Table of Content

20 April 2008, Volume 19 Issue 04

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Articles

Obstacles for natural regeneration of Larix olgensis plantations in montane regions of eastern Liaoning Province, China.

ZHU Jiao-jun¹; LIU Zu-gen²;WANG He-xin³

2008, 19(04):  695-703 . 

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Based on the field investigations about the seed bank, seed germination, seedling emergence, and seedling survival and growth in the Larix olgensis plantations with different thinning intensities and various ground preparations in the montane regions of eastern Liaoning Province, the main factors affecting the natural regeneration of L. olgensis were analyzed in this paper. The results showed that in the seed rain of 40 years old L. olgensis lantation, 30% of the seeds had viability, which could meet the needs of natural regeneration. The seeds in soil seed bank mainly distributed in litter layer, and the seedlings younger than one-year old emerged in April and reached the peak in June. The accumulative emergence rate of the seedlings had no significant correlation with thinning intensities, but was affected by ground preparations. The average survival rate of appeared seedlings increased with increasing thinning intensities, but the seedling growth was generally slow in the plantation stands, e.g., the seedling height was less than 6 cm, and most of the seedlings disappeared in September. In the plantation stands, it was difficult to find the L. olgensis seedlings elder than one-year; but in the clearcut area with enough light and less ground cover, more seedlings could survive and grew well. Based on the above mentioned results, it was concluded that the main obstacles for the natural regeneration of L. olgensis plantations in montane regions of eastern Liaoning Province could be light intensity and ground cover.

Effects of leaf litter replacement on soil biological and chemical characteristics in main artificial forests in Qinling Mountains.

LIU Zeng-wen;DUAN Er-jun;GAO Wen-jun;ZHANG Li-ping;DU Hong-xia; FU Gang; CUI Fang-fang

2008, 19(04):  704-710 . 

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Through 2 years leaf litter replacement experiments in 4 typical artificial pure forests Larix kaempferi, Pinus tabulaeformis, Catalpa fargesii, and Quercus aliena var. acuteserrata in Qinling Mountains of China, this paper studied the effects of leaf litter replacement on soil biological and chemical characteristics and the interspecific relationships between different tree species. The results showed that the annual decomposition rate of broad-leaved litter was 33.70% higher than that of needle-leaved litter. The annual decomposition rate of needleleaved litter increased by 8.35%-12.15% when replaced to broad-leaved forests, whereas that of broad-leaved litter decreased by 5.38%-9.49% when replaced to needle-leaved forests. Leaf litter replacement between needle and broad-leaved forests could increase the contents of soil organicC and available N, P and K, and the increments were obviously higher in needleleaved forests (8.70%-35.84%) than in broad-leaved forests (3.73%-10.44%). In needle-leaved forests, the increments with the replacement of C. fargesii litter (24.63%-35.84%) were higher than those with the replacement of Q. aliena var.acuteserrata litter (8.70%-28.15%). Furthermore, the replacement of broad-leaved litter could make the soil pH in needle-leaved forests changed from light-acid to neutral, and increase soil enzyme activities, microbial amounts, and microbial biomass C and N contents. The increments with the replacement of C. fargesii litter were higher than those with the replacement of Q. aliena var. acuteserrata litter. The soil enzyme activities, microbial amounts, and microbial biomass C and N contents in broad-leaved forests after the replacement of needle-leaved litter differed with broad-leaved tree species. Q. aliena var.acuteserrata forest had the higher soil enzyme activities and microbial biomass C and N contents, while C. fargesii forest was in adverse. It was suggested that in the control of soil degradation under artificial pure forests, much attention should be paid to the direction of interspecific relationship in mixed forestation and leaf litter replacement.

Effects of different irrigations on the water physiological characteristics of Haloxylon ammodendron in Taklimakan Desert hinterland.

XIE Ting-ting^1,2;ZHANG Xi-ming¹;LIANG Shao-min^1,2;SHAN Li-shan³;YANG Xiao-lin^1,2;HUA Yong-hui⁴

2008, 19(04):  711-716 . 

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By using heat-balance stem flow gauge and press chamber, the water physiological characteristics ofHaloxylon ammodendron under different irrigations in Taklimakan Desert hinterland were measured and analyzed. The results indicated that the diurnal variation curve of H. ammodendron stem sap flow varied with irrigations. When irrigated 35 and 24.5 kg·plant^-1 once time, the diurnal variation of stem sap flow changed in single peak curve and the variation extent was higher; while irrigated 14 kg·plant^-1 once time, the diurnal variation changed in two-peak curve and the variation extent was small. With the decrease of irrigations, the average daily sap flow rate and the daily water consumption of H. ammodendron decreased gradually, the dawn and postmeridian water potential also had a gradual decrease, and the correlations of stem sap flow with total radiation, air temperature, relative humidity, and wind speed enhanced. Under different irrigations, the correlation between stem sap flow rate and total radiation was always the best.

Seasonal dynamics of hydrochemical characteristics of streams under different forest types.

SHI Fu-chen¹; LI Feng-ying¹;CAI Ti-jiu²;Hideaki Shibata³

2008, 19(04):  717-722 . 

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Stream water samples under the Korean pine broad leaved forest, spruce fir forest, and larch plantation in Liangshui Nature Reserve of Xiaoxing’an Mountains were collected monthly from March to October 2006 to study the dynamic changes of their hydrochemical characteristics. The results indicated that the content of major cations in the streams was in the sequence of Ca²⁺>Na⁺>K⁺>Mg²⁺, and that of anions was HCO₃^->SO₄^2->NO₃^->Cl^-. The average content of Na⁺, Ca²⁺, Mg²⁺, Fe²⁺ and Fe³⁺ was in the order of sprucefir forest>larch plantation>Korean pine broadleaved forest, while that of K+ was in the order of larch plantation>spruce-fir forest>Korean pine broadleaved forest. The average monthly content of anions in stream water was the highest under larch plantation.

Characteristics of CO₂ exchange at leaf and canopy levels in tropical seasonal rain forest of Xishuangbanna.

SONG Qing-hai^1,3;ZHANG Yi-ping¹;YU Gui-rui²;YANG Zhen^1,3; ZHAO Shuang-ju^1,3;GAO Ju-ming^1,3; SUN Xiao-min²

2008, 19(04):  723-728 . 

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By the methods of chamberbased and eddy covariance measurements, the CO₂ exchange of dominant tree species Pometia tomentosa and Gironniera subaequalis at leaf and canopy levels in the tropical seasonal rain forest of Xishuangbanna was measured in different seasons of 2004. The results showed that for the two tree species, the maximum net photosynthesis (P_{max A}) of canopy based on chamberbased measurement ranked in the order of rainy season (RS)> end of rainy season (ERS)>foggycool season (FS)>dryhot season (DS), and the dark respiration rate (R_d) of leaf was RS>ERS>DS>FS. The P_maxB based on eddy covariance measurement was in the same order as that based on chamberbased measurement, while the canopy respiration rate (R_e) was RS>DS>FS>ERS. The maximum net photosynthetic rate of canopy in different seasons measured by the two methods had a comparatively small difference, ranging from 0.9 to 2.0 μmol·m^-2·s^-1.

Effects of selective cutting on soil respiration in conifer/broad-leaved mixed forests in Xiao-xing’anling.

MENG Chun;WANG Li-hai;SHEN Wei

2008, 19(04):  729-734 . 

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By using LI-8100 CO₂ Flux Meter, the CO₂ flux of soil surface and the temperature and moisture content at soil depth of 10 cm in conifer/broadleaved mixed forests under different intensity of selective cutting in Dailing Forest Bureau of Heilongjiang Province were determined simultaneously from 2003 to 2007, with the changes of soil surface CO₂ flux after selective cutting and their affecting factors studied. The results showed that the CO₂ flux was correlated with soil temperature and moisture content, with a relatively high confidence ranged from 68% to 98%. Selective cutting increased the CO₂ flux, with an average annual increment being from 7.17% to 26.89%. There was a significant quadratic correlation between soil surface CO2 flux and cutting intensity (R²=0.961). Soil organic matter content and cutting intensity were the main factors affecting the changes of soil surface CO₂ flux after selective cutting.

Soil microelements under different vegetation restoration patterns in yellow soil slope region of mid-subtropics.

QI Liang-hua^1;ZHANG Xu-dong²; PENG Zhen-hua^1,2;FAN Shao-hui¹; ZHOU Jin-xing²

2008, 19(04):  735-740 . 

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With the Nüerzhai watershed in Wuling Mountain as a case, this paper studied the contents and availabilities of soil microelements and their relationships with soil organic matter and pH value in yellow soil slope region of midsubtropics under seven typical vegetation restoration patterns, i.e., Pinus massoniana natural forest (Ⅰ), Cunninghamia lanceolata plantation (Ⅱ), Eucommia ulmoides plantation (Ⅲ), Vernicia fordii plantation (Ⅳ), Machilus pingii secondary forest (Ⅴ), Phyllostachys edulis-C. lanceolata mixed forest (Ⅵ), and wasteland-shrub community (Ⅶ). It was found that in 0-20 cm soil layer, the contents of B and Mn, Mo and Cu, Zn, and Fe reached the peaks under Ⅶ, Ⅳ, III and Ⅵ; while in 20-40 cm soil layer, Ⅲ, Ⅳ, Ⅴand Ⅶ had the highest contents of Cu, Zn, B, and Fe and Mn, Mo, respectively. In both two soil layers under Ⅵ, the contents of B, Mo, Cu and Mn were the lowest. Mn had the biggest single element available index, while Cu had the smallest one. The biggest and smallest total available index of soil microelements was 12.28 for Ⅶ and 2.95 for Ⅵ, respectively. There existed the regularities of Mn>Zn>Fe>Mo>B>Cu for single microelement available index and Ⅶ>Ⅴ>III>Ⅳ＞Ⅰ＞Ⅱ＞Ⅵ for comprehensive microelement available index under different vegetation patterns. A good linear relationship was observed between soil organic matter and B and Zn availabilities, and the relationship of soil organic matter with available Mn could be described by a quadratic equation. Soil pH was highly positively correlated with soil Cu and Zn contents, correlated with soil Mo and Mn contents, slightly correlated with soil B content, and slightly negatively correlated with soil Fe content.

Multi-species and multi-scale patterns and species associations of sandfixing plantations.

LI Hui-yong³;LI Hui-qing^1,2;LI Qing-he^1,2;LIU Jian-feng^1,2;JIANG Ze-ping1,2

2008, 19(04):  741-746 . 

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Taking three sandfixing plantations Hedysarum scoparium and Calligonum mongolicum, Haloxylon ammodendron- on the oasis verges in northeast Ulanbuhe desert irrigated by Huanghe River as test objects, the multi-species and multi-scale patterns and the species associations of the plantations were investigated by contiguous quadrats transects method, with the natural vegetation nearby as the control. The results showed that 74.29% of the natural vegetation was dominated by single species pattern of Artemisia ordosica, and 24.99% was dominated by single species pattern of Nitraria tangutorum. The sand-fixing plantations gradually became-close-to-natural vegetation. Compared with natural vegetation, the sandfixing plantations had higher pattern intensity, and played important role in sand-fixing and in accelerating the regeneration and succession of natural sand-fixing plants. However, with the succession, artificially planted shrubs would decline, while natural plants would be dominant. Therefore, it should be better to make use of the native dominated species in sand-fixing engineering. Under the almost same conditions, pattern scale was highly correlated with the characters and the associations of dominated species. The species association was correlated with the patch scale and species composition, as well as the species contribution to the patch.

Characteristics of caloric value and nutrient content of four garden tree species.

CHEN Mei-ling^1，2;SHANGGUAN Zhou-ping^1，2

2008, 19(04):  747-751 . 

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In this study, the caloric value, nutrient content, and ash content in the stem, leaf, and root of four garden tree species Prunus mume Meiren, P. serrulata, Magnolia denudata and M. grandiflora were determined to explore the distribution characteristics of caloric value in different tree organs at different development stages, and related affecting factors. The results showed that the gross caloric value (GCV) and ash free caloric value (AFCV) in different organs of the tree species ranged from 17.02 to 21.93 kJ·g^-1 and from 18.42 to 22.57 k J·g^-1, respectively. Leaf and fine root had relatively higher GCV and AFCV than stem, and AFCV had a decreasing trend with the development of stem and root. P. mume Meiren and P. serrulata had higher GCV and AFCV than M. grandiflora and M. denudate. Both GCV and AFCV of fine root were significantly correlated with its nutrient and ash contents (P<0.01). With the development of root, the correlations of GCV and AFCV with organic carbon content declined gradually, while the GCV of different organs had the strongest correlation with total nitrogen content.

Cadmium and zinc absorption and distribution in various tree species in a mining area.

LIU Wei-tao^1,2;ZHANG Yin-long¹;CHEN Zhe-min¹;ZHOU Qi-xing^2,3; LUO Hong-yan¹

2008, 19(04):  752-756 . 

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The study on the characteristics of cadmium (Cd) and zinc (Zn) absorption and distribution in 11 tree species in a mining area of Nanjing showed that the absorption and accumulation of test heavy metals differed with tree species, their organs, and heavy metals themselves. Among the test tree species, Viburnum awabuki had the highest Cd absorption, accumulation, and translocation rates, which could be used for the remediation of polluted soils via phytoextraction. Cd was mainly accumulated in tree roots, and its accumulation in tree organs was generally in the order of root＞leaf and shoot＞bark＞stem. Zn was generally accumulated in above-ground part, such as in leaf and shoot, but not in root. For the test 11 tree species, the accumulation coefficients of Cd and Zn were all less than 0.2, while the translocation coefficients differed markedly, with that of Zn being higher than that of Cd in general.

Age structure of the modules of clonal Heteropappus altaicus population on weedy meadow steppe in Songnen Plain of China.

YANG Yun-fei; XING Fu

2008, 19(04):  757-762 . 

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Heteropappus altaicus is a root sucker type perennial herbaceous clonal plant of compositae. The age structure of its modules on the weedy meadow in Songnen Plain of China was studied by a method, in which, age class was compartmentalized according to the propagared generations in bud section of taproot. The results showed that both ramets and buds of the clonal population consisted of 4 age classes. The modules of ramets showed stable age structure, with the age spectrum being 22.6%, 44.8%, 28.8% and 3.8% from 1st to 4th age classes at flowerbud stage, respectively. At milk stage, the modules of reproductive ramets showed a stable age structure, with the proportion of 2nd age class being the largest (45.6%) and of 4th age class being the least (0.8%), while those of vegetative ramets showed an expansive age structure, with the largest proportion (47.5%) of 1st age class and the least (1.1%) of 4th age class. The taproot of the ramets could survive for five years at most. The productivity of 2nd age class ramets was most vigorous at different growth stages. The ramets of 1st age class had the biggest productive potential, while the ramet productivity of 4th age class was generally weakened at milk stage. The potential population in the bud banks presented an expansive age structure.

Surface erosionresistance of Nitraria tangutorun nebkhas at different succession stages in Minqin oasis and related affecting factors.

DU Jian-hui^1,2;YAN Ping^1,2;ZHAN Xiu-li^1,2;E You-hao³

2008, 19(04):  763-768 . 

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By measuring the surface shear strength of Nitraria tangutorun nebkhas at different succession stages in the fringe of Minqin oasis, and selecting several typical nebkhas at stabilizing stage to investigate its surface erosion rates before and after removing crust and vegetation, the surface-erosionresistance of N. tangutorun nebkhas and related affecting factors were studied. The results showed that the nebkhas had the highest surface shear strength (0.31-0.79 kg·cm^-2) at stabilizing stage, and the lowerest one (0.06-0.15 kg·cm^-2) at rudimental stage. The surface shear strength of nebkhas at stabilizing stage was significantly higher than that at other succession stages (P＜0.01), and at the other succession stages except degradation stage, there was no significant difference in the surface shear strength in windward and leeward (P＞0.05). After removing crust and vegetation, the surface shear strength of nebkhas at stabilizing stage was greatly reduced, with the difference before and after removing the crust and vegetation being significant (P＜0.01). However, there was no obvious difference between different slope positions (P＞0.05). Keeping both vegetation and crust, deposition occured on both slope positions of nebkhas; removing crust but keeping vegetation, the deposition reduced a little; removing vegetation but keeping crust, the deposition reduced greatly; while removing both vegetation and crust, nebkhas surface was severely eroded.

Application of five atmospheric correction models for Landsat TM data in vegetation remote sensing.

SONG Wei-wei;GUAN Dong-sheng

2008, 19(04):  769-774 . 

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Based on the Landsat TM image of northeast Guangzhou City and north Huizhou City on July 18, 2005, and compared with apparent reflectance model, five atmospheric correction models including four dark object subtraction models and 6S model were evaluated from the aspects of vegetation reflectance, surface reflectance, and normalized difference vegetation index (NDVI). The results showed that the dark object subtraction model DOS4 produced the highest accurate vegetation reflectance, and had the largest information loads for surface reflectance and NDVI, being the best for the atmospheric correction in the study areas. It was necessary to analyze and to compare different models to find out an appropriate model for atmospheric correction in the study of other areas.

Relationships between distribution of soil-born bryophytes in urban area of Hangzhou and related ecological factors.

LIU Yan^1,2;CAO Tong^1,3;WANG Jian³;CAO Yang⁴

2008, 19(04):  775-781 . 

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At the 21 sampling sites in urban area of Hangzhou, 47 species of soil-born bryophytes belonging to 31 genera and 22 families were recorded. Based on the ecological importance value of these species and the data of ecological factors at the sampling sites, the relationships between the distribution of the bryophytes species in urban area of Hangzhou and related ecological factors were studied by canonical correspondence analysis. The results showed that human disturbance and soil pH were the most important factors determining the distribution of the bryophytes. In urban parks and green lands where human disturbance was greater, soil pH was alkali, and the species were mainly belonging to the genera of Haplocladium and Bryum and the family of Pottiaceae. In hilly area where human disturbance was lesser, soil pH turned to acidic, and the bryophytes were more, with pleurocarpous mosses and liverworts being relatively rich. The niche width of the 47 bryophytes was calculated, which revealed that most of them had very narrow niche width (<0.1). The Pseudotaxiphyllum pohliaecarpum widely distributed in the hilly area of southwest Xihu Lake had the widest niche width (0.3510), followed by Trichostomum planifolium (0.2239) and Haplocladium microphyllum (0.2185), the commonest species in the parks and greenlands in urban area of Hangzhou.

Effects of soil compactness on ginger plant senescence.

SHANG Qing-wen; KONG Xiang-bo;WANG Yu-xia;XU Kun

2008, 19(04):  782-786 . 

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Based on the determinations of main physiological parameters of ginger plant grown in different compactness soils, this paper studied the effects of soil compactness on the senescence of ginger plant. The results showed that with the increase of soil compactness, the root activity and the leaf NRase activity, chlorophyll content and photosynthetic rate of ginger plant declined, while the leaf electrolytic leakage and MDA content increased. The activities of leaf SOD, POD and CAT decreased with increasing soil compactness at early growth stage but were in adverse at late growth stage. At vigorous growth stage, the root activity and the leaf chlorophyll content and photosynthetic rate in the soil with a compactness of 1.49 g·cm^-3 were 30.9%, 19.0% and 17.9% lower, and the leaf electrolytic leakage and MDA content were 57.2% and 26.3% higher, respectively, compared with those in the soil with a compactness of 1.20 g·cm^-3, which indicated that compacted soil could accelerate the senescence of inger plant.

Effects of subsoil bulk density on late growth stage photosynthetic characteristics and grain yield of maize (Zea mays L.).

WANG Qun;LI Chao-hai;HAO Si-ping;ZHANG Yong-en;HAN Jin-feng

2008, 19(04):  787-793 . 

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A pool-culture experiment was conducted to study the effects of different subsoil bulk density at the depths of 20-40 and 40-60 cm on the late growth stage photosynthetic characteristics and grain yield of maize. The results showed that there existed significant differences in the net photosynthetic rate (P_n) and grain yield when the subsoil bulk density was differed. The P_n and grain yield decreased with increasing subsoil bulk density, and the higher the bulk density, the more significant the decrement inP_n and grain yield. The diurnal changes of P_n and intercellular CO₂ concentration (C_i) were not in the same trend. P_n was high at noon and low at twilight and dusk, and decreased with increasing subsoil bulk density; while C_i was in adverse. The stomatal limitation (L_s) and stomatal conductance (G_s) also decreased with increasing subsoil bulk density. With the development of maize, the P_n,L_s and G_s decreased gradually, while C_i increased continuously.

Effects of wheat and soybean stubbles on soil microbial ecological characteristics in cucumber field.

WU Feng-zhi;WANG Xue-zheng;PAN Kai

2008, 19(04):  794-798 . 

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The study with traditional dilution plate method and BIOLOG ECO system indicated that under wheat and soybean stubbles, the amounts of soil fungi, bacteria and actinomyces in cucumber field increased, while that of Fusarium oxysporum f. sp. cucumerinum decreased (P<0.05). The ShannonWiener index, evenness index, Simpson index, and McIntosh index of soil microbial communities as well as soil microbial biomass C increased (P<0.05), basal respiration and metabolic quotient qCO₂ decreased (P<0.05), and soil microbe’s sole-carbon-source utilization enhanced. In addition, the contents of soil available P and K and the cucumber yields were also increased markedly. All of these illustrated that wheat and soybean stubbles improved the ecological environment of soil microbes.

Utilization rate of fertilizer N and dynamic changes of soil NO_{3 ^{- -N}} in summer maize field in semi－humid area of Northwest China.

FAN Ya－ning^1,2；LI Shi－qing^1,2； LI Sheng－xiu²

2008, 19(04):  799-806 . 

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A field experiment on manual loessial soil was conducted to study the dynamic changes of NO₃^--N in soil profile, utilization rate of fertilizer N, and relationships between N application rate and soil residual N accumulation during the growth period of summer maize under different N application rates (0, 45, 90, 135, and 180 kg·hm^-2). The results showed that in the whole growth period of summer maize, the NO₃^--N concentration in the soil profile was the highest in 0-20 cm layer, and increased with increasing N application rate. The NO₃^--N concentration in 0-60 cm soil layer changed significantly, but no significant change was observed in 60-100 cm soil layer. In the growth season of summer maize, soil NO₃^--N accumulation presented a fluctuated decreasing trend due to the N uptake by crop and the precipitation. The N utilization rate (NUR) increased with increasing N application rate when the application rate was less than 135 kg·hm^-2, but tended to decrease when the application rate exceeded 135 kg·hm^-2. With the increase of N application rate, the N agronomy efficiency (NAE) decreased but the N physiology efficiency (NPE) increased. There was a significant positive correlation between soil residual N accumulation and N application rate (R²=0.957^**,n=5). The grain yield under N application was significantly higher than that without N application (P<0.05), and there existed a significant positive correlation between grain yield and N application rate (R²=0.934^**,n=5). In our experiment, the optimal 〖LM〗application rate of fertilizer N was 135 kg·hm^-2, which could harmonize the relationship between economic benefits and environment.

Effects of rice-duck farming system on biotic populations in paddy field.

YU Sheng-miao;ZHU Lian-feng;OUYANG You-nan; XU De-hai;JIN Qian-yu

2008, 19(04):  807-812 . 

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A field experiment was conducted to study the effects of rice-duck farming on the related biotic populations in paddy field. The results showed that rice-duck farming had greater effects on the occurrence and damage of pests, pathogens and weeds, as well as the amount of pests’ natural enemies in paddy field. The population of rice planthopper and leafhopper decreased by 64.8% and 78.5% after 12 and 42 days of duck-release, and the weeds decreased by 67.7% and 98.1% after 15 and 45 days of duck-release, respectively, compared with the control. The sheath blight index at the maximum tillering stage and full-heading stage in the rice-duck plots were 40.4% and 62.0% lower than those in the control plot, respectively. The population of spiders in duck-released field was increased obviously, which in turn decreased the damage of rice pests.

Profile distribution of exchangeable calcium and magnesium in an aquic brown soil as affected by land use type.

ZHANG Yu-ge^1,2;LIANG Wen-ju²;JIANG Yong²

2008, 19(04):  813-818 . 

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A comparative study was made on the profile distribution of exchangeable Ca and Mg and Ca/Mg ratio at the depth of 0-150 cm in an aquic brown soil under four land use patterns, i.e., paddy field, maize field, fallow field, and woodland. The results showed that less difference was observed in the soil exchangeable Ca content and storage among different land use patterns. For soil exchangeable Mg, it was significantly higher in woodland than in paddy field, and its storage was in the sequence of woodland>maize field>fallow field>paddy field (P<0.05). The exchangeable Ca/Mg ratio tended to decrease with soil depth, and was significantly lower in paddy field than in other three land use patterns in the soil layers below 40 cm (P<0.05). The preferential retention of Mg in soil ecosystem, soil management practices, and plant characteristics， e.g., biomass cycling rate, biomass above and below0-ground allocation, root distribution, and maximum rooting depth) might play important roles in shaping soil exchangeable Ca and Mg profiles and in reconstructing soil exchangeable Ca and Mg pools.

Regulation effects of various training modes on source-sink relation of cotton.

DONG He-zhong;NIU Yue-hua;LI Wei-jiang;TANG Wei;LI Zhen-huai;ZHANG Dong-mei

2008, 19(04):  819-824 . 

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With the removal of vegetative branches plus the maintenance of early fruiting branches as the control, the effects of various training modes on the sourcesink relation of field-grown cotton were examined in 2005 and 2006. The results showed that compared with the control, either the removal of vegetative branches plus the removal of early fruiting branches (Ⅰ), the maintenance of vegetative branches plus the removal of early fruiting branches (Ⅱ), or the maintenance of vegetative branches plus the maintenance of early fruiting branches (Ⅲ) could increase the leaf area per plant significantly, with the average maximum LAI across the two years increased by 10.3%, 28.3%, and 9.5%, respectively, and resulting in the decreases of the load per leaf area and the ratio of sink to source. Ⅰand Ⅱ alleviated the leaf senescence of cotton plants as indicated by the enhanced leaf chlorophyll content and the reduced percentage of yellow leaves and C/N ratio of functional leaves, and Ⅱ also induced the late-maturing of cotton plants. Ⅲ had no significant effects on senescence alleviation. Ⅰ produced approximately equal seed cotton, but Ⅱ and Ⅲ produced 6.4%-15.6% less and 6.3% more seed cotton than the control, respectively. It was concluded that either the maintenance of vegetative branches or the removal of early fruiting branches could be an effective pathway to regulate the ratio of sink to source, C/N, and maturity performance of cotton plants.

Roles of spermidine in induced resistance of cucumber seedlings to Botrytis cinerea Pers.

SHANG Qing-mao;ZHANG Zhi-gang

2008, 19(04):  825-830 . 

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Under the conditions of root substrate injection and foliar spray of different concentration spermidine, this paper measured the disease index, defense enzyme activities, and contents of disease resistance-related substances in cucumber (Cucumis sativus L.) seedlings infected by Botrytis cinerea Pers., aimed to investigate the roles of spermidine in induced resistance of cucumber seedlings to B. cinerea. The results showed that after treated with spermidine, the disease index decreased by 25.4%, phenylalanine ammonia lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO) activities increased by 48.4%, 635.9% and 38.9%, respectively, and total polyphenol, flavonoid and lignin contents increased significantly, compared with the control. All of these suggested that spermidine could induce the disease resistance of cucumber seedlings, and its optimum concentration was 150 mg·L^-1.

Effects of exogenous Ca²⁺ on the growth and Zn accumulation of two Sedum alfredii Hance ecotypes.

HUANG Hua-gang^1,2;LI Ting-xuan¹;ZHANG Xi-zhou¹;TIAN Sheng-ke²;YANG Xiao-e²

2008, 19(04):  831-837 . 

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A hydroponic study was conducted to investigate the biomass, root morphology, and zinc (Zn), calcium (Ca) and sulfur (S) contents of two Sedum alfredii- ecotypes under effects of different concentration calcium (Ca²⁺) addition. The results showed that with increasing exogenous Ca²⁺ concentration, the dry mass of the two S. alfrediiecotypes increased, and the shoot dry mass of hyperaccumulation ecotype increased significantly (P<0.05). The root length and root surface area of hyperaccumulation ecotype increased with increasing exogenous Ca²⁺ concentration, while those of nonhyperaccumulation ecotype were in adverse. The Zn accumulation in the root, stem and leaf of hyperaccumulation ecotype was increased with increasing exogenous Ca²⁺ concentration though the differences among Ca²⁺ treatments were not significant (P>0.05), while the Zn accumulation in the shoot of nonhyperaccumulation ecotype was significantly low (P<0.05). The Ca accumulation in the root, stem and leaf of non-hyperaccumulation ecotype had a significant positive correlation with the concentration of exogenous Ca²⁺ (P<0.05), so as the S accumulation in the root of hyperaccumulation ecotype (P<0.01). Exogenous Ca²⁺ promoted the Zn absorption and accumulation of hyperaccumulation ecotype, while inhibited the Zn accumulation of nonhyperaccumulation ecotype. Appropriate concentration of exogenous Ca²⁺ could promote the growth of hyperaccumulation ecotype S. alfredii, and improve its ability of accumulating more zinc.

Effects of dissolved organic matter derived from hyperaccumulator Sedum alfredii Hance rhizosphere on Zn adsorption and desorption in soil.

LI Ting-qiang¹;ZHU En²;YANG Xiao-e¹;SHENTU Jia-li¹

2008, 19(04):  838-844 . 

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The study with pot experiment and simulation test showed that after planted hyperaccumulator Sedum alfredii Hance on mining soil, the water soluble Zn and NH₄OAc extractable Zn in rhizosphere were decreased obviously, while the available Zn in nonrhizosphere had less change. The pH value of rhizosphere soil was decreased by 0.3 units, whereas the organic matter and dissolved organic matter (DOM) contents were increased by 13.6% and 20.9%, respectively, compared with the soil without S. alfredii. The effects of DOM from S. alfredii rhizosphere on Zn absorption and desorption varied with the kinds of test soils. After the addition of rhizosphere DOM, the maximal absorption capacity (X_m) of mining soil, quaternary red clay soil, and fluaviomarine yellow loamy soil was reduced by 17.8%, 21.9% and 27.7%, respectively, whereas the addition of nonrhizosphere DOM had no effects on Zn absorption. The Zn desorption in the three soils, especially in fluavio-marine yellow loamy soil, was promoted by the addition of rhizosphere DOM. It was indicated that the DOM from S. alfredii rhizosphere could reduce the maximal absorption capacity and accelerate the desorption of adsorbed Zn, and thus, increase the Zn mobility and bioavailability.

Ecological quality of Beijing urban area from 1996 to 2005.

HUANG Bao-rong¹;OUYANG Zhi-yun¹;ZHANG Hui-zhi²;ZHENG Hua¹;XU Wei-hua¹; WANG Xiao-ke¹

2008, 19(04):  845-852 . 

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From the aspects of four ecological themes, i.e., ecological element, ecological process, ecological function and ecological destruction, an indicator framework including 16 indicators was developed to make an integrated assessment on the ecological quality of Beijing urban area. The weights of the indicators were determined by the methods of entropy weight, optimal state weight, and worst state weight, and the ecological element index (EEI), ecological process index (EPI), ecological function index (EFI), ecological destruction index (EDI), and composite ecological index (CEI) were computed by a weighted sum method and served as effective tools for analyzing the evolvement of the ecological quality of Beijing urban area from 1996 to 2005. The results showed that during the period of 1996-2005, the EEI of Beijing urban area did not display visible improvement and maintained a low level, far from the ideal state. The EPI and EFI increased dramatically, and approached to the ideal state in 2005. The EDI fluctuated within a low level, far from ideal state, and did not show an evolutionary trend. The CEI improved year after year, but was still low and did not reach the ideal state. The EPI, EFI, and CEI increased rapidly with economic development when the GDP per capita was less than US$3 000, but the decrease was decelerated after the GDP exceeded US$3 000. The EEI and EDI were less affected by economic development, but mainly restrained by the natural conditions and global and regional ecoenvironmental evolvement.

Human appropriation of net primary production in the middle reach of Heihe River basin.

LONG Ai-hua^1,2;WANG Hao¹;CHENG Guo-dong²; YU Fu-liang¹

2008, 19(04):  853-858 . 

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Based on Miami model, this paper calculated the human appropriation of net primary production (HANPP) in the middle reach of Heihe River basin, discussed the relations between the HANPP and ecosystem diversity, and compared the values of HANPP and ecological footprint (EF) in sustainability assessment. The results showed that the increase of HANPP decreased the ecosystem diversity, and the current average HANPP in study area was 38.61%. The HANPP in Suzhou and Ganzhou districts already exceeded the potential maximum productivity. Considering the climate change and the development of social-economics, the ecosystems in study area would face more stress in the coming 40 years. Comparing with EF, HANPP was more available for the assessment of sustainability in the sight of ecosystem function change.

Vulnerability of eco-economy in northern slope region of Tianshan Mountains.

WU Jian-zhai;LI Bo;ZHANG Xin-shi;ZHAO Wen-wu;JIANG Guang-hui

2008, 19(04):  859-865 . 

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Based on the theoretical meaning of vulnerability, a vulnerability assessment of eco-econom- in fifteen counties in the northern slope region of Tianshan Mountains was conducted. The ecosystem services change to land use was regarded as the impact, and based on the fourteen indices from resource holding, society development, and economy development statistic data, the adaptive ability was evaluated by using the methods of analytic hierarchy process (AHP) and fuzzy synthetic evaluation. On the basis of assessment results of impact and adaptive capacity, the fifteen counties were divided into five classes under the assessment principles, and the district with higherclass number was of more vulnerability. The first class included Usu City and Changji City, the second class included Hutubi County, Miquan County, Fukang City, Jimsar County, Qitai County and Mori Kazak Autonomous County, the third class included Karamay City and Urumqi City, the fourth class included Kuitun City and Shawan County, and the fifth class included Jinghe County, Shihezi City and Manas County. The vulnerability reflected the level of eco-environment change and socio-economic development, and the vulnerability assessment could be a good way to ensure the sustainable development. Aiming to decrease the vulnerability, various districts belonging to different class of vulnerability should establish relevant tactics according to the vulnerability factors to accelerate the region’s sustainable development.

Bioremediation potential of Apostichopus japonicus (Selenka) in coastal bivalve suspension aquaculture system.

YUAN Xiu-tang^1,2;YANG Hong-sheng¹;ZHOU Yi¹;MAO Yu-ze³;XU Qiang1;WANG Li-li²

2008, 19(04):  866-872 . 

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Suspension aquaculture of filter-feeding bivalves can produce large amount of faeces and pseudofaeces (biodeposits) that may impact aquaculture environment, while deposit-feeding sea cucumbers may effectively utilize such particulate wastes and act as a scavenger in mariculture system. In this paper, the ingestion, growth, and excretion of deposit-feeder Apostichopus japonicus were investigated in situ seasonally to evaluate its bioremediation potential of a suspension aquaculture system of filter-feeding bivalves. The results showed that A. japonicus could grow well in newly designed culture nets, with its maximum specific growth rate being 0.34%·d^-1. The A. japonicus could effectively use the biodeposits generated by co-cultured bivalves, and the ingestion rate at 21.2 ℃ in summer, 19.2 ℃ in autumn, and 7.7 ℃ in winter was 0.1746, 0.0989, and 0.0050 g·g^-1·d^-1, respectively. A. japonicus could promote the regeneration of nutrients in biodeposits via the excretion of considerable amount of dissolved N and P, and the excretion also showed obvious seasonal fluctuation. The extrapolation based on the in situ investigation results showed that when co-cultivated with bivalves in lantern nets, A. japonicus would ingest 4.5-159.6 kg·hm^-2·d^-1 of dry biodeposits and excrete 1 382.5-3 6781 mmol·hm^-2·d^-1 of NH₄⁺-N and 74.6-335.7 mmol·hm^-2·d^-1 of PO₄^3--P, indicating that the deposit-feeding A. japonicus had a great bioremediation capability in suspension aquaculture systems. The integrated model of deposit-feeding A. japonicus and filter-feeding bivalve could not only benefit the economy, but also sustain the environment.

Variation characteristics of macrobenthos productivity in Daya Bay of South China Sea.

DU Fei-yan;WANG Xue-hui; LI Chun-hou;JIA Xiao-ping

2008, 19(04):  873-880 . 

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Based on the 7 cruises survey data collected from 63 research stations in the Daya Bay of South China Sea in January and July 1988 and in March, May, September and December 2004, the variation characteristics of the abundance, biomass, productivity, and P/B value of macrobenthos in the two years were analyzed by using Brey’s empirical formula. The results showed that in 2004, the mean productivity and P/B value of macrobenthos in study area were 10.22 g AFDM ·m^-2·a^-1 and 0.85·a^-1, respectively, being at the medium-high level among the sea areas in China and higher than those in 1988 (7.25 g AFDM ·m^-2·a^-1 and 0.76·a^-1, respectively), which corroborated the conclusion that the high output system of Daya Bay relied on the fast turnover to maintain its high productivity. The variation characteristics of the productivity and P/B value varied among the four main groups of macrobenthos, and the horizontal distribution of macrobenthos productivity also had a greater variation. The regional differences of the productivity and P/B value were closed related to human activities, and the areas in which the productivity varied significantly were intensively affected by human activities.

Spatiotemporal variation of epilithic algae in Xiangxi River-system.

JIA Xing-huan^1,2; WU Nai-cheng^1,2; TANG Tao¹;CAI Qing-hua¹

2008, 19(04):  881-886 . 

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Xiangxi River system is the greatest branch in the Hubei reservoir area of the Three Gorges reservoir. In this paper, the epilithic algae in the River and its three major tributaries were investigated from July 2005 to June 2006. A total of 218 taxa were identified, including 183 species of Bacillariophyta, 24 species of Chlorophyta, 10 species of Cyanophyta, and one species of Xanthophyta. The diatom Achnanthes linearis was the most predominant species. The richness and Shannon-Wiener diversity indices varied significantly (or almost significantly) over time and space, and the total average values were 32 and 1.54, respectively. The total averages of annual epilithic algal density and chlorophyll a concentration were 8.75×10.9 cells·m^-2 and 14.62 mg·m^-2, respectively. There were significant differences in the algal density and chlorophyll a concentration among different sampling sites, and the maximum values were observed in Gufu River tributary, which were one order of magnitude higher than the minimum ones in Jiuchong River tributary. The algal density and chlorophyll a concentration tended to be higher in winter and spring than in summer and autumn, but no significant differences were observed in various seasons. Epilithic algal density and chlorophyll a concentration were significantly negatively correlated with elevation and water current, but positively correlated with the total nitrogen concentration in water.

Effects of species richness on colony biomass and tests of sampling- and complementary effect.

DAI Fei-fei; WANG Zong-ling; LI Yan;XIAO Yong-jin

2008, 19(04):  887-892 . 

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With eight species of unicellular algae cultured in random combinations to construct the assemblages with different degrees of richness, the increase pattern of colony biomass with the change of species richness was investigated, and the sampling effect was detected by using multiple variance analysis (MANOVA) method. Three analysis methods, i.e., over-yielding analysis, relative yield total (RYT) index, and subset approach, were applied to explore the complementary effect, and additive partitioning method was applied to separate the sampling effect and complementary effect quantitatively. The results showed that the colony biomass presented a saturated rise with the increase of species richness, and a strong complementary effect was observed in phytoplankton colonies. At exponential growth phase, some specific algal species affected the colony biomass significantly, but after reaching the stable phase, the biomass was not affected by the presence of given phytoplankton. The sampling effect was generally negative at stable phase, while the complementary effect and net biodiversity effect were always positive.

Molecular mechanisms of insect pests-induced plant defense.

LI Xin-gang¹; LIU Hui-xia²;HUANG Jian¹

2008, 19(04):  893-900 . 

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This paper reviewed the newest research advances in insect pestsinduced plant defense, including insect pests-induced system wounding signals of plants, elicitors of insects, indirect defense, direct defense, and negative defense. In the interactions between plants and insect pests, plants can use the induced defensive substances to counteract insect pests, while the latter can use their specific elicitors to beat plant defense. This paper also compared the four metabolic pathways involved in indirect defense, i.e., lipoxygenase pathway, isoprenoid pathway, shikimate pathway, and extrfloral nectar, discussed the release mechanisms of induced volatile organic compounds in plants, and illustrated the conception of direct defense, defensive substances, and their action mechanisms. Finally, the research advances in the mechanisms of inset pests-induced negative defense of plants were reviewed, with the focus on the molecular mechanisms of insect pests-induced defense of forests.

Responses of rice growth and development to elevated near-surface layer ozone (O₃) concentration: A review. 〖STBZ〗

YANG Lian-xin¹;WANG Yu-long¹;SHI Guang-yao¹;WANG Yun-xia¹;ZHU Jian-guo²; Kazuhiko Kobayashi³;LAI Shang-kun¹

2008, 19(04):  901-910 . 

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Ozone (O₃) is recognized as one of the most important air pollutants. At present, the worldwide average tropospheric O₃ concentration has been increased from an estimated preindustrial level of 38 nl·L^-1 (25-45 nl·L^-1, 8h summer seasonal average) to approximately 50 nl·L^-1 in 2000, and to 80 nl·L^-1 by 2100 based on most pessimistic projections. Oryza sativa L. (rice) is the most important grain crop in the world, and thus, to correctly evaluate how the elevated near-surface layer O₃ concentration will affect the growth and development of rice is of great significance. This paper reviewed the chamber (including closed and open top chamber)based studies about the effects of atmospheric ozone enrichment on the rice visible injury symptoms, photosynthesis, water relationship, phenology, dry matter production and allocation, leaf membrane protective system, and grain yield and its components. Further research directions in this field were discussed.

Quantitative changes of anticancer active components in Taxus chinensis var.mairei branches and leaves.

YANG Feng-jian; PANG Hai-he;ZHANG Xue-ke; SUN Jia-yin;ZU Yuan-gang

2008, 19(04):  911-914 . 

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The quantitative changes of anticancer ingredients such as taxol, cephalomannine, baccatin Ⅲ and 10-deacetylbaccatin Ⅲ in the branches and leaves of Taxus chinensis var. maireiduring one growth season were measured by HPLC. The results showed that the contents of these anticancer ingredients had an obvious change from April when the new branches began to germinate to November when the branches basically stopped growing. The contents of taxol and cephalomannine in the branches and leaves of T. chinensis had the same change pattern, with the peaks appeared in May, and those of Baccatin Ⅲ and 10-deacetylbaccatin Ⅲ had the same change trend, with the highest values appeared in September and April, respectively. There was a significant positive correlation between the contents of taxol and cephalomannine (P<0.05), and a negative correlation between the contents of cephalomannine and 10-deacetylbaccatin Ⅲ (P<0.05).

Long-term effects of different management strategies on Larix gmelinii forests in Great Hing’an Mountains after the catastrophic fire in 1987.

WANG Xu-gao;LI Xiu-zhen;HE Hong-shi

2008, 19(04):  915-921 . 

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In this paper, LANDIS model was used to study the effects of different management strategies on the larch (Larix gmelinii) forests of Tuqiang Forest Bureau on the northern slopes of Great Hing’an Mountains after the catastrophic fire in 1987. Three management strategies,i.e., natural regeneration if the catastrophic fire in 1987 was not happened (M₁), natural regeneration after the catastrophic fire in 1987 (M₂), and current management strategy after the catastrophic fire in 1987 (M₃), were compared over a 300year period. The results showed that the abundance of larch forests over 300 simulation years under the three management strategies had significant difference. In the whole Bureau, the abundance of larch forests under M₂ was obviously lower than that under M₁ and M₃ over 300 years, and the abundance under M₃ was lower than that under M₁ at the beginning. Due to the reforestation after the catastrophic fire in 1987, the abundance of larch under M₃ increased rapidly, and caught up with that under M₁ after about 100 years. In addition, different forest management strategies also had significant influence on the age structure of larch forests, especially for mature and overmatured larch forests. The abundance of mature and over-matured larch forests under M₁ was higher than that under M₂. This abundance under M₃ had tremendous decrease because of forest harvesting for about 10 years, and then, increased with time and would exceed that under M₁ and M₂ for over 100 years. Furthermore, in unburned areas and burned areas, the -abundance of mature and over-matured larch forests also had significant difference over 300 simulation years under the three management strategies.

Accumulation and release characteristics of heavy metals in Crassostrea rivalaris under mixed exposure.

CHEN Hai-gang;JIA Xiao-ping;LIN Qin;MA Sheng-wei;CAI Wen-gui;WANG Zeng-huan

2008, 19(04):  922-927 . 

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With a mixed solution of lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), chromium (Cr), mercury (Hg) and arsenic (As), this paper studied the accumulation and release characteristics of test heavy metals in Crassostrea rivalaris. The results showed that C. rivalaris had a strong ability to accumulate Pb, Cu, Ni, Cd, Cr and Hg, being able to indicate the concentration levels of these heavy metals in solution, but a weak ability to accumulate Zn and As. In the following 35 days release stage, no significant change was observed in the contents of test heavy metals in C. rivalaris, suggesting that C. rivalaris had weak ability to release heavy metals. Twocompartment kinetic model could well fit the accumulation of heavy metals in C. rivalaris, but failed in simulating their release characteristics.