Table of Content

18 April 2011, Volume 22 Issue 04

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Articles

Effects of simulated nitrogen deposition on soil respiration in a Bambusa pervariabilis ×Dendrocala mopsi plantation in  Rainy Area of West China.

2011, 22(04):  829-836. 

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From January 2008 to February 2009, a field experiment was conducted in  Rainy Area of West China to understand the effects of nitrogen (N) deposition on the soil respiration in a Bambusa pervariabilis × Dendrocala mopsi plantation. Four treatments were installed, i.e., no N added (control), 5 g N·m^-2·a^-1  (low-N), 15 g N·m^-2·a^-1  (medium-N), and 30 g N·m^-2·a^-1 (high-N), and soil respiration rate was determined by infra-red CO₂ analyzer. In the plantation, soil respiration rate had an obvious seasonal change, with the maximum in July and the minimum in January. In control plot, the annual cumulative soil respiration was (389±34) g·m^-2·a^-1. Soil respiration rate had significant positive exponential relationships with soil temperature at 10 cm depth and air temperature, and significant positive linear relationships with soil microbial biomass carbon (MBC) and nitrogen (MBN). Simulated N deposition promoted soil respiration significantly, with significant differences between the low- and medium-N and the control but no significant difference between high-N and the control. In control plot, surface soil (0-20 cm) MBC and MBN were 0.460 and 0.020 mg·g^-1，respectively. In N-added plots, both the MBC and the MBN had significant increase. The fine root density in surface soil was 388 g·m^-2, which was less affected by simulated N deposition. The soil respiration Q₁₀ value calculated from soil temperature at 10 cm depth and air temperature was 2.66 and 1.87, respectively, and short-term N deposition had lesser effects on the Q₁₀ value. The variation of soil respiration in the plantation was mainly controlled by temperature and soil microbial biomass, and simulated N deposition could increase the CO₂ emission via increasing soil microbial biomass.

Effects of land use pattern on soil microbial biomass carbon in Xishuangbanna.

2011, 22(04):  837-844. 

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In January 2006-September 2007, a controlled litter-removal and root-cutting experiment was conducted to study the effects of different land use patterns (secondary forest or rubber plantation) on soil microbial biomass carbon in Xishuangbanna, China. After the secondary forest converted into rubber plantation, soil nutrient contents and plant carbon input decreased obviously, and soil microbial biomass carbon had a significant decrease. These two forest types had a higher soil microbial biomass carbon in rainy season than in dry season. In secondary forest, soil microbial biomass carbon was significantly positively correlated with soil temperature; while in rubber plantation, the microbial biomass carbon was positively correlated with soil moisture. In secondary forest, soil microbial biomass carbon was controlled by the nutrient inputs from plant roots, but less affected by litter amount. Also in secondary forest, soil microbial biomass carbon was significantly positively correlated with fine-root biomass and its C and N inputs. In rubber plantation, both the fine-root biomass and its C and N inputs and the litter amount had lesser effects on soil microbial biomass carbon. These results suggested that planting rubber induced the decreases of soil nutrient contents and pH value, and, added with serious artificial disturbances, reduced the soil microbial biomass carbon and changed its controlling factors, which in turn would affect other soil ecological processes.

Effects of UV-B radiation on the decomposition of Cunninghamia lanceolata leaf litter.

2011, 22(04):  845-850. 

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A litterbag experiment was conducted to study the decomposition of Cunninghamia lanceolata leaf litter under ambient and reduced UV-B radiation (22.1% below ambient). Comparing with ambient treatment, the reduced treatment decreased the decomposition rate of C. lanceolata leaf litter by 69.6% (P<0.001), making the relative contents of nitrogen (N), phosphorus (P), and lignin in the litter increased by 150%, 83.3%, and 13.8%, respectively, and the release of potassium (K) and carbon (C) slowed down. In the process of litter decomposition, photo-degradation of lignin didn’t play crucial role. The results suggested that UV-B radiation could accelerate the decomposition rate of C. lanceolata leaf litter, promote the release of N, P, K, and C from it, and increase the nutrients turnover rate in litter layer as well as the carbon flux on the ground, giving potential effects on the function of C. lanceolata forest as a carbon source or sink in humid subtropical China.

Decomposition of eucalyptus-alder mixed litters and dynamics of soil faunal community.

2011, 22(04):  851-856. 

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In order to understand the decomposition characteristics of eucalyptus (Eucalyptus grandis)-alder (Alnus formosana) mixed litters and the roles of soil fauna in the decomposition process, litter samples of the two tree species were collected from the Suji Town of Leshan, Sichuan Province, and mixed with different proportions. The mixtures were put in 6-, 30-, and 260-mesh litterbags to investigate their mass loss and the dynamics of soil faunal community during the process of decomposition. Different proportion mixtures all presented the same decomposition pattern, i.e., decomposed rapidly in early period and slower in later period. The mixtures had the highest decomposition rate in 6-mesh litterbag, followed by in 30-mesh, and in 260-mesh litterbag. In the litterbags with same meshes, the decomposition rate of different proportion mixed litters also varied. In 6-mesh litterbag, the durations for the decomposition of the litters had slight difference; while in 30- and 260-mesh litterbags, the durations for pure E. grandis and A. formosana litters getting 95% mass loss had a difference of 1175 and 908 days, respectively. During the decomposition of the litters, soil macrofauna had an obvious change in community structure. In early period, Psocoptera dominated; in mid period, Opisthopora dominated; in later period, Coleoptera dominated; and by the end, Diptera dominated. This study provided important information to understand the material cycling in eucalyptus-alder mixed plantation.

Short-term effects of fire disturbance on greanhouse gases emission from Betula platyphylla- forested wetland in Xiaoxing’an Mountains, Northeast China.

2011, 22(04):  857-865. 

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By the methods of static chamber and gas chromatography, this paper studied the effects of fire disturbance on the seasonal dynamics and source/sink functions of CH₄, CO₂ and N₂O emissions from Betula platyphylla-forested wetland as well as their relations with environmental factors in Xiaoxing’an Mountains of China. In growth season, slight fire disturbance on the wetland induced an increase of air temperature and ground surface temperature by 1.8-3.9 ℃ and a decrease of water table by 6.3 cm; while heavy fire disturbance led to an increase of air temperature and 0-40 cm soil temperature by 1.4-3.8 ℃ and a decrease of water table by 33.9 cm. Under slight or no fire disturbance, the CH₄ was absorbed by the wetland soil in spring but emitted in summer and autumn; under heavy fire disturbance, the CH₄ was absorbed in spring and summer but emitted in autumn. The CO₂ flux had a seasonal variation of summer > spring = autumn under no fire disturbance, but of summer > autumn > spring under fire disturbance; and the N₂O flux varied in the order of spring > summer > autumn under no fire disturbance, but of autumn > spring > summer under slight fire disturbance, and of summer > spring = autumn under heavy fire disturbance. At unburned site, the CO₂ flux was significantly positively correlated with air temperature and ground surface temperature; at slightly burned site, the CO₂ flux had significant positive correlations with air temperature, 5-10 cm soil temperature, and water table; at heavily burned sites, there was a significant positive correlation between CO₂ flux and 5-40 cm soil temperature. Fire disturbance made the CH₄ emission increased by 1695% at lightly burned site or turned into weak CH₄ sink at heavily burned site, and made the CO₂ and N₂O emissions and the global warming potential (GWP) at burned sites decreased by 21.2%-34.7%, 65.6%-95.8%, and 22.9%-36.6% respectively,compared with those at unburned site. Therefore, fire disturbance could decrease the greenhouse gases emission from Betula platyphylla-forested wetland, and planned firing could be properly implemented in wetland management.

Dynamic changes of dominant tree species in broad-leaved Korean pine forest at different succession stages in Changbai Mountains.

2011, 22(04):  866-872. 

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Taking the broad-leaved Korean pine forest stands at four different succession stages after clear-cutting in Changbai Mountains as test objects, this paper studied the change characteristics of community composition and dominant species. The tree species richness, Shannon diversity index, and Simpson dominance index at different succession stages had less change, but the evenness and abundance changed greatly. As succession progressed, the community composition changed constantly, i.e., species number decreased, while the basal area sum and the maximum importance value of dominant tree species increased, suggesting that the dominance of dominant species was continuously improved with succession. In the succession process of broad-leaved Korean pine forest in Changbai Mountains, Betula platyphylla, Populus davidiana, Phellodendron amurense, Ulmus japonica, and other intolerant or semi-intolerant tree species decreased, while Tilia amurensis, Fraxinus mandshurica, Pinus koraiensis, Acer mono, and other shade-tolerant species increased.

Genetic diversity of natural and planted Glyptostrobus pensilis populations: A comparative study.

2011, 22(04):  873-879. 

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Glyptostrobus pensilis is a rare and endangered relict species in China. To make a comparative study on the genetic diversity and genetic structure of
 natural and planted G. pensilis populations would have significance in the conservation and proliferation of the species. Samples from the main distribution regions of G. pensilis were analyzed by ISSR (inter simple sequence repeats) molecular marker. A total of 95 discernible DNA fragments were detected with 10 ISSR primers, of which, polymorphic loci occupied 39.0%, suggesting that the genetic variation in the test G. pensilis populations was at a very low level,compared with other endangered gymnosperm．The genetic differential index (G_st=0.3982) and the gene flow (N_m=0.3778) indicated that there existed genetic differentiation among populations but the differentiation dominated within populations. There was a significant positive correlation between genetic distance and geographical distance. The mean values of polymorphic loci (P), Nei’s gene index (H_e), and Shannon information index (I) of natural populations (P=39.9%, H_e=0.1499, I=0.2202) were much higher than those of planted G. pensilis populations (P=30.7%, H_e=0.1265, I=0.1759), and the coefficient of gene differentiation (G_st) and genetic distance (D) of natural populations (G_st=0.4513, D=0.0301) were also much higher than those of the planted populations (G_st=0.3025, D=0.0192).

Spatiotemporal distribution pattern of photosynthetic photon flux density in forest gaps of Korean pine broadleaved mixed forest.

2011, 22(04):  880-884. 

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Taking the forest gaps of natural Pinus koraiensis broadleaved mixed forest in Xiao Xing’an Mountains as test object, and by the method of grids, the photosynthetic photon flux density (PPFD) in the gaps was continuously measured during growth season, and the spatiotemporal distribution patterns of the PPFD were analyzed by fundamental statistics and geostatistics methods. In the forest gaps, the high-value region of PPFD presented an obvious diurnal change, with the maximum PPFD appeared at 12:00 and in the northern part of the gaps. The mean monthly PPFD was the highest in June, and then decreased in the sequence of July, August, and September, with the largest coefficient of variation at different locations occurred in July and the medium variability in all the months. In different months, the intensity and the scale of PPFD spatial heterogeneity in the gaps differed, with the variation degree being the highest in June and the sill and proportion being the largest in July. The complex degree of the monthly PPFD patches also differed, with the maximum located in the northeast part of the gaps. The variation sequence of the mean monthly PPFD in understory and open ground was consistent with that in gap, and the mean monthly PPFD was the highest in open ground, medium in forest gap, and the lowest in understory.

Effects of converting cultivated land into forest land on the characteristics of soil organic carbon in limestone mountain area in Ruichang, Jiangxi.

2011, 22(04):  885-890. 

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Taking the forest lands having been converted from cultivated land for 5 years in Ruichang City of Jiangxi Province as test objects, this paper studied the characteristics of soil organic carbon (SOC) under 4 different conversion models (forest-seedling integration, pure medicinal forest, bamboo-broadleaved mixed forest, and multi-species mixed forest). After the conversion from cultivated land into forestlands, the contents of SOC, microbial biomass carbon (MBC), and mineralizable carbon (PMC) in 0-20 cm soil layer increased by 24.4%, 29%, and 18.4%, respectively, compared with those under the conversion from cultivated land into wasteland (P<0.05), which indicated that the conversion from cultivated land into forest lands significantly increased the SOC content and SOC storage. The SOC, MBC, and PMC contents in 0-10 cm soil layer were significantly higher than those in 10-20 cm soil layer (P<0.01), and the differences between the soil layers of the four forest lands were higher than those of the wasteland. Among the 4 conversion models, forest-seedling integration had more obvious effects on SOC.

Characteristic of distribution and chemical forms of Pb in tea plant varieties.

2011, 22(04):  891-896. 

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A hydroponics experiment combined with subcellular fractionation and sequential extraction was conducted to study the Pb concentration in different organs of two tea plant varieties (Longjing 43 and Yingshuang) and the Pb subcellular distribution and chemical forms in the roots of the varieties. Under Pb stress, the root system of the two varieties had different features in morphology. With the increasing concentration of Pb in culture solution, the Pb concentration in Longjing 43 young leaves increased, but that in Yingshuang’s had no significant variation. A marked difference was observed in the Pb subcellular distribution and its chemical forms in roots between the two varieties under Pb stress. In Longjing 43 roots, all subcellular fractions except soluble ones had a lower Pb concentration at low Pb stress, and all the subcellular fractions except cell wall ones had a higher Pb concentration at higher Pb stress, compared with those in Yingshuang’s. In Longjing 43 roots, the HAc-extractable Pb occupied the greatest proportion, followed by NaCl-extractable Pb, HCl- and H₂O- extractable Pb, and ethanol-extractable Pb; while in Yingshuang’s, NaCl-extractable Pb had the greatest proportion, followed by HAc-extractable Pb, HCl- and H₂O- extractable Pb, and ethanol-extractable Pb. Based on these findings, tea plant variety Yingshuang was likely to possess a higher tolerance to Pb than Longjing 43 did.

Variation trends of natural vegetation net primary productivity in China under climate change scenario.

2011, 22(04):  897-904. 

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Based on the widely used Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) for climate change study, and according to the features of natural environment in China, the operation mechanism of the model was adjusted, and the parameters were modified. With the modified LPJ model and taking 1961-1990 as baseline period, the responses of natural vegetation net primary productivity (NPP) in China to climate change in 1991-2080 were simulated under the Special Report on Emissions Scenarios (SRES) B2 scenario. In 1961-1990, the total NPP of natural vegetation in China was about 3.06 Pg C·a^-1; in 1961-2080, the total NPP showed a fluctuant decreasing trend, with an accelerated decreasing rate. Under the condition of slight precipitation change, the increase of mean air temperature would have definite adverse impact on the NPP. Spatially, the NPP decreased from southeast coast to northwest inland, and this pattern would have less variation under climate change. In eastern China with higher NPP, especially in Northeast China, east of North China, and Loess Plateau, the NPP would mainly have a decreasing trend; while in western China with lower NPP, especially in the Tibetan Plateau and Tarim Basin, the NPP would be increased. With the intensive climate change, such a variation trend of NPP would be more obvious.

Changes of China agricultural climate resources under the background of climate change. Ⅳ. Spatiotemporal change characteristics of agricultural climate resources in sub-humid warm-temperate irrigated wheat-maize agricultural area of Huang-Huai-Hai Plain.

2011, 22(04):  905-912. 

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Based on the 1961-2007 observation data from 66 meteorological stations in the sub-humid and warm-temperate irrigated wheat-maize agricultural area of Huang-Huai-Hai Plain, this paper analyzed the spatiotemporal change characteristics of agro-climate resources for chimonophilous and thermophilic crops in the area in 1961-1980 and 1981-2007. The analyzed items included the length of temperature-defined growth season and the active accumulative temperature, sunshine hours, precipitation, reference evapotranspiration, and aridity index during the temperature-defined growth season. With climate warming, the length of temperature-defined growth season of chimonophilous and thermophilic crops in the area in 1981-2007 extended by 7.4 d and 6.9 d, and the ≥0 ℃ and ≥10 ℃ accumulative temperature increased at a rate of 4.0-137.0 and 1.0-142.0 ℃·d·(10 a)^-1, respectively, compared with those in 1961-1980. The sunshine hours during the temperature-defined growth season of the crops decreased markedly; and the precipitation during the temperature-defined growing season decreased in most parts of the area, being obvious in Hebei and north Shandong Province, but increased in north Anhui and southeast Henan Province. In most parts of the area, the reference evapotranspiration of chimonophilous and thermophilic crops during their temperature-defined growth season decreased, and the aridity index increased.

Perceptions and adaptation strategies of herders in desert steppe of Inner Mongolia to climate change.

2011, 22(04):  913-922. 

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Desert steppe is very vulnerable to climate change. The herders caring for their livestock in such a natural environment have to face the challenges of rapid climate change. In this paper, a household-level questionnaire was conducted in the Suniteyou District of Inner Mongolia, China, aimed to analyze the herders’ perceptions and adaptation strategies to climate change, extreme climate events in particular. In this Steppe where precipitation is rare and meteorological disasters are frequent, drought is the main extreme climate event with the broadest affecting area, the highest affecting degree, and the greatest frequency. The sensitivity of the herders to drought is far higher than that to other extreme climate events, and also, the perceptions to drought induce the herders having deep perceptions to the extreme climate events such as strong wing, dust storm, and heavy snow. Relative to the perceptions to long-term climate change, the perceptions to short-term climate change are more deep and precise. The herders can estimate the long-term climate change trend according to their perceptions to the latest 10 years climate change. They attribute the poor livestock health and the reduced forage yield greatly to climate change. Yet, the herders are inexperienced in implementing efficient adaptation strategies. Generally, their adaptation measures are quite simplex and rather passive.

Reproductive tillers phenotypic plasticity of Elymus excelsus population at different earring time in Songnen Plain of Northeast China.

2011, 22(04):  923-928. 

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The reproductive tillers of Elymus excelsus population in Songnen Plain were randomly marked with labels every other four days (five times in total) at early earring stage, and the marked tillers were harvested at dough stage, with the differences of their quantitative characteristics as well as the relationships between the quantitative characteristics and the shortened time of reproductive growth were analyzed. With the shortened time of reproductive growth, the quantitative characteristics of the reproductive tillers decreased gradually, which was not beneficial to the reproductive growth, reproductive allocation, and fruiting of reproductive tillers. The later the earring time, the larger the impact on fruiting and reproductive allocation was. When the reproductive growth time was shortened by 16 days, the grain biomass, setting penentage,  reproductive allocationⅠ, and reproductive allocation Ⅱ decreased by 99.4%, 98.8%, 54.3%, and 99.2%, respectively. With the shortened time of reproductive growth, the tiller height decreased linearly, spike biomass, reproductive allocationⅠ, and setting penentage decreased exponentially, tiller biomass, spike length, and floret number decreased powerly, and grain biomass, grain number, and reproductive allocationⅡ decreased logarithmically.

Diversity and community structure of soil ammonia-oxidizing bacteria in Hulunbeier Grassland, Inner Mongolia.

2011, 22(04):  929-935. 

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By the methods of polymerase chain reaction-denaturing gradient gel electrophoresis and sequence analysis, a comparative study was conducted on the diversity and community structure of soil ammonia-oxidizing bacteria in the Filifolium sibiricum steppe, Stipa baicalensis steppe, Leymus chinensis steppe, Stipa grandis steppe, and Stipa kryrowi steppe in Hulunbeier Grassland, Inner Mongolia. A significant difference was observed in the community structure of soil ammonia-oxidizing bacteria among the five steppes, with the similarity lower than 50%. The diversity of soil ammonia-oxidizing bacteria was the highest in F. sibiricum steppe, followed by in S. baicalensis steppe, L. chinensis steppe, S. kryrowi steppe, and S. grandis steppe. In the five steppes, Nitrosospira cluster 3 was the dominant group, and the Nitrosospira cluster 1, 2, and 4 as well as Nitrosomonas were also found. The community structure of soil ammonia oxidizing bacteria in F. sibiricum steppe was most complex, while that in L. chinensis steppe and S. grandis steppe was relatively simple. Correlation analysis indicated that there existed significant positive correlations between the diversity of soil ammonia-oxidizing bacteria and the soil moisture, total nitrogen, total organic carbon, and C/N ratio (P<0.05).

Influence of different concentration Ni and Cu on the photosynthesis and chlorophyll fluorescence characteristics of Peganum harmala.

2011, 22(04):  936-942. 

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A pot experiment was conducted to study the influence of different concentration (0, 50, 100, 200, and 400 mg·kg^-1) Ni and Cu on the growth, photosynthesis, and chlorophyll fluorescence characteristics of Peganum harmala seedlings. With increasing concentration Ni in the medium, the seedlings growth parameters, photosynthetic pigment content, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), maximal photochemical efficiency of PSⅡ (F_v/F_m), quantum efficiency of electric transport of PSⅡ(Φ_PSⅡ), and coefficient of photochemical quenching (q_P) of P. harmala decreased significantly, while the intercellular CO₂ concentration (C) and the coefficient of non-photochemical quenching (q_N) were in adverse. The decrease of P_n under Ni stress was mainly caused by non-stomatal limitation. At 50 mg·kg^-1 Cu, the growth parameters, photosynthetic pigment content, P_n, G_s, T_r, C_i, F_v/F_m, Φ_PSⅡ, and q_P reached their peak values; at 100 mg·kg^-1 Cu, the growth parameters, chlorophyll a and b contents, P_n, G_s, T_r,C, and F_v/F_m were still slightly higher than the control; while with the further increasing Cu concentration in the medium, all the test indices except q_N tended to decrease. The decrease of P_n under Cu stress was mainly caused by stomatal limitation. 

Temporal changes of shoal reclamation in Jinzhou Bay sea area based on remote sensing analysis.

2011, 22(04):  943-949. 

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By using Landsat TM and high resolution ALOS images, and based on the comparison of the precision of sea area extracted from various water indices, a modified index MNDWI was adopted to study the shoal reclamation in Jinzhou Bay sea area in 1988, 1995, and 2006. In the period 1988-2006, the reclaimed area in Jinzhou Bay sea area reached 23.63 km², among which, 12.38 km², 5.48 km², 3.47 km², 1.37 km², and 0.93 km² were used for development zone, industry, port construction, seawater aquaculture, and beach bathing, respectively. The large acreage shoal reclamation reflected the urgent demand of land for coastal urban construction and economic development along the Jinzhou Bay, while at the meantime, brought about greater impacts on the local eco-environment, which needed to be further monitored and assessed.

Soil nutrients spatial variability and soil fertility suitability in Qujing tobacco-planting area.

2011, 22(04):  950-956. 

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By adopting GPS technique, 2088 sampling sites were installed in the tobacco-planting area of Qujing City, Yunnan Province, with 0-20 cm soil samples collected to determine their main nutrients contents. The overall characteristics and spatial variability of the tobacco soil nutrients were analyzed by classic statistics and geo-statistics, and the soil fertility suitability in planting tobacco was evaluated by the methods of fuzzy mathematics. In the study area, soil pH and soil organic matter, available S, and water-soluble Cl contents were appropriate, soil total N and alkali-hydrolyzable N contents were too high, soil available K, Ca, Mg, Cu, Fe, Zn, Mo, and Mn contents were abundant, soil available P content was at medium level, while soil total P and K and available B contents were insufficient. All the nutrient indices presented anisotropic distribution, among which, the spatial variability of soil available P and B was mainly caused by random factors, and that of other nutrients was caused by the co-effects of structural and random factors. The spatial distribution map of soil fertility suitability index (SFI) showed that there was no the excellent grade region for tobacco-planting, good grade region accounted for 8.0%, general grade region accounted for 51.6%, moderate grade region accounted for 39.0%, and low grade region accounted for 1.4%.

Land use simulation and landscape assessment by using genetic algorithm based on cellular automata under different sampling schemes.

2011, 22(04):  957-963. 

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Simulating land use change scenarios with cellular automata (CA) can help to the policy makers in understanding the mechanisms of land change, and support the spatial decision-making for the sustainable use of land resources. Genetic algorithm (GA), an intelligent approach originally conceived from the biological process of evolution, has the capability of minimizing the difference between simulated and observed land use patterns with optimum chromosomes (i.e., feasible CA parameters) obtained through a set of selection, crossover, and mutation operations. In this paper, GA-based CA model was developed, and applied to simulate the land use change in Jiaxing City of Zhejiang Province in 1992-2008. This model was calibrated with 6% (66 samples·km^-2) and 3% (33 samples·km^-2) samplings, and the simulation results were evaluated based on confusion matrix, Kappa coefficient, and landscape metrics analysis. Over 80% of the land use features generated by the GA-based CA model matched the observed classification of land features geographically, and much higher simulation accuracy could be obtained with a larger sample. The simulation accuracy and the landscape metrics for 2001 were better than those for 2008, suggesting a tendency that the model’s accuracy decreased over the simulating process.

Physicochemical and biological characteristics of coastal saline soil under different vegetation cover.

2011, 22(04):  964-970. 

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Taking seven plots of coastal saline soil under different vegetation cover in North Jiangsu as study sites, this paper studied the seasonal fluctuations of soil basic physicochemical and biological characteristics, and analyzed the relationships between these fluctuations and vegetation cover. In the test plots, there was a greater variability of soil basic physicochemical and biological characteristics. The average soil electrical conductivity was lower in crop plots (0.95 dS·m^-1) than in natural vegetation plots (2.77 dS·m^-1), but parts of the crop plots showed an increased soil electrical conductivity compared with pre-planting. Overall, the soil fertility of the plots was generally at a low level, with the hydrolysable nitrogen content averagely lower than 50 mg·kg^-1, available phosphorus content (except fertilized plots) lower than 3 mg·kg^-1, and organic matter content less than 1%. Due to fertilization, the soil conditions in crop plots somewhat improved. For the test coastal saline soil, its electrical conductivity and nutrient level were the key factors affecting the vegetation distribution and plant growth, and soil electrical conductivity was most important. There existed close correlations between soil nitrogen
 and phosphorus contents and soil microbial amount. The seasonal fluctuations of soil characteristics were closely related with vegetation type and human disturbance, being relatively stable under higher vegetation coverage and lesser human disturbance, and dramatic in bare land and castor experimental plots.

Effects of human disturbance on soil aggregates content and their organic C stability in Karst regions.

2011, 22(04):  971-978. 

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Taking the primary forest land (PF), natural restoration land (NR), grazing grassland burned annually in winter (GB), and maize-sweet potato cropland  (MS) in Karst regions of Northwest Guangxi as test objects, this paper studied the soil aggregates content and their organic C stability in the four ecosystems under different human disturbance patterns. The soil water-stable aggregates (>0.25 mm) content in PF, NR, and GB accounted for more than 70%, while that in MS was only 37%. The destruction rate of soil aggregates structure in the four ecosystems decreased in the sequence of MS (54.9%) > GB (23.2%) > NR (9.8%) and PF (9.6%), with significant differences among them (P<0.05). With increasing incubation time, the mineralization rate of soil aggregate organic C decreased after an initial increase and kept stable after 20 days, and increased with decreasing aggregate size. In the same size aggregates, the mineralization rate of organic C in the four ecosystems increased in the sequence of MS < GB and NR < PF. In PF, the mineralization ratio of soil organic C was 1.7%-3.8%, being significantly higher than that in NR, GB, and MS. The cumulative mineralization amount of soil organic C had the same change trend with the mineralization rate. The contents of soil organic C and aggregate organic C were significantly positively correlated with the mineralization rate and cumulative mineralization amount of organic C, respectively, and significantly negatively correlated with the mineralization ratio of organic C.

Effects of atmospheric CO₂ concentration eahancement and nitrogen application rate on wheat grain yield and quality.

2011, 22(04):  979-984. 

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FACE platform was applied to study the effects of elevated atmospheric CO₂ concentration on wheat grain yield and quality under two nitrogen(N) application rates. Elevated atmosphericCO₂ concentration and applying N increased the grain yield, spike number, grain number per spike, and biomass significantly, but elevated CO₂ concentration had no significant effects on harvest index (HI). Under elevated CO₂ concentration, there was a significant decrease in the protein, gliadin, gluteinin, and glutein contents of the grain and the sedimentation value of the flour, and a significant increase in the starch and its components contents of the grain; under N application, an inverse was observed. The dough stability time and the dough viscosity characteristics, such as peak viscosity, final viscosity, and setback value, increased significantly under elevated CO₂ concentration and high N application rate. The interaction of atmospheric CO₂ concentration and N application rate had significantly positive effects on wheat grain yield and  biomass, but less effect on grain quality. Therefore, with elevated atmospheric CO₂ concentration in the future, maintaining a higher N application level would benefit wheat grain yield and paste characteristics, and mitigate the decline of grain quality.

Distribution characteristics of soil humus fractions stable carbon isotope natural abundance (δ¹³C) in paddy field under long-term ridge culture.

2011, 22(04):  985-991. 

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A 16-year field experiment was conducted in a ridge culture paddy field in the hilly region of Sichuan Basin, aimed to investigate the distribution characteristics of stable carbon isotope natural abundance (δ¹³C) in soil humus fractions. The soil organic carbon (SOC) content in the paddy field under different cultivation modes ranked in the order of wide ridge culture ＞ ridge culture ＞ paddy and upland rotation. In soil humus substances (HS), humin (HU) was the main composition, occupying 21%-30% of the total SOC. In the extracted soil carbon, humic acid (HA) dominated, occupying 17%-21% of SOC and 38%-65% of HS. The δ¹³C value of SOC ranged from -27.9‰ to -25.6‰, and the difference of the δ¹³C value between 0-5 cm and 20-40 cm soil layers was about 1.9‰. The δ¹³C value of HA under different cultivation modes was 1‰-2‰ lower than that of SOC, and more approached to the δ¹³C value of rapeseed and rice residues. As for fulvic acid (FA), its δ¹³C value was about 2‰ and 4‰ higher than that of SOC and HA, respectively. The δ¹³C value of HU in plough layer (0-20 cm) and plow layer (20-40 cm) ranged from -23.7‰--24.9‰ and -22.6‰--24.2‰, respectively, reflecting the admixture of young and old HS. The δ¹³C value in various organic carbon fractions was HU＞FA＞SOC＞rapeseed and rice residues＞HA. Long-term rice planting benefited the increase of SOC content, and cultivation mode played an important role in affecting the distribution patterns of soil humus δ¹³C in plough layer and plow layer.

Effects of long-term applying sulfur- and chloride-containing chemical fertilizers on weed growth in paddy field.

2011, 22(04):  992-998. 

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An investigation was made at a double-rice paddy field in the Qiyang Red Soil  Field Experimental Station, Hunan Province, China to study the species and biomass of weeds growing in rice (Oryza sativa L.) growth season after 34-year application of sulfur (SO₄^2--) and chloride (Cl^-)-containing chemical fertilizers under the same application rates of nitrogen (N), phosphorus (P), and potassium (K). Long-term application of Cl^--containing chemical fertilizer resulted in the greatest species number of weeds and the highest biomass of floating weeds and wet weeds, compared with long-term application of SO₄^2-- and Cl^-+SO₄^2--containing chemical fertilizers. In early rice growth season, the biomass of weeds after applying Cl^--containing chemical fertilizer was 51.4% and 17.6% higher than that after applying Cl^-+SO₄^2-- and SO₄^2--containing chemical fertilizers, respectively; in late rice growth season, the increment was 144% and 242%, respectively. More floating weeds were observed after applying Cl^-+SO₄^2-- and SO₄^2--containing chemical fertilizers, but few of them were found after applying Cl^--containing chemical fertilizer. The total dry mass of weeds and the dry mass of wet weeds were positively correlated with soil Cl^- content (r=0.764, P<0.01 and r=0.948, P<0.01, respectively), but negatively correlated with soil SO₄^2--S content (r=0.849, P<0.01 and r=0.641, P<0.05). Soil alkali-hydrolyzable N and available P, under the co-effects of soil SO₄^2--S, Cl^-, and pH, had indirect effects on the total dry mass of weeds. By adopting various fertilization measures to maintain proper soil pH and alkali-hydrolyzable N and available P contents, increase soil SO₄^2--S content, and decrease soil Cl^- content, it could be possible to effectively inhibit the growth of wet weeds and to decrease the total biomass of weeds in double-rice paddy field.

Effects of γ-aminobutyric acid on the photosynthesis and chlorophyll fluorescence parameters of muskmelon seedlings under hypoxia stress.

2011, 22(04):  999-1006. 

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By the method of hydroponic culture, this paper studied the effects of exogenous γ-aminobutyric acid (GABA) on the photosynthetic pigment contents,
photosynthesis, and chlorophyll fluorescence parameters of muskmelon seedlings under hypoxia stress. Hypoxia stress induced a significant decrease of photosynthetic pigment contents, resulting in the decrease of photosynthesis. Applying GABA could significantly increase the photosynthetic pigment contents, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), carboxylation efficiency (CE), maximal photochemical efficiency of PSⅡ(F_v/F_m), photochemical quenching (q_P), apparent photosynthetic electron transfer rate (ETR), and quantum yield of PSⅡelectron transport (Φ_PSⅡ), and decrease the stomatal limitation value (L_s), minimal fluorescence (F_o), and non-photochemical quenching (NPQ) under both hypoxic and normal conditions. The alleviation effect of GABA on photosynthetic characteristics was more obvious under hypoxia stress. However, simultaneously applying GABA and VGB could significantly decrease the alleviation effect of GABA under hypoxia stress.

Effects of combined application of biogas slurry and chemical fertilizer on winter wheat rhizosphere soil microorganisms and enzyme activities.

2011, 22(04):  1007-1012. 

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This paper studied the effects of combined application of biogas slurry and chemical fertilizer under same N application rate on the quantities of bacteria, actinomycetes and fungi as well as the activities of urease, protease and catalase in winter wheat rhizosphere soil. With the growth of winter wheat, the quantities of test microorganisms and the activities of urease and catalase showed a trend of increasing after an initial decrease, while the protease activity showed an S-type change. Combined application of biogas slurry and chemical fertilizer increased the quantities of test microorganisms significantly, and improved the activities of soil urease and protease. Applying 50% biogas slurry N as basal plus 50% chemical N as topdressing and applying 25% biogas slurry N as basal plus 75% chemical N as topdressing had the best effect, while applying single conventional urea or biogas slurry had the worst effect. At all growth stages, the activity of soil catalase was the highest in treatments 25% biogas slurry N as basal plus 75% chemical N as topdressing and single biogas slurry, but had greater differences in other treatments among the growth stages. The results suggested that proper biogas slurry application combined with chemical fertilization could increase the microbial quantity and enzyme activities in winter wheat rhizosphere soil.

Differential expression of proteins in Oryza sativa leaves in response to cadmium stress.

2011, 22(04):  1013-1019. 

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In order to explore the cadmium (Cd)-tolerance mechanism of rice (Oryza sativa), a hydroponic experiment with Cd-tolerant rice cultivar PI312777 and Cd-sensitive rice cultivar IR24 was conducted. The cultivars were treated with 0 (control), 50, and 100 μmol·L^-1 of Cd²⁺ for 7 days, and the differential expression of proteins in their leaves were analyzed by two-dimensional electrophoresis and MALDI-TOF/MS approach. Under Cd stress, 31 protein spots in PI312777 leaves and 19 protein spots in IR24 leaves had significantly different expression, compared with the control. In PI312777 leaves, the 24 of 31 proteins had 4 proteins related to photosynthesis, 11 proteins related to cell metabolism and defense, 3 proteins related to other metabolism pathway, and 2 proteins were unknown proteins; in IR24 leaves, the 15 of 19 proteins were identified. Under Cd- stress, the heat shock protein, glutathione-diulfide reductase, poteasome subunit alpha type-6, 1,6-bisphosphate aldolase, thioredoxin, and DNA repair-recombination protein in PI312777 leaves were up-regulated expressed, while these proteins in IR24 were not significantly changed except the down-regulation of 1,6-bisphosphate aldolase and thioredoxin. The higher Cd-tolerance of PI312777 could have close relations with the differentially expressed proteins.

Characteristics of microbial community structure in Luzhou-flavor fermentation pits.

2011, 22(04):  1020-1026. 

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Fermentation pit is a kind of solid bioreactors with unique feature for brewing liquor, especially for Luzhou-flavor, which has significant effects on the quality of produced liquor. There exists a close and complicated correlation between pit age (using time) and microbial community. Taking the characteristic component phospholipid fatty acid (PLFA) in microbial cell membrane as an index, this paper studied the characteristics of the microbial community structure in the pit mud, fermented grains, and yellow water of different age (5-year, 100-year, and 300-year) fermentation pits. The results showed that the total PLFA content was the highest in pit mud, followed by in fermented grains, and in yellow water. The composition of PLFA differed with pit age, and the total PLFA content in yellow water decreased with increasing pit age. In pit mud, straight chain saturated fatty acid had the highest content, occupying 50.7-73.3% of total PLFA and being the highest in 300-year pit. As for the microbial community structure, the PLFA content characterizing Gram-positive (G⁺) anaerobic bacteria was higher in pit mud, and that characterizing Gram-negative (G^-) anaerobic bacteria was higher in fermented grains and yellow water. The PLFA content characterizing G⁺ and G^- bacteria in the pit mud of 100-year pit was higher than that in the pit mud of other ages’ pits, while the PLFA content characterizing fungi was higher in the pit mud, fermented grains, and yellow water of 5-year pit, as compared with other ages’ pits.Principal component analysis showed that the main varied microbial populations in 5- and 100-year pits were G^- bacteria and fungi, and the main varied microbial population in 300-year pit was of bacteria. The indices frequency index, Simpson index, and Shannon index could be chosen for characterizing the diversity of microbial community in fermentation pits.

Effects of intermittent aeration on nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water.

2011, 22(04):  1027-1032. 

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Aiming at the carbon source limitation of denitrification in oligotrophic habitat, this paper studied the effects of intermittent aeration on the nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water, and approached the feasibility and process mechanism of shortcut nitrification and denitrification in the system. Under the condition of 8 h-1 6 h anoxic-aerobic phase (Ⅰ), the remediation system performed stably, and its average removal efficiency of ammonium (NH₄⁺-N), permanganate index (COD_Mn), and total nitrogen (TN) was 93.0%, 78.1%, and 19.4%, respectively. Under the condition of 16 h-8 h anoxic-aerobic phase (Ⅱ), the NH₄⁺-N and COD_Mn removal efficiency still maintained at 81.2% and 76.4%, respectively, the accumulation of nitrite (NO₂^--N) was significant, and the removal efficiency of TN reached more than 50%. The nitrogen transformation characteristics in the system during a cycle under condition Ⅱ demonstrated that at the prerequisite of effluent NH₄⁺-N and DO concentrations reaching the standards, shortening aerobic phase length could maintain the DO concentration at 0.5-1.5 mg·L^-1 in a long term, inhibit the growth and activity of nitrite-oxidizing bacteria, and thereby, NO₂^--N had an obvious accumulation, and the nitrogen removal via shortcut nitrification-denitrification in the biological contact oxidation remediation system for micro-polluted source water was finally achieved.

Controlling effect of antagonist bioorganic fertilizer on tomato root-knot nematode.

2011, 22(04):  1033-1038. 

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Indoor in vitro culture experiment and greenhouse pot experiment were conducted to evaluate the capabilities of three bacterial strains XZ-173 (Bacillus amyloliquefaciens), SL-25 (B. gibsonii), and KS-62 (Paenibacillus polymyxa) that can hydrolyze collagen protein in controlling tomato root-knot nematode. In the in vitro culture experiment, suspensions of XZ-173, SL-25, and KS-62 induced a mortality rate of 75.9%, 66.7%, and 50.0% to the second-stage junior nematode within 24 h, and decreased the egg hatching rate to 17.8%, 28.9% and 37.6% after 7-day incubation, respectively, in contrast to the 17.4% mortality rate and 53.6% egg hatching rate in the control (sterilized water). In the greenhouse pot experiment, the bioorganic fertilizer mixed with equal parts of fermented XZ-173, SL-25, and KS-62 gained the best result, with the root-knot nematode population in rhizosphere soil decreased by 84.0% as compared with the control. The bioorganic fertilizer also decreased the numbers of galls and eggs on tomato roots significantly, and increased the underground and aboveground biomass of tomato. Therefore, antagonist bioorganic fertilizer has promising potential in controlling root-knot nematode.

Zoning of water environment protection in Three Gorges Reservoir watershed. 

2011, 22(04):  1039-1044. 

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Regional differences in socio-economic development, land use, vegetation cover, and relative location of water body within a watershed bring about significant effects on the water environment quality of the watershed. Concerning about the core demands of water body protection, it is important and necessary to carry out zoning water environment protection for whole watershed. With a view to the spatial differences in regional characteristics of eco-environment and water body pressure-respond features, this paper studied the zoning of water environment protection in the Three Gorges Reservoir watershed, based on the methods of ecological factors overlay and ecological sensitivity analysis. The factors considered included hydrothermal conditions, terrain topography, administrative unit, and ecological sensitivity. Three regions in the watershed were zoned, i.e., 1) red region, namely strictly protected region, with an area of 2924 km² and occupying 5.1% of the total; 2) yellow region, namely first class protection region, with an area of 10477 km² and occupying 18.4%; and 3) blue region, namely second class protection region, with an area of 43599 km² and occupying 76.5%. The key environmental problems of the regions were identified, and the strategies for the regions’ development and water environment protection were proposed.

Phytoplankton assemblages in Yangtze River Estuary in the first sluice discharge duration of Three Gorges Dam in late spring.

2011, 22(04):  1045-1052. 

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In June 15-25, 2003, the first sluice discharge duration of the Three Gorges Dam, water samples were taken from a grid of survey stations around the Yangtze River Estuary and its adjacent waters to analyze the characteristics of phytoplankton assemblages. In the survey area, the major phytoplankton groups were diatoms and dinoflagellates, and a few species belonging to Chrysophyceae and Chlorophyceae were observed. The cell abundance of the assemblages ranged from 0.2 to 1504.2 cells·ml^-1, with an average of 72.7 cells·ml^-1, and the dominant species were Skeletonema spp., Prorocentrum dentatum, and Scrippsiella trochoidea. The highest cell abundance was appeared in north diluted waters and southwest inshore waters. The cell abundance was the maximum in mid (10 m) water layer, and the minimum in bottom layer. In diluted waters, Skeletonema spp. was the dominant species, and mainly presented in surface water layer; while in the waters with the diluted water of Yangtze River and the mixed water of Taiwan Warmer Current and Yellow Sea, Prorocentrum dentatum dominated, and mainly distributed in surface and mid water layers.

Total phosphorus removal from eutrophic water in Baiyangdian Lake by Potamogeton crispus.

2011, 22(04):  1053-1058. 

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Taking the water, sediment, and Potamogeton crispus collected from Shihoudian, Wangjiazhai, and Xiaodian in Baiyangdian Lake area into laboratory, three simulated static systems were built to study the growth of P. crispus and its effect on the removal of total phosphorus from eutrophic water and sediment. Among the three systems, Shihoudian system had the best purification effect, with the removal efficiency of total phosphorus from water body being 87.9%, followed by Wangjiazhai system 47.4%, and Xiaodian system 76.9%. The largest total phosphorus removal efficiency per gram biomass in Shihoudian, Wangjiazhai, and Xiaodian systems was 2.2%, 0.9%, and 1.4%, and the largest total phosphorus adsorption rate of sediments was 9.1%, 7.4%, and 7.7%, respectively. The TP-t and v-t fitted equations of the three systems indicated that the total phosphorus concentration in water and the removal rate of the total phosphorus were negatively exponentially decreased with time.

Effects of low salinity stress on the antioxidant enzyme activities in juvenile Pampus argenteus liver and the APTase activities in its gill and kidney.

2011, 22(04):  1059-1066. 

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By decreasing water salinity gradually, the Pampus argenteus juveniles were cultured at water salinity 25, 20, 15 and 10 , for 24 h, 48 h, 96 h and 120 h, respectively, with the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (GST), and glutathione reductase (GR) in liver and the activities of Na⁺/K⁺- and Ga²⁺/Mg²⁺-ATPase in gill and kidney determined. With the lowering of water salinity and the elongation of treated time, the liver SOD and GST activities had a trend of decreasing after an initial increase (P<0.05), while the CAT activity was lower than the control except that it had a slight increase at salinity 20 cultured for 24 h and at salinity 15 cultured for 48 h (P<0.05). The liver GPX activity had an increasing trend (P<0.05), while the GR activity at salinity 15 cultured for 24 h increased first and then fell down to a relatively low level (P<0.05). The Na⁺/K⁺- and Ga²⁺/Mg²⁺-ATPase activities in the gill and kidney also decreased after an initial increase (P<0.05), only the increase of ATPase activity at the thresholds of water salinity and treated time differed between the two organs. The results indicated that the decrease of water salinity could effectively stimulate and enhance the antioxidant enzyme activities in juvenile P. argenteus liver and the ATPase activities in its gill and kidney, and thereby, could effectively eliminate the excessive reactive oxygen species (ROS), sustain the intracellular homeostasis, and minimize the body damage. However, characterized by certain specificity and time sequentiality, the activation of test enzymes could also be inhibited when the salinity varied beyond the tolerance range of the body.

A new assessment method for the quality of ecological monitoring data: Taking CERN’s tree growth dataset as a case.

2011, 22(04):  1067-1074. 

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This paper presented a new and simple assessment method for the quality of ecological monitoring data. This method theorized the associations between the data reliability as an ordinal variable with different number of classes and the data sources such as natural main ecological processes, secondary ecological processes, and extraneous and exotic processes, and offered a new data quality index to estimate the quality of the whole dataset by using the reasonableness ratio of observations. The assessment results provided the reliability class of each dataset, good explanations for outlier (or error data) flagging decisions, and quality value of the whole dataset. The method was applied to assess two tree growth datasets from Chinese Ecosystem Research Network (CERN), and the results demonstrated that the new data quality index could quantitatively evaluate the quality of the tree growth datasets. The new method would facilitate the development of corresponding software.

Responses of forest soil carbon pool and carbon cycle to the changes of carbon input.

2011, 22(04):  1075-1081. 

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Litters and plant roots are the main sources of forest soil organic carbon (C). This paper summarized the effects of the changes in C input on the forest soil C pool and C cycle, and analyzed the effects of these changes on the total soil C, microbial biomass C, dissoluble organic C, and soil respiration. Different forests in different regions had inconsistent responses to C input change, and the effects of litter removal or addition and of root exclusion or not differed with tree species and regions. Current researches mainly focused on soil respiration and C pool fractions, and scarce were about the effects of C input change on the changes of soil carbon structure and stability as well as the response mechanisms of soil organisms especially soil fauna, which should be strengthened in the future.

Bioremediation of petroleum hydrocarbon-contaminated soils by cold-adapted microorganisms: Research advance.

2011, 22(04):  1082-1088. 

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Cold-adapted microorganisms such as psychrotrophs and psychrophiles widely exist in the soils of sub-Arctic, Arctic, Antarctic, alpine, and high mountains, being the important microbial resources for the biodegradation of petroleum hydrocarbons at low temperature. Using the unique advantage of cold-adapted microorganisms to the bioremediation of petroleum hydrocarbon-contaminated soils in low temperature region has become a research hotspot. This paper summarized the category and cold-adaptation mechanisms of the microorganisms able to degrade petroleum hydrocarbon at low temperature, biodegradation characteristics and mechanisms of different petroleum fractions under the action of cold-adapted microorganisms, bio-stimulation techniques for improving biodegradation efficiency, e.g., inoculating petroleum-degrading microorganisms and adding nutrients or bio-surfactants, and the present status of applying molecular biotechnology in this research field, aimed to provide references to the development of bioremediation techniques for petroleum hydrocarbon-contaminated soils.

The 1st International Youth Ecologist Forum in China, 2009: A review.

2011, 22(04):  1089-1093. 

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To promote the communication and cooperation between Chinese and overseas youth ecologists, a conference entitled “The 1st International Young Ecologist Forum” was held at Lanzhou University in June 29-30, 2009. This conference was organized by outstanding overseas ecologists and hosted by Lanzhou University. The presentations covered broad areas of ecology, including plant-soil interactions, structure and function of regional ecosystems, ecological security and ecological planning, global change ecology, and environmental sustainability, demonstrating that the development of China ecology is gradually from traditional basic research transforming into applied research. The presentations also reflected in some extent the development characteristics, evolution direction, and distribution pattern of China ecological research. China ecological research has gradually formed four centers, the Northeast, North, Northwest, and Southeast China, and each of them has its definite regional characteristics. Some suggestions about the organization form and future planning of the forum were put forward.

Effects of organic manure on wheat growth under lead stress.

2011, 22(04):  1094-1100. 

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A pot experiment was conducted to study the effects of organic manure on the wheat growth under different levels of lead stress. With increasing lead stress level, whether fertilization or not, the plant height, shoot dry mass, adventitious root number, root total length, root dry mass, root activity, root total and active absorbing area, and root SOD and POD activities decreased, and root MDA content presented an increasing trend. The decrement of the above-mentioned parameters differed with fertilization treatments. Applying organic manure mitigated the impact of lead stress on wheat growth to some extent, delayed the senescence of wheat roots, and promoted root development and growth, ultimately leading to the increase of wheat yield and the decrease of lead content in grain.

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2011, 22(04):  1101-1106. 

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A pot experiment with artificial shading was conducted to study the effects of soil moisture content and light intensity on the plant growth and leaf physiological characteristics of squash variety “Jingyingyihao”. Under all test soil moisture conditions, 30% shading promoted the growth of “Jingyingyihao”, with the highest yield at 70%-80% soil relative moisture contents. 70% shading inhibited plant growth severely, only flowering and not bearing fruits, no economic yield produced. In all treatments, there was a similar water consumption trend, i.e., both the daily and the total water consumption decreased with increasing shading and decreasing soil moisture content. Among all treatments, 30% shading and 70%-80% soil relative moisture contents had the highest water use efficiency (2.36 kg·mm^-1·hm^-2) and water output rate (1.57 kg·mm^-1·hm^-2). The net photosynthetic rate, transpiration rate, stomatal conductance, and chlorophyll content of squash leaves decreased with increasing shading, whereas the intercellular CO₂ concentration was in adverse. The leaf protective enzyme activity and proline content decreased with increasing shading, and the leaf MAD content decreased in the order of 70% shading, natural radiation, and  30% shading. Under the three light intensities, the change characteristics of squash leaf photosynthesis, protective enzyme activity, and proline and MAD contents differed with the increase of soil relative moisture content.