Table of Content

18 March 2012, Volume 23 Issue 03

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Articles

Stoichiometric characteristics of leaf carbon, nitrogen, and phosphorus of 102 dominant species in forest ecosystems along the North-South Transect of East China.

2012, 23(03):  581-586. 

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One hundred and twelve sampling sites in the forest ecosystems along the North-South Transect of Eastern China (NSTEC) were selected to study the stoichiometric characteristics and variability of leaf carbon (C), nitrogen (N), and phosphorous (P) of 102 dominant species. The contents of leaf C (Cmass), leaf N (Nmass), and leaf P (Pmass) ranged in 374.1-646.5 mg·g-1, 8.4-30.5 mg·g-1, and 0.6-6.2 mg·g-1, with the arithmetic mean (AM) being 480.1, 183 and 2.0 mg·g-1, and the variation coefficient (CV) being 11.1%, 27.5%, and 56.4%, respectively. The leaf C/N, C/P and N/P ranged from 14.1 to 64.1, from 70.9 to 838.6, and from 1.5 to 21.2, with the AM being 29.1, 313.9 and 11.5, and the CV being 32.8%, 48.3% and 44.1%, respectively. The mass ratio of C:N:P was 313.9:11.5:1, and the atom ratio was 8109:254:1. As compared with those at global scale, the tree leaf Cmass and C/N in the study area were significantly higher, Nmass and N/P were significantly lower, while Pmass and C/P had less differences.

Foliar water use efficiency and nitrogen use efficiency of dominant plant species in main forests along the North-South Transect of East China.

2012, 23(03):  587-594. 

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Based on the measurements of the foliar carbon content (Cmass), nitrogen content (Nmass), isotope abundance (δ13C and δ15N), and light response curve of 10 dominant plant species (Larix gmelinii, Quercus mongolica, Fraxinus mandshurica, Tilia amurensis, Acer mono, Pinus koraiensis, Cunninghamia lanceolata, Schima superba, Pinus massoniana, and Castanea henryi) in the main forests along the North-South Transect of Eastern China (NSTEC), this paper analyzed the differences  and the relationships between the foliar water use efficiency and nitrogen use efficiency of the plant species. There existed significant differences in the foliar Nmass and δ15N among the plant species, manifesting as broadleaved species > coniferous species, and deciduous species > evergreen species. The maximum photosynthetic rate (Pn max) was coniferous species > broadleaved species, and deciduous species > evergreen species. Broadleaved and evergreen species tended to have higher foliar instantaneous water use efficiency (WUEi) and long-term water use efficiency (WUE), as compared to coniferous and deciduous species, but an opposite trend was observed in the foliar instantaneous nitrogen use efficiency (NUEi) and long-term nitrogen use efficiency (NUE). Moreover, there was a significant difference in the foliar NUE between evergreen and deciduous species. No significant correlation was observed between WUEi and WUE, but a significant positive correlation existed between NUEi and NUE. There was a significant negative correlation between the foliar water use efficiency and nitrogen use efficiency at instantaneous or long-term time scales. In sum, the foliar water use efficiency and nitrogen use efficiency were dominated by plant life-form, and a trade-off existed between the two resources use efficiencies.

Effects of mixed decomposition of Populus simonii and other tree species leaf litters on soil properties in Loess Plateau.

2012, 23(03):  595-602. 

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In this study, the leaf litters of Populus simonii and other 11 tree species were put into soil separately or in mixture after grinding, and incubated in laboratory to analyze the effects of their decomposition on soil properties and the interactions between the litters decomposition. The decomposition of each kind of the leaf litters in soil increased the soil urease, dehydrogenase, and phosphatase activities and the soil organic matter and available N contents markedly, but had greater differences in the effects on the soil available P content and CEC. The decomposition of the leaf litters of Caragana microphylla and of Amorpha fruticosa showed obvious effects in improving soil properties. The decomposition of the mixed leaf litters of P. simonii and Pinus tabulaeformis, Platycladus orientalis, Robinia pseudoacacia, or Ulmus pumila showed interactive promotion effects on the abundance of soil microbes, and that of the mixed leaf litters of P. simonii and P. orientalis or C. microphylla showed interactive promotion effects on the soil organic matter, available P, and available K contents and soil CEC but interactive inhibition effects on the activities of most of the soil enzymes tested. The decomposition of the mixed leaf litters of P. simonii and Larix principis-rupprechtii showed interactive promotion effects on the activities of most of the soil enzymes and soil nutrient contents, while that of the mixed leaf litters of P. simonii and P. sylvestris var. mongolica showed interactive inhibition effects. Overall, the decomposition of the mixed leaf litters of P. simonii and U. pumila, P. tabulaeformis, L. principis-rupprechtii, or R. pseudoacacia could improve soil quality, but the mixed leaf litters of P. simonii and P. orientalis, C. microphylla, P. sylvestris var. mongolica, Hippophae rhamnoides, or A. fruticosa showed an interactive inhibition effect during their decomposition.

Responses of Picea likiangensis radial growth to climate change in the Small Zhongdian area of Yunnan Province, Southwest China.

2012, 23(03):  603-609. 

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Picea likiangensis (Franch.) Pritz. primary forest is one of the dominant forest types in the Small Zhongdian area in Shangri-La County of Yunnan Province. In this paper, the responses of P. likiangensis tree-ring width to climate change were analyzed by dendrochronological methods, and the dendrochronology was built by using relatively conservative detrending negative exponential curves or linear regression. Correlation analysis and response function analysis were applied to explore the relationships between the residual chronology series (RES) and climatic factors at different time scales, and pointer year analysis was used to explain the reasons of producing narrow and wide rings. In the study area, the radial growth of P. likiangensis and the increasing air temperature from 1990 to 2008 had definite ‘abruption’. The temperature and precipitation in previous year growth season were the main factors limiting the present year radial growth, and especially, the temperature in previous July played a negative feedback role in the radial growth, while the sufficient precipitation in previous July promoted the radial growth. The differences in the temperature variation and precipitation variation in previous year were the main reasons for the formation of narrow and wide rings. P. likiangensis radial growth was not sensitive to the variation of PDSI.

Characteristics of soil net nitrogen  mineralization in subalpine/alpine forests of west Sichuan, Southwest China during seasonal freeze-thaw period.

2012, 23(03):  610-616. 

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Seasonal freeze-thaw cycle and its change pattern under the scenarios of climate warming might exert strong effects on the soil nitrogen mineralization in alpine forests. In this paper, intact soil cores were collected from the subalpine/alpine forests along an altitudinal gradient in west Sichuan, and an incubation test was conducted to study the soil  net nitrogen mineralization rate and the amount of soil mineralized nitrogen in the forests during growth season and seasonal freeze-thaw period under simulated scenarios of global warming. In the test soils, the NH4+-N and NO3--N contents both showed a clear tendency of decreased in the period from growth season to the onset stage of freezing, increased at deep freezing stage, and decreased again at the early stage of thawing. The soil net nitrogen  mineralization rate and the amount of soil mineralized nitrogen were significantly lower in freeze-thaw period than in growth season, and the
soil inorganic nitrogen was obviously immobilized. The soil nitrogen immobilization was stronger at middle altitudes but weaker at high altitudes, as compared with that at low altitudes, possibly due to the variation of soil temperature and its induced different freeze-thaw cycle. During growth period, the soil  net nitrogen mineralization rate and the amount of soil mineralized nitrogen showed an obvious increasing trend with the decrease of altitude, and the soil nitrogen mineralization was the strongest at low altitudes, implying that under the scenarios of climate warming, the increase of soil temperature promoted the soil nitrogen mineralization during growth season, and affected the soil nitrogen mineralization rate by increasing the frequency of freeze-thaw cycle and shortening the time period of freeze-thaw. Soil micro-environment could also affect the soil nitrogen mineralization in alpine forest regions.

Effects of the variations in precipitation and temperature on
photosynthetic parameters and growth of Fraxinus mandshurica seedlings  in Changbai Mountains of Northeast China.

2012, 23(03):  617-624. 

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Taking Fraxinus mandshurica, a main tree species in the temperate zone of Northeast China, as test material, two experimental sites were installed at the altitudes 740 m and 1200 m in Changbai Mountains, respectively, and three precipitation regimes including 30% precipitation enhancement (+W), 30% precipitation deduction (-W), and naturally occurring precipitation (CK) were designed, aimed to investigate the effects of the variations in precipitation and temperature on the photosynthesis in Fraxinus mandshurica seedlings, with their growth, leaf photosynthetic parameters, and leaf soluble protein and photosynthetic pigment contents examined. Temperature variation had significant effects on the growth and photosynthesis of the seedlings. For the seedlings grown at altitude 740 m, their stem basal diameter, plant height, and leaf chlorophyll and soluble protein contents under the three precipitation regimes had significant increase, leaf carotenoid content decreased, leaf net photosynthesis rate, stomatal conductance, transpiration rate, and stomatatal limitation all increased significantly, whereas leaf intercellular CO2 concentration and water use efficiency had significant decrease, as compared with the seedlings grown at altitude 1200 m. Non-stomatal factors limitation was the main reason for the decrease of the seedlings photosynthetic capacity. Precipitation variation had little effects on the growth and photosynthesis of F. mandshurica seedlings.

Effects of NaCl and Na2CO3 stresses on the growth and photosynthesis characteristics of Morus alba seedlings. 〖STBZ〗

2012, 23(03):  625-631. 

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Taking 1-year old Morus alba variety ‘Qinglong’ seedlings as test materials, this paper studied their
 growth and photosynthetic characteristics under the stresses of different concentration neutral salt NaCl and alkali salt Na2CO3. Salt stresses decreased the plant height and the leaf number, biomass, and photosynthetic capacity of the seedlings markedly. With increasing concentration Na+, the leaf stomatal conductance, transpiration rate, net photosynthetic rate, actual photochemical efficiency, electron transport rate, and photochemical quenching (qP) decreased obviously, the energy dissipation rate increased, and the light use efficiency and photosynthetic capacity dropped down. At low concentrations Na+〖KG*5〗(＜150 mmol·L-1), the seedlings growth and leaf photosynthetic capacity were slightly inhibited, and the adaptability of the seedlings to the salt stresses increased via the increase of root/shoot ratio. However, this protection mechanism was impaired by increasing salt concentration. Na2CO3 stress (Na+ concentration＞50 mmol·L-1) had stronger inhibitory effects on the seedlings growth and leaf photosynthetic capacity, and the effect increased with increasing Na+ concentration. It was concluded that at Na+ concentration ＜150 mmol·L-1, the photosynthetic adaptability of M. alba to neutral salt stress was mainly dependent on the plant morphology and photosynthetic metabolism, but at Na+ concentration ＞150 mmol·L-1, the photosynthetic adaptability of M. alba to alkali salt stress was mainly dependent on the photosynthetic metabolism.

Effects of drought stress and nitrogen fertilization rate on the accumulation of osmolytes in Jatropha curcas seedlings.

2012, 23(03):  632-638. 

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A pot experiment with controlled water supply was conducted to study the effects of different drought stress degree (80% FC, 60% FC, 40% FC, and 20% FC) and nitrogen fertilization rate (0 g·pot-1, 1.2 g·pot-1, 3.6 g·pot-1, and 6.0 g·pot-1） on the accumulation of osmolytes in different organs of Jatropha curcas seedlings. Under drought stress, the soluble protein and free proline in seedling shoots and roots and the soluble sugar in seedling shoots had a great accumulation, and the free proline content in seedling leaves had a great increase with increasing drought stress degree. Also under drought stress, the Na+, Ca2+, and Mg2+ all highly accumulated in seedling various organs, while K+ only accumulated greatly in shoots but slightly in leaves and roots. The effects of nitrogen fertilization on the accumulation of osmolytes in seedlings  depended on drought stress degree and nitrogen fertilization rate. At 80% FC and 60% FC, increasing nitrogen fertilization rate could markedly promote the accumulation of osmolytes in the organs of J. curcas seedlings; at 40% FC, applying 6.0 g·pot-1 weakened the promotion effect on the osmolytes accumulation; whereas at 20%, applying 1.2 g·pot-1 made the plants have a higher capability in osmoregulation, but applying 3.6 g·pot-1 and 6.0 g·pot-1 had less promotion effect, and even, inhibited osmolytes accumulation.

Effects of different water-saving irrigation modes on chestnut growth and fruiting in drought hilly land.

2012, 23(03):  639-644. 

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Taking the chestnut trees in a semi-arid and semi-humid hilly orchard of Tai’an, Shandong Province of East China as test objects, a field experiment was conducted to study the effects of different water-saving irrigation modes (pottery jar storing water, small hole storing water, and border irrigation with covering) on the soil moisture characteristics and the growth, fruiting, and development of chestnut roots. Comparing with the control (border irrigation), all the three water-saving irrigation modes could prolong the period of soil keeping moist, and the best effect came from pottery jar treatment, with the soil keeping moist for 32 days, 13 days longer than the control. Under water-saving irrigations, the bearing branches length and number, leaf area and mass, and shoot mixed buds all increased obviously. Both pottery jar storing water and small hole storing water could irrigate deeper roots and induce root growth in deeper soil layers, and thus, relieve the drought stress on superficial roots. The three water-saving irrigation modes could increase chestnut yield markedly, with an increment of 18.8%, 16.5%, and 14.2%, respectively, as compared with the control.

Characteristics of soil microelements contents in the rhizospheres of different vegetation  in hilly-gully region of Loess Plateau.

2012, 23(03):  645-650. 

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To explore the rhizosphere effect of the microelements in the soils under different vegetation types in Loess Plateau, this paper analyzed the organic C, total N, Mn, Cu, Fe, and Zn contents in the rhizosphere soil and bulk soil of six vegetation types in hilly-gully region of Loess Plateau. Among the six vegetation types, Caragana korshinskii, Heteropappus altaicus, and Artemisia capillaries had higher organic C and total N contents in rhizosphere soil than in bulk soil. With the exception of C. korshinskii and H. rhamnoides, all the six vegetation types had a significantly lower pH in rhizosphere soil than in bulk soil. The six vegetation types had a lower available Mn content in rhizosphere soil than in bulk soil, and the C. korshinskii, Astragalus adsurgen, and Panicum virgatum had a significantly higher available Cu content in rhizosphere soil than in bulk soil. The six vegetation types except A. adsurgens had a slightly higher available Fe content in rhizosphere soil than in bulk soil, and  A. adsurgens, P. virgatum, H. altaicus, and A. capillaries had a significant accumulation of available Zn in rhizosphere soil. There existed significant positive correlations between the rhizosphere soil and bulk soil of the six vegetation types in the relationships between the organic C and total N contents and the available Mn and Zn contents and between the contents of available Mn and Zn. In rhizosphere soil, available Mn and Zn contents were significantly negatively correlated with pH value. Due to the differences in root growth characteristics, rhizosphere pH value, and microbial structure composition, the microelements contents in the rhizosphere soil of the six vegetation types differed, with the contents of Mn, Cu, Fe, and Zn being higher in the rhizosphere soil of H. altaicus than in that of the other vegetation types.

Characteristics of stable isotopes in soil water under several typical land use patterns on Loess Tableland.

2012, 23(03):  651-658. 

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In this study, the precipitation over the Loess Tableland in Changwu County of Shaanxi Province and the soil water in 0-20 m loess profiles under different land use patterns on the Tableland were sampled, and their isotope compositions were analyzed, aimed to understand the characteristics of stable isotopes in the soil water and the mechanisms of the soil water movement. In the study area, the equation of the local meteoric water line (LMWL) was δD=7.39δ18O+4.34 (R2=0.94, n=71), and the contents of the stable isotopes in the precipitation had an obvious seasonal variation of high in winter and spring and low in summer and autumn. The contents of the stable
isotopes in the soil water were fell on the underside of the LMWL, and higher than those in the precipitation from July to October, indicating that the soil water was mainly replenished by the precipitation with lower stable isotope contents in summer and autumn. In the soil profiles of different land use patterns, the stable isotope contents in soil water tended to be the same with the increasing soil depth; while under the same land use patterns, the water’s stable isotope composition in shallow soil layers changed greatly with time, but changed less with increasing depth. Through the comparison of the stable isotope contents in precipitation and in soil water, it was observed that the piston flow and preferential flow on the Tableland were coexisted in the process of precipitation infiltration, and the occurrence of the preferential flow had a certain relation with land use pattern. Generally, the soil desiccation caused by the negative water balance resulted from the artificial plantations of high water consumption could reduce the probability of preferential flow occurrence, whereas the precipitation infiltration in the form of preferential flow could easily occur on the farmland or natural grassland so that the soil water in deep layers or the ground water could be replenished.

Effects of the conversion from native shrub forest to Chinese chestnut plantation on soil carbon and nitrogen pools.

2012, 23(03):  659-665. 

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To investigate the effects of the conversion from native shrub forest (NF) to Chinese chestnut plantation (CP) on the soil carbon (C) and nitrogen (N) pools, soil samples were collected from the adjacent NF and CP in Anji County of Zhejiang Province, with their water-soluble organic C (WSOC), microbial biomass C (MBC), readily oxidizable C (ROC), water-soluble organic N (WSON), and microbial biomass N (MBN) determined. The spectral characteristics of soil organic C were also determined by using nuclear magnetic resonance (NMR) technique. After the conversion from NF to CP, the soil alkalyzable N, available phosphorus, and available potassium contents increased significantly, while the soil WSOC, MBC, ROC, WSON, and MBN were in adverse. The soil organic C in both NF and CP was dominated by alkyl C and O-alkyl C, but the proportions of O-alkyl C and carbonyl C in soil organic C decreased while the proportions of alkyl C and aromatic C as well as the alkyl C / O-alkyl C ratio and the aromaticity of soil organic C all increased significantly after the conversion from NF to CP, indicating that this conversion increased the stability of soil organic C pool significantly. In conclusion, the conversion from NF to CP and the intensive management of CP decreased the contents of soil labile C and soil N but increased the stability of soil C pool significantly.

Spatial patterns of plant species diversity in a degraded successional series of fragmented Leymus chinensis meadow in
 Songnen Plain of Northeast China.

2012, 23(03):  666-672. 

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Species diversity pattern is a hot topic in the forward field of international biodiversity research. Taking a degraded successional series (six communities distributed in 144 isolated patches) of fragmented Leymus chinensis meadow in Songnen Plain as test objects, this paper studied the spatial patterns of SymbolaA@, β, and γ diversities and related mechanisms. Eighty seven plant species were recorded, but none of them were distributed across all patches. L. chinensis + Kalimeris integrifolia community or L. chinensis community had higher SymbolaA@, β, and γ diversities, with more rare species and endemic species, while Kochia sieversiana community had lower SymbolaA@, β, and γ diversities, with few rare species and no endemic species. The γ diversity showed significant positive correlation with SymbolaA@ 〖KG*2〗diversity, but no correlation with β diversity. There was a significant power function correlation between the α〖KG*2〗diversity and the area of single patch of the six communities, but no correlation between the β diversity (Bray-Curtis similarity index, Sjk) and the area of single patch of the communities except for L. chinensis + K. integrifolia. Both the α and  γ diversity showed significant correlations with the mean patch area and total patch area, but the β diversity did not. The higher the species richness in the communities, the more the rare species and endemic species, the larger the possibility of species depopulation in local patches was. The importance of β diversity for shaping species diversity pattern was related to the degree of
habitat fragmentation.

Allelopathic effects of Artemisia sacrorum population in typical steppe based on niche theory.

2012, 23(03):  673-678. 

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By using modified Levins niche width index and Pianka niche overlap index, this paper analyzed the ecological competition between constructive and dominant species in a typical steppe. The stem- and leaf extracts from the constructive species (Artemisia sacrorum) were utilized to study their allelopathic potential on the seed germination and plant growth of the dominant species (Stipa bungeana, Thymus mongolicus, S. grandis, and Leymus secalinus), and the ecological position of A. sacrorum in the steppe succession. In the steppe, S. bungeana had the widest niche width (099), followed by T. mongolicus (0.94), A. sacrorum (0.82), S. grandis (0.76), and L. secalinus (073). The niche overlap value between A. sacrorum and S. bungeana, S. bungeana and T. mongolicus, T. mongolicus and S. grandis, and A. sacrorum and T. mongolicus was 0.90, 0.95, 0.94, and 0.86, respectively. The allelopathic effects of A. sacrorum extracts varied with their concentration. For the seed germination, root growth, and shoot growth of the dominant species, A. sacrorum extracts showed a trend of promoting at low concentrations and inhibiting at high concentrations. The extracts of A. sacrorum had a stronger promotion effect on the root growth of S. bungeana than on that of T. mongolicus, but a stronger inhibition effect on the shoot growth of T. mongolicus than on that of S. bungeana. Methanol extracts had stronger allelopathic effects than aqueous extracts. The high niche overlap between A. sacrorum and S. bungeana, and T. mongolicus and S. grandis indicated that the steppe community would continue succession to S. bungeana, while A. sacrorum population was only an important transitional stage during the succession. The allelopathic effect of A. sacrorum played a driving role in the succession process.

Effects of urban river width on the temperature and humidity of nearby green belts in summer. 

2012, 23(03):  679-684. 

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As an important part of urban ecosystem, urban river plays a vital role in improving urban ecological environment. By the methods of small scale quantitative measurement, this paper analyzed the effects of seven urban rivers with different widths along the Third to Fifth Ring in Beijing on the air temperature and relative humidity of nearby green belts. The results showed that urban river width was the main factor affecting the temperature and humidity of nearby green belts. When the river had a width of 8 m, it had no effects in decreasing temperature but definite effects in increasing humidity; when the river width was 14-33 m, obvious effects were observed in decreasing temperature and increasing humidity; when the river had a width larger than 40 m, the effects in decreasing temperature and increasing humidity were significant and tended to be stable. There existed significant differences in the temperature and humidity between the green belts near the seven rivers and the corresponding controls. The critical width of urban river for the obvious effects in decreasing temperature and increasing humidity was 44 m. The regression equation of the temperature (x) and humidity (y) for the seven green belts nearby the urban rivers in summer was y=173.191-3.247x, with the relative humidity increased by 1.0% when the air temperature decreased by about 0.3 ℃.

Compositional characteristics and roles of soil mineral substances in depressions between hills in karst region. 

2012, 23(03):  685-693. 

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Based on the investigation and analysis of seven soil mineral substance variables, nine vegetation factors, four topographical factors, and ten soil physicochemical factors in the 200 m×40 m dynamic monitoring plots in farmland, forest plantation, secondary forest, and primary forest in the depressions between hills in karst region, and by using traditional statistical analysis, principal component analysis (PCA), and canonical correlation analysis (CCA), this paper studied the compositional characteristics and roles of soil mineral substances as well as the coupling relationships between the mineral substances and the vegetation, topography, and other soil properties. In the depressions, soil mineral substances were mainly composed of SiO2, Al2O3, K2O, and Fe2O3, whose contents were obviously lower than the mean background values of the soils in the world and in the zonal red soils at the same latitudes. The soil CaO and MgO contents were at medium level, while the soil MnO content was very low. The composition of soil mineral substances and their variation degrees varied with the ecosystems, and the soil development degree also varied. There was a positive correlation between vegetation origin and soil origin, suggesting the potential risk of rock desertification. Due to the high landscape heterogeneity of the four ecosystems, PCA didn’t show good effect in lowering dimension. In all of the four ecosystems, soil mineral substances were the main affecting factors, and had very close relationships with vegetation, topography, and other soil properties. Especially for SiO2, CaO, and MnO, they mainly affected the vegetation species diversity and the soil organic matter, total nitrogen, and total potassium. This study indicated that soil mineral substances were the one of the factors limiting the soil fertility and vegetation growth in the depressions between hills in karst region. To effectively use the soil mineral resources and rationally apply mineral nutrients would have significances in the restoration and reconstruction of karst degraded ecosystems.

Differentiation of vegetation characteristics on slope micro-topography of fenced watershed in loess area of north Shaanxi Province, Northwest China.

2012, 23(03):  694-700. 

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Based on the investigation data of the vegetations in Hegou valley in Wuqi County of Shaanxi Province, this paper studied the vegetation characteristics on the five typical micro-topography categories including shallow gully, gully, collapse, platform, and scarp in the loess area of north Shaanxi, with the undisturbed slope as the control. There existed distinct differences in the species composition, quantitative characteristics, and species diversity of plant communities on the five typical micro-topography categories and the undisturbed slope. After twelve years of enclosure recovery, the study area formed herbaceous plant community, with Artemisia sacrorum and Artemisia giraldii as the dominant species. Among the main companion species, shrubs such as Prinsepia uniflora and Caragana korshinskii were found in scarp and gully, and hygrophyte Phragmites australis appeared in platform. The coverage, height, and biomass of the plant communities on most of the micro-topography categories, especially on the gully and collapse, were larger than those on the undisturbed slope. The Shannon index on the micro-topography categories and undisturbed slope was in the order of scarp > gully> shallow gully> undisturbed slope> platform> collapse.

Spatial tendency of urban land use in new Yinzhou Town of Ningbo City, Zhejiang Province of East China.

2012, 23(03):  701-709. 

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By adopting gradient analysis combining with the analysis of urban land use degree, this paper studied the spatial layout characteristics of residential and industrial lands in new Yinzhou Town, and explored the location characters of various urban land use by selecting public green land, public facilities, and road as the location advantage factors. Gradient analysis could effectively connect with the spatial layout of urban land use, and quantitatively depict the spatial character of urban land use. In the new town, there was a new urban spatial center mostly within the radius of 2 km, namely, the urban core area had obvious location advantage in the cross-shaft direction urban development. On the south of Yinzhou Avenue, the urban hinterland would be constructed soon. In the future land use of the new town, the focus would be the reasonable vicissitude of industrial land after the adjustment of industrial structure, the high-efficient intensive use of the commercial land restricted by the compulsive condition of urban core area, and the agricultural land protection in the southeastern urban-rural fringe.

Monitoring  and simulation of soil electrical conductivity based on the hyperspectral parameters of cotton (Gossypium hirsutum) functional leaves.

2012, 23(03):  710-716. 

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Taking the salt-tolerant cotton variety CCRI-44 and salt-sensitive cotton variety Sumian 12 as test materials, a two-year pot experiment was conducted at the Pailou experimental station of Nanjing Agricultural University in 2008 and 2009 to study the relationships of soil electrical conductivity (EC) with the spectral reflectance and hyperspectral indices of cotton functional leaves at different growth stages under five simulated salinity levels (0, 035%, 060%, 085%, and 100%) of coastal saline soils, and the quantitative monitoring models on the cotton soil EC were established. With increasing salinity level, the cotton functional leaves had an increased spectral reflectance in near-infrared and middle-infrared regions, and the spectral parameter normalized difference spectrum index (NDSI) based on 1350 nm and 2307 nm, i.e., NDSI (R1350, R2307), correlated well to the soil EC. With the NDSI (R1350, R2307) as independent variable, the soil EC monitoring model was constructed as EC=-42.899NDSI (R1350, R2307) +27.338. Among the derivative spectral parameters, TM5-SWIR was most correlated to soil EC, and thus, the soil EC monitoring model was constructed as EC=0.0574TM5-SWIR2-2.5928TM5-SWIR+30.021. The two models with NDSI (R1350, R2307) and TM5-SWIR as the independent variables respectively all had higher prediction precision, with the determination coefficient being 0.887 and 0.814 and the root mean square error being 1.09 and 1.29 dS·m-1, respectively, suggesting that using the hyperspectral parameters NDSI (R1350, R2307) and TM5-SWIR of cotton functional leaves could effectively monitor the soil EC of saline cotton fields.

Effects of exogenous salicylic acid on  membrane lipid peroxidation and photosynthetic characteristics of
Cucumis sativus seedlings under drought stress.

2012, 23(03):  717-723. 

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To approach the related mechanisms of exogenous salicylic acid (SA) in improving plant drought-resistance, this paper studied the effects of applying exogenous SA to the rhizosphere on the plant growth, membrane lipid peroxidation, proline accumulation, water use efficiency, net photosynthetic rate (Pn), and chlorophyll fluorescence parameters of cucumber (Cucumis sativus) seedlings under drought stresses (60% and 50% of saturated water capacity). Applying SA relieved the inhibitory effects of drought stress on plant growth, Pn, and water use efficiency, decreased membrane lipid peroxidation, and promoted proline accumulation. Meanwhile, the SA decreased the decrements of the maximum photochemical efficiency of PSⅡ, actual photochemical efficiency of PSⅡ, potential activity of
PSⅡ, effective photochemical efficiency of PSⅡ, and photochemical quenching coefficient  under drought stress significantly, and limited the increase of non-photochemical quenching coefficient. All the results suggested that applying exogenous SA could alleviate the oxidation damage of cell membrane resulted from the drought-caused membrane lipid peroxidation, improve the Pn by increasing
PSⅡ activity to benefit water utilization, enhance the regulation capability of osmosis to decrease water loss and increase water use efficiency, and thereby, improve the plant drought-resistance.

Responses of wheat seedlings root growth and leaf photosynthesis to drought stress.

2012, 23(03):  724-730. 

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Taking drought-sensitive wheat cultivar Wangshuibai and drought-tolerance cultivar Luohan 7 as test materials, a hydroponic experiment was conducted to study the effects of drought stress on  root system morphology,  physiological characteristics and leaf photosynthesis of wheat seedlings, aimed to elucidate the adaptation mechanisms  to drought stress. Under drought stress, the root vitality of the cultivars increased markedly, but the root number and root surface area decreased. Drought stress decreased  relative water content and increased the
ratio of bound water to  free water
in leaves of  Wangshuibai, but had less effects on Luohan 7.  Drought stress decreased, the leaf chlorophyll content, Pn, gs, Ci, and transpiration rate of the two cultivars, but had no significant effects on
 leaf chlorophyll content and Pn of Luohan 7. Drought stress decreased the leaf area of the two cultivars and the root biomass, shoot biomass, and plant biomass of Wangshuibai, but had no significant effects on Luohan 7. The results indicated that under drought stress, drought-tolerant wheat cultivar was able to compensate  decreased root  absorption area and retain  higher root water uptake capability via enhancing  root vitality and maintaining higher root biomass, and further, to keep  higher leaf photosynthetic area and Pn to mitigate the inhibition  of drought on wheat seedlings growth.

Variation characteristics of soil moisture in apple orchards of Luochuan County, Shaanxi Province of Northwest China.

2012, 23(03):  731-738. 

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To have an overall understanding on the soil moisture characteristics in the apple orchards of Luochuan County can not only provide theoretical basis for selecting apple orchard sites, choosing the best root-stock combination, and improving the soil water management, but also has reference importance in increasing the productive efficiency of our apple orchards. In this study, a fixed-point continuous monitoring was conducted on the overall soil moisture environment and the variation characteristics of soil moisture in the County apple orchards differed in age class, stand type, and tree type (standard or dwarfed). For the apple orchards in the County, the rhizosphere (0-200 cm) soils of most apple trees were water-deficient, and the deficit in 0-60 cm soil layer was less than that in 60-200 cm layer. During growth season, the water storage in 0-60 cm soil layer had the same variation trend as the rainfall pattern. The relative soil moisture content in most orchards was less than 60%, and seasonal drought was quite severe. The coefficient of variation of soil moisture content decreased with soil depth. With the increasing age of the orchards, soil water storage decreased. At the same planting density, the orchards with dwarfed trees had more water storage in 0-5 m soil layer than the orchards with standard trees. However, when the orchards were planted with dwarfed trees at a higher density, the soil water storage in the orchards with dwarfed trees was lesser than that in the standard orchards. The mature orchards on highland had the highest soil moisture content, followed by the mature orchards on flat land, and on terraced land. Tree density had great effects on the soil moisture content. When the tree density was the same, planting dwarfed trees could decrease the water consumption, and increase the soil moisture content significantly. To decrease the planting density through the removal of trees would be an effective way to maintain the soil water balance of apple orchards, and achieve the sustainable development of the orchards.

N2O emission from an intensively managed greenhouse vegetable field in Nanjing suburb, Jiangsu Province of East China.

2012, 23(03):  739-744. 

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By using static opaque chamber and gas chromatography, this paper studied the dynamic changes of N2O fluxes and their relationships with soil temperature, soil moisture content, and soil nitrate and ammonium contents in an intensively managed greenhouse celery-
Tung choy-Bok choy-amaranth rotation field and in a bare fallow land in Nanjing suburb. The cumulative N2O emission from the rotation vegetable field was as high as 137.2 kg N·hm-2, being significantly higher than that from the bare fallow land (29.2 kg N·hm-2), and the N2O-N emission factor of the rotation vegetable field ecosystem was up to 4.6%. In the rotation field, the planting of Tung choy had the greatest contribution to the annual cumulative N2O emission, occupying 53.5% of the total, followed by the planting of Bok choy (31.9%), celery field (4.5%), and amaranth (4.8%). The N2O flux of the rotation field had significant positive correlation with soil temperature, the Q10 being 2.80, but no significant correlations with soil moisture content and soil nitrate and ammonium contents.

Gene expression of the key enzymes controlling starch synthesis and metabolism in rice grain endosperm under effects of high temperature after anthesis.

2012, 23(03):  745-750. 

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Taking an early-season indica cultivar ‘Jiazao 935’ whose grain quality was sensitive to temperature as test material, and by using artificial climatic chamber and real-time fluorescence quantitative PCR (FQ-PCR), this paper studied the relative expression amount and its dynamic changes of ten isoform genes of the key enzymes controlling starch synthesis and metabolism in rice grain endosperm, including sbe1, sbe3, and sbe4 of starch branching enzyme (SBE), isa1, isa2, isa3, and pul of starch debranching enzyme (DBE), and Wx, sss1, and sss2a of starch synthase (SS), at the mean daily temperature 22 and 32 ℃ after anthesis. There existed obvious differences in the expression patterns of these genes under the high temperature stress, and the expression patterns were isoform-dependent. The relative expression amount of sbe1 and sbe3 under high temperature decreased significantly, and both of the genes were the sensitive isoform genes of SBE to high temperature stress. Among the DBE genes, pul was the isoform gene with high expression level, being more sensitive to high temperature stress than isa1, isa2, and isa3. Among the SS genes, sss2a had a significantly lower relative expression amount than sss1 and Wx, but sss2a and sss1 were more sensitive to high temperature than Wx, suggesting that sss2a and sss1 could be the important genes that adjusted the starch structure in rice endosperm under high temperature stress, especially at the middle and late grain filling stages.

Effects of intensive agricultural production on farmland soil carbon and nitrogen contents and their δ13〖KG-*8〗C and δ15〖KG-*8〗N
 isotope abundances.

2012, 23(03):  751-757. 

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Farmland soil carbon and nitrogen contents under intensive agricultural production are the important indices for the assessment of the soil fertility sustainability. This paper measured the soil pH, electrical conductivity (EC), organic carbon (SOC), total nitrogen (TN), and δ13C and δ15N isotope abundances of four types of farmland, i.e., conventional rice-broad bean rotation field, open vegetable field, 3-year plastic covered greenhouse field, and >10-year plastic covered greenhouse field, aimed to understand the effects of intensive agricultural production degree on soil properties. In the open vegetable field, 3-year plastic covered greenhouse field, and >10-year plastic covered greenhouse field, the soil (0-20 cm) pH decreased by 1.1, 0.8, and 0.7, and the soil EC was 42, 49, and 5.2 folds of that in conventional rice-broad bean rotation field, respectively. With the increasing year of plastic covered greenhouse production, the soil SOC and TN contents decreased after an initial increase. Comparing with those under rice-broad bean rotation, the SOC content in 0-20, 20-40, 40-60, 60-80 and 80-100 cm soil layers in >10-year plastic covered greenhouse decreased by 54%, 46%, 60%, 63%, and 59%, and the TN content decreased by 53%, 53%, 71%, 82%, and 85%, respectively. Intensive agricultural production degree had significant effects on the soil SOC and TN contents and δ13C and δ15N abundances. The δ13C abundance was significantly negatively correlated with the soil SOC, suggesting that the soil δ13C abundance could be regarded as an index for the assessment of carbon cycle in farmland soils under effects of human activities.

Effects of seeding rate and nitrogen fertilization rate on physiological traits of winter wheat after anthesis in a field with plastic mulched rides and unmulched furrows.

2012, 23(03):  758-764. 

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Taking winter wheat cultivar Xiaoyan 22 as test material, a field experiment with central composite rotatable design was conducted to investigate the effects of seeding rate and nitrogen (N) fertilization rate on the physiological traits of the cultivar after anthesis under ridge-furrow cultivation with plastic film mulching, aimed to harmonize the relationships between winter wheat population and its individuals and to fully use the advantages of ridge-furrow cultivation in dry land areas. With increasing N fertilization rate, the leaf area index and the flag leaf chlorophyll content and net photosynthesis rate after anthesis increased; with increasing seeding rate, the leaf area index increased first and was stable then at early and middle milking stages but decreased at later milking stage, the flag leaf chlorophyll content and net photosynthesis rate decreased, and the grain yield per plant increased after an initial decrease. Appropriate seeding rate could optimize the relationships between winter wheat population and its individuals, and optimal N fertilization rate benefited the improvement of winter wheat physiological traits after anthesis and the enhancement of winter wheat yield. Under our experimental condition, seeding rate 1125 kg·hm-2 plus N fertilization rate 180-222 kg N·hm-2 is a scheme beneficial to optimize the relationships between winter wheat population and its individuals and to establish a good winter wheat community structure with a reasonable leaf area index after anthesis, higher flag leaf chlorophyll content and net photosynthesis rate, higher grain yield per plant, and high yield per unit area.

Optimal C/N ratio of pig manure-rice straw mixture for its composting with earthworm and maturity assessment of the mixture compost.

2012, 23(03):  765-771. 

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Taking the pig manure-rice straw mixtures with different C/N ratios (20, 25, 30, and 35) as the feed of earthworm
(Eisenia fetida), a 90-day incubation test was conducted to study the growth and reproduction of  E. fetida, with the average body mass, daily body mass increase, daily cocoon production, and accumulated cocoon production as the indicators. In the meantime, a 35-day composting experiment was arranged to assess the maturity of the same mixtures with C/N 25, 30, and 35, using pH, dissolved organic carbon (DOC), and C/N as the indicators. In the 90-day incubation test, the mixture with a C/N ratio 30 was most suitable for the growth and reproduction of E. fetida. In the 35-day composting experiment, the mixtures’ pH and DOC decreased in the first 21 days and increased thereafter, while the C/N decreased persistently during the 35 days. With the comprehensive consideration of the three indicators, the mixtures were still not fully matured by the end of the experiment. For the mixture with a C/N ratio 25, its C/N ratio was < 20 in the 7-35 days. Traditionally, the mixture was considered as composted matured when the C/N ratio was below 20, but based on the assessment of pH and DOC, the mixture was still under immature condition. Therefore, C/N＜20 alone was not a proper indicator for the maturity assessment on the composting of pig manure-rice straw mixture.

Thermal tolerance of diamondback moth Plutella xylostella.

2012, 23(03):  772-778. 

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Diamondback moth Plutella xylostella is a worldwide important pest on cruciferous vegetables. Critical thermal maximum (CTMax) is often used as an index for the thermal tolerance of insects. By the method of dynamic heating, this paper measured the CTMax of P. xylostella in a self-assembled device, and studied the effects of development stage, rearing temperature, generation, sex, and heat shock on the thermal tolerance of P. xylostella based on the CTMax values. Reared at 25 ℃, the mean CTMax of the 4th larva  (50.31 ℃) was significantly higher than that of the 1st larva (43.03 ℃), 2nd larva (46.39 ℃), 3rd larva (49.67 ℃), female adult (45.76 ℃), and male adult (47.73 ℃); reared at 20, 25, and 30 ℃, the adults had no significant difference in their CTMax; reared at 30 ℃ for 1-, 3-, and 6 generations, the CTMax of the adults also had no significant difference. In all the treatments, the CTMax of the female and male adults had less difference. Heat shock with 40 ℃ for 45 minutes could make the CTMax of 5 day-old male moth increased from 45.51 ℃ to 46.49 ℃.

Effects of composting with earthworm on the chemical and biological properties of agricultural organic wastes: A principal component analysis.

2012, 23(03):  779-784. 

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Taking mixed agricultural organic wastes cattle manure and rice straw (C：N=28.7：1) as the substrate of earthworm Eisenia foetida, an experiment was conducted to study the effects of earthworm on the changes of the  chemical and biological properties of wastes during vermi-composting. After 30 days of vermi-composting, the substrate’s pH and C/N decreased while the total P content increased significantly, and the total N, available N, dissolved organic carbon, available P content, microbial biomass-C, respiration rate, and microbial quotient increased by 85%, 26%, 18%, 63%, 212%, 44%, and 300% whereas the organic matter content and metabolic quotient decreased by 5.0% and 21.9%, respectively, as compared with natural composting. Vermi-composting made the substrate have higher invertase, acid phosphatase, and alkaline phosphatase activities but lower catalase and urease activities. Principal component analysis and discriminant analysis confirmed the significant differences in the substrate’s chemical and biological properties between vermi-composting and natural composting. This study indicated that vermi-composting was superior to natural composting, which could obviously improve the chemical and biological properties of composted organic materials, being a high efficient technology for the management of agricultural organic wastes.

Diversity of geometrid moth (Lepidoptera: Geometridae) in cropland and reforested semi-natural habitats at different altitudes of Bashang Plateau, Hebei Province of China.

2012, 23(03):  785-790. 

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In order to understand the effects of landscape heterogeneity induced by habitat restoration and landform change on the biodiversity in degraded landscapes, an investigation by using light trap was conducted on the geometrid moth (Lepidoptera: Geometridae) diversity in the cropland and reforested semi-natural habitats in three villages at different altitudes of Bashang Plateau in 2006 and 2007. There existed significant differences in the species richness and individual number of geometrid moth between cropland and reforested semi-natural habitats and in the species richness of geometrid moth between the villages at different altitudes, but no significant differences in the individual number of geometrid moth between the villages at different altitudes and in the standardized sparseness index and Fisher’s alpha index between the villages and between the cropland and reforested semi-natural habitats within each village. The non-metric multi-dimensional scaling (NMDS) indicated that the community structure of geometrid moth in different habitats and at different altitudes differed significantly. This study indicated that the landscape heterogeneity induced by landform change had significant effects on the community structure and diversity of geometrid moth on Bashang Plateau, and, both cropland and reforested semi-natural habitats were the important habits for geometrid moth. It was suggested that to protect the landscape mosaics containing cropland and reforested semi-natural habitats across the varied landform of Bashang Plateau would have significances in the conservation of high gamma-diversity of geometrid moth, but whether the reforestation and creation of semi-natural habitats could improve the biodiversity of geometrid moth should be monitored in long term.

Responses of Arma chinensis cold tolerance to rapid cold hardening and underlying physiological mechanisms.

2012, 23(03):  791-797. 

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Rapid cold hardening can enhance the cold tolerance of some insects. To explore the effects of different cold hardening induction temperature on the cold tolerance of Arma chinensis and related physiological mechanisms, the 3rd generation A. chinensis adults reared indoor were treated with cooling at 15, 10, and 4 ℃ for 4 h, respectively, or with gradual cooling from 15 ℃ for 4 h to 10 ℃ for 4 h, and finally to 4 ℃ for 4 h. The super-cooling point, water content, and the contents of low molecular carbohydrates, glycerol, and amino acids of the adults after cooling and the adults cold tolerance at 0, -5, and -10 ℃ were measured by thermocouple, high performance liquid chromatography, and other analytical techniques. When exposed at -10 ℃ after cooling, the survival rate of the adults treated with gradual cooling or treated with cooling at 4 ℃ for 4 h was averagely 58.3%, while that of the adults reared at room temperature (25 ℃±2 ℃) or treated with cooling at 15 ℃ or 10 ℃ for 4 h decreased significantly, with an average of 8.9%. The super-cooling point of the adults treated with gradual cooling or with cooling at 4 ℃ for 4 h was -15.6 ℃, which was averagely 1.3 ℃ lower than that of the other treatments. The water content of the adults had no significant difference among all treatments, with an average of 61.8%, but the glucose, sorbitolum, glycerol, Ala, and Glu contents in treatments gradual cooling and cooling at 4 ℃ for 4 h increased by 2.82-fold, 2.65-fold, 3.49-fold, 51.3%, and 80.2%, while the fucose, mannose, and Pro contents decreased by 68.4%, 52.2%, and 30.2%, respectively, as compared with the other treatments. The fructose content showed no significant difference among all treatments. It was suggested that rapid cool hardening had a critical temperature to induce the physiological metabolism process of adult A. chinensis, and gradual cooling hardening could not further increase the cold tolerance of adult A. chinensis on the basis of rapid cool hardening.

Effects of heavy metals pollution on soil microbial communities metabolism and soil enzyme activities in coal mining area of Tongchuan, Shaanxi Province of Northwest China.

2012, 23(03):  798-806. 

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This paper studied the metabolism of soil microbes, functions of soil microbial communities, and activities of soil enzymes in a coal mining area of Tongchuan. In the coal mining area, the concentrations of soil Cu, Zn, Cd, and Pb were significantly higher than those in the non-mining area, of which, Cd contributed most to the heavy metals pollution. By adopting Biolog method combining with principal component analysis (PCA) and cluster analysis, it was found that the metabolic characteristics of different soil microbial communities varied significantly with increasing soil heavy metals pollution, and the variation was mainly manifested in the metabolic patterns of carbon sources such as saccharides and amino acids. In slightly and moderately polluted soils, the utilization of carbon sources by soil microbial communities was activated; while in heavily polluted soils, the carbon sources utilization was inhibited. The activities of soil urease, protease, alkaline phosphatase, and catalase all tended to decline with intensifying soil heavy metals pollution. The soil urease, protease, alkaline phosphatase, and catalase activities in the coal mining area were 505%-65.1%, 19.1%-57.1%, 87.2%-97.5%, and 77.3%-86.0% higher than those in the non-mining area, respectively. The activities of soil sucrase and cellulase were activated in slightly and moderately polluted soils, but inhibited in heavily polluted soils.

Bioremediation of chlorothalonil-contaminated soil by utilizing Pseudomonas sp. strain CTN-3.

2012, 23(03):  807-811. 

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Chlorothalonil is the priority organic pollutant listed by the U.S. Environmental Protection Agency. To utilize the function of microbial degradation in the bioremediation of chlorothalonil-contaminated soil is of practical significance. In this study, a chlorothalonil-degrading Pseudomonas sp. strain CTN-3 isolated from pesticide-contaminated soil was used to examine the chlorothalonil- degrading capacity of the strain and related affecting factors in a microcosm. In sterilized soil, the effect of CTN-3 on chlorothalonil degradation was better than that in unsterilized soil. Various factors, including soil pH, temperature, initial chlorothalonil concentration, and inoculum size, affected the degradation of chlorothalonil by the strain. With the inoculum size of 106 CFU·g-1 soil, the CTN-3 at 15-30 ℃ and pH 5.8-8.3 could effectively degrade 10-200 mg·kg-1 of chlorothalonil, suggesting that the strain CTN-3 had great potential in the bioremediation of chlorothalonil-contaminated soil.

Structure and function of Fenshuijiang Reservoir ecosystem based on the analysis with Ecopath model. 

2012, 23(03):  812-818. 

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Based on the 2008-2009 survey data of fishery resources and eco-environment of Fenshuijiang Reservoir, a mass balance model for the Reservoir ecosystem was constructed by Ecopath with Ecosim software. The model was composed of 14 functional groups, including silver carp, bighead carp, Hemibarbus maculates, Cutler alburnus, Microlepis and other fishes, Oligochaeta, aquatic insect, zooplankton, phytoplankton, and organic detritus, etc., being able to better simulate Fenshuijiang Reservoir ecosystem. In this ecosystem, there were five trophic levels (TLs), and the nutrient flow mainly occurred in the first three TLs. Grazing and detritus food chains were the main energy flows in the ecosystem, but the food web was simpler and susceptible to be disturbed by outer environment. The transfer efficiency at lower TLs was relatively low, indicating that the ecosystem had a lower capability in energy utilization, and the excessive stock of nutrients in the ecosystem could lead to eutrophication. The lower connectance index, system omnivory index, Finn’s cycled index, and Finn’s mean path length demonstrated that the ecosystem was unstable, while the high ecosystem property indices such as Pp/R and Pp/B showed that the ecosystem was immature and highly productive. It was suggested that Fenshuijiang Reservoir was still a developing new reservoir ecosystem, with a very short history and comparatively high primary productivity.

Integrated risk evaluation of multiple disasters affecting Longyan yield in Fujian Province, East China.

2012, 23(03):  819-826. 

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In this study, an index system for the integrated risk evaluation of multiple disasters on the Longyan production in Fujian Province was constructed, based on the analysis of the major environmental  factors affecting the Longyan growth and yield, and from the viewpoints of potential hazard of disaster-causing factors, vulnerability of hazard-affected body, and disaster prevention and mitigation capability of Longyan growth regions in the Province. In addition, an integrated evaluation model of multiple disasters was established to evaluate the risks of the major agro-meteorological disasters affecting the Longyan yield, based on the yearly meteorological data, Longyan planting area and yield, and other socio-economic data in Longyan growth region in Fujian, and by using the integral weight of risk indices determined by AHP and entropy weight coefficient methods. In the Province, the Longyan growth regions with light integrated risk of multiple disasters were distributed in the coastal counties (except Dongshan County) with low elevation south of Changle, the regions with severe and more severe integrated risk were mainly in Zhangping of Longyan, Dongshan, Pinghe, Nanjin, and Hua’an of Zhangzhou, Yongchun and Anxi of Quanzhou, north mountainous areas of Putian and Xianyou, Minqing, Minhou, Luoyuan, and mountainous areas of Fuzhou, and Fuan, Xiapu, and mountainous areas of Ninde, among which, the regions with severe integrated risk were in Dongshan, Zhangping, and other mountainous areas with high altitudes, and the regions with moderate integrated risk were distributed in the other areas of the Province.

Emergy evaluation and dynamic measurement analysis of agro-ecosystems in Sichuan Province of Southwest China.

2012, 23(03):  827-834. 

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Agro-ecosystem is the most basic system for human beings survival, while the analysis of the structure and function of the system is the key to solve the problems of agro-ecological environment. In this paper, emergy theory and related economic measurement methods including data envelopment analysis, cointegration test, and error correction model were applied to quantitatively analyze the operation dynamics, environmental loading, operation efficiency, and input-output relation of the agro-ecosystems in Sichuan Province and its 21 cities in 1997-2009. In the study period, Sichuan Province was in the transition period from traditional agriculture to modern agriculture. The agricultural mechanization level of the Province improved constantly, resources utilization efficiency enhanced continually, overall structural dominant degree was better, but the over-reliance on economic emergy input caused the sustainability of the system weakened gradually. The development status of the agro-ecosystems in the Province varied among regions. Chengdu Plain and Western Sichuan Highland were either in overexploited or in underutilized, while the hilly areas were full of vitality and development potential, tended to be the important areas for the future development of Sichuan agriculture. Generally, the operation efficiency of the agro-ecosystems in the Province was relatively low, with the situation differed in different regions due to the lower technical efficiency or improper scale. There was a long-term equilibrium between the economic emergy indices and output emergy, but the short-term emergy input didn’t reach the ideal output.

Photoprotective mechanisms of leaf anthocyanins:  Research progress.

2012, 23(03):  835-841. 

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Anthocyanin is widely distributed in plant organs such as root, stem, leaf, flower and fruit,  being a kind of secondary metabolites generated in plant morphogenesis or for stress response. Leaf anthocyanin has special chemical structure and spectral properties, playing important roles in plant photoprotection, and becomes a hotspot in plant photosynthetic physiological ecology. This paper summarized the recent research progress in the effects of leaf anthocyanin on plant photosynthesis, including the distribution of leaf anthocyanin, its spectral properties, and its relationships with photosynthetic pigments, with the focus on the potential mechanisms of anthocyanins photoprotection, including light absorption, antioxidation, and osmotic regulation.  The further research directions on the effects of leaf anthocyanin on photoprotection were proposed.

Absorption and metabolism mechanisms of inorganic arsenic in plants: A review.

2012, 23(03):  842-848. 

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Arsenic pollution seriously threatens human health and environment safety, being a very prominent environmental issue to be urgently solved in the world. In natural environment and soil systems, arsenic exists in complicated forms, but the plant arsenic poisoning is mainly from As(V) and As(Ⅲ) exposure. As(V) can be absorbed by plant roots through Pi channel, and reduced rapidly to As(Ⅲ) by arsenate reductase. As(Ⅲ) can be transported into plants through NIP channel, and subsequently either transformed into methylated arsenic by arsenic methyltransferase or chelated with the thiol of GSH and PCs. These arsenic compounds can be sequestrated in root cell vacuoles or transported to plant aerial parts. Meanwhile, a part of absorbed arsenic can be discharged to external media. All of these can help to detoxify the arsenic in plants. This paper reviewed the latest research progress on the arsenic- resistance of crops, especially rice, with the focus on the mechanisms of As(V) and As(Ⅲ) absorption and excretion, As(V) reduction, and As(Ⅲ) methylation and chelation. The major topics of future research on arsenic toxicity were proposed.

Research progress in anammox-denitrification coupling process.

2012, 23(03):  849-856. 

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Anammox (anaerobic ammonium oxidation) is an important process of nitrogen cycle, with great potential for the practical use in removing nitrogen from the wastewater containing high concentration ammonium. However, the presence of high concentration organic carbon source is considered unfavorable to anammox. Coupling anammox and denitrification under the presence of organic carbon source could be a useful technique for removing both nitrogen and carbon. This paper reviewed the mechanisms of anammox-denitrification coupling process, functional microbial groups, initiation of the coupling process and its control, and related environmental affecting factors. The future research prospects and potential applications of anammox-denitrification coupling process in wastewater treatment were discussed.

Research advances in heavy metals pollution ecology of diatom.

2012, 23(03):  857-866. 

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Diatom, due to its high sensitivity to environmental change, is one of the bio-indicators of aquatic ecosystem health, and some typical diatom species have been applied to indicate the heavy metals pollution of water body. With the focus on the surface water heavy metals pollution, this paper reviewed the research advances in the toxic effect of heavy metals pollution on diatom, biosorption and bioaccumulation of heavy metals by diatom, ecological adaptation mechanisms of diatom to heavy metals pollution, and roles of diatom as bio-indicator and in ecological restoration of heavy metals pollution. The growth tendency of diatom and the morphological change of frustule under heavy metals pollution as well as the differences in heavy metals biosorption and bioaccumulation by diatom, the ecological adaptation mechanisms of diatom on heavy metals surface complexation and ion exchange, and the roles of diatom as bio-indicator and in ecological restoration of heavy metals polluted water body were also discussed. This review could provide scientific evidences for the prevention of aquatic ecosystems heavy metals pollution and related early warning techniques.