Table of Content

18 September 2006, Volume 17 Issue 09

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Articles

Aboveground biomass of Tamarixon piedmont plain of Tianshan Mountains south slope

ZHAO Zhenyong^1,2;WANG Ranghui¹;ZHANG Huizhi¹;WANG Lei^1,2

2006, 17(09):  1557-1562 . 

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Based on the geo-morphological and hydro-geological characteristics, the piedmont plain of Tianshan Mountains south slope was classified into 4 geo-morphological belts, i.e., flood erosion belt, groundwater spill belt, delta belt, and the joining belt of piedmont plain and Tarim floodplain. A field investigation on the Tamarix shrub in this region showed that there was a significant difference in its aboveground biomass among the four belts, ranged from 1428.53 kg·hm^-2 at groundwater spill belt to 111.18 kg·hm^-2 at the joining belt of piedmont plain and Tarim floodplain. The main reason for such a big difference might be the different density of Tamarix shrub on different belts. Both the Tamarix aboveground biomass and the topsoil’s salinity were decreased with increasing groundwater level. Groundwater level was the main factor limiting Tamarix growth, while soil salinity was not.

Effects of different sampling modes on the results of vegetation ordination analysis

LENG Wenfang^1,2;HE Hongshi¹;LI Xiuzhen¹; HU Yuanman¹

2006, 17(09):  1563-1569 . 

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The relationships between plant and environment are an important topic in community ecology. To study these relationships, quadrate is often used to sample vegetation and environmental data, and ordination techniques are used to analyze the data. However, the size and shape of quadrate considerably affect the ordination results. To understand this effect remains a research item for various vegetation and environmental data settings. This paper studied the effects of different sampling quadrate (size and shape) on the results obtained from three common ordination techniques (CA, DCA and CCA). We did this by sampling the same transect in forest form map six times, using six different quadrates (0.5 km×0.5 km, 0.5 km×2 km, 2 km×0.5 km, 1 km×1 km, 1 km×4 km, 2 km×2 km). The results showed that large rectangle quadrate could capture greater percent variance of species data and more information about rare and unique species than small square quadrate. All sizes and shapes of quadrate used in this study had little effect on the dominant species. The captured soil information was sensitive both to the size and to the shape of quadrate, and the information of slope, longitude and latitude was sensitive to the change of quadrate size. Slope position, altitude, temperature and precipitation were sensitive to the change of quadrate shape. Large quadrate reduced the importance of altitude, temperature and precipitation while increased the importance of exposure, but these environmental factors appeared to be important in small quadrate sampling.

Eco-hydrological characteristics of a subtropical evergreen broadleaved forest in Japan

XU Xiaoniu¹; WANG Qin¹;HIRATA Eiji²

2006, 17(09):  1570-1574 . 

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A three years (1998～2000) observation on the eco-hydrological characteristics of Castanopsis sieboldii and Schima wallichii dominated subtropical evergreen broadleaved forest on the Okinawa Island of Japan showed that during the observation period, the mean annual precipitation was 3325 mm, and 42.3% of it was directly or indirectly contributed by typhoon rainfall, implying that typhoon played a very important role in the hydrology of the forest. Through-fall and stem-flow contributed to 53.9% and 30.9% of the annual rainfall, respectively. The higher stem-flow could be due to the high wind velocity, intense rainfall, and the crown morphology of dominant species C. sieboldii with inclined branches and concave-shaped leaves. Interception loss occupied 15.2% of the total rainfall, being the lowest in the range of 15%～30% widely reported for many broadleaved evergreen forests. The annual surface runoff and lateral flow were 1 092 mm and 613 mm, respectively, and the high proportion of surface runoff (32.8%) was probably due to the poor physical properties of soil, particularly the low non-capillary porosity (8%～12%), high clay content (51.9%～60.5 %), and low infiltration rate (12 ml·min^-1) in deeper soil layers. The effective and maximum water storage capacity of 0～70 cm soil layer were 85 mm and 324 mm, respectively, and the maximum water-holding capacity of forest floor was 2.8 mm, which were close to or lower than those of the subtropical and tropical rain forests in China.

Light response curve of dominant tree species photosynthesis in broadleaved Korean pine forest of Changbai Mountain

ZHANG Mi^1,2;WU Jiabing^1,2;GUAN Dexin¹;SHI Tingting^1,2;CHEN Pengshi³;JI Ruipeng³

2006, 17(09):  1575-1578 . 

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Based on the measurements of leaf photosynthesis, the light response curves of Pinus koraiensis, Tilia amurensis, Quercus mongolica and Fraxinus mandshuricaphotosynthesis in broadleaved Korean pine forest of Changbai Mountains were fitted with rectangle and non-rectangle hyperbolae. The results showed that rectangle hyperbola was simpler for fitting, while non-rectangle hyperbola was more reasomable because of its fitted results better matched physiological meanings. The values of intrinsic quantum efficiency for CO₂ uptake (α), light-saturated net photosynthetic rate (P_max), and dark respiration rate (R_d) of the four tree species were higher when fitted with rectangle hyperbola than with non-rectangle hyperbola, while that of light compensation point (L_cp) varied with tree species. The values of α and R_d obtained from the two hyperbolae had the same sequences, i.e., F. mandshurica＞T. amurensis＞Q. mongolica＞P. koraiensis for α, and F. mandshurica＞Q. mongolica＞T. amurensis＞P. koraiensis for R_d, but for P_max and L_cp, the sequences were not the same.

Forest biomass carbon storage and its dynamics in Tanjiang River basin

YANG Kun¹;GUAN Dongsheng¹;ZHOU Chunhua²

2006, 17(09):  1579-1582 . 

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Based on an improved estimation method of forest carbon storage and the inventory of forest resources, this paper estimated the forest carbon storage and its dynamic changes in Tanjiang River basin, and analyzed the relationships of the carbon storage and its density with the increase of population density and GDP during the urbanization in 1990～2001. The results showed that the forest carbon storage in Tanjiang River basin increased from 5.906×10⁶ t in 1990 to 7.52×10⁶ t in 2001, with an annual average accumulation amount of 0.8×10⁶ t or an annual average accumulation rate of 3.05%, and playing a role of carbon sink. The rapid increase of population density and GDP didn’t influence the increase of forest carbon storage and density, but the development of forestry was far lower than that of economy. To have a better service function of forest ecosystem in the process of urbanization, and to promote the sustainable development of regional ecological environment, the key point is the reasonable coordination of forestry management with the development of economy.

Plant biodiversity and community structure of semi-humid evergreen broadleaved forests at different secondary succession stages

WANG Zhenhong¹;DUAN Changqun²; YANG Jiansong¹

2006, 17(09):  1583-1587 . 

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To analyze the relationships between plant diversity and community structure of semi-humid evergreen broadleaved forests at different secondary succession stage in the Samachang area of Yunnan Province, some numeral indices were tested, and the results showed that the plant diversity increased gradually with succession, and the species number reached 24 at the latest succession stage. There was a positive linear correlation between plant individual density and species diversity, which could be described by y=506.99x+554.56. A negative correlation was observed between the average height of plant individuals and plant species diversity, and the equation y=-0.3862x+11.406 could describe it well. The crown density and basal area increased in logarithm with plant species diversity, and the two equations y=21.756ln x +11.607 and y=7.4028lnx+9.6198 could describe the relations. No regular patterns were observed for the changes of aboveground biomass and plant individual density with plant species diversity. The relations of plant species with plant individual number could also be described by negative power function. Plant competition was intensified with plant species diversity, and each plant species might take the strategy to conserve its greatest population, and to avoid decreasing to less than its critical population, which led to a high individual density, and might change the structural character of the community.

Responses of rice leaf photosynthetic parameters to light intensity under NaCl s-tress

LI Haibo^1,2,3;HEN Wenfu¹;LI Quanying⁴

2006, 17(09):  1588-1592 . 

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With rice varieties salt-tolerant Liaoyan 2 and salt-sensitive Akihikari as test materials, this paper determined their leaf net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductivity (G_s), and intercellular CO₂ concentr-ation (C_i) at different light intensities under long-term NaCl stress. The results showed that under NaCl stress, the P_n and G_s of the two varieties had an increase tendency with increasing light intensity, but in comparing with no NaCl stress, the P_n of Liaoyan 2 increased by 14.87%, while that of Akihikari decreased by 17.91%. The dynamic changes of C_i, L_s and P_n/G_s indicated that stomatal and non-stamatal factors played a positive role in the changes of Liaoyan 2 photosynthesis, while stomatal factor was the main reason inducing the changes of Akihikari photosynthesis.

Effects of nitrogen application level on soil nitrate accumulation and ammonia volatilization in high-yielding wheat field.

WANG Dong; YU Zhenwen; YU Wenming; SHI Yu; ZHOU Zhongxin

2006, 17(09):  1593-1598 . 

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The study showed that during the period from sowing to pre-wintering, the soil nitrate in highyielding wheat field moved down to deeper layers, and accumulated in the layers below 140 cm. An application rate of 96～168 kg N·hm^-2increased the nitrate content in 0～60 cm soil layer and the wheat grain yield and its protein content, and decreased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen. Applying 240 kg N·hm^-2 promoted the downward movement of soil nitrate and its accumulation in deeper layers, increased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen, had no significant effect on the protein content of wheat grain, but decreased the grain yield. The appropriate application rate of nitrogen on high-yielding wheat field was 132～204 kg N·hm^-2.

Effects of nitrogen and phosphorus application rate on population growth and grain yield of hybrid wheat C6-38/ Py85-1

ZHANG Yongli^1,2;LI Yanming^1; XIAO Kai¹; WANG Fengcai³

2006, 17(09):  1599-1603 . 

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This paper studied the effects of different nitrogen and phosphorous application rates (112.5～337.5 kg N·hm^-2 and 90～270 kg P₂O₅·hm^-2) on the population growth and grain yield of hybrid wheat C6-38/Py85-1 under field condition. The results showed that the total number of population stems (PS), population dry weight (PDW), leaf area index (LAI), photosynthetic potential (PP) and crop growth rate (CGR) were the lowest under low fertilization rate(112.5 kg N·hm^-2 and 90 kg P₂O₅·hm^-2), PS and PDW were higher under high fertilization rate (337.5 kg N·hm^-2and 270 kg P₂O₅·hm^-2) than under medium fertilization rate (225 kg N·hm^-2and 180 kg P₂O₅·hm^-2), and LAI, PP and CGR were higher under high than under medium fertilization rate before flagging, jointing, and anthesis stage, respectively, but in adverse after these stages. Under low and medium fertilization rates, PS had no mid-parent heterosis (H_m), while under high fertilization rate, it had the positive values of 6.3%, 49.7%, 4.2% and 10.8% at before winter, jointing, anthesis, and maturing stages, respectively. The H_m of LAI and PDW increased significantly with increasing fertilization rate, except that the H_m of LAI was 3.8% higher under medium than under high fertilization rate at filling stage while that of PDW had no significant difference between these two fertilization rates at maturing stage. The H_m values of PP and CGR were the lowest in the whole growth period under low fertilization rate, and lower before jointing-flagging and flagging-anthesis stage but higher after these stages respectively under medium than under high fertilization rate. The grain yield and itsH_m of the hybrid wheat were the highest under medium fertilization rate, lower under high fertilization rate, and the lowest under low fertilization rate. The grain yield under medium fertilization rate was 216.2 kg·hm^-2 higher than that under high fertilization rate, but its H_m had no significant difference between these two fertilization rates.

Effects of urea and coated urea on harmful gases concentrations in plastic greenhouse.

ZHOU Xihong¹; ZENG Qingru^1,2;MAO Xiaoyun³; ZHANG Litian²,;LIAO Bohan¹; TIE Baiqing¹; LIAO Zongwen³

2006, 17(09):  1604-1608 . 

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With simulation test and plastic greenhouse experiment, this paper studied the effects of urea and minerals-coated urea on the soil pH and harmful gases concentrations in plastic greenhouse. The results showed that under simulated condition, the application of these two N fertilizers led to an initial increase of soil pH, which reached the maximum (an increment of ＞50%) within the first week and dropped to the initial level by the end of the fifth week. In plastic greenhouse, applying urea and coated urea resulted in the increase of NH₃, NO₂ and O₃ concentrations. The daily volatilization amount of NH₃ and NO₂ was higher in urea treatment than in coated urea treatment, and the highest value in urea treatment was 42.36μg·m^-3·d^-1 for NH₃ , 41.95 μg·m^-3·d^-1 for NO₂, and 86.00μg·m^-3·d^-1 for O₃. The volatilization intensity of NH₃ and NO₂ was influenced by temperature and sunlight, while the O₃ concentration was influenced by sunlight.

Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress

WANG Tian^1,2; WANG Suping¹; GUO Shirong¹;SUN Yanjun¹

2006, 17(09):  1609-1612 . 

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With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (P_n), intercellular CO₂ concentrations (C_i), stomatal conductance (G_s), transpiration rate (T_r), apparent quantum yield (Φ_c), and carboxylation efficiency (CE) of cucumber seedlings under hypoxia stress. The results showed that the P_n decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63.33% of the control. Compared with that of hypoxia-stressed plants, the P_n after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R²=0.4730～0.7118) was found between P_n and C_i. G_s and T_r changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between G_s and T_r (R²=0.7821～0.9458), but these two parameters had no significant correlation with P_n; Hypoxia stress induced a decrease of Φ_c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made Φ_c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by nonstomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

Effective constituents contents in indigowoad roots and leaves from different re-gions

DONG Juan’e^1,2; LIANG Zongsuo^1,2; WEI Qin²; CHEN Shenglong²

2006, 17(09):  1613-1618 . 

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By the method of HPLC, and with indigo and indirubin as indicative constituents, this paper determined the effective constituents contents in indigowoad roots and leaves collected from different regions. The results showed that the total content of effective constituents in indigowoad root was the highest (16.27 mg·kg^-1) from Hanyin of Shaanxi Province, followed by Longde of Ningxia Autonomous Region (15.67 mg·kg^-1), Bozhou of Anhui Province (14.90 mg· kg^-1), and Linquan of Anhui Province and Jiamusi of Heilongjiang Province (13.97 mg·kg^-1), and that in indigowoad leaf had the same order, with the values being 698.32, 683.68, 680.11, 654.19 and 642.23 mg·kg^-1, respectively. The HPLC chromatograms of leaf samples collected from different regions were differed, not only in the test constituents, but also in the other constituents manifested as various peaks in the chromatogram. It was suggested that besides meteorological factors, the selection of geo-authentic region should be also involved in the cultivation of Isatis indigotica.

Appropriate parameters for high-yielding cultivation of machine-transplanted rice

PENG Changqing^1,2; LI Shifeng²; BIAN Xinmin¹; WU Jiulin²;ZHOU Yu²;LIU rongrong²

2006, 17(09):  1619-1623 . 

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A field experiment with japonica rice variety Wuxiangjing 14 in 2002～2005 showed that the appropriate sowing rate was 150～180 g per tray (1624 cm²), seedling-strengthening agent was more conducive than compound fertilizer in improving the quality of machine-transplanted seedlings, the rational dose of compound fertilizer (N-P₂O_5^-K₂O) was 150 g·m^-2, seedlings should be machine-transplanted within 21 days after sowing, densely planting a fewer seedlings in each cluster could improve the individual and population quality of machine-transplanted rice, and applying 315 kg·hm^-2 of N and 6∶4 of basal-tillering: heading fertilizer could obtain the highest rice yield. The marked increase of glumous flowers per unit area was the main cause of the increase of machine-transplanted rice yield.

Effects of water supply and 3-methylphenol on soil microbial diversity and enzyme activity in wheat field intercropped with horse bean

CHAI Qiang; HUANG Gaobao; HUANG Peng

2006, 17(09):  1624-1628 . 

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With pot experiment, this paper studied the effects of water supply levels (45%, 60% and 75% of soil water hold capacity) and allelochemical 3-methylphenol (300×10^-6mol·kg^-1 soil) on the soil microbial diversity and enzyme activity in mono-cropped and horse bean-intercropped wheat fields during vigorous growth period. The results showed that with the decrease of water supply, the numbers of soil bacteria, fungi and actinomytes in the two fields decreased significantly, and 3-methylphenol enlarged this negative effect. 3-methylphonel had a negative effect on soil microbial diversity, but the increase of water supply could weaken this effect in intercropped field. The strongest allelopathic effect of 3-methylphenol was observed in mono-cropped field when the water supply was 75% of soil water hold capacity, while intercropping could maintain a relatively stable soil microbial diversity, compared to the mono-cropping with3-methylphenol and low water supply. The allelopathic effect of 3-methylphenol was not significant on soil catalase activity, but significant on soil urease and phosphatase activities. Water supply level affected soil enzyme activity significantly, the lower the water supply level, the weaker the soil enzyme activity was. The interactions of water supply with 3-methyl phenol or cropping pattern were not significant, but intercropping could significantly affect the activities of soil catalase and phosphatase.

Effects of two kinds of allelochemicals on photosynthesis and chlorophyll fluorescence parameters of Solanum melongena L. seedlings

YU Jihua; ZHANG Yun; NIU Caixia; LI Jianjian

2006, 17(09):  1629-1632 . 

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In a culture experiment, the effects of different concentration 2,6-bis (1,1-dimethylethyl) phenol and 1,2-benzodicarboxylic dimethyl ester on the photosynthesis and chlorophyll fluorescence characteristics of eggplant seedlings were studied, and the results showed that these two allelochemicals were the barriers of chlorophyll content, net photosynthetic rate(P_n), and stomatal conductance(G_s). The intercellular CO₂ concentration(C_i) decreased in the former period, and then increased. The allelochemicals increased initial fluorescence(F_o), but decreased maximum photochemical efficiency of PSⅡ(F_v/F_m), quantum efficiency of non-cyclic electron transport of PSⅡ(Ф_PSⅡ), photochemical quenching ((q_P) and antenna conversion efficiency (F_v′/F_m′). 2,6-bis (1,1-dimethylethyl) phenol made non-photochemical quenching (q_N) increase first and decrease then, while 1,2-benzodicarboxylic dimethyl ester decreased q_N, which was harmful to the photosynthesis structure.

Potential allelopathic effects of Piper nigrum，Mangifera indica and Clausena lansium

YAN Guijun;ZHU Chaohua;LUO Yanping;YANG Ye;WEI Jinju

2006, 17(09):  1633-1636 . 

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With Piper nigrum,Mangifera indica and Clausena lansium as the donators, this paper studied their potential allelopathic effects on the germination and growth of Zea mays,Glycine max,Cucurbita moschata,Arachis hypogaea,Raphanus sativus, Echinochloa crusgalli,Digitaria sanguinalis and Stylosanthes guianensis. The results showed that the aqueous extracts of these donators could inhibit the germination and growth of Z. mays,G. max,C. moschata, E. crus-galli and D. sanguinalis at high concentration, but stimulate them at low concentration. In rhizosphere soil of P. nigrum and M. indica, the germination and growth of Z.mays L was stimulated, while A. hypogaea was inhibited. The aqueous extracts of the donators were extracted by ethyl acetate and n-butanol, respectively, and the inhibitory activity of both aqueous and n-butanol fractions from P.nigrum and M. indica on Z. mays,R. sativus and S. guianensis was stronger than that of ethyl acetate fraction, indicating that P. nigrum and M. indica contained the allelochemicals with high polarity.

Inhibitory effects of Lantana camera and its contained phenolic compounds on Eichhornia crassipes growth

YI Zhen; ZHANG Maoxin;LING Bing; XU Di;YE Jingzhong

2006, 17(09):  1637-1640 . 

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This paper studied the effects of Lantana camera fresh leaves aqueous extract and its contained phenolic compounds on the growth and physiologic-biochemical indexes of Eichhornia crassipes. The results showed that this extract had obvious inhibitory effects on the growth and development of E. crassipes. When the concentration was higher than 30 g FW·L^-1, it could kill E. crassipes after 6 days treatment. A total of seven phenolic compounds in the abstract were identified by HPLC, which were salicylic acid, gentisic acid， β-resorcylic acid，coumarin，ferulic acid, p-hydroxybenzoic acid and 6-methyl coumarin，with the concentrations being,50.95，13.46,5.28,3.36,2.92,2.19 and 0.34 mg·L^-1, respectively. The mixture of the seven compounds had the strongest inhibitory effect, followed by salicylic acid, 6-methyl coumarin, coumarin, and p-hyroxybenzoic acid, while the effects of β-resorcylic acid and gentisic acid were not significant.

Changes of DIMBOA contents in resistant and susceptible wheat near-isolines infected by Puccinia striiformis f.sp. tritici

XU Guofeng^1,2;ZHENG Yongquan¹; DONG Fengshou¹;XU Shichang¹;YAO Jianren¹

2006, 17(09):  1641-1644 . 

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With two sets of wheat near-isolines having different genetic background as test materials, this paper studied the dynamics of their DIMBOA (2,4-dihydroxy7-methoxy-1,4-benzoxazin-3-one) contents during Puccinia striiformis f. sp. tritici infection. It was revealed that in un-inoculated plants, no significant difference was observed in DIMBOA contents among various resistant and susceptible inbred lines within the same set. But, at the initia1 stage of infection, the DIMBOA contents in all resistant isolines displayed a quicker and greater increase, resulting in a significantly higher content of DIMBOA in resistant isolines than in susceptible one throughout the period of disease development. The infection ultimately led to a decline of DIMBOA contents in all infected plants, but the decrement was significantly less in resistant lines than in susceptible one. It could be concluded that DIMBOA was associated with the monogenic resistance to Puccinia striiformis f. sp. tritici in wheat. The study of DIMBOA dynamics in plants suffered from diseases and pests would be usefu1 for understanding the mechanism of resistance, and the screening and breeding of crop varieties with multiple-resistance.

Interference of allelopathic rice Huakangcao 78 on weeds under different ecological conditions.

WU Jinglun; LI Yongfeng; CHEN Zhishi; WANG Yizhuan

2006, 17(09):  1645-1648 . 

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A pot culture experiment was conducted to examine the interference effectiveness of allelopathic rice Huakangcao 78 on weeds Echinochloa crusgalli L., Cyperus difformis L.,and Eclipta prostrata L. as affected by rice leaf age during transplanting, plant density, and soil surface water depth and its retaining days. The results showed that Huakangcao 78 could significantly reduce the dry weight of weeds compared with non-allelopathic rice Lemont. The control effectiveness of Huakangcao 78 onE. crusgalli L. was better when the weed was at 0～1.5 leaf age than at 1.5～2.4 leaf age, and that onC. difformis L. was better when the weed was at 0～0.3 leaf age than at 0.8～2.0 leaf age. The interactive effectiveness between rice leaf age during transplanting and plant density on weed control was better than that between the leaf age and soil surface water depth and its retaining days. To increase the rice leaf age during transplanting and plant density could significantly promote the control effectiveness of Huakangcao 78 on weeds.

Effects of Zanthoxylum bungeanum leaf extract on soil microbe quantity and enzyme activities

Lü Ke^1,2; PAN Kaiwen¹; WANG Jinchuang¹; WAN Tao³

2006, 17(09):  1649-1654 . 

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In a pot experiment, the aqueous extract of 10 years old Zanthoxylum bungeanum’s leaves was used to water Z. bungeanum seedlings to test its effects on soil microbes and enzyme activities. The results showed that the leaf extract decreased the total amount of microbes and the quantity of bacteria, fungi and actinomyces in rhizosphere soil, but increased the total amount of microbes in non-rhizosphere soil. After watering with the extract, the roteinase, invertase and acid phosphatase activities in rhizosphere soil were considerably lower than those in non-rhizosphere soil, while catalase and polyphenol oxidase activities were in adverse. Soil proteinase activity had a significant positive correlation with invertase activity, but a significant negative correlation with actinomyces amount. Soil polyphenol oxidase activity had a significant negative correlation with invertase activity, but a positive correlation with the total amount of microbes and the quantity of bacteria, fungi and actinomyces. Soil actinomyces only had significant correlations with proteinase, polyphenol oxidase and invertase activities and fungi.

Allelopathic effects of Lycoris radiate on radish, cucumber, tomato and rape seedlings

JIANG Hongyun;ZHANG Yanning;FENG Pingzhang;ZHANG Heng

2006, 17(09):  1655-1659 . 

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The laboratory test showed that Lycoris radiate water extract had a stronger inhibitory effect on the seed germination and seedling growth of radish, cucumber, tomato and rape. After treated with 0.0125 g·ml^-1 of the extract, tomato seed could not germinate, but the seed germination inhibition rate of rape, radish and cucumber was only 17.73%, 14.97% and 2.65％, respectively. Under the same concentrations of the extract, sprout growth was inhibited more strongly than root growth. L. radiate methanol extract could inhibit the sprout and root growth of endosperm-removed wheat and sorghum, and the effect was stronger for sorghum than for wheat. All of these illustrated that L. radiate extracts mainly inhibited non-photosynthesis activity, but could also inhibit photosynthesis activity to some degree.

Segmentation-based multi-scale urban green space landscape

SUN Xiaofang¹; LU Jian¹;SUN Yibin²

2006, 17(09):  1660-1664 . 

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In this study, three scales urban green space landscapes were generated by multi-resolution segmentation. With 50 and 300 pixels as the object segmentation thresholds, the small- and large-scale landscape object image layers were produced, and the two object image layers were obtained by the nearest neighbor classification method. The result of small-scale landscape classification image was segmented into middle-scale landscape image, and then classified. Green space information was extracted through vector form of object image layers of three scales landscape classification. The landscape indexes diversity, dominance, evenness, fractal dimension, fragmentation, and interior to edge ration were calculated, with the largest values of the former four indexes being 2.2, 0.681, 0.948, and 0.326, and the smallest values being 1.641, 0.122, 0.707, and 0.113, respectively, indicating that the diversity, evenness and fragmentation decreased,while the dominance increased with increasing landscape scale. The method of multi-resolution segmentation to generate multi-scale landscape could meet the needs of urban green space landscape research.

Landscape structure of desertification grassland in source region of Yellow River

WANG Hui^1,2; YUAN Hongbo¹; XU Xianghong³; LIU Shujuan⁴

2006, 17(09):  1665-1670 . 

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This paper analyzed the spatial pattern and its characteristics of different landscape types on the desertification grassland of Maqu County in the source region of Yellow River, based on the principles of landscape ecology, with the help of GIS techniques, and by using landscape heterogeneity indices(landscape diversity and dominance), landscape isolation indices (patch density and fragmentation), and shape indices (elongation index and fractal dimension). The results showed that on the whole, the landscape structure of this region was simple, but varied locally. Natural landscapes such as grassland, marsh and shrubs were the main body of landscape change. The regional landscape patches had a ribbon shape spatial distribution, and the differences were significant among sub-regions. From fluvial terrace to low hillsides and alpine grassland, the landscape patch type, landscape diversity, and landscape fragmentation degree decreased gradually, and the landscape structure presented a simplification trend. Desertification landscape, and mobile dune in particular, had great impact on landscape structure, playing an important role in the increment of landscape heterogeneity and fragmentation. Fixed sand lands, semi-fixed sand lands, and potential sand lands had different influences on regional landscape composition and its changes. Compared with desertification landscape, artificial landscape had less effect on landscape structure, but exhibited a wider potential variation range. These two types of landscape would be the dominant factors affecting the landscape structure changes of this region in the future.

Spatio-temporal change and gradient differentiation of landscape pattern in Guangzhou City during its urbanization

GUO Luo¹; XIA Beicheng¹; LIU Weiqiu²; JIANG Xueding¹

2006, 17(09):  1671-1676 . 

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Guangzhou City is a rapidly urbanizing city in China, and a constructed city with holistic planning. By using the remote sensing images of 1985, 1990, 1995, 2000 and 2004,this paper studied the 20 years spatio-temporal changes of landscape pattern in Guangzhou, and analyzed the relationships between these changes and urbanization. The landscape and class-level pattern indices of whole Guangzhou City and its five districts were compared, and the results indicated that the landscape pattern in Guangzhou had an obvious spatio-temporal variation, and an increase of diversity and fractal dimension. The landscape structural complexity and fragmentation increased gradually from 1985 to 2004, and the variation intensity and tendency varied during four comparative stages 1985～1990, 1990～1995, 1995～2000, and 2000～2004. It was a rapid development period from 1985 to 1995 in Guangzhou. The represents of ten districts varied in their spatio-temporal landscape pattern, because of the different development progress and planning motive. The urbanization of Panyu was from1990 to 2000, and its natural landscape was seriously disturbed by human activities. The represents of Conghua and Zengcheng districts were of integrative disturbance, and also, the urbanization process mainly took place during 1990-2000. In the city center consisting of 8 official constructed districts, the urbanization process happened earlier. In Huadu district, the landscape change revealed the frequent and severe human disturbance.

Landscape pattern change and its driving forces in Xixi National Wetland Park since 1993

CHENG Qian¹; WU Xiuju²

2006, 17(09):  1677-1682 . 

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Under the support of GIS technology and the TM images of Xixi National Wetland Park, this paper studied the past ten years′ landscape pattern change and its driving forces of Xixi Wetland. The results showed that the landscape diversity index increased from 1.7854 in 1993 to 1.8438 in 2001 and 2.2096 in 2003, and the landscape fragmentation index increased from 0.0036 in 1993 to 0.0042 in 2001, and 0.0047 in 2003, suggesting that the landscape fragmentation was increased with time. Human activity was the main driving force, while the exploitation of real estate was the main internal factor of the landscape pattern change of Xixi wetland. In addition, social and economic development level had a strong effect on the overall diversity of the landscape.

Construction of urban green space ecosystem by using corridor network: A case study in west urban area of Dongying City, Shandong Province

HUANG Yi¹; CHEN Hui¹; HUANG Zhiji¹;CAI Mantang¹;KANG Junshui²

2006, 17(09):  1683-1687 . 

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This paper discussed the ecological significance of urban green corridors network in urban green space ecosystem, analyzed the present status of green space ecosystem in the west urban area of Dongying in Shangdong Province, and figured out the ways of constructing urban green corridors network in this area to strengthen the linkage between its fragmented greenbelts, and between these greenbelts and rural natural environment. Through the construction of this network, the greenbelt area in the west urban area of Dongying would increase 1400 hm², greenbelt area per capita would increase to 66 m², and urban and rural greenbelts would be integrated into a whole system to serve the whole city, giving a powerful support to enhance the life quality of local people and the stability of urban ecosystem.

Effects of organic acids on Cd desorption of South China red soil

DING Yongzhen^1,2;LI Zhian¹; ZOU Bi¹;CAO Yusong¹;TAN Wanneng^1,2;GU Wei^1,2

2006, 17(09):  1688-1692 . 

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Cadmium (Cd) pollution greatly threatens the environment of South China,where the economy developed very fast during last 20 years. In this paper, batch experiments were conducted to study the effects of three organic acids and their mixed solutions on the Cd desorption of red soil in this region. The results showed that oxalic acid and malic acid retarded the Cd desorption, but oxalic acid promoted it when the concentration was 20 mmol·L^-1 and soil pH value was higher than 5.0. With the increase of soil pH, Cd desorption decreased rapidly in the presence of oxalic acid and malic acid. Citric acid retarded Cd desorption at pH＜5.0, but promoted it at pH＞5.0. When the concentration of citric acid was 2 mmol·L^-1 and pH value changed from 3.0 to 7.0, Cd desorption declined first, increased then, and declined again. But, at the citric acid concentration of 20 mmol·L^-1, Cd desorption declined first till pH 4.0, and increased then till pH 7.0. At low pH (3.0 and 4.0), malic acid desorbed most Cd; while at high pH (5.0～7.0), citric acid desorbed most Cd. The Cd desorption ratewas much higher in the presence of citric acid than oxalic acid and malic acid. Organic acids did not interactive effect on Cd desorption. The Cd desorption rate by mixed acids was within the range of that by single acid alone.

Atmospheric water vapor conditions of Cnaphalocrocis medinalis outbreak in 2003

WANG Cuihua¹; BAO Yunxuan¹;WANG Jianqiang²;ZHAI Baoping¹;XIANG Yong³

2006, 17(09):  1693-1698 . 

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To reveal the influence of atmospheric water vapor conditions on the outbreak of Cnaphalocrocis medinalis in 2003, the geographic distributions of the pest per 667 m² of China on June 16th, July 21st, and September 1st,2003were analyzed under the support of ArcGIS, and the air relative humidity and water vapor flux fields on 850, 925 and 1 000 hPa that had the greatest influence on the pest immigration were selected to do simulation and objective analysis. The results showed that the transferring status of water vapor and the distribution ofrelative humidity on the upper air had significant indicative meanings for the immigration. In the regions of C. medinalis outbreak, the air relative humidity on each layer from the ground to 850 hPa was higher than 50%. The shorter the distance to the landing region of C. medinalis, the higher the humidity was, while the shorter the distance to the takingoff region, the lower this humidity was. 850 hPa was the main layer of water vapor transferring during C. medinalis migration, and the key pathway of the migration. On this height, the direction of water vapor transferring was basically concurrent with that of C. medinalis migration.

Diurnal dynamics of microclimate at different succession stages of vegetation communities in inner-river wetland of Zhenjiang City

FU Weiguo¹; LI Pingping²; WU Yanyou²; BIAN Xinmin¹

2006, 17(09):  1699-1704 . 

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To study the diurnal dynamics of microclimate at different succession stages of vegetation communities in the inner-river wetland of Zhenjiang City, three typical communities were chosen, and the light intensity, air temperature, soil temperature, and air relative humidity were measured. The results showed that with the succession of barren land →Phalaris arundinacea→Phragmites communis ,the diurnal mean values of light intensity,air temperature, and soil temperature decreased from 1 204.7 μmol·m^-2·s^-1 to 141.28 μmol·m^-2·s^-1, 32.2 ℃ to 24.9 ℃, and 21.83 ℃ to 19.47 ℃, and their daily variations decreased from 1 126 μmol·m^-2·s^-1 to 265 μmol·m^-2·s^-1, 12.75 ℃ to 4.8 ℃, and 4.5 ℃ to 2.1 ℃, respectively. The air relative humidity increased from 58.95% to 87.3%, while its variation decreased from 29.75% to 5.15%. Habitats were open at early succession stage but more closed at late succession stage, microclimatic conditions developed towards much more cloudy, cold, and moist, and microclimate had a less fluctuation. There were definite correlations among the light intensity, air temperature, soil temperature, and air relative humidity in the vegetation communities, but the correlation coefficients among the test factors were differed at different succession stages.

Application and effectiveness of soil bioengineering in ecological restoration of stream bank

LI Xiaoping¹;ZHANG Liquan²

2006, 17(09):  1705-1710 . 

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Soil bioengineering is a kind of engineering by using living plant materials to construct the structures with some engineering and ecological functions, which can provide an effective means for the slope stabilization and site restoration of stream banks. In this paper, the principles of soil bioengineering, basic planting methods, live stakes, live fascines, brush layering, and integrated technologies were discussed in brief, and the first demo project of soil engineering in ecological restoration of stream bank in our country was introduced. After 10-month project implementation, significant effectiveness was obtained on slope stability, habitat improvement, and ecological restoration of stream banks. It was concluded that the approach could be widely applied in ecological restoration of all kinds of slopes in China.

Species characteristics and diversity of pelagic Mysidacea in East China Sea

XU Zhaoli

2006, 17(09):  1711-1714 . 

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Based on the investigation data of four oceanographic cruises in the East China Sea (23°30′～33°00′N, 118°30′～128°00′E) in 1997～2000, this paper studied the species characteristics and diversity of mysids, and the relationships between its species number and environmental factors. A total of 18 mysids species were observed, with 14 species occurred in autumn, 9 species occurred in summer, 7 species occurred in spring, and 4 species occurred in winter. The species composition showed a clear seasonal alternation, especially from autumn to winter. Seawater salinity was the main environmental factor affecting the distribution of the mysids. In summer and winter, mysids distribution was mainly affected by the runoff from continental rivers, and species number had a significant negative correlation with seawater salinity, while in autumn, the species number had a negative correlation with surface seawater temperature but a positive correlation with bottom seawater salinity. The spatial-temporal variation of mysids geographical distribution was linked with the ebb and flow of the Changjiang River, and the dominant species of mysids tended to agglomerate, which was the major reason of the low diversity of mysids in the East China Sea.

Fish resources and their conservation strategies in Hepu Dugong StateNature Reserve and its adjacent waters

WANG Qian^1,2; YANG Guang²;WU Xiaobing¹;XU Xinrong²;LAI Chunmiao³;NING Yun³;LUO Jinfu³

2006, 17(09):  1715-1720 . 

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An investigation was made on the fish resources and fish habitats of Hepu Dugong State Nature Reserve and its adjacent waters from June 2003 to May 2004. The local fish markets were surveyed, and fishermen and fishmongers were interviewed to get fishery information. A total of 57 fish species belonging to 41 families and 14 orders were recorded, among which, 55 were bony fish, and 2 were elasmobranch. There were 41 fish species belonging to warm-water fish, and 37 fish species belonging to benthonic fish. The faunal characteristic was mainly of Northern Pacific and Indo-Pacific fauna. Devastating fishing and environmental pollution were the most serious threats to the local fishery resources, and some counter measures were proposed for conservation and management of the resources.

Distribution ofLittoraia melanostoma Gray (Littorinidae) and Nerita lineata Gmelin (Neritadae) in rehabilitated mangroves

CHEN Guangcheng; YE Yong; LU Changyi; LI Rong; WENG Jin; XU Yuyu

2006, 17(09):  1721-1725 . 

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An investigation was made in April and July 2005 on the abundance and biomass of Littoraia melanostoma (Littorinidae) and Nerita lineata (Neritadae) in the rehabilitated mangrove forests with different mangrove species and stand ages at the Jiulongjiang Estuary of Fujian Province. The results showed that Nerita lineata was more abundant in mature stands, and had greater biomass and density in Kandelia candelstand than in Aegiceras corniculatum stand. A. corniculatum stand had greater density and biomass of L. melanostoma than K. candel stand, when the two stands had similar ages. In A. corniculatum stands, the biomass of L. melanostoma increased with the age of younger stands; while in K. candel stands, it decreased with the development of the forests. Different habitation patterns of the two snails in different mangrove stands indicated that N. lineate had a strong inhabitation preference for mature K. candel forest, while L. melanostoma was apt to inhabit in younger A. corniculatum forests.

Effects of fire on major forest ecosystem processes：An overview

CHEN Zhong

2006, 17(09):  1726-1732 . 

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Fire and fire ecology are among the best-studied topics in contemporary ecosystem ecology. The large body of existing literature on fire and fire ecology indicates an urgent need to synthesize the information on the pattern of fire effects on ecosystem composition, structure, and functions for application in fire and ecosystem management. Understanding fire effects and underlying principles are critical to reduce the risk of uncharacteristic wildfires and for proper use of fire as an effective management tool toward management goals. This overview is a synthesis of current knowledge on major effects of fire on fire-prone ecosystems, particularly those in the boreal and temperate regions of the North America.Four closely related ecosystem processes in vegetation dynamics, nutrient cycling, soil and belowground process and water relations were discussed with emphases on fire as the driving force. Clearly, fire can shape ecosystem composition, structure and functions by selecting fire adapted species and removing other susceptible species, releasing nutrients from the biomass and improving nutrient cycling, affecting soil properties through changing soil microbial activities and water relations, and creating heterogeneous mosaics, which in turn, can further influence fire behavior and ecological processes. Fire as a destructive force can rapidly consume large amount of biomass and cause negative impacts such as post-fire soil erosion and water runoff, and air pollution; however, as a constructive force fire is also responsible for maintaining the health and perpetuity of certain fire-dependent ecosystems. Considering the unique ecological roles of fire in mediating and regulating ecosystems, fire should be incorporated as an integral component of ecosystems and management. However, the effects of fire on an ecosystem depend on the fire regime, vegetation type, climate, physical environments, and the scale of time and space of assessment. More ecosystem-specific studies are needed in future, especially those focusing on temporal and spatial variations of fire effects through long-term experimental monitoring and modeling.

Aesthetics theory and method of landscape resource assessment

WANG Baozhong¹; WANG Baoming²;HE Ping²

2006, 17(09):  1733-1739 . 

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With the destruction of natural environment by human beings, scenic resources are no longer inexhaustible in supply and use. Human beings begin to lay the scenic resources on the same important strategic status as other natural resources, while landscape resources assessment is the prerequisite of their sustainable exploitation and conservation. This paper illustrated the psychological mechanisms of aesthetic and its approaches, compared with the methodologies of traditional and modern landscape aesthetic research, discussed the characteristics of important aesthetic theories (Platonism, Kant paradigm, Empathizing theory, Gestalt paradigm, Marxism aesthetics theory, and Appleton theory) and the landscape assessment theories of 4 paradigms(expert, psychological, cognitive, and empirical) and 2 groups (landscape environment science and landscape architecture culture), and summarized the important practices and successful examples at home and abroad.It was demonstrated that the historical development of landscape assessment had the feature of a contest between expert- and perception-based approaches, with the expert approach dominated in landscape management, while the perception-based approach dominated in landscape research. Both of these approaches generally accepted that landscape quality was derived from the interaction between the biophysical features of landscape and the perceptual (judgmental) processes of human viewer. In the future, landscape quality assessment will evolve toward a shaky marriage, both expert- and perceptual approaches will be applied in parallel and merged in the final landscape management decision-making process in some but unspecified way, landscape information and complex geo-temporal dynamics representation central to scenic ecosystem management will present major challenges to the traditional landscape aesthetic assessment, and modern science and technology will continue to help meet these challenges. The main trends of landscape resources aesthetic assessment in this century will be the amalgamation and incorporation of diverse paradigms, the cross-disciplinary intersection and quantitative assessment, the emphasis of environment information and landscape ecological value recognition, the universal application of modern science and technology and of the dynamic and intellectual approaches of landscape information, the reality of landscape simulation and its scene technology of human perception, and the more attention to history and landscape culture.

Transcription factors networks and their roles in plant responses to environmental stress

WANG Jiping¹; SHI Huaping²; MAO Xue¹; LI Runzhi¹

2006, 17(09):  1740-1746 . 

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The regulation networks of gene expression mediated by transcription factors play important roles in plant responses to a range of environmental stresses. Transcription factors and their families identified to be involved in plant stress responses include APETALA2/EREBP, bZIP, WRKY, MYB, etc., which can constitute regulation networks to regulate the temporalspatial expression of each kind of related genes in plant stress responses. The genetic modifications of transcription factors and their regulation networks are increasingly becoming the effective approaches for understanding stress biology at system level, and a new way for enhancing the stress tolerance and resistance of plants.

Interactive effects between plant allelochemicals, plant allelopathic potential and soil nutrients

XIAO Huilin^1,2,3; PENG Shaolin^1,4; ZHENG Yuji²; MO Jiangming¹;LUO Wei²; ZENG Xiaoduo²;HE Xiaoxia²

2006, 17(09):  1747-1750 . 

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Plant allelopathy relates to many ecological factors. The deficit of soil nutrients can influence the production of plant allelochemicals, and thus, influence plant allelopathic potential, while plant allelochemicals can influence the form and level of soil nutrients by the ways of complexation, adsorption, acid dissolution, competition, inhibition, and others. In this paper, the interactive effects between plant allelochemicals, plant allelopathic potential and soil nutrients were summarized, and further research aspects in this field were prospected. It was suggested that following aspects should be strengthened: 1) the integration of plant allelopathy and soil-plant nutrition research to more precisely and deeply interpret the relationships between plant allelochemicals, plant allelopathic potential and soil nutrients, 2) the integration of plant allelopathy and ecosystem nutrient cycling research to simulate the plant nutrients disturbance in nature and make the allelopathy research results more true and more reliable, and 3) the allelopathy research with soils containing excessive nutrients or polluted to provide new ideas and scientific basis in revealing the mechanisms of plants interaction and biomass variation in agricultural and forestry production, and in ecological protection.

Present status and prospects of estuarine wetland research in China

HUANG Guilin^1,2; HE Ping^2，3; HOU Meng¹

2006, 17(09):  1751-1756 . 

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Estuarine wetland has become a research hotspot in China, due to its unique processes of evolution and formation, rich biodiversity, and important roles in supporting economic development. Based on the analysis of the distribution and the characteristics of estuarine wetlands in China, this paper summarized the present status of estuary wetland research in this country from the aspects of biodiversity, ecological processes and dynamic changes, mechanisms of formation and development, landscape patterns and dynamic evolution, restoration and rehabilitation, relationships between human activities and conservation, estuary wetland and global change, assessment, and construction of digital estuarine wetlands. Although great achievements have been made in various research aspects of estuary wetlands, there still existed many gaps, especially in advanced idea and technology, compared with developed countries. Combined the up-to-date research trend of estuary wetland at home and abroad, four important research hotspots in the future in China were put forward, including the relationships between human activities and conservation, restoration and rehabilitation, estuary wetland and global change, and construction of information system.

Soil respiration of Pinus koraiensis and P. sylvestriformis trees growing at levated CO₂ concentration

ZHOU Yumei¹; HAN Shijie¹; Xin Lihua²

2006, 17(09):  1757-1760 . 

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The study with open-top chamber showed that at 500 μmol CO₂·mol^-1, the soil respiration rate under Pinus koraiensis and P. sylvestriformis decreased significantly, probably due to the slow diffusion of increased soil surface CO₂ concentration. The soil surface CO₂ concentration at 500 μmol CO₂·mol^-1 was significant higher than that in the control chamber and un-chambered field, with an increment of 40～150 μmol CO₂·mol^-1. The soil surface CO₂ concentration of P. sylvestriformis in the control chamber was higher than that on unchambered field, but the difference was not significant, while a significant difference was observed in P. koraiensis. The total nitrogen and total organic carbon contents in P. sylvestriformis soil at 500 μmol CO₂·mol^-1 had no significant difference with those in the control chamber and on unchambered field, while their contents in P. koraiensis soil were significantly lower on unchambered field than those in the control chamber and at 500 μmol CO₂·mol^-1. Elevated CO₂ and the microenvironment of open-top chamber had little effect on the soil temperature at 3 cm depth.

Soil microbial characters under different vegetation communities in Taihang Mountain Area

YANG Xitian¹; NING Guohua²; DONG Huiying¹; LI You¹

2006, 17(09):  1761-1764 . 

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This paper measured the numbers and biomass of soil microbes as well as the soil respiration rate under mixed coniferous-broadleaved forest, mixed coniferous forest, pure coniferous forest, pure deciduous broadleaved forest, shrubs, and bare land in Taihang Mountain area, aimed to evaluate the soil microbial characters under different vegetation communities in this area. The results showed that shrub land had the greatest numbers and biomass of soil microbes, followed by deciduous broadleaved forestland, mixed coniferous-broadleaved forestland, pure coniferous forestland, and bare land. Soil respiration rate had the similar trend. When restoring the vegetations on degraded mountain land, more attention should be paid to the natural restoration capability of forest ecosystems.

Effects of probiotics on Penaeus vannamei pond sediments

WANG Yanbo^1,2; ZHA Longying¹; XU Zirong¹

2006, 17(09):  1765-1767 . 

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This paper studied the effects of probiotics on the sediment of Penaeus annamei pond during 117 days of culture period. The results showed that probiotics application significantly decreased the concentrations of total nitrogen, total phosphorous, and sulfide in sediment, but no significant difference was observed in total plate count (TPC) of microbes between treated and control ponds. The final average presumptive vibrio count (PVC) of treated pond sediment (3.65×10³ cfu·g^-1) was significantly lower than that of the control (1.16×10⁵ cfu·g^-1), while the average number of BS (Bacillus), AB (ammonifying bacteria), PSOB (presumptive sulphur oxidizing bacteria) and SRB (sulphur reducing bacteria) in treated pond sediment was higher than that of the control. These data showed that probiotics could decrease the nutrients (nitrogen, phosphate and sulfur) accumulation and improve the composition of bacterial populations in pond sediment, and thus, supply a good sediment environment for the healthily culture of the shrimp.

Protective effects of exogenous ascorbic acid on antioxidant system in Hydrilla verticillata under Cd²⁺ stress

XU Bingjun;SHI Guoxin;XU Qinsong;WANG Xue;ZHAO Juan;HU Jinzhao

2006, 17(09):  1768-1770 . 

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In this paper, Hydrilla verticillata was cultured in the hoagland solution containing 5 mg·L^-1 Cd²⁺ and different concentration ascorbic acid (AsA) to investigate the protective action of AsA to aquatic plant suffered from heavy metal′s stress. The O₂^-generation rate, H₂O₂ content, antioxidants (AsA and GSH) contents, and antioxidant enzymes (SOD, POD, CAT and APX) activities were analyzed. The results showed that compared with single Cd²⁺ treatment, AsA addition lessened the reactive oxygen species (O₂^- and H₂O₂) generation rates, endogenous AsA content, and antioxidant enzyme activities. It was concluded that exogenous AsA could relieve the Cd²⁺ poison to H. verticillata, and its optimum concentration was 60 mg·L^-1.