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    18 November 2014, Volume 25 Issue 11
    Effects of snow cover on water soluble and organic solvent soluble components during foliar litter decomposition in an alpine forest.
    XU Li-ya, YANG Wan-qin, LI Han, NI Xiang-yin, HE Jie, WU Fu-zhong
    2014, 25(11):  3067-3075. 
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    Seasonal snow cover may change the characteristics of freezing, leaching and freezethaw cycles in the scenario of climate change, and then play important roles in the dynamics of water soluble and organic solvent soluble components during foliar litter decomposition in the alpine forest. Therefore, a field litterbag experiment was conducted in an alpine forest in western Sichuan, China. The foliar litterbags of typical tree species (birch, cypress, larch and fir) and shrub species (willow and azalea) were placed on the forest floor under different snow cover thickness (deep snow, medium snow, thin snow and no snow). The litterbags were sampled at snow formation stage, snow cover stage and snow melting stage in winter. The results showed that the content of water soluble components from six foliar litters decreased at snow formation stage and snow melting stage, but increased at snow cover stage as litter decomposition proceeded in the winter. Besides the content of organic solvent soluble components from azalea foliar litter increased at snow cover stage, the content of organic solvent soluble components from the other five foliar litters kept a continue decreasing tendency in the winter. Compared with the content of organic solvent soluble components, the content of water soluble components was affected more strongly by snow cover thickness, especially at snow formation stage and snow cover stage. Compared with the thicker snow covers, the thin snow cover promoted the decrease of water soluble component contents from willow and azalea foliar litter and restrain the decrease of water soluble component content from cypress foliar litter. Few changes in the content of water soluble components from birch, fir and larch foliar litter were observed under the different thicknesses of snow cover. The results suggested that the effects of snow cover on the contents of water soluble and organic solvent soluble components during litter decomposition would be controlled by litter quality.
    Dimensional characteristics and spatial distribution patterns of pit and mound complexes in Pinus koraiensisdominated broadleaved mixed forest.
    DUAN Wen-biao1, WEI Quan-shuai1, QIAO Lu1,2, CHEN Li-xin1, WANG Ting1, ZHANG Xin1, GU Wei3, SUN Hu3
    2014, 25(11):  3076-3082. 
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    Characteristics of pit and mound complexes in different sizes of forest gaps and closed stands and their distribution patterns were compared and analyzed. The results showed that mean mound width, mound height, mound thickness of all pit and mound complexes were larger than corresponding mean pit length, pit width, pit depth in large, medium and small gaps as well as in closed stands. Mound width, mound height, mound thickness, pit length, pit width, pit depth were the largest in large gap, being 2.85, 0.37, 2.00, 2.99, 2.10, 0.39 m, respectively, and the smallest in closed stands, being 2.35, 0.19, 1.60, 2.66, 1.65, 0.21, respectively. Mean mound volume (1.66 m3) was larger than mean pit volume (1.44 m3). The difference in characteristic values between the most of pit and mound complexes was significant for the same size of forest gap, not significant for closed stands, significant for different sizes of forest gaps and closed stands. Most of characteristic values for pit and mound complexes within the plot in 2012 were significantly less than those in 2011. 89.5% and 60.5% of type and shape of pit and mound complexes were hinge and semiellipse, respectively. Their distribution was relatively centralized.
    Effects of gaps on distribution of soil aggregates and organic carbon in Pinus massoniana plantation.
    SONG Xiao-yan, ZHANG Dan-ju, ZHANG Jian, LI Jian-ping, DENG Chang-chun, DENG Chao
    2014, 25(11):  3083-3090. 
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    The effects of forest gap size on the distribution of soil aggregates, organic carbon and labile organic carbon were investigated in a 39-year-old Pinus massoniana plantation in Yibin, Sichuan Province. The results showed that the composition of soil aggregates was dominated by particles >2 mm, which accounted for 51.7%-78.7% of the whole soil samples under different sized forest gaps and beneath P. massoniana plantation. Soil organic carbon content and labile organic carbon content in >5 mm aggregates were significantly positively correlated with the soil organic carbon and labile organic carbon contents. Furthermore, the amounts of organic carbon and labile organic carbon storage >5 mm particles were higher than those in other size particles. Therefore, particles >5 mm of aggregates dominated the soil carbon pool. Compared with those  P. massoniana plantations, the contents of organic carbon in aggregates and total topsoil decreased during the formation of forest gaps, whereas the soil organic carbon storage under 1225 m2 gap was higher. In addition, the soil labile organic carbon content under 225 and 400 m2 gaps and the labile organic carbon storage under 225, 400, 900 and 1225 m2 gaps were higher than those  the plantations, but were lower than under the other gaps. It was suggested that an appropriate size of forest gap would increase the accumulation of soil organic carbon and labile organic carbon content. The size of forest gap had significant effects on the distribution of soil aggregates, organic carbon and labile organic carbon. The soil sample under 1225 m2 gap had the highest organic carbon content and storage and a better aggregate proportion, and the higher labile organic carbon storage. Therefore, it was suggested that 1225 m2 gap might be an optimal logging gap size.
    Fine root biomass and production of four vegetation types in Loess Plateau, China.
    DENG Qiang1,2, LI Ting3, YUAN Zhi-you1,4, JIAO Feng1,4
    2014, 25(11):  3091-3098. 
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    Fine roots (≤2 mm) play a major role in biogeochemical cycling in ecosystems. By the methods of soil cores and ingrowth soil cores, we studied the biomass and annual production of fine roots in 0-40 cm soil layers of four main vegetation types, i.e., Robinia pseudoacacia plantation, deciduous shrubs, abandoned grassland, and Artemisia desertorum community in Loess Plateau, China. The spatial patterns of fine root biomass and production were negatively associated with latitudes. The fine root biomass in the 0-40 cm soil layer was in the order of deciduous shrubs (220 g·m-2), R. pseudoacacia plantation (163 g·m-2), abandoned grassland (162 g·m-2) and A. desertorum community (79 g·m-2). The proportion of ≤1 mm fine root biomass (74.1%) in the 0-40 cm soil layer of abandoned grassland was significantly higher than those in the other three vegetation types. The fine root biomass of  the four vegetation types was mainly distributed in the 0-10 cm soil layer and decreased with soil depth. The proportion of fine root biomass (44.1%) in the 0-10 cm soil layer of abandoned grassland was significantly higher than those in other three vegetation types. The fine root productions of four vegetation types were in the order of abandoned grassland (315 g·m-2·a-1) >deciduous shrubs (249 g·m-2·a-1) >R. pseudoacacia plantation (219 g·m-2·a-1) >A. desertorum community (115 g·m-2·a-1), and mainly concentrated in the 0-10 cm top soil layer and decreased with the soil depth. The proportion of the annual production (40.4%) in the 0-10 cm soil layer was the highest in abandoned grassland. Fine roots of abandoned grassland turned over faster than those from the other three vegetation types.
    Estimation for vegetation carbon storage in Tiantong National Forest Park.
    GUO Chun-zi1,2,3, WU Yang-yang1,2,3, NI Jian1,2,3
    2014, 25(11):  3099-3109. 
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    Based on the field investigation and the data combination from literature, vegetation carbon storage, carbon density, and their spatial distribution were examined across six forest community types (Schima superba-Castanopsis fargesii community, S. superba-C. fargesii with C. sclerophylla community, S. superba-C. fargesii with Distylium myricoides community, Illicium lanceolatum-Choerospondias axillaris community, Liquidambar formosana-Pinus massoniana community and Hedyotis auricularia-Phylostachys pubescens community) in Tiantong National Forest Park, Zhejiang Province, by using the allometric biomass models for trees and shrubs. Results showed that: Among the six communities investigated, carbon storage and carbon density were highest in the S. superba-C. fargesii with C. sclerophylla community (storage: 12113.92 Mg C; density: 165.03 Mg C·hm-2), but lowest in the I. lanceolatum-C. axillaris community (storage: 680.95 Mg C; density: 101.26 Mg C·hm-2). Carbon storage was significantly higher in evergreen trees than in deciduous trees across six communities. Carbon density ranged from 76.08 to 144.95 Mg C·hm-2, and from 0.16 to 20.62 Mg C·hm-2 for evergreen trees and deciduous trees, respectively. Carbon storage was highest in stems among tree tissues in the tree layer throughout communities. Among vegetation types, evergreen broadleaved forest had the highest carbon storage (23092.39 Mg C), accounting for 81.7% of the total carbon storage in all forest types, with a carbon density of 126.17 Mg C·hm-2. Total carbon storage for all vegetation types in Tiantong National Forest Park was 28254.22 Mg C, and the carbon density was 96.73 Mg C·hm-2.
    Regeneration mode of Xanthoceras sorbifolia population and its contribution to population regeneration. 
    GUO You-yan1,2, ZHOU Jian-yun1, HE Jing-feng1, ZHANG Wen-hui1
    2014, 25(11):  3110-3116. 
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    Sexual and asexual propagation of Xanthoceras sorbifolia natural populations in different habitats and their importance in population regeneration were studied. The results showed that X. sorbifolia populations were capable of the sexual and asexual propagation in 3 slope aspects, but a balance between the two propagation modes was observed. In sunny and semishady slope habitats, seedling amount and spaceoccupying competence were relatively high, suggesting that the sexual propagation was dominant. In semisunny slope habitat, the populations were superior in sexual sprout amount and spaceoccupying competence, suggesting that the predominant propagation mode was asexual. In the same habitats, asexual sprouts grew better than seedlings, while the growth of seedlings was in the order of sunny slope>semisunny slope>semishady slope on the basis of the same origin. The bottleneck stage appeared from seeds to seedlings for sexual propagation and from seedling to ramet for asexual propagation. X. sorbifolia invaded and settled in a way of sexual propagation in new habitats, and then rapidly occupied habitat space in a way of asexual propagation.
     
    Applicability analysis of spatially explicit model of leaf litter in evergreen broadleaved forests.
    ZHAO Qing-qing1,2, LIU He-ming1,2, JONARD Mathieu3, WANG Zhang-hua4, WANG Xi-hua1,2
    2014, 25(11):  3117-3124. 
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    The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broadleaved forest in Tiantong, Zhejiang Province, eastern China. Applicability of the model was analyzed. The model assumed an allometric equation between diameter at breast height (DBH) and leaf litter amount, and the leaf litter declined exponentially with the distance. Model parameters were estimated by the maximum likelihood method. Results showed that the predicted and measured leaf litter amounts were significantly correlated, but the prediction accuracies varied widely for the different tree species, averaging at 49.3% and ranging from 16.0% and 74.0%. Model qualities of tree species significantly correlated with the standard deviations of the leaf litter amount per trap, DBH of the tree species and the average leaf dry mass of tree species. There were several ways to improve the forecast precision of the model, such as installing the litterfall traps according to the distribution of the tree to cover the different classes of the DBH and distance apart from the parent trees, determining the optimal dispersal function of each tree species, and optimizing the existing dispersal function.
    Age structure and dynamics of Quercus wutaishanica population in Lingkong Mountain of Shanxi Province, China.
    ZHANG Jie1, SHANGGUAN Tie-liang2,3, DUAN Yi-hao2, GUO Wei3, LIU Wei-hua3, Guo Dong-gang2
    2014, 25(11):  3125-3130. 
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    Using the plant survivorship theory, the age structure, and the relationship between tree height and diameter (DBH) of Quercus wutaishanica population in Lingkong Mountain were analyzed, and the static life table was compiled and the survival curve plotted. The shuttle shape in age structure of Q. wutaishanica population suggested its temporal stability. The linear regression significantly fitted the positive correlation between tree height and DBH. The maximal life expectancy was observed among the trees beyond the age of the highest mortality and coincided with the lowest point of mortality density, suggesting the strong vitality of the seedlings and young trees that survived in the natural selection and intraspecific competition. The population stability of the Q. wutaishanica population was characterized by the Deevey-Ⅱ of the survival curve. The dynamic pattern was characterized by the recession in the early phase, growth in the intermediate phase, and stability in the latter phase.
    Effects of salinealkali stress on electrical impedance spectroscopy parameters and ion contents in shoots of Ping’ou hybrid hazelnut.
    ZHANG Li1,2, JIA Zhi-guo2, MA Qing-hua1, ZHANG Gang3, WANG Gui-xi1
    2014, 25(11):  3131-3138. 
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    To study the adaptability to saltalkaline stress of Ping’ou hybrid hazelnut, ‘Liaozhen 3’ shoots which were treated with three types of stress neutral NaCl, alkaline Na2CO3, and mixed saltalkali, and the changes in electrical impedance spectroscopy (EIS) parameters and mineral ion contents were subsequently determined. The correlations between the EIS parameters and mineral ion contents were analyzed. The results showed that with the increasing level of NaCl, specific highfrequency resistance (r), specific lowfrequency resistance (r1), specific intracellular resistance (ri) and specific extracellular resistance (re) of shoots decreased firstly, then increased, and finally decreased again. However, these parameters increased gradually with the increasing level of Na2CO3, while r1 and re decreased slowly in the mixed saltalkali treatments. The Na+ contents of shoots increased significantly under the three saltalkali stresses with the order of NaCl stress > mixed saltalkali stress > Na2CO3 stress. Furthermore, Na2CO3 stress resulted in the decreases in the contents of three elements Zn, B and Ca. The significant negative correlation was found between the sum of five cations and four EIS parameters r1, re, relaxation time (τ), and distribution coefficient of relaxation time (Ψ). The shoots of ‘Liaozhen 3’ might be tolerant of Na2CO3 stress of 200 mmol·L-1, while they could be resistant to NaCl stress of 100-150 mmol·L-1.
    Effects of shading on the aboveground biomass and stiochiometry characteristics of Medicago sativa
    MA Zhi-liang, YANG Wan-qin, WU Fu-zhong, GAO Shun
    2014, 25(11):  3139-3144. 
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    In order to provide scientific basis for interplanting alfalfa in abandoned farmland, a shading experiment was conducted to simulate the effects of different light intensities on the aboveground biomass, the contents of carbon, nitrogen, phosphorus and potassium, and the stoichiometric characteristics of alfalfa under the plantation. The results showed that the aboveground biomass of alfalfa correlated significantly with the light intensity, and shading treatment reduced the aboveground biomass of alfalfa significantly. The aboveground alfalfa tissues under the 62% shading treatment had the highest contents of carbon, nitrogen and phosphorus, which was 373.73, 34.38 and 5.47 g·kg-1, respectively, and significantly higher than those of the control. However, shading treatments had no significant effect on the potassium content of aboveground part. The C/N ratio in aboveground tissues under the 72% shading treatment was significantly higher than that of the control, but no significant differences among other treatments were found. The ratios of N/P and C/P in aboveground tissues showed a tendency that decreased firstly and then increased with the increase of light intensity.
     
    Effects of root exudates of clover (Trifolium repens) on PAH microbial degradation and dioxygenase.
    WANG Yue1,2, GUO Mei-xia1,2, JIN Jing-hua3, GONG Zong-qiang1, JIA Chun-yun1, LI Xiao-jun1, ZHANG Wei4
    2014, 25(11):  3145-3151. 
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    To demonstrate rhizospheric effect on the mechanism of (polycyclic aromatic hydrocarbon) PAH degradation, and to establish a proper joint phytomicrobial remediation mode, microcosms containing microorganisms and PAHs (pyrene and benzo\[a\]Pyrene) were added with clover (Trifolium repens) root exudates to study their effects on PAH degradation. Dioxygenase gene and 16S rDNA gene copy number changes during the biodegradation process were analyzed, and the microorganism with a good ability for degrading PAHs was identified. The results showed that Mycobacterium M1 had the capability to degrade PAHs. When total organic carbon (TOC) concentration of clover root exudates was 35.5 mg·L-1, pyrene and benzo\[a\]pyrene degradation rates increased significantly, and the proportion of dioxygenase gene to 16S rDNA of Mycobacterium M1 increased. In the biodegradation process, dioxygenase gene copy number increased significantly, whereas 16S rDNA copy number increase was not so obvious, showing that the former was related to degradation process, but the latter was related to microbial numbers. It was concluded that the clover root exudates promoted the dioxygenase gene copy number of Mycobacterium M1, which contributed to the degradation of PAHs.
     
    Effect of bamboo leaf biochar addition on soil CO2 efflux and labile organic carbon pool in a Chinese chestnut plantation.
    WANG Zhan-lei1,2, LI Yong-fu1,2, JIANG Pei-kun1,2, ZHOU Guo-mo1,2, LIU Juan1,2
    2014, 25(11):  3152-3160. 
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    Effect of biochar addition on soil CO2 efflux in a typical Chinese chestnut (Castanea mollissima) plantation in Lin’an, Zhejiang Province, China was investigated from July 2012 to July 2013 by the static closed chamberGC technique. Soil temperature, soil moisture, WSOC and MBC concentrations were determined as well. Results showed that soil CO2 efflux exhibited a strong seasonal pattern. Compared with the control (without biochar application), the biochar treatment increased the soil CO2 efflux only in the first month since application, and then the effect diminished thereafter. There were no significant differences in the annual cumulative value of soil CO2 efflux between the biochar and control treatments. The annual mean value in soil MBC concentration (362 mg·kg-1) in the biochar treatment was higher than that (322 mg·kg-1) in the control. However, no significant difference in the soil WSOC concentration was found between the biochar and control treatments. Strong exponential relationships between soil temperature and soil CO2 efflux were observed regardless of the treatment and soil layer. The apparent temperature sensitivity (Q10) of soil CO2 efflux in the biochar treatment was higher than that in the control. Soil CO2 efflux was related to soil WSOC concentration but not with soil MBC or moisture content. To conclude, the application of bamboo leaf biochar did not affect the annual cumulative CO2 emission in the Chinese chestnut plantation but increased the Q10, and the CO2 efflux was predominantly controlled by the soil temperature and soil WSOC level.
    Effects of biochar application on the vertical transport of NO3-N in the red soil and its simulation. 
    JING Yan1,2, CHEN Xiao-min1, LI Qiu-xia1, JIN Ze-wen1, HUANG Qian-ru2, ZHANG Jia-bao2, CHEN Chen1, LU Shao-shan1
    2014, 25(11):  3161-3167. 
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    Soil column experiments in laboratory were conducted to determine the effect of biochar application on the vertical transport of NO3-N in red soil. Biochar was mixed thoroughly with soil at rates of 0, 5, 10, 20, 30 and 40 t·hm-2, i.e., biochar/soil ratios of 0, 2.22%, 4.45%, 8.95%, 13.37% and 17.80%. The CXTFIT 2.0 model was used to simulate the breakthrough curve of NO3-N. The results were as follows: the breakthrough curve of NO3-N varied remarkably with the increase of biochar application rate under saturated condition. The peak values of relative concentration (C/Co), leaching rate and cumulative loss of NO3-N all significantly decreased with the increasing biochar application rate. There existed a certain prolongation of the breakthrough curves among all treatments.  The more the biochar was applied, the more obviously the breakthrough curve was prolonged. According to the correlation analysis between the NO3-N breakthrough curves and soil properties, biochar affected the bulk density, organic carbon, total porosity, CEC of red soil, which would exert an effect on the breakthrough curves. The simulation value and the actual obtained value of the breakthrough curves were positively correlated with the correlation coefficients being over 0.850 in all breakthrough curves, which indicated the CXTFIT 2.0 model could best fit the prediction of nitrateN transport and relative infiltration. These results could provide a scientific basis for predicting the effect of biochar on nitrateN in underground water after biochar incorporation into field.
    Source identification and potential ecological hazards assessment of trace metalloid/heavy metals in the soil of Tianshan Mountains, Xinjiang, China.
    ZHANG Zhao-yong1,2, JILILI Abuduwailil1, JIANG Feng-qing1
    2014, 25(11):  3168-3176. 
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    In this study, the contents of ten metalloid/heavy metals (As, Pb, Ni, Cd, Co, Hg, Cu, Mn, Zn and Cr) in soil samples collected from three sections including the central UrumqiAkesu, eastern BlikunYiwu and western ZhaosuTekesi in Tianshan Mountains were determined, and their sources were identified by using typical statistical and multivariate statistical methods. The potential ecological risks of these heavy metals were assessed by employing pollution index method, potential ecological risk index and the background values of Tianshan Mountains, and Xinjiang, and also the Second National Standard of the Soil Qualities of China. The results showed that the contents of the heavy metals (Pb, Ni, Cd, Co, Hg, Cu, Mn Zn and Cr) and metalloid As were all higher than the soil background values of the Tianshan Mountain or Xinjiang, and their variation coefficients belonged to the medium variation. In general, the contents of the ten metalloid/heavy metals in the soil of Tianshan Mountains were low. Principal component analysis showed that the ten metalloid/heavy metals could be identified as two principal components, among which PC1 (Cd, Pb, Hg, Mn and Zn) could be seen as ‘human influence sources factor’, PC2 (Cu, Ni, Cr, Co and As) as ‘natural sources factor’. Mn and As had larger loads both in PC1 and PC2, and they could be coinfluenced by human and natural sources. The pollution assessment showed that Hg and Cd in central UrumuqiAkesu section and As in western ZhaosuTekesi section were all at alert level, while the other heavy metals in other sections were all at security level. From the comprehensive pollution indices (Pz) of heavy metals, it was found that the ten metalloid/heavy metals in the soils of central UrumqiAkesu section were at low pollution level, but those in the other two sections were at clean level. The potential ecological risk assessment showed that the potential ecological risk coefficient (Eir) and the ecological damage index (RI) of Hg and Cd in central UrumqiAkesu section and that of As in western ZhaosuTekesi section were relatively high.
    Influence of weeds in Echinochloa on growth and yield of rice.
    ZHANG Zi-chang, LI Yong-feng, ZHANG Bin, YANG Xia
    2014, 25(11):  3177-3184. 
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    In order to investigate effects of different barnyardgrass species on growth and yiled of rice, two rice cultivars, Xinliangyou 6 hao (an indica hybrid cultivar) and Nanjing 46 (a japonica cultivar), were cocultured with four barnyardgrass species grown at a density of six plants·m-2 from 10 days after transplanting to maturity. The treatments were designed as follow: weed free (control), rice with Echinochloa crusgalli var. mitis  (T1), rice with E. crusgalli (T2), rice with E. crusgali var. zelayensis (T3), and rice with E. colonum (T4). The result showed that barnyardgrassinduced reductions in grain yield of rice were obviously different among the four treatments. T1, T2 and T3 treatments reduced the grain yield of indicia cultivar by 19.2%, 10.8% and 21.9%, and the respective reductions in japonica cultivar were 39.7%, 25.3% and 47.3%, respectively. However, no significant difference was detected for T4 treatment. During rice coculture with barnyardgrass, T1, T2 and T3 significantly reduced rice dry matter accumulation at maturity, flag leaf photosynthetic rate, root oxidation activity and the activity of adenosine triphosphate enzyme (ATPsse) in rice grains at the filling stage, and the magnitude of decrease was in the order of T3> T1 >T2, while no significant difference was observed between T4 and CK. In addition, all treatments had no effects on the final tiller number and plant height of rice. It indicated that the negative effect of barnyardgrass on rice growth and yield differed among the four species of barnyardgrass, in the order of T3>T1>T2>T4. Barnyardgrass reduced the flag leaf photosynthetic rate of rice, both root oxidation activity and ATPsse activity in grains, which resulted in the reduction in final productivity of rice when cocultured with barnyardgrass.
     
    Effects of nitrogen application rates on apparent soil nitrogen surplus of late sowing wheat with straw returning in ricewheat rotation.
    SHI Zu-liang, GU Dong-xiang, GU Ke-jun, ZHANG Chuan-hui, ZHANG Si-mei, YU Jian-guang, YANG Si-jun
    2014, 25(11):  3185-3190. 
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    Field experiments were conducted to study the effects of varying rates of nitrogen application on soil mineral nitrogen content, amount of nitrogen released from the straw, and grain yield of late sowing wheat with straw returning. The result showed that a high nitrogen fertilizer application rate enhanced the mineral nitrogen content in the soil layer of 0 to 50 cm, and also in the lower soil layers when using N at 270 and 360 kg·hm-2 with the advance of growth stages. The amount of nitrogen released form the straw increased as the nitrogen application rate increased; the lowest appeared from overwintering to jointing, and the highest from jointing to maturity. During the whole growing season, apparent nitrogen surplus occurred when the nitrogen application rate was higher than 180 kg·hm-2. The N surplus before jointing was significantly higher than that from jointing to maturity. Grain yield reached the highest at a nitrogen application rate of 270 kg·hm-2, and a higher application rate obviously decreased the nitrogen use efficiency. It could be concluded that applying nitrogen at 270 kg·him-2 could improve the grain yield of late sowing wheat with straw returning with the optimal ecological benefit.
     
    Effects of continuous cropping of wheat and alfalfa on soil enzyme activities and nutrients.
    ZHANG Li-qiong1,2, HAO Ming-de1,3, ZANG Yi-fei1, LI Li-xia4
    2014, 25(11):  3191-3196. 
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    Based on a long-term rotation and fertilization experiment in Changwu, Shaanxi, China, we determined the enzymatic activities and nutrients in soils after 27 years continuous cropping of alfalfa and wheat, respectively. The activities of invertase, urease and phosphatase were not affected by fertilization treatment within each cropping system, but they were significantly higher in the alfalfa continuous cropping system than in the wheat continuous cropping system under each fertilization treatment. The activity of hydrogen peroxidase  was not affected by the type of cropping system or fertilization treatment. Across the cropping systems, the activities of soil urease, phosphatase and hydrogen peroxidase were higher while soil invertase activity was lower in N, P and manure (NPM) combined treatment compared with the other fertilization treatments. The accumulations of soil organic matter, total nitrogen and available nitrogen were greater in the alfalfa cropping system than in the wheat continuous cropping system, and the NPM treatment could improve the soil fertility.
    Effects of plastic mulch on soil moisture and temperature and limiting factors to yield increase for dryland spring maize in the North China.
    LIU Sheng-yao1,2, ZHANG Li-feng1, LI Zhi-hong2, JIA Jian-ming2, FAN Feng-cui2, SHI Yu-fang2
    2014, 25(11):  3197-3206. 
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    Four treatments, including ridge tillage with plastic mulch (RP), ridge tillage without mulch (RB), flat tillage with plastic mulch (FP) and flat tillage without mulch (FB), were carried out to examine the tillage type and mulch on the effects of soil moisture and temperature, yield and water use efficiency (WUE) of dry land spring maize in the North China. Results showed that the average soil temperature was increased by 1-3 ℃ and the accumulated soil temperature was increased by 155.2-280.9 ℃ from sowing to tasseling by plastic mulch, and the growing duration was extended by 5.9-10.7 d. The water conservation effect of plastic mulch was significant from sowing to the seedling establishment, with WUE being increased by 81.6%-136.4% under mulch as compared with that without mulch. From the seedling to jointing stage, which coincided with the dry period in the region, soil water utilization by the maize under mulch could reach the depth of 80-100 cm, and its WUE was about 17.0%-21.6% lower than the maize without mulch, since the latter was affected by dry stress. With the coming of rainy season around the trumpeting stage, soil water in each treatment was replenished and maintained at relative high level up to harvest. Yield of maize was increased by 9.5% under RP as compared with RB. However, yield was reduced by 5.0% under FP, due to the plastic film under flat tillage prevented the infiltration of rainfall and waterlogging occurred. No significant difference in yield was found between RB and FB. Higher yield of spring maize was limited because of the mismatching in water supply and demand characterized by soil water shortage before the rainy season and abundant soil water storage after the rainy season.
    Effects of phosphorus sources on phosphorus fractions in rhizosphere soil of wild barley genotypes with high phosphorus utilization efficiency.
    CAI Qiu-yan, ZHANG Xi-zhou, LI Ting-xuan, CHEN Guang-deng
    2014, 25(11):  3207-3214. 
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    High P-efficiency (IS-22-30,IS-22-25) and low P-efficiency (IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization, and properties of phosphorus fractions in rhizosphere and nonrhizosphere in a pot experiment with 0 (CK) and 30 mg P·kg-1  supplied as only Pi (KH2PO4), only Po (phytate) or Pi+Po (KH2PO4+ phytate). The results showed that dry matter and phosphorus accumulation of wild barley in the different treatments was ranked as Pi> Pi+Po> Po>CK. In addition, dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency. The concentration of soil available phosphorus was significantly different after application of different phosphorus sources, which was presented as Pi> Pi+Po> Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low Pefficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley, especially in Pi and Pi+Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment, and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. The contents of Ca2-P and Ca8-P for high P-efficiency wild barley showed deficits in rhizosphere soil under each phosphorus source treatment. In addition, enrichment of Al-P and Fe-P was observed in Pi treatment in rhizosphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows: moderate labile organic phosphorus > moderate resistant, resistant organic phosphorus > labile organic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pi treatment. Furthermore, the concentrations of moderate resistant organic phosphorus and resistant organic phosphorus decreased in rhizosphere soil. The concentrations of labile and moderate labile organic phosphorus in rhizosphere soil of high P-efficiency wild barley were significantly higher than that of low P-efficiency wild barley in each phosphorus source treatment. However, moderate resistant organic phosphorus and resistant organic phosphorus concentrations had no significant difference between the two genotypes. Wild barley with high P-efficiency demonstrated a greater ability of mobilization and uptake Ca2 -P, Ca8-P, Al-P and labile organic phosphorus than that with low P-efficiency under Pi deficiency.
     
    Effects of mulching patterns on soil water, broomcorn millet growth, photosynthetic characteristics and yield in the dryland of Loess Plateau in China.
    SU Wang1, ZHANG Yan-ping1, QU Yang2, LI Cui1, MIAO Jia-yuan1, GAO Xiao-li1, LIU Jian-hua3, FENG Bai-li1
    2014, 25(11):  3215-3222. 
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    The objective of this study was to explore the effects of mulching patterns on soil water, growth, photosynthetic characteristics, grain yield and water use efficiency (WUE) of broomcorn millet in the dryland of Loess Plateau in China. In a threeyear field experiment from 2011 to 2013, we compared four different mulching patterns with traditional plat planting (no mulching) as the control (CK). The mulching patterns included W ridge covered with common plastic film + intredune covered with straw (SG), common ridge covered with common plastic film + intredune covered with straw (LM), double ridges covered with common plastic film + intredune covered with straw (QM), and the traditional plat planting covered with straw (JG). The results showed that the soil water storage in 0-100 cm layer was significantly higher in all mulching patterns than in CK, particularly in SG then followed by LM, QM and JG, and the differences among the mulching patterns reached a significant level at the different growth stages of broomcorn millet. Among all mulching patterns, SG had the greatest effect on the growth and photosynthesis of broomcorn millet, respectively increasing the yield and WUE by 55.9% and 64.9% over CK, and the differences among the mulching patterns also reached a  significant level. Therefore, SG was recommended as an efficient planting pattern for broomcorn millet production in the dryland of Loess Plateau in China.
    Effects of interaction of genotypes with environments on major latently fragrant substances of fluecured tobacco in Baoshan of Yunnan, Southwest China.
    SONG Shu-fang1,2, ZHOU Ji-heng1, LI Qiang1, ZHANG Yi-yang1, CHENG Chang-xin3, YANG Ying-ming3, SHEN Han1
    2014, 25(11):  3223-3228. 
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    To study the stability of major latently fragrant substances of flue-cured tobacco of different varieties in Baoshan of Yunnan, three tobacco cultivars (K326, Y87 and Y99) in two soil types at three test sites with different altitudes were tested. The contents of major latently fragrant substances were measured and the effects of genotypes, environments and their interactions were analyzed by AMMI model. The results showed that genotypes, environments and their interactions had significant effects on the contents of lutein, β-carotene, and chlorogenic acid. The rutin content was mainly influenced by genotypes while the major latently fragrant substances and their stability were affected significantly by the interactions of genotypes and environments. The contents of lutein, β-carotene, and chlorogenic acid increased remarkably with altitude, and their stabilities were strengthened to different extents. K326 adapted well to middle-lower altitude, while Y87 and Y99 adapted well to middlehigher altitude.

     
    Estimating individual tree aboveground biomass of the mid-subtropical forest using airborne LiDAR technology.
    LIU Feng1, TAN Chang1, LEI Pi-feng2
    2014, 25(11):  3229-3236. 
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    Taking Wugang forest farm in Xuefeng Mountain as the research object, using the airborne light detection and ranging (LiDAR) data under leafon condition and field data of concomitant plots, this paper assessed the ability of using LiDAR technology to estimate aboveground biomass of the midsubtropical forest. A semiautomated individual tree LiDAR cloud point segmentation was obtained by using condition random fields and optimization methods. Spatial structure, waveform characteristics and topography were calculated as LiDAR metrics from the segmented objects. Then statistical models between aboveground biomass from field data and these LiDAR metrics were built. The individual tree recognition rates were 93%, 86% and 60% for coniferous, broadleaf and mixed forests, respectively. The adjusted coefficients of determination (R2adj) and the root mean squared errors (RMSE) for the three types of forest were 0.83, 0.81 and 0.74, and 28.22, 29.79 and 32.31 t·hm-2, respectively. The estimation capability of model based on canopy geometric volume, tree percentile height, slope and waveform characteristics was much better than that of traditional regression model based on tree height. Therefore, LiDAR metrics from individual tree could facilitate better performance in biomass estimation.
    Spatial analysis of LAIe of montane evergreen broad-leaved forest in southwest Sichuan, Northwest China, based on image texture.
    ZHAO An-jiu1, YANG Chang-qing2, LIAO Cheng-yun2
    2014, 25(11):  3237-3246. 
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    Optical remote sensing is still one of the most attractive choices for obtaining leaf area index (LAI) information, but currently may be derived from remotely sensed data with limited accuracy. Effective leaf area index (LAIe) of montane evergreen broad-leaved forest  in southwest Sichuan was inventoried and assessed in 83 sample field plots of 20 m×20 m using different types of image processing techniques, including simple spectral band, simple spectral band ratios and principal component. Texture information was extracted by gray level co-occurrence matrices (GLCM) from different types of processing image. The results showed that there were correlations of different degrees between LAIe and texture parameters, and highly significant correlations were observed between LAIe with the homogeneity of the B1 band, B1/B4 band ratio or principal component PC1. Using texture information of remotely sensed data as auxiliary variables, we developed geostatistics models. Compared with the model based on NDVI auxiliary variable, the accuracy of LAIe were improved, presenting an increase by 5.3% with the homogeneity of the B1 band, 11.0% with the homogeneity B1/B4 band ratio, and 14.5% with the homogeneity principal component PC1, and the statistical errors were also reduced to some extent. The optimal LAIe model of spatial geostatistics was obtained when taking NDVI and homogeneity principal component PC1 as auxiliary variables (R2=0.840,RMSE=0.212). Our results provided a new way to estimate regional spatial distribution of LAI using other auxiliary variables besides the vegetation index.
    Spatial distribution of human activities and their influences on landscape patterns in Daqingshan Nature Reserve.
    SUN Ya-hui1, MENG Li2, TIAN Lü3, LI Guo-liang3, LI Yue-hui4, SUN Jian-xin1
    2014, 25(11):  3247-3254. 
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    Based on forest inventory data and field survey information, and by using GIS spatial analysis technique and landscape indices, this paper studied the spatial distribution of three categories of human activities (settlement, roads, and other sources of disturbances) and their impacts on landscape patterns in three subdivided regions, i.e., the west, central and east regions of the Daqingshan Nature Reserve in Inner Mongolia. Results showed that the impacts of human activities were stronger in the east and west regions and weaker in the central region. Among the three subdivided regions, the landscape pattern in the west region was predominantly affected by other sources of disturbances, making the landscape patterns of coniferous forests, broadleaf forests and shrubs tended to be of aggregated distribution; the central region was mainly affected by roads, resulting in reduced landscape patch aggregation of broadleaf forests and shrubs; the east region was mostly affected by settlement, resulting in increased fragmentation of coniferous forests and broadleaf forests and apparent increases in landscape patch aggregation of shrubs and grasslands.
     
    Dynamic changes of landscape pattern and hemeroby in Ximen Island wetland, Zhejiang Province, China.
    XIAO Cui, XIE Xue-feng, WU Tao, JIANG Guo-jun, BIAN Hua-jing, XU Wei
    2014, 25(11):  3255-3262. 
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    The hemeroby type classification system of Ximen Island wetland of Zhejiang Province was established based on the multiple datasets: SOPT-5 image data with a spatial resolution of 5 m in  2007 and 2010, its wetland land cover and land use status, the National Land Use Classification (on trail), and sea area use classification of marine industry standards as well as remote sensing data features. Meanwhile, the dynamic relationship between the landscape pattern and the degree of hemeroby in Ximen Island was investigated with the landscape indices and hemeroby index (HI) derived from the landscape pattern index and GIS spatial analysis. The results showed that the wetland landscape spatial heterogeneity, fragmentation and dominance index dropped, and the landscape shape index complexity was low. The human disturbance center developed from a dispersion type to a concentration type. The landscape type of the disturbance center was bare land and settlement. The HI rose up from the sea to the land. Settlement, wharf and traffic land had the highest HI. The HI of the mudflat cultivation, mudflats and raftcultivation dramatically changed. Marineterrestrial interlaced zone showed a low total HI with unstable characteristics. The number of patches declined of undisturbed, partially disturbed and completely disturbed landscapes. Mean patch areas of partially disturbed and completely disturbed landscapes increased, and that of the undisturbed decreased. Mean shape index of the undisturbed landscape decreased, while the partially disturbed and completely disturbed landscapes showed a trend of shape complication.
    Dynamics of salinization land based on EVI series data and landscape pattern analysis in Songnen Plain: A case study in Da’an City.
    LIU Shi-liang1, DONG Yu-hong2, AN Nan-nan1, WANG Jun3, ZHAO Hai-di1
    2014, 25(11):  3263-3269. 
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    The west part of Jilin Province is one of the most salinization regions in China and much attention has been  paid to the dynamics and monitoring of the salinization land. Based on the land use data derived from TM images in 2000, 2005 and 2010 and the enhanced vegetation index (EVI) series data from 2000 to 2012 of Da’an City as a typical salinization region, we used landscape pattern analysis to elucidate the dynamics of salinization land, and used gray incidence method to analyze the main driving factors for the dynamics of land salinization. The results showed that the dominant land use types in Da’an City were cultivated land, grassland and salinization land. From 2000 to 2010, the area of salinization land and construction land showed an increasing trend, while that of grassland tended to decrease. Salinization land, which showed increased connectivity and integrity, was mainly transformed from grassland, swamp land and water area. Annual EVI values in Da’an City showed an overall increasing trend while the average values showed obvious spatial differences with the lowest EVI level in salinization land. From 2000 to 2012, the increment of vegetation cover area was larger than that of the degraded area. Landscape transformation affected the changing trends of EVI. Both natural factors and human activities affected the dynamics of salinization land, and human activities showed a greater impact on land salinization than climate factors.
     
    Prediction method of rural landscape pattern evolution based on life cycle: A case study of Jinjing Town, Hunan Province, China.
    2014, 25(11):  3270-3278. 
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    Taking Jinjing Town in Dongting Lake area as a case, this paper analyzed the evolution of rural landscape patterns by means of life cycle theory, simulated the evolution cycle curve, and calculated its evolution period, then combining CA-Markov model, a complete prediction model was built based on the rule of rural landscape change. The results showed that rural settlement and paddy landscapes of Jinjing Town would change most in 2020, with the rural settlement landscape increased to 1194.01 hm2 and paddy landscape greatly reduced to 3090.24 hm2. The quantitative and spatial prediction accuracies of the model were up to 99.3% and 96.4%, respectively, being more explicit than single CA-Markov model. The prediction model of rural landscape patterns change proposed in this paper would be helpful for rural landscape planning in future.
    Changes of climate and fire dynamic in China vegetation zone during 1961-2010. 
    TIAN Xiao-rui, ZHAO Feng-jun, SHU Li-fu, MIAO Qing-lin, WANG Ming-yu
    2014, 25(11):  3279-3286. 
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    Climate, vegetation and human activities have influences on regional fire regimes. To understand the fire regimes for ecological zones on national scale is the base for carrying on the forest fire management. Daily observed temperature and precipitation data in 1961-2010 were interpolated into grids for China mainland with spatial resolution of 0.25° × 0.25°, which was used to analyze their changes in fire season for eight ecological zones. Mann-Kendall test method was used for trend analysis of climate and fire dynamics. The results indicated that the average temperature for the areas with forests showed a significant linear upward trend in 1961-2010, but the precipitation didn’t have the tendency. The average temperature in fire season for all the ecological zones increased significantly in the study period, and the most increment occurred in temperate semiarid/arid steppe regions. There was no significant change in precipitation in fire season for most regions. Forest fire numbers for the mainland showed obvious fluctuations, but the affected forest areas decreased significantly. The curves of fire numbers and affected forest areas showed a bimodal shape for all ecological zones, except those showed a significant increase in the coniferous forest region in the temperate arid areas.

     
    Effect of water depths on hydraulic performance of pond wetlands.
    GUO Chang-qiang1, DONG Bin1, LIU Jun-jie1, LIU Chun-guo1, FENG Da-peng1, LIU Fang-ping2
    2014, 25(11):  3287-3295. 
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    Pond wetlands have been widely used in the treatment of drainage water from paddy fields. However, wetland hydraulic performance and purification effects are affected by many factors, such as water depth, flow rate, aspect ratio and vegetation distribution, and the better understanding of these factors would be helpful to improve the quality of wetland design, operation and management. This paper analyzed the effect of three different water depths (20, 40 and 60 cm) on the hydraulic performance of pond wetland through the dye tracer experiments with Rhodamine WT. The hydraulic indices, i.e., effective volume ratio, nominal serial complete mixing tanks (N), hydraulic efficiency (λ), were selected for analysis through the hydraulic residence time distribution (RTD) curve. The results showed that the effective volume rate rose from 0.421 to 0.844 and the hydraulic efficiency from 0.281 to 0.604 when the water depth declined from 60 cm to 20 cm. This indicated that the wetland hydraulic performance improved as the water depth decreased. In addition, the hydraulic performance of the first half of the wetland was significantly better than that of the second half. The flow regime of the first half approached complete mixing because of the mixing index (N) approaching 1 and its effective volume rate was above 0.9 when the water depth was relatively low (20 and 40 cm). The normalized RTD curves demonstrated a good agreement between moment analysis parameters and hydraulic parameters, and a great consistency between the hydraulic parameters and moment index which was not affected by tail truncation error. The experimental study concluded that a lower water depth was favorable to improve the hydraulic performance of pond wetlands.
    Accuracy evaluation of the TRMM satellite-based precipitation data over the mid-high latitudes.
    CAI Yan-cong1,2, JIN Chang-jie1, WANG An-zhi1, GUAN De-xin1, WU Jia-bing1, YUAN Feng-hui1, XU Lei-lei1, BU Chang-qian3
    2014, 25(11):  3296-3306. 
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    Satellite-based precipitation product plays a significant role in analyzing spatial pattern of precipitation. TRMM 3B42 (3B42), as one of important precipitation products, is a key forcing factor for ecological, climate and hydrological models with its sufficient spatial and temporal scales. At present, there is still limited knowledge of accuracy and error structure of new version 3B42 V7, especially the lack of evaluating its accuracy in regions of mid-high latitudes, which restricts its application in the field of ecology, climate and hydrology. Based on 3B42 V7 product and data obtained from 53 weather stations in the period of 1998-2012 over Inner Mongolia, the paper evaluated the accuracy of 3B42 and revealed the spatial distribution of accuracy evaluation indices and its influencing factors. The result of overall accuracy evaluation indicated that there was overestimation of the amount of precipitation by 3B42 at daily, monthly and annual timescales. Error of 3B42 increased with the increasing  timescale, and mean error and mean absolute error of daily precipitation were just -0.06 and 0.88 mm, respectively. It showed good performance for detecting the occurrence of rain events with equitable threat score (ETS) of 0.23, but slightly overestimated the frequency of rainy events. Moreover, altitude and average annual precipitation had impacts on data accuracy. The absolute error of precipitation decreased and yet the ability of detecting rain events became weak with the increasing  altitude, while the effect of average annual precipitation on data accuracy was opposite.
    Interactions of straw, nitrogen fertilizer and bacterivorous nematodes on soil labile carbon and nitrogen and greenhouse gas emissions.
    ZHANG Teng-hao, WANG Nan, LIU Man-qiang, LI Fang-hui, ZHU Kang-li, LI Hui-xin, HU Feng
    2014, 25(11):  3307-3315. 
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    A 3×2 factorial design of microcosm experiment was conducted to investigate the interactive effects of straw, nitrogen fertilizer and bacterivorous nematodes on soil microbial biomass carbon (Cmic) and nitrogen (Nmic), dissolved organic carbon (DOC) and nitrogen (DON), mineral nitrogen (NH4+-N and NO3--N), and greenhouse gas (CO2, N2O and CH4) emissions. Results showed that straw amendment remarkably increased the numbers of bacterivorous nematodes and the contents of Cmic and Nmic, but Cmic and Nmic decreased with the increasing dose of nitrogen fertilization. The effects of bacterivorous nematodes strongly depended on either straw or nitrogen fertilization. The interactions of straw, nitrogen fertilization and bacterivorous nematodes on soil DOC, DON and mineral nitrogen were strong. Straw and nitrogen fertilization increased DOC and mineral nitrogen contents, but their influences on DON depended on the bacterivorous nematodes. The DOC and mineral nitrogen were negatively and positively influenced by the bacterivorous nematodes, respectively. Straw significantly promoted CO2 and N2O emissions but inhibited CH4 emission, while interactions between nematodes and nitrogen fertilization on emissions of greenhouse gases were obvious. In the presence of straw, nematodes increased cumulative CO2 emissions with low nitrogen fertilization, but decreased CO2 and N2O emissions with high nitrogen fertilization on the 56th day after incubation. In summary, mechanical understanding the soil ecological process would inevitably needs to consider the roles of soil microfauna.
     
    Community structure and diversity of entophytic bacteria in Tricholoma matsutake in Sichuan Province, Southwest China.
    LI Qiang1, LI Xiao-lin2, HUANG Wen-li3, XIONG Chuan1, YANG Yang1, YANG Zhi-rong1, ZHENG Lin-yong1,4
    2014, 25(11):  3316-3322. 
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    In order to understand the diversity and community structure of endophytic bacteria in Tricholoma matsutake, 14 Tricholoma matsutake samples were collected from 7 main production counties of Xiaojin, Yajiang, Muli, Yanyuan, Yanbian, Huidong and Mianning. The entophytic bacterial community structure and diversity were investigated by PCR denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the diversity and community structure of endophytic bacteria in T. matsutake varied significantly, while those from the environments alike had high similarity. In addition, each T. matsutake sample contained more than 15 species of endophytes, with that from Yanyuan having the highest endophytes diversity index and abundance, while those from Xiaojin were the lowest. Phylogenetic tree showed that endophytic bacterial species in T. matsutake were abundant. Dominant bacterial population in T. matsutake collected from different places varied, and Pseudomonas, Ewingella and Bacillus were distributed in all samples and retained a certain advantage. Alcaligenes and Sphingobacterium distributed in most samples, while Duganella and Lysinibacillus only in certain ones. This study demonstrated that the endophytic bacteria in T. matsutake were abundant and diversified, which could be in favor of searching the dominant bacteria promoting the growth of T. matsutake. 
    Impact of biocontrol agent Bacillus subtilis on bacterial communities in tobacco rhizospheric soil.
    YOU Cai1, ZHANG Li-meng2, JI Si-gui2, GAO Jia-ming3, ZHANG Cheng-sheng1, KONG Fan-yu1
    2014, 25(11):  3323-3330. 
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    The impact of inoculation with the biocontrol agent Bacillus subtilis on bacterial communities and bacterial diversity in rhizospheric soil of Nicotiana tabacum was assessed by constructing a 16S rRNA gene clone library and conducting amplified ribosomal DNA restriction analysis (ARDRA). The bacterial diversity was evaluated by coverage value (C), Shannon index (H), Pielou evenness index (E) and Margalef richness index (R). Phylogenetic analysis revealed that the inoculation significantly affected the composition of bacterial communities in tobacco rhizospheric soil. A total of twelve bacterial groups including Acidobacteria, Proteobacteria (including α, β, δ, γ-Proteobacteria), Planctomycetes, Firmicutes, Nitrospirae, Gemmatimonadetes, Actinobacteria, Chloroflexi and Bacteroidetes were detected to be shared by inoculated soil and control soil. The community composition and proportions of different bacteria in the communities showed significant variations between the two samples. The dominant bacteria were Acidobacteria (27.1%) and Proteobacteria (26.5%) in control soil, while in the inoculated soil Proteobacteria (38.0%) and Acidobacteria (29.6%) were dominant. B. subtilis inoculation increased the numbers of γ-Proteobacteria and α-Proteobacteria but reduced the numbers of bacterial groups such as β-Proteobacteria, Planctomycetes, Firmicutes. Diversity analysis showed that bacterial diversity was rich for both soil samples, and soil bacterial Shannon index and Margalef richness index were promoted after inoculation.
    Species diversity and temporal niche of entomopathogenic fungi in the extensively managed tea plantation soil.
    GUO Xian-jian1, SHEN Wan-fang2, LIU Yu-jun1, CHEN Ming-jun1
    2014, 25(11):  3331-3336. 
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    The species diversity and temporal niche of entomopathogenic fungi community in the rhizosphere soil collected from the extensively managed Huangshan fuzz tip tea plantation were investigated. A total of 140 soil samples were collected at the location of Tangkou Town, Huangshan of Anhui Province during August, 2012 to June, 2013, and totally 1041 fungal isolates were obtained on selective medium with soil dilution plating. The results showed that the entomopathogenic fungi community in the tea plantation soil was diverse with 13 species in 6 genera. Purpureocillium lilacinum (309 strains), Beauveria bassiana (255 strains), and Metarhizium anisopliae (101 strains) were the dominant species accounting for 29.7%, 24.5% and 9.7% of the relative frequency, respectively. P. lilacinum had the widest temporal niche breadth among these dominant entomopathogenic fungi from the tea plantation soil, while B. bassiana had the narrowest. Among the entomopathogenic fungi, B. bassiana and B. brongniartii had the biggest temporal niche overlap of 1.965, while Isaria javanicus and B. bassiana had the smallest of 0.374.
    Recovery growth of Microcystis aeruginosa after the sub-high temperature stress.
    LI Ting1,2, JING Yuan-shu1,2,3, HAN Wei1,2, ZHANG Xiao-yi3
    2014, 25(11):  3337-3343. 
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    Recovery growth of Microcystis aeruginosa after sub-high temperature stress was investigated in this paper. The treated groups under 35 ℃ were cultured for 3, 6, and 12 days before being transferred to normal conditions, and the algae under 25 ℃ all the time was set as the control. Cell density, chlorophyll a, carotenoid, malondialdehyde and antioxidant enzymes activities were measured. The results showed that the growth of M. aeruginosa was inhibited significantly under the sub-high temperature stress. The cell density and chlorophyll a content were 14.5% and 22.3% lower than the control respectively on the 12th day, but carotenoid synthesis was not inhibited obviously. The longer the stress was, the higher the malondialdehyde content and SOD, CAT activities became. After the relief of stress, algal cells got recovered with the decreasing malondialdehyde content and antioxidase activities. The 3-, 6- and 12-day stress treatments at 35 ℃ showed undercompensation, overcompensation and exactcompensation, respectively, indicating that the compensatory degree was decided by the time under stress. As the recovery time proceeded, the difference between treated groups and the control reduced gradually. The growth parameters tended to be stable. Regression equations of cell density and chlorophyll a changing with the stress time and recovery time were revealed. The compensation effect of M. aeruginosa was similar to the process of algal bloom. According to this endogenous biological characteristic, this study provided a theoretical support for prediction system of algal bloom.
    Bacterial diversity in the mantle of Patinopecten yessoensis revealed by 454 pyrosequencing.
    DING Jun, DOU Yan, XU Gao-rong, WANG Yi-nan, CHANG Ya-qing
    2014, 25(11):  3344-3348. 
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    Pyrosequencingtechnique was used to analyze and compare bacterial diversity in the mantle of healthy and incised symptoms of Patinopecten yessoensis, respectively. For the two samples, 20872 and 16333 effective sequences were selected and utilized to perform bacterial diversity analysis, respectively. Bacterial diversity and richness in the incised samples were higher than that in the healthy samples. The effective sequences acquired from both samples included eight known phyla bacteria, i.e., Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Cyanobacteria, Planctomycetes, Spirochaetes and Tenericutes, among which the front seven phyla were present in the two samples. Proteobacteria was absolutely dominant in the mantle of healthy P. yessoensis accounting for 97.7% of the entire bacterial community, and Firmicutes was the subdominant group accounting for 0.8%. In contrast, the most abundant bacterial group in the mantle of incised P. yessoensis was Firmicutes, accounting for 52.2% of the entire bacterial community, and the sub-dominant was Proteobacteria accounting for 47.7%.
    Effects of lipid extraction on stable carbon and nitrogen isotope analyses of Ommastrephes bartramii muscle
    GONG Yi1, CHEN Xin-jun1,2,3, Gao Chun-xia1,2,3, LI Yun-kai1,2,3
    2014, 25(11):  3349-3356. 
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    Stable isotope analysis (SIA) has become an important tool to investigate diet shift, habitat use and trophic structure of animal population. Muscle is considered to be the most common tissue for SIA, however, lipid content in muscle causes a considerable bias to the interpretation of isotopic ratios of animals. Neon flying squid (Ommastrephes bartramii) is an important economic cephalopod of Chinese distant water fishery, and plays a major role in marine ecosystems. In this study, the effects of lipid extraction on stable isotope ratios of the muscles of 53 neon flying squids were investigated and the interference mechanism of lipid in SIA was clarified with the aim of contrasting the suitability of different lipid correction models of stable carbon isotope. Results showed that the stable carbon and nitrogen isotopic values of non-lipid extracted samples significantly increased after lipid extractions by 0.71‰ and 0.47‰, respectively, which suggested that lipid extraction in cephalopod isotope study is needed prior to stable carbon isotope analysis but not recommended for stable nitrogen isotope analysis. The results could help remove the effects of lipid contents and standardize SIA muscle samples, thereby getting better understanding of the isotopic change of neon flying squids in the future.
     
    Research advances in macroinvertebrate ecology of the stream hyporheic zone.
    ZHANG Yue-wei1,2,3, YUAN Xing-zhong1,2,3, LIU Hong1, REN Hai-qing1,2,3
    2014, 25(11):  3357-3365. 
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    The stream hyporheic zone is an ecotone of surface waterground water interactions, which is rich in biodiversity, and is an important component of stream ecosystem. The macroinvertebrates, which are at the top of food webs in the hyporheic zone to directly influence the matter and energy dynamics of the hyporheic zone, and are potential indicators of river ecological health to adjust the function of environment purification and ecological buffer. The macroinvertebrates in the hyporheic zone are divided into three categories: stygoxenes, stygophiles and stygobites. The key factors which influenced macroinvertebrates distribution in the hyporheic zone are physical size of interstitial spaces, interstitial current velocity, dissolved oxygen (DO), water temperature, available organic matter, hydraulic conductivity and hydraulic retention time. A suitable sampling method should be used for diverse research purposes in the special ecological interface. In the future, some necessary researches should focus on the lifehistory and life history strategy of the macroinvertebrates in the hyporheic zone, the quantitative analysis on the matter and energy dynamics in the ecological system of stream, the assessment systems of river ecological health based on the macroinvertebrates of the stream hyporheic zone, and the ecological significance of the hyporheic zone as a refuge for distribution and evolution of the macroinvertebrates.
    Characteristics of carbon storage of Inner Mongolia forests: A review.
    YANG Hao, HU Zhong-min, ZHANG Lei-ming, LI Sheng-gong
    2014, 25(11):  3366-3372. 
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    Forests in Inner Mongolia account for an important part of the forests in China in terms of their large area and high living standing volume. This study reported carbon storage, carbon density, carbon sequestration rate and carbon sequestration potential of forest ecosystems in Inner Mongolia using the biomass carbon data from the related literature. Through analyzing the data of forest inventory and the generalized allometric equations between volume and biomass, previous studies had reported that biomass carbon storage of the forests in Inner Mongolia was about 920 Tg C, which was 12 percent of the national forest carbon storage, the annual average growth rate was about 1.4%, and the average of carbon density was about 43 t·hm-2. Carbon storage and carbon density showed an increasing trend over time. Coniferous and broadleaved mixed forest, Pinus sylvestris var. mongolica forest and Betula platyphylla forest had higher carbon sequestration capacities. Carbon storage was reduced due to human activities such as thinning and clear cutting. There were few studies on carbon storage of the forests in Inner Mongolia with focus on the soil, showing that the soil carbon density increased with the stand age. Study on the carbon sequestration potential of forest ecosystems was still less. Further study was required to examine dynamics of carbon storage in forest ecosystems in Inner Mongolia, i.e., to assess carbon storage in the forest soils together with biomass carbon storage, to compute biomass carbon content of species organs as 45% in the allometric equations, to build more speciesspecific and sitespecific allometric equations including root biomass for different dominant species, and to take into account the effects of climate change on carbon sequestration rate and carbon sequestration potential.
    Microbial response mechanism for drying and rewetting effect on soil respiration in grassland ecosystem: A review.
    HE Yun-long1,2, QI Yu-chun1, DONG Yun-she1, PENG Qin1, SUN Liang-Jie1,2, JIA Jun-qiang1,2, GUO Shu-fang 1,2, YAN Zhong-qing1,2
    2014, 25(11):  3373-3380. 
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    As one of the most important and wide distribution community type among terrestrial ecosystems, grassland ecosystem plays a critical role in the global carbon cycles and climate regulation. China has extremely rich grassland resources, which have a huge carbon sequestration potential and are an important part of the global carbon cycle. Drying and rewetting is a common natural phenomenon in soil, which might accelerate soil carbon mineralization process, increase soil respiration and exert profound influence on microbial activity and community structure. Under the background of the global change, the changes in rainfall capacity, strength and frequency would inevitably affect soil drying and wetting cycles, and thus change the microbial activity and community structure as well as soil respiration, and then exert important influence on global carbon budget. In this paper, related references in recent ten years were reviewed. The source of soil released, the trend of soil respiration over time and the relationship between soil respiration and microbial biomass, microbial activity and microbial community structure during the processes of dry-rewetting cycle were analyzed and summarized, in order to better understand the microbial response mechanism for drying and rewetting effecting on soil respiration in grassland ecosystem, and provide a certain theoretical basis for more accurate evaluation and prediction of future global carbon balance of terrestrial ecosystems and climate change.