable' standards.

Ecophysiological effects of CO₂ enrichment on bottle gour in plastic house

ZHU Shidong, XU Wenjuan

2002, (4):  429-432. 

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In vegetable growing under protection, lack of carbon dioxide is one of the most important factors limiting photosynthesis. The application of 600～1200 μmol·mol^-1 CO₂ in the plastic house increased photosyntheitc rates and ratio of C/N, promoted both vegetative and reproductive growth of bottle gourd plants. Plant height, stem diameter, leaf thickness and leaf area increased by 3.90～19.48%, 11.58～27.37%, 38.46～69.23% and 26.09～49.38%, respectively. Average single fruit weight and yield were 4.05～19.62% and 8.65～19.47% higher than that in normal air. Primary female flower position was lowered by 2.6～4.0. Net photosyntheitc rate and the carboxylase activity of RuBP were greatest under CO₂ 1000μmol· mol^-1. The optimal concentration of CO₂ applied to bottle gourd in spring was about 1000 μmol·mol^-1.

Effect of mutual interference and spatial heterogeneity on predation of adult Chrysopa septempunctata

LI Guiting, ZOU Yunding, ZHOU Xiazhi, LIU Tongwen

2002, (4):  433-434. 

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The more wheat stalks the adult Chrysopa septempunctata encountered, the more interference was met during the predation of C. septempunctata, which means that the predation efficiency was low when the spatial heterogeneity was complex. The coefficient of mutual interference within C. septempunctata was 0.9390, and that between C. septempunctata and Propylaea japonica was 0.8722. The frontier was greater than the latter. The correlation of competition strength(I) and the number of natural enemy (P) could be described as I=0.0640+1.11271gP.

Effects of cumulative parthenogenetic generation and age of amictic female on the reproduction of rotifer Bra-chionus calyciflorus

XI Yilong, HU Haoyuan, GENG Hong, JIN Hongjun, HUANG Xiangfei

2002, (4):  435-438. 

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Effects of cumulative parthenogenetic generation and age of amictic female on mictic female production and fecundity of the rotifer Brachionus calyciflorus were studied by means of individual culture. The results showed that percentage of total mictic females produced by the parental females in each of four generations increased with the increasing generations. More mictic females were produced from younger maternal amictic females. Amictic offspring from older mothers produced more mictic daughters. There was no significant effect of the cumulative parthenogenetic generation on the mean number of eggs produced by amictic females per life cycle, and no significant effect of the age of amictic female on the mean number of eggs produced by the offspring of amictic female.

Variation in the viability and the metabolism of internally reserved nutrients of Beauveria bassiana conidia during storage at different regimes of water content and temperature

FENG Mingguang, YING Shenghua

2002, (4):  439-443. 

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While the fresh powder (with water content of 58.9 ± 1.6%) and vacuum-freeze dried (VFD) one (with water content of 7.4±0.9%) of Beauveria bassiana SGBB8702 conidia were stored at 4℃ and 20℃, their viability and contents of internally reserved saccharides and proteins were examined at 5 days intervals. It was found during one-month storage that the water content and temperature interactively affected the levels of conidia viability and the contents of the reserved saccharides and proteins, which in turn correlated considerably well to the viability. Stored at 4℃ and 20℃, the VFDconidia lost content of saccharides by 13.4% and 14.1%, content of proteins by 39.2% and 38. 2%, and viability by 32. 0% and 55. 8% when germinating in water only and 6.7% and 10.4% when germinating in2% glucose solution plus 0. 5% peptone, respectively. In contrast, the four estimates of the fresh conidia stored at 4℃ and 20℃ decreased by 42. 4% and 43. 2%, 66. 3% and 65. 4%, 96.4% and 99.4%, and 9.9% and 98.4%, respectively. Thus, water content of B. bassiana conidia affected variation ranges of the viability and the internally reserved nutrients whereas storage temperature influenced their variation rates. However, depletion of the internally reserved nutrients did not necessarily inactivate the conidia. Instead, such conidia may germinate at relatively high level during a period of time as long as being supplied with sufficient nutrients. In another experiment, the powder of VFDconidia with water content being reduced to 4.0 ±0.9% were half-monthly examined for viability during one-year storage. The viability only decreased slightly from 99.0% to 90.2% at 4℃ by the end of one year. Stored at 20℃, the viability also declined slowly during the first 165 days but dramatically decreased afterwards with little being detected on day 240. Amodeling analysis showed that the time for the VFDconidia to lose 50% viability was 1006 days at 4℃ and 197 days at 20℃, respectively. Conclusively, the B. bassiana conidia powder, even though its water content was controlled below 5%, can be safely stored for one year or longer at low temperature only but for no longer than6 months at ambient temperature.

Integrated control of maind diseases and insects of Dendranthema morifolium

WANG Jie, HU Huilu, ZHANG Chenglin, HU Yibing, LIU Mingfang

2002, (4):  444-448. 

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The main virus diseases, downy mildew, leaf spot, leaf-injuring insects and aphid' s natural enemies in Den-dranthema morifolicum were investigated and identified, and the development laws of pests and natural enemies were studied respectively. The effectiveness of integrated control of stem-tip culture, film covering, interplating with tall stalk crops, micronutrient application, terminal bud excising, and use of natural enemies were evaluated. The results showed that after the application of above integrated control measures, the virus-free rate and the yield-increasing rate of the seedlings from stem-tip culture were about 60% and over 50%, respectively. The incidence of downy mildew and leaf-spot decreased by 28% to 30%. The injurious insect density reduced by 40%. The detection of pesticides residue indicated that three pyrethroids insecticides such as cypermethrin, fenvalter-ate, and deltamthrin were applied one month before harvest, the residues in Dendranthema morifolium after harvest were 0.017,0.058 and 0.019mol稬^-1, respectively, and all lower than the relevant tolerance values.

Spatial heterogeneity of grassland pattern under grazing and forage condition

XIN Xiaoping, LI Xianglin, YANG Guixia, XU Bin

2002, (4):  449-453. 

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Spatial heterogeneity and spatial autocorrelation of grassland pattern under grazing and forage condition were studied using semivariance analysis and fractal method. The results indicate that vegetation patterns are scale-dependent. Spatial heterogeneity and spatial autocorrelation of foraged grassland are more complex than grazed grassland and have more scale regions which determined by different fractal characteristics. Spatial autocorrelation of species diversity on foraged grassland was weaker, in another word, gradient of species diversity(β-diversity) was smaller. Spatial heterogeneity of grazed grassland was simplified by grazing, because topographical variation was partly wiped out.

Difference between two wheat cultivars in Cd and mineral nutrient uptake under different Cd levels

ZHANG Guoping, Motohiro Fukami, Hitoshi Sekimoto

2002, (4):  454-458. 

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Cadmium pollution in soil not only affects growth and yield formation of crop plants, but also develops a potential risk to food health. The experiment was conducted to study growth and Cd and mineral nutrient uptake of two wheat cultivars differed in agronomic performance in seedling stage under 5 Cd levels ranged from 0 to 1.0mg? kg^-1 Cd. The results showed that the growth and dry matter accumulation were stimulated in low Cd concentration (0. 03mg穔g^-1) for both cultivars, while inhibited significantly under high concentration (>0.3mg? kg^-1). The inhibited extension was dependence on cultivars and Genguo 534 had higher tolerance to Cd toxicity in comparison with E18513. There was the significant interaction between Cd level and cultivar in the influence of Cd treatment on Cd content in both root and shoot in that Genguo 534 had higher Cd content in lower Cd levels and E81513 showed more rapid increase in higher Cd levels. Cd treatment had significant influence on mineral nutrient uptake and two cultivars showed different response. In the treatment of 0. 1mg穔g^-1 Cd, the contents of five macro-nutrients were significant lower for E81513 in comparison with those in control, while Genguo remained little changed.

Eco-toxicology of heavy metals on the inhibition of seed germination and root elongation of wheat in soils

SONG Yufang, ZHOU Qixing, XU Huaxia, REN Liping, GONG Ping

2002, (4):  459-462. 

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The eco-toxicity of Cu, Zn, Pb, and Cd in the single form was tested with four types of soils(red loam soils, meadow brown soils, chestnut soils, and dark brown soik) and their combined effect was determined with meadow brown soils. The results showed that with the same content of heavy metals, the root elongation was strongly inhabited than the seed germination, and it indicated that root was more sensitive to heavy metals pollution. The inhibition rate of heavy metals pollution on the root elongation (IRHMRE) of wheat was significantly related with the contents of organic matter (OR) and Kjedahl-nitrogen (K-N) in soils (R_OR²=0.91, R_K-N²=0.92). However, IRHMRE was not significantly related with soil pH as did with OR and K-N, so does the content of CEC (R_pH²= 0.62, R_CEC²=0.60). Whether under the low concentration of Cu, Zn, Pb, and Cd resulted in an irritated effect in root elongation, or under high concentration resulted in an inhibition effect in the single form, an synergistic effect occurred in the combined form.

Sewage sludge as fertilizer for grassland

CHEN Tao, WANG Xin, LIANG Renlu

2002, (4):  463-466. 

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The experiment of sewage sludge composted as fertilizer for Zoysia japonica was conducted, and the results showed that Cd content in soil was lower than0.3mg穔g^-1 under the condition of the fertilizer application lower than45t穐m^-2(dry weight)and the pHvalue of soil lower than6.5 (Cd as the limiting factor for the amount of fertilizer application). NO₃^- -Ncontent of groundwater was lower than the standard of the first class groundwater (10mg穔g^-1).The contents of organic matter, available N, total N, and total Pwere higher than those under control by 16%, 78%, 61%, and 140%, respectively. The biomass of Zoysia japonica was increased two times a-gainst the control. Therefore, sewage sludge utilized as fertilizer for grassland might be a valuable approach.

Changes of chemical and biological properties during composting sewage sludge by using forced aerated static pile model

ZHANG Xueyin, ZHOU Lixiang, SHEN Qirong, ZONG Lianggang, ZHAN Xinhua, WU Qitang, LIAO Xinti, W. C. Wong

2002, (4):  467-470. 

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Municipal sewage sludge was composted for 53 days with Chinese medical herb residues as bulking agent through forced aerated static pile model. The temperature of the pile could quickly rise to more than55℃ after the second day after composting. Furthermore, the temperature of more than 55℃ maintained as long as 8 days, which was helpful in inactivation of pathogens in compost. The cress seed germination index (GI) and the ratio of wa-ter-soluble organic carbon to organic nitrogen (soluble C/N-organic), used as indicators of phytotoxicity and maturation of compost, exhibited that the sludge compost was almost stabilized and matured near the 40^th day of composting, when 80% of GI and 6.4 of soluble C/N-organic were obtained. The content of total N, P, Cu, Zn and Cd in compost increased as the composting time elapsed, while volatile solids, solid and water soluble organic carbons, pH, and NH₄⁺-Ndecreased. F. coli, as a common indicator of pathogens in sludge, was reduced greatly from 1.41×10⁵ to 2.32×10¹ in the final examination of the compost.

Toxicity effect of substituted benzenes in oilfield wastewater by molecular orbital method

JI Guodong, SUN Tiehang, SUI Xin

2002, (4):  471-475. 

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The quantum parameters of energy of highest occupied molecular orbital (E_HOMO), energy of lowest unoccupied molecular orbital (ELUMO), energy of next highest occupied molecular orbital (E_NHOMO), energy of next lowest unoccupied molecular orbital (E_NLUMO), heat of molecular formation(△Hf₀) and dipole moment (μ) of 55 substituted benzenes are calculated based on MOPACsoftware of molecular orbital AM1 method. The QSAR model of multiple descriptors was established by the above parameters and the parameters of first-order valence-corrected molecular connectivity index (¹X^v), octanol-water partition coefficient (logP), observed 30 min-EC₅₀ values of photobacteria. The QSAR model of 55 substituted benzenes was also established by two parameters of ¹X^vand E_HOMO. The toxicity mechanism of different substitutions was discussed. Results showed that the combination of quantum and physio-chemical parameters was very useful in predicting biological activity of substituted benzenes in oilfield wastewater. The quantum parameters were ideal parameters in describing the toxicity of organic compounds in oilfield wastewater.

Problems and trends of long-term ecological research

FU Bojie, LIU Shiliang

2002, (4):  476-480. 

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Long-Term Fcological Research (LTER) has been focused on the monitoring and controlling the factors that influence the ecological process in a long period. The results are also the basis for the ecological assessment and management. Referring to the experiences of long-term research in international perspectives, this paper attempts to elucidate the problems, research contents, research trends and solutions of LTER with the expansion of temporal and spatial scales. It also has an instructive role in the long-term research, the construction of ecological research network and the terrestrial assessment in China.

Land-use strategy in riverine area

PENG Zhenhua, WANG Cheng

2002, (4):  481-485. 

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The land near river is one kind of land zone that is inseparably related to the ecological process of river and lake, and directly affected or endangered by flood. Combined with ecological principles and the theory of forest eco-network system in China, the landscape security, the principles and directional thoughts, the theoretical basis and strategy were comprehensively studied in this paper. The landscape security should include three aspects of ecological benefit security, economical benefit security, and social benefit security. The land-use principles should be to find the best uniting section and ensure integration of the three principles together. The directional thoughts should be to combine management and development together, strengthen the landscape security by various measures, and carry out the near natural land-use and managing strategy by increasing the proportion of forest. Different development models should be selected in different rivers and regions. According to the risk grades of flood disturbance and spatial differentiation of lands near river, the different managing strategy with different disturbance degree should be carried out in different reach in upstream, midstream, and downstream based on the spatial differentiation of river and lands nearby in longitudinal direction, while based on the spatial differentiation and security during flood in cross direction, the utilization strategy should be classified and aimed at fragile use zone, stable use zone, and elastic use zone, respectively.

Assessment method of ecosystem health

KONG Hongmei, ZHAO Jingzhu, JI Lanzhou, LU Zhaohua, DENG Hongbing, MA Keming, ZHANG Ping

2002, (4):  486-490. 

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Ecosystem is the basic unit to maintain human environment. Ecosystem function mainly includes two aspects:e-cosystem service function and goods function. These two functions are the basis for human living and development. Ecosystem health is the presupposition of ecosystem function. The completeness (structure and function), resilience, stabilty, and sustainability are the characteristics of ecosystem health. Ecosystem health assessment selects the indicator based on the ecosystem structure and function, including completeness, suitability, and effectiveness of ecosystem. Ecosystem health assessment mainly has two methods :one is indicator species assessment, and the other is structure and function index assessment which includes single index assessment, complex index assessment, and index system assessment which includes natural index system assessment and social-economic-natural index system assessment. In this paper, different assessment methods on ecosystem health are compared, and different health assessment method for different ecosystem types are also expatiated.

Effects of transgenic crops on soil ecosystem

WANG Jianwu, FENG Yuanjiao, LUO Shiming

2002, (4):  491-494. 

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The effects of transgenic crops on the soil ecosystem were reviewed. The activity of Cry I Ab gene and proteinase inhibitor gene in the soil was summarized. The differences of soil microbes'components, soil enzyme activities, and soil fauna between genetic crops and isogenic strain crops were analyzed. According to current progress, the potential impacts of transgenic plant on soil microorganisms depend on the characteristics of the gene transferred into the crops and the soil properties. The change of soil ecosystem affected by many factors, and among them, the complex and stability of the ecosystem are the most important. The ecological effects of transgenic crops on the soil ecosystem need to be evaluated more fully before they are planted over extensive areas. Much effort should be devoted to the development of molecular techniques method to assess the effects of transgenic crops on soil ecosystem.

Review on landscape heterogeneity

ZHAO Yutao, YU Xinxiao, GUANG Wenbin

2002, (4):  495-500. 

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On the base of precedent studies, the occurring mechanism, classification, measurement methods, and the important role of landscape heterogeneity in landscape ecology were reviewed. The inner and outer uncertain factors result in landscape heterogeneity. Landscape heterogeneity has colose relations with landscape stability, landscape design, architecture, management and disturbance, scale and ecological diversity in ecology. Complexity of landscape heterogeneity research, non-system of measurement indices and methods, difficulties and limitations of landscape heterogeneity modelling were all discussed respectively. In addition, it is suggested that the theory and methods of ecological complexity shoold be used to improve landscape heterogeneity research.

Behaviors of polycylic aromatic hydrocarbons (PAHs) in the soil

GAO Xuesheng, JIANG Xia, OU Ziqing

2002, (4):  501-504. 

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Adsorption equilibrium of PAHs in the soil can be reached by two mainly processes, "quick" and "slow". Although PAHs with low molecular may be absorbed by the plant root, and transferred and transformed into other upper part of plant, the main accumulation pathway for PAHs in plant is from the air to the leaf surface. Micro-bial degradation of PAHs by its enzymatic capacity is the main process of the degradation of PAHs in nature. In addition, factors effecting the biodegradation of PAHs are analyzed in details in this review.

Phytogenic isoprene and its ecological significance

GUI Xiaoyong, ZHAO Guangdong, LIU Shirong

2002, (4):  505-509. 

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Isoprene is the main component of numerous volatile hydrocarbons emitted by vegetation. Its biosynthesis and e-mission from vegetation plays an important role in global carbon balance, greenhouse effect, and atmospheric pollution. In this paper, the main factors determining isoprene emission rate, isoprene emission amount and its calculation methods, as well as its potential ecological functions were reviewed. The importance of further study on the relationships between multiple stresses and isoprene biosynthesis and emission was emphasized.

Response of some protective enzymes in Brassica chinensis seedlings to Pb²⁺, Cd²⁺ and Cr⁶⁺ stresses

REN Anzhi, GAO Yubao, LIU Shuang

2002, (4):  510-512. 

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Seedlings of Brassica chinensis were cultured in 1/2 Hoagland solution for seven days before they were treated with Pb²⁺, Cd²⁺ and Cr⁶⁺. The activities of their superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) responded to the increasing concentrations of the metals, and the responsive characters varied with different metals and different durations of metal treatments. CATactivity decreased with the increase of metal concentrations, and the order of its sensitivity to the three metals was Cd²⁺>Cr⁶⁺> Pb²⁺. SOD activity followed a rise-fall pattern along metal concentration gradient, but its sensitivity decreased with the duration of metal treatment. There was an obvious difference in PODactivity to different metals, only when the treatment was proceeded for a period of time.