Table of Content

18 March 2014, Volume 25 Issue 3

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Accumulation of soil organic carbon and total nitrogen in Pinus yunnanensis forests at different age stages.

MIAO Juan1,4, ZHOU Chuan-yan2,5, LI Shi-jie3, YAN Jun-hua1

2014, 25(3):  625-631. 

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Taking three Pinus yunnanensis forests at different ages (19, 28 and 45 a) in Panxian County of Guizhou Province as test objects, we investigated vertical distributions and accumulation rates of soil organic carbon (SOC) and total nitrogen (TN), as well as their relationships with soil bulk density. For the three forests at different age stages, SOC and TN changed consistently along the soil profile, dec〖JP〗lining with the soil depth. Both SOC and TN storage increased with the forest age. The SOC and TN storage amounts were 96.24, 121.65 and 148.13 t·hm^-2, and 10.76, 12.96 and 13.08 t·hm^-2 for the forest stands with 19 a, 28 a and 45 a, respectively. SOC had a significant positive correlation with soil TN, while both of them had a significant negative relationship with the soil bulk density. The accumulation rates of both SOC and TN storage at different growth periods were different, and the rate in the period from age 19 to 28  was higher than in the period from age 28 to 45.

N and P stoichiometric traits of plant and soil in different forest succession stages in Changbai Mountains.

HU Yao-sheng, YAO Xu-yang, LIU Yan-hong

2014, 25(3):  632-638. 

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The typical forest communities under four different succession stages in Changbai Mountains were selected to study the stoichiometric traits of stems and leaves of dominant species in different layers, and the relationships between these stoichiometric traits and terrain factors. The results showed that leaf nitrogen content (LNC) was significantly positively correlated with leaf phosphorus content (LPC) and stem nitrogen content (SNC), and positively with stem phosphorus content (SPC). The LPC was positively correlated with SPC and negatively with leaf N/P, stem N/P. The leaf N/P was positively correlated with stem N/P. SNC was positively correlated with SPC. There were significant differences in the stoichiometric traits of the plant species at tree layers among the different succession forest communities, while no obvious difference in shrub layers except for leaf N/P. Based on RDA analysis, it indicated that the plant communities in the Changbai Mountains is Naffected in the primary stage of succession, while N and Paffected in the mid and later stages with a stronger impact from P.

Carbon sequestration status of forest ecosystems in Ningxia Hui Autonomous Region.

GAO Yang1, JIN Jing-wei2, CHENG Ji-min1,2, SU Ji-shuai1, ZHU Ren-bin3, MA Zheng-rui2, LIU Wei4

2014, 25(3):  639-646. 

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Based on the data of Ningxia Hui Autonomous Region forest resources inventory, field investigation and laboratory analysis, this paper studied the carbon sequestration status of forest ecosystems in Ningxia region, estimated the carbon density and storage of forest ecosystems, and analyzed their spatial distribution characteristics. The results showed that the biomass of each forest vegetation component was in the order of arbor layer (46.64 Mg·hm^-2) > litterfall layer (7.34 Mg·hm^-2) > fine root layer (6.67 Mg·hm^-2) > shrubgrass layer (0.73 Mg·hm^-2). Spruce (115.43 Mg·hm^-2) and Pinus tabuliformis (94.55 Mg·hm^-2) had higher vegetation biomasses per unit area than other tree species. Over-mature forest had the highest arbor carbon density among the forests with different ages. However, the young forest had the highest arbor carbon storage (1.90 Tg C) due to its widest planted area. Overall, the average carbon density of forest ecosystems in Ningxia region was 265.74 Mg C·hm^-2, and the carbon storage was 43.54 Tg C. Carbon density and storage of vegetation were 27.24 Mg C·hm^-2 and 4.46 Tg C, respectively. Carbon storage in the soil was 8.76 times of that in the vegetation. In the southern part of Ningxia region, the forest carbon storage was higher than in the northern part, where the low C storage was mainly related to the small forest area and young forest age structure. With the improvement of forest age structure and the further implementation of forestry ecoengineering, the forest ecosystems in Ningxia region would achieve a huge carbon sequestration potential.

Surface roughness characteristics of biological soil crusts and its influencing factors in the hilly Loess Plateau region, China

WANG Yuan1,2, ZHAO Yun-ge2, YAO Chun-zhu1,2, ZHANG Pei-pei2,3

2014, 25(3):  647-656. 

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Soil surface roughness exerts profound influence on runoff and sediments yield from slopes. Biological soil crusts (BSCs) are ubiquitous living cover in the open spaces between plants in arid and semiarid ecosystems, which considerably impact the surface roughness. Aimed to determine the effect of biological crusts on the surface roughness and its influence factors, this study investigated the surface roughness of soil with BSCs at their different successional stages by using the chain method. Besides, the impacts of slope aspects, soil water content and freezing and thawing on surface roughness were also investigated. Then, the correlations between roughness and soil chemical and physical properties were evaluated. The results showed that soil surface roughness decreased at the initial successional stage of BSCs but increased along with BSCs’ development in the region. Soil roughness tended to be stabile since BSCs developed ten years later.  The roughness was reduced by 47.0% by the light cyanobacteria-dominated crust and 20.4% by the dark cyanobacteriadominated crust (moss coverage <20%), compared with the bare soil. Soil moisture significantly impacted surface roughness. The surface roughness of BSCs changed obviously with soil moisture  in the early development, but only slightly in their later succession. Freezing-thawing also affected surface roughness with BSCs. Roughness was more susceptible to freezing-thawing in the early development of BSCs, with an increase of 29.7% compared with the bare soil. The surface roughness of late successional BSCs exhibited a slight change only after repeated freezing-thawing. The surface roughness of BSCs showed a statistically significant relationship with the coverage of moss (P<0.1).

Impact of biological soil crusts on soil water repellence in the hilly Loess Plateau region, China.

ZHANG Pei-pei1,3, ZHAO Yun-ge1,2, WANG Yuan2, YAO Chun-zhu2

2014, 25(3):  657-663. 

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By using water drop penetration time (WDPT) and molarity of ethanol droplet (MED) methods, the soil water repellence of undisturbed biological soil crusts (biocrusts) in five successional stages, from the hilly Loess Plateau region of China was tested. The five stages of biocrusts were light cyanobacterial crust, dark cyanobacterial crust, cyanobacterial with sparse moss crust, moss and tiny cyanobacteria patches crust and moss dominated crust. The results showed that 1) the soil water repellence was markedly increased both in the intensity and persistence since the formation of biocrusts. 2) The soil water repellence showed a decrease trend along with the successional stages of biocrusts. The soil water repellence of the biocrusts with the moss coverage above 20% was significantly lower than that of the cyanobacterial crusts. 3) The soil water repellence of the biocrusts was closely related to soil moisture and the dominant organism. The soil water repellence increased with the decrease of soil water content for the moss dominated biocrusts, while changed in a bimodal curve with the decrease of soil water content for the cyanobacterial biocrusts.

Effects of nitrogen addition on soil physico-chemical properties and enzyme activities in desertified steppe.

2014, 25(3):  664-670. 

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To investigate the impacts of nitrogen (N) enrichment on soil physico-chemical property and soil enzyme activities in desert ecosystems, a field experiment by adding N at 0, 1.75, 3.5, 7, or 14 g N·m^-2·a^-1 was conducted in a temperate desert steppe in the southeastern fringe of the Tengger Desert. The results showed that N addition led to accumulations of total N, NO₃^--N, NH₄⁺-N, and available N in the upper soil (0-10 cm) and subsoil (10-20 cm), however, reductions in soil pH were observed, causing soil acidification to some extent. N addition pronouncedly inhibited soil enzyme activities, which were different among N addition levels, soil depths, and years, respectively. Soil enzyme activities were significantly correlated with the soil N level, soil pH, and soil moisture content, respectively.

Stability and organic carbon characteristics of soil aggregates under different ecosystems in karst canyon region.

TAN Qiu-jin1,3, SONG Tong-qing1,2, PENG Wan-xia1,2, ZENG Fu-ping1,2, DU Hu1,2, YANG Gai-ren1,3, FAN Fu-jing1,4

2014, 25(3):  671-678. 

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Soil aggregates and their organic carbon distributions were studied under six ecosystems, i.e., farmland (short for ST), dry land (HD), grassland (CD), shrubbery (GC), plantation (RGL) and secondary forest (CSL), in a karst canyon region of China by a combination of field investigation and laboratory analysis. The result showed that, soil aggregates were dominated by particles with sizes>8 mm in the ecosystems except HD under dry sieving, and basically presented a trend of decreasing firstly, then increasing and finally decreasing along with particle sizes decreasing; while soil aggregates were dominated by particles with sizes >5 mm in the ecosystems except HD under wet sieving and decreased with decreasing of particle sizes. The mean mass diameter (MMD) was in the order of ST>CD>RGL>CSL>GC>HD and the geometric mean diameter (GMD) was ST>CD>RGL>CSL>HD>GC by dry sieving, and MMD was RGL>CSL>GC>CD>ST>HD and GMD was CSL>RGL>GC>CD>ST>HD by wet sieving. Therefore, MMD and especially GMD of wet sieving were more accurate than that of dry sieving to evaluate soil aggregates quality in the karst cannon region. The fractal dimension (D) of mechanical stability in soil aggregates followed the order of CD>HD>ST>RGL>CSL>GC and the water stability was in the order of GC>CSL>RGL>HD>CD>ST. The higher the SOC content was, the larger values of D, MMD, GMD became, and the more sense the soil structure made. Soil organic carbon content was highest in the aggregate particles with sizes ranging from 0.25 to 0.053 mm, and the content in some particles with sizes >5 mm was lowest. However, the contribution rate of particles with sizes >5 mm was largest to soil organic carbon, which gradually decreased with the decrease of particle size.

Soil particle size distribution and its fractal dimension among degradation sequences of the alpine meadow in the source region of the Yangtze and Yellow River, QinghaiTibetan Plateau, China.

WEI Mao-hong, LIN Hui-long

2014, 25(3):  679-686. 

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The alpine meadow in the source region of the Yangtze and Yellow River is suffering serious deterioration. Though great efforts have been put into, the restoration for the degraded grassland is far from being effective, mainly due to poor understanding of the degradation mechanism of alpine meadow in this region. In order to clarify the formation mechanism of degradation grassland and provide the new ideas for restoration, degradation sequences of the alpine meadow in the source region of the Yangtze and Yellow River were taken as target systems to analyze the soil particle size distribution, the fractal dimension of the soil particle size, and the relationship between soil erosion modulus and fractal dimension. The results showed that, with increasing grassland degradation, the percentage contents of clay increased while the percentage contents of silt sand and very fine sand showed a decreasing trend. The fractal dimension presented a positive correlation with clay among the degradation sequences while negative correlations were found with very fine sand and silt sand. The curvilinear regression of fractal dimension and erosion modulus fitted a quadratic function. Judged by the function, fractal dimension 2.81 was the threshold value of soil erosion. The threshold value has an indicative meaning on predicting the breakout of grazinginduced erosion and on restoration of the degraded grassland. Taking fractal dimension of 2.81 as the restoration indicator, adoption of corresponding measures to make fractal dimension less than 2.81, would an effective way to restore the degradation grassland.

Effect of fertilization on soil respiration in the Stipa breviflora desert steppe of Inner Mongolia.

ZHAO Bayinnamula1, HONG Mei1, LIANG Cun-hu2, BAO Wuyun1, ZHANG Jia-in1

2014, 25(3):  687-694. 

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In 2012, a field experiment with different fertilizer treatments was conducted in the Stipa breviflora desert steppe of Inner Mongolia. The LI-8100 was used to investigate daily and seasonal variations of soil respiration rate, and the relationships between soil respiration rate and environmental factors were analyzed. The results showed that: 1) In the rapidly growing stage (August), the respiration rate in 10 g N·m^-2 was significantly higher than in the other treatments. No significant differences were observed among 5 g N·m^-2, 2.5 g N·m^-2 and CK. 2) During the early and middle growing stage (May to September), P fertilizer improved the soil respiration rate. 3) Fertilization did not change the daily and seasonal variations of soil respiration. The daily variations of soil respiration of all fertilization treatments were almost the same, with the highest values occurring within 10:00-14:00 and the lowest values occurring within 03:00-05:00. The peak of seasonal variation occurred in August. 4) The soil respiration rate was significantly related to soil temperature at 5 cm depth and soil moisture at 0-10 cm depth, and the determined coefficients were 0.40-0.58 and 0.51-0.70, respectively, indicating that soil moisture was the major factor affecting soil respiration.

Effects of thinning intensities on population regeneration of natural Quercus variabilis forest on the south slope of Qinling Mountains.

RAN Ran, ZHANG Wen-hui, HE Jing-feng, ZHOU Jian-yun

2014, 25(3):  695-701. 

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Taking the natural Quercus variabilis forest in Shangluo, south slope of Qinling Mountains as the object in May 2006 and August 2011, which was under closetonatural management of different thinning intensities (30%, 20%, 10%), and the un-thinned forest as the control, changes of the stand growth situation before and after thinning, population regeneration, species diversity and soil fertility after 5 years of thinning were analyzed, and the effects of thinning on forestland revegetation and community development were evaluated comprehensively. The results showed that the number of 1-6 years old Q. variabilis seedlings increased with increasing thinning intensity, while no significant difference was found for above 6 years old seedlings. The regeneration potentials of population under 10%, 20% and 30% thinning were respectively increased by 10.8%, 28.5% and 32.9% compared with the control. Thinning promoted the DBH and crown of the trees and shrubs, as well as the height of shrubs, especially for light-loving plants, and the effect of promotion increased with increasing thinning intensity. The species diversity and soil fertility were improved after thinning, in order of 30% > 20% > 10% > control. The thinning intensity of 30% (canopy density 0.6) was more conducive to the continuable development of the natural Q. variabilis forest in which canopy density was above 0.85.

Microclimate dynamics of  pit and mound complex within different sizes of forest gaps in Pinus koraiensisdominated broadleaved mixed forest.

WEI Quan-shuai1, WANG Jing-hua2, DUAN Wen-biao1, CHEN Li-xin1, WANG Ting1, HAN Dong-hui1, GU Wei3

2014, 25(3):  702-710. 

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An investigation was conducted in a 2.25 hm² plot of Pinus koraiensisdominated broadleaved mixed forest to study basic characteristics of 7 small gaps, 5 middle gaps, 3 large gaps and 7 closed stands within 38 pit and mound complexes caused by treefall in May 2012. From June to September 2012, the soil temperature, soil water content and relative humidity at five microsites (pit bottom,   pit wall, mound top, mound face and undisturbed closed stands) were measured in six sunny days each month. The results showed that among the five microsites in every month, the mound top had the highest soil temperature and the lowest water content and relative humidity, and vice versa for the pit bottom. Mostly, the differences in the above indicators among the five microsites were significant. From June to September, the mean soil temperatures for all microsites at pit and mound complex in the various gaps and closed stands were in the order of large gap>middle gap>small gap>closed stand; but the soil water content ranked differently every month. In June, August and September, the mean relative humidities for all microsites in the various gaps and closed stands were in the order of closed stand>small gap>middle gap>large gap. Mostly, the differences in the above indicators between all microsites in the various gaps and closed stand were significant. The mean monthly soil temperature and relative humidity were highest in July, but lowest in September. The maximal mean monthly soil water content occurred in July and the minimal one in September for each microsite except the undisturbed closed stands, where the maximal mean monthly soil water content occurred in July.  The variation of the microclimate at the pit and mound complex was mainly influenced by gap size, microsite, and time.

Effects of salt stress on Nitraria roborowskii growth and physiological characteristics of stress resistance.

LU Yan, LEI Jia-qiang, ZENG Fan-jiang, XU Li-shuai, LIU Guo-jun, PENG Shou-lan, HUANG Cai-bian

2014, 25(3):  711-717. 

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A pot experiment was conducted to study the influences of different NaCl concentrations (0, 50, 100, 200, 400 mmol·L^-1) on the growth, leaf hydrogen peroxide (H₂O₂), malonaldehyde (MDA) content, superoxide dismutases (SOD), catalases (CAT), peroxidase (POD), ascorbate peroxidase (APX) enzymes activity, water potential, soluble sugar and proline contents of Nitraria roborowskii. The results showed that the growth of N. roborowskii was not affected at lower NaCl concentrations (≤50 mmol·L^-1), while the SOD, POD, CAT and APX activities in leaves of N. roborowskii were increased. However, higher NaCl concentrations (＞50 mmol·L^-1) restrained the growth parameters of crown area, number of branches, dry mass of leaf, branch and lateral root, and remarkably reduced the SOD, POD and CAT activities, soluble sugar and proline contents in leaves of N. roborowskii. H₂O₂ and MDA contents in leaves were increased and water potential was reduced with increasing NaCl concentrations.

Effect of NaHCO₃ stress on uptake and transportation of Na⁺, K⁺ and Ca²⁺ in three shrub species.

MAO Gui-lian1, LI Guo-qi2, XU Xing2, ZHANG Xin-xue3

2014, 25(3):  718-724. 

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We detected absorption and transportation of ions in the leaves of Atriplex nummularia, Atriplex canescens and Lycium barbarum under NaHCO₃ stress (300 mmol·L^-1) by using atomic absorption spectrophotometry and non-invasive ion flux measurement. The results showed that leaves of the A. nummularia, A. canescens and L. barbarum exhibited a high capacity to induce the Na⁺ accumulation when compared with that of control. The higher the concentration of NaHCO₃ treatment, the more Na⁺  accumulated in the leaves of the three plants under experimental condition. L. barbarum showed a higher Na⁺ efflux in the mesophyll cells, whereas A. nummularia and A. canescens showed a relative lower efflux. A lower K⁺ content and a higher Na⁺/K⁺  ratio were detected in leaves of A. nummularia and L. barbarum. However, a higher K⁺ content and a lower Na⁺/K⁺ ratio were seen in leaves of A. canescens. Due to induction of Ca²⁺ efflux under the NaHCO₃ treatment, a lower Ca²⁺ content and a higher Na⁺/Ca²⁺ratio were observed in L. barbarum. On the contrary, a higher Ca²⁺ influx was observed in A. nummularia and A. canescens. These results suggested that the three shrubs species had different Na⁺ segmentation strategies. The accumulation of Na⁺ inhibited Ca²⁺ absorption in leaves of L. barbarum, while in the A. nummularia and A. canescens, Ca²⁺ influx induced \[Ca²⁺\]cyt which preserved a lessdepolarized PM and then inhibited K efflux. The maintaining of cellular K⁺/Na⁺ homeostasis in A.nummularia and A. canescens might be achieved by the induction of \[Ca²⁺\]cyt under the NaHCO₃ treatment.

Indoor simulation on dew formation on plant leaves.

GAO Zhi-yong1, WANG You-ke1,2, WEI Xin-guang1, LIU Shou-yang1, HE Zi-li1， ZHOU Yu-hong1

2014, 25(3):  725-730. 

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Dew forming on plant leaves through water condensation plays a significant ecological role in arid and semi- arid areas as an ignorable fraction of water resources. In this study, an artificial intelligent climate chamber and an automatic temperature-control system for leaves were implemented to regulate the ambient temperature, the leaf surface temperature and the leaf inclination for dew formation. The impact of leaf inclination, ambient temperature and dew point-leaf temperature depression on the rate and quantity of dew accumulation on leaf surface were analyzed. The results indicated that the accumulation rate and the maximum volume of dew on leaves decreased with increasing the leaf inclination while increased with the increment of dew point-leaf temperature depression, ambient temperature and relative humidity. Under the horizontal configuration, dew accumulated linearly on leaf surface over time until the maximum volume (0.80 mm) was reached. However, dew would fall down after reaching the maximum volume when the leaf inclination existed (45° or 90°), significantly slowing down the accumulative rate, and the zigzag pattern for the dynamic of dew accumulation appeared.

Selection of advantage prediction model for forest fire occurrence in Tahe, Daxing’an Mountain.

QIN Kai-lun1, GUO Fu-tao2, DI Xue-ying1, SUN Long1, SONG Yu-hui2, WU Yao3, PAN Jian-feng4

2014, 25(3):  731-737. 

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This study chose zero-inflated model and Hurdle model that have been widely used in economic and social fields to model the fire occurrence in Tahe, Daxing’an Mountain. The AIC, LR and SSR were used to compare the models including zero-inflated Poisson model (ZIP), zero-inflated negative binomial model (ZINB), Poisson-Hurdle model (PH) and negative Binomial Hurdle (NBH) (two types, four models in total) so as to determine a better-fit model to predict the local fire occurrence. The results illustrated that ZINB model was superior over the other three models (ZIP, PH and NBH) based on the result of AIC and SSR tests. LR test revealed that the negative binomial distribution was suitable to both the “count” portion of zero-inflated model and hurdle model. Furthermore, this paper concluded that the zero-inflated model could better fit the fire feature of the study area according to the hypotheses of the two types of models.

Distribution of soil organic carbon storage and carbon density in Gahai Wetland ecosystem.

MA Wei-wei1, WANG Hui1, HUANG Rong1, LI Jun-zhen2, LI De-yu1

2014, 25(3):  738-744. 

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The profile distribution and accumulation characteristics of organic carbon of four typical marshes (herbaceous peat, marsh wetland, mountain wetland, subalpine meadow) were studied in Gahai Wetlands of Gannan in July 2011. The results showed that the soil bulk densities of the four typical marshes ranged from 0.22 to 1.29 g·cm^-3. The content of soil organic carbon in the herbaceous peat was higher than in other types, with its average content of organic carbon (286.80 g·kg^-1) being about 2.91, 4.99, 7.31 times as much as that of the marsh wetland, mountain wetland and subalpine meadow, respectively. The average organic carbon densities were in order of herbaceous peat ＞ subalpine meadow ＞ marsh wetland ＞ mountain wetland, with the highest in the 0-10 cm layer. The change of organic carbon density along the soil profile was basically in accordance with the organic carbon content in the four typical marshes, but fluctuated with soil depth. There were obviously two carbon storage layers (0-10 and 20-40 cm, espectively) in the four typical marshes. The amounts of organic carbon stored in the 0-60 cm layer of the four typical marshes were 369.46, 278.83, 276.16, 292.23 t·hm^-2, respectively. The total amount of organic carbon stored in the 0-60 cm of the four typical marshes was about 9.50×10⁶ t.

Characteristics of Carex brevicuspis and its impact factors in Dingzidi, East Dongting Lake.

HU Jia-yu1,2, XIE Yong-hong1, LI Feng1, HOU Zhi-yong1

2014, 25(3):  745-751. 

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In recent 20 years, the area of lake grass has been drastically reduced and degraded. In order to search for reasonable recovery ways of the lake grass, the vegetational characteristics (plant height, coverage, density, biomass and biodiversity index) and soil physicochemical characteristics (soil organic carbon, SOC; total nitrogen, TN; total phosphorus, TP; soil bulk density and moisture) were investigated in the Carex brevicuspis community from 63 sampling plots in 7 sampling belts along an elevation gradient in Dingzidi, East Dongting Lake. All biological characteristics showed an inverted “U” distribution pattern along with increasing elevation, except for diversity index, which showed a tendency of increasing at first and then decreasing. Plant growth was inhibited near water body (low elevation region) and levee (high elevation region). In contrast, the intermediate elevation region had a favorable condition for plant growth. For soil physical properties, soil water moisture decreased but soil bulk density increased along with increasing elevation. However, SOC and TN contents were higher in the intermediate elevation region and lower in both low and high elevation regions. TP content was fluctuant along with increasing elevation. The principal component analysis (PCA) showed that the key factors influencing biomass of C. brevicuspis were soil C and N contents, soil moisture and bulk density. These results indicated that increasing soil fertility and maintaining proper soil moisture might be efficient to recover the vegetation of C. brevicuspis.

Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region.

CHEN Xiang-bi1,2, WANG Ai-hua1, HU Le-ning3, HUANG Yuan1,2, LI Yang1,2, HE Xun-yang1,2, SU Yi-rong1,2

2014, 25(3):  752-758. 

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Typical paddy and upland soils were collected from a hilly subtropical redsoil region. ^14Clabeled dissolved organic carbon (¹⁴CDOC) was extracted from the paddy and upland soils incorporated with ¹⁴Clabeled straw after a 30-day (d) incubation period under simulated field conditions. A 100-d incubation experiment (25 ℃) with the addition of ¹⁴CDOC to paddy and upland soils was conducted to monitor the dynamics of ¹⁴CDOC mineralization under different soil moisture conditions \[45%, 60%, 75%, 90%, and 105% of the field water holding capacity (WHC)\]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO₂. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex composition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil moisture (45%-90% WHC). Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% (paddy soil) and 66.3%-72.4% (upland soil) of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction.

Effects of tillage rotation and fertilization on soil aggregates and organic carbon content in corn field in Weibei Highland.

WANG Li1, LI Jun2, LI Juan1, BAI Wei-xia2

2014, 25(3):  759-768. 

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A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of notillage and subsoiling (NT-ST), subsoiling and conventional tillage (ST-CT), or conventional tillage and no-tillage (CT-NT), and yearly practice of no-tillage (NT-NT), subsoiling (ST-ST) or conventional tillage (CT-CT). The fertilization treatments included balanced fertilization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters (MWD), geometrical mean diameters (GMD) and fraction dimension numbers (D) of soil aggregates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that: 1) The increased tillage intensity caused the reduced mechanical stability and content of soil aggregates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT>NT-ST>NT-CT>ST-ST>CT-ST>CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or low-rate fertilization than with the conventional fertilization. 2) Mathematical fractal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2.247-2.681 by dry sieving and 2.897-2.976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabilize at the soil depth of 40 cm. 3) The different fertilization treatments exerted significantly different influences on the contents of soil organic carbon (P<0.05), which tended to decline with soil depth. Compared to the conventional fertilization, the balanced fertilization increased the content of soil organic carbon by 6.9%, and the contents of soil organic carbon increased as the diameters of soil aggregates increased. The correlation analysis showed that the contents of soil aggregates with diameters of 0.25-2 mm significantly affected the content of soil organic carbon, with the  coefficient of determination being 0.848 (P<0.01).

Effect of controlled release fertilizer on nitrous oxide emission from paddy field under plastic film mulching cultivation.

ZHANG Yi1,3, LU Shi-hua2, MA Jing1, XU Hua1, YUAN Jiang2, DONG Yu-jiao2

2014, 25(3):  769-775. 

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A field experiment was conducted to assess the effect of controlled release fertilizer on N₂O emission in paddy field under plastic film mulching cultivation (PM) with watersaving irrigation. Results showed that in the rice growing season, cumulative N₂O emissions from the plots applied with urea (PM+U) and with controlled release fertilizer (PM+CRF) were (38.2±4.4) and (21.5±5.2) mg N·m^-2, respectively. The N₂O emission factors were 0.25% and 0.14% in the treatments PM+U and PM+CRF, respectively. The controlled release fertilizer decreased the total N₂O emission by 43.6% compared with urea, of which 49.6% was reduced before the drying period. It also reduced the peak of N₂O emission by 52.6%. However, it did not affect soil microbial biomass N and soil NH₄⁺-N content at any rice growing stage, and grain yield either. No significant correlation was observed between N₂O flux and soil Eh or soil temperature at the depth of 5 cm.

Border effect and physiological characteristics of broomcorn millet  under film mulching on ridge-furrow for harvesting rainwater model in the semiarid region of Northern Shaanxi, China.

QU Yang1,2, SU Wang1, LI Cui1, GAO Jin-feng1, GAO Xiao-li1, WANG Peng-ke1, FENG Bai-li1, CHAI Yan1

2014, 25(3):  776-782. 

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To explore the border effect and physiological characteristic of broomcorn millet growing under different film mulching on ridge-furrow for harvesting rainwater models in the semiarid region of Northern Shaanxi, China, a three-year field experiment was conducted with four different widths of ridge and furrow, and the bare land flat sowing as the control (NM). The width of ridge and furrow varied as ridge : furrow=40 cm : 40 cm (P₄₀), 60 cm : 60 cm (P₆₀), 80 cm : 80 cm (P₈₀), and 100 cm : 100 cm (P₁₀₀). The results showed that the wider the width of furrow and ridge was, the stronger the border advantage and the border effect index of the yield were. With the increase in width of furrow and ridge, the yield increasing effect of side rows increased with the maximum of 207.7%, and the yield increasing effect of middle rows decreased with the minimum of 10.3%. P₆₀ reached the highest yield within three years. The yield contribution rate of side rows was higher than that of middle rows (P<0.05). The chlorophyll contents, Chl a/Chl b, and photosynthetic rate of side rows were higher than those of middle rows among the different harvesting rainwater models. The wider the width of furrow and ridge was, the stronger the photosynthetic capacity of side rows was, and the weaker the photosynthetic capacity of middle rows was. The optimal type of ridge and furrow was P₆₀ in the semiarid region of Northern Shaanxi.

Effects of mechanical transplanting of rice with controlled release bulk blending fertilizer on rice yield and soil fertility.

ZHANG Xuan, DING Jun-shan, LIU Yan-ling, GU Yan, HAN Ke-feng, WU Liang-huan

2014, 25(3):  783-789. 

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A₂year field experiment with a yellow-clay paddy soil in Zhejiang Province was conducted to study the effects of different planting measures combined with different fertilization practices on rice yield, soil nutrients, microbial biomass C and N and activities of urease, phosphatase, sucrase and hydrogen peroxidase at the maturity stage. Results showed that mechanical transplanting of rice with controlled release bulk blending (BB) fertilizer (BBMT) could achieve a significantly higher mean yield than traditional manual transplanting with traditional fertilizer (TFTM) and direct seeding with controlled release BB fertilizer (BBDS) by 16.3% and 27.0%, respectively. The yield by BBMT was similar to that by traditional manual transplanting with controlled release BB fertilizer (BBTM). Compared with TFTM, BBMT increased the contents of soil totalN, available N, available P and microbial biomass C, and the activities of urease, sucrase and hydrogen peroxidase by 21.5%, 13.6%, 41.2%, 27.1%, 50.0%, 22.5% and 46.2%, respectively. Therefore, BBMT, a simple high-efficiency rice cultivation method with use of a light-weighted mechanical transplanter, should be widely promoted and adopted.

Nutrient spatial variability of tobacco soil restoration area and fertility suitability level evaluation.

XU Da-bing1, DENG Jian-qiang2, LIU Dong-bi1, SI Guo-han1, PENG Cheng-lin1, YUAN Jia-fu1, ZHAO Shu-jun1, WANG Rui2

2014, 25(3):  790-796. 

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By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH<5.5). Low SFI was found in 77.6%, 17.1% and 31.4% of the soils taken from the suburb, Baiyang and Qingjiangyuan, respectively. In conclusion, attentions should be paid on soil acidification in Baiyang, soil fertility and equalization in the suburb, and soil fertility in the region of Qingjiangyuan with low SFI.

Effect of adding different amounts of wheat straw and phosphorus on soil microorganism community.

ZHANG Si-hai1, HUANG Jian1, LUO Zheng-rong1, DONG Shuguang1, WANG Yi-kun1, ZHU Qiang-gen1, ZHANG Long1, JIN Ai-wu1

2014, 25(3):  797-802. 

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A pot experiment was conducted to study the effects of adding different amounts of wheat straw  (0 g·kg^-1, N₀; 2.08 g·kg^-1, N₁) and phosphorus (0 mg·kg^-1, P₀; 100 mg·kg^-1, P₁; 200 mg·kg^-1, P₂; 400 mg·kg^-1, P₃) on microorganism community in a soil of low-phosphorus. Adding straw and phosphorus had significant effects on the soil microbial total biomass (MTB), bacterial biomass (MB), fungal biomass (FB), and fungi to bacteria ratio (F/B), which all decreased in order of N₁P₁>N₁P₀>N₁P₂>N₁P₃> N₀P₁> N₀P₂>N₀P₃. MTB, MB, FB and F/B ratio of the wheat straw addition treatments were all significantly higher than in the non-straw addition treatments under the same level of phosphorus addition. As for the same wheat straw addition, MTB, MB, FB and F/B ratio increased firstly and then decreased with increasing the level of phosphorus addition, and the combinations of P₁ level were optimal.

Genetic analysis of accumulation and remobilization of water soluble carbohydrates regulated by drought in wheat RIL stem at grain-filling stage.

YANG De-long1, LI Meng-fei1, CHENG Hong-bo1, CHAI Shou-xi2, LI Wei1

2014, 25(3):  803-812. 

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Recombinant inbred lines (RIL, Longjian 19 × Q9086, F₈) and their parents were undertaken to study characteristics of quantitative genetics of water soluble carbohydrates (WSC) accumulation, remobilization and its contribution to grain mass in different main stem internodes at the grainfilling stage as well as the correlations among the target traits under the rainfed (DS) or wellwatered (WW) condition. All of the target traits of RIL had wide variations under both water conditions. The variation coefficient ranged from 2.7% to 62.1% under the DS, and from 1.9% to 52.1% under the WW. The diversity index varied from 0.61 to 0.90 under the DS, and from 0.64 to 0.89 under the WW. All tested traits were significantly affected by the genotype, water condition, internode and growth stage. The growth stage exerted strong impacts on the WSC content. The water condition and internode greatly influenced the WSC remobilization rate. But, the WSC contribution rate to grain was jointly controlled by the genotype, water condition and internode. There were significantly positive correlations between the WSC contents at the early flowering and grain-filling stages,  the WSC remobilization rate and its contribution rate to grain at preanthesis stage, with the higher correlation coefficients under the DS than under the WW. All traits showed low heritability under both water conditions (hB₂=0.31-0.56 under the DS, 0.44-0.67 under the WW). The numbers of gene pairs controlling all traits ranged from 6 to 29 under the DS, and from 3 to 19 under the WW. It indicated that alleles responsible for all the target traits of RIL showed substantially transgressive segregation and greatly significant sensitivity to the water condition, confirming the characteristics of quantitative traits.

Effect of bagging with different colors on the fruit coloration of ‘Yunhongli No.2’ pear.

MA Ce1, XIAO Chang-cheng1, HU Hong-ju2, HUANG Xiao-san1, ZHANG Shao-ling1, WU Jun1

2014, 25(3):  813-818. 

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The present study was conducted to reveal the effect of bags with different colors on the fruit coloration of ‘Yunhongli No.2’. The differences in fruit skin color, chlorophyll, flavonoids, total phenol, anthocyanin contents and the activities of related enzymes involved in anthocyanin synthesis among different bagging treatments were evaluated. The results showed that dark treatment at the fruit development stage was beneficial to skin coloration after bag removing. After removing bags, the anthocyanin content in the treatment of natural light was highest and the red coloration of the fruit skin were best, followed by the treatment of white bags. The different bagging treatments significantly affected the contents of chlorophyll, flavonoids, total phenol, anthocyanin in the fruit skin, thereby affected the skin coloration. The activities of related enzymes for anthocyanin synthesis showed significant differences among the different bagging treatments. The correlation analysis suggested that the anthocyanin content was significantly positively related with the activities of dihydroflavonol 4-reductase (DFR) and UDP-glucose flavonoid 3-O-glucosyltransf-erase (UFGT), however, it had no significant correlation with the activity of phenylalanin ammonialyase (PAL).

Effects of temperature on fecundity of nine lepidopteran species in Tiantong National Forest Park, Zhejiang Province, China.

JING Jun 1,2, SU Chao1,2, FANG Yan1, LI Kai 1,2

2014, 25(3):  819-824. 

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Detailed experiments were carried out to investigate the effects of temperature on fecundity of nine lepidopteran species in Tiantong National Forest Park, Zhejiang Province, China. In the temperature range of 19-28 ℃, nine lepidopteran moths laid eggs and the eggs hatched successfully, and the preoviposition period was shortened with the rising of temperature. The largest fecundity of Ourapteryx ebuleata szechuana and other seven lepidopteran species occurred at 22 ℃, while that of Miltochrista ziczac occured at 25 ℃. The period of the embryonic stages of the nine lepidopteran species were shortened with the rising of the temperature. O. ebuleata szechuana had a lower developmental threshold temperature at 9.52 ℃ and a higher effective accumulated temperature of 12082 degreeday, while the other 8 species got the developmental threshold temperature between 13.32 ℃ to 14.72 ℃, and the effective accumulated temperature between 45.09 degreeday to 6830 degreeday. The regressive equation of effective accumulated temperature obtained in the research could be used to preliminarily forecast the occurring of the nine lepidopterans.

Geostatistical analysis on distribution pattern of the tobacco budworm larva in Enshi, Hubei, China.

XIA Peng-liang, WANG Rui, TAN Jun

2014, 25(3):  825-830. 

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Tobacco budworm (Helicoverpa assulta) larvae feed on tobacco leaves (Nicotiana sp.), resulting in significant loss in tobacco production. Geostatistical method was used to analyze H. assulta spatial patterns and dynamics in this paper. The results showed that, H. assulta larvae appeared 40 days after the tobacco plants transplanting, and reached its peak at the earlymature period. The nested spherical and exponential model was the major model for tobacco budworm larva in the field, suggesting its aggregated distribution. The spatial variability C/(C₀+C) was larger than 0.75, which indicated H. assulta larva had wider structural variation and narrower random variation. There was a massive migration of tobacco budworm larva in the fastgrowing stage of tobacco. Its quantity became stable after that, especially at the mature stage of tobacco.

Study on foraging behaviors of honeybee Apis mellifera based on RFID technology.

TIAN Liu-qing1, HE Xu-jiang1,2, WU Xiao-bo1, GAN Hai-yan1, HAN Xu1, LIU Hao1, ZENG Zhi-jiang1

2014, 25(3):  831-835. 

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Honeybee foragers can flexibly adjust their out-hive activities to ensure growth and reproduction of the colony. In order to explore the characteristics of honey bees foraging behaviors, in this study, their flight activities were monitored 24 hours per day for a duration of 38 days, using an radio frequency identification (RFID) system designed and manufactured by the Honeybee Research Institute of Jiangxi Agricultural University in cooperation with the Guangzhou Invengo Information Technology Co., Ltd. Our results indicated that 63.4% and 64.5% of foragers were found rotating more than one day off during the foraging period in two colonies, and 22.5% and 26.4% of the total foraging days were used for rest respectively. Further, although the total foraging time between rotating dayoff foragers and continuously working foragers was equal, the former had a significant longer lifespan than the latter. Additionally, the lifespan of the early developed foragers was significantly lower than that of the normally developed foragers. This study enriched the content of foraging behaviors of honey bees, and it could be used as the basis for the further explorations on evolutionary mechanism of foraging behaviors of eusocial insects.

Reconstructing habitat history of Larimichthys polyactis in Lüsi coastal waters of Jiangsu Province, China based on otolith microchemistry.

XIONG Ying1,2, LIU Hong-bo3, LIU Pei-ting2, TANG Jian-hua2, YANG Jian1,3, JIANG Tao1, WU Lei2, GAO Yin-sheng2, SHI Jin-jin2

2014, 25(3):  836-842. 

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An electron probe microanalyzer (EPMA) was applied to analyze the element Sr and Ca microchemistry patterns in otoliths of Larimichthys polyactis in Lüsi coastal waters of Jiangsu Province, China. The results showed that Sr was heterogeneously distributed along the sagittal plane of the otoliths. The highest Sr concentration was normally found in the otolith cores while much lower concentrations were found in the remaining areas. The corresponding Sr/Ca ratios were (7.10±1.00) and (4.79±1.01) in the former and latter, respectively, which were significantly differed (P<0.01), but low Sr/Ca ratios even as low as (3.51±0.76) were also observed in several fish. Based on the above results of otolith microchemistry, the habitat history of L. polyactis was reconstructed as that high salinity habitats seemed to be required at the stages of hatching and posthatching development, while the reduced salinity habitats seemed to be preferable for the growth and development at the remaining stages of the life history. Furthermore, several fish in this study had likely even experienced much lower salinity habitats at the early stages.

Applying multi-model inference to estimate growth parameters of greater lizard fish Saurida tumbil in Beibu Gulf, South China Sea.

HOU Gang1,2, LIU Jin-dian3,4, FENG Bo1,2, YAN Yun-rong1,2, LU Huo-sheng1,2

2014, 25(3):  843-849. 

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Age and growth parameters are key parameters in fish stock assessment and management strategies, thus it is crucial to choose an appropriate growth model for a target species. In this study, 〖JP〗five growth models were set to fit the length-age data of greater lizard fish Saurida tumbil (n=2046) collected monthly from December 2006 to July 2009 in the Beibu Gulf, South China Sea. The parameters for each model were estimated using the maximum likelihood method under the assumption of the additive error structure. Adjusted coefficient of determination (R²_adj), root mean squared error (RMSE), Akaike’s information criterion (AIC), and Bayesian information criterion (BIC) were calculated for each model for fitness selection. The results indicated that the four statistical approaches were consistent in selection of the best growth model. The MMI approach indicated that the generalized VBGF was strongly verified and made up 95.9% of the AIC weight, indicating that this function fitted the lengthage data of the greater lizard fish well. The growth function was L_t=578.49^{\[1-e-0.051(t-0.14)\]0.361}.

Petroleum pollution and the microbial community structure in the soil of Shengli Oilfield.

LIU Jian1，2, SONG Xue-ying3, SUN Rui-lian1,2, XIE Fu-ju4, WANG Ren-qing1,2, WANG Wen-xing1

2014, 25(3):  850-856. 

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Soils around a new oil well (2011- ) and an old oil well (1966-2003) were sampled to investigate the characteristics of petroleum pollution in the oilfield. The structure of soil microbial community was analyzed by PCRDGGE and clone sequencing techniques. Results showed that the soils around the two oil wells were generally contaminated with petroleum, and the concentrations of total petroleum hydrocarbons mostly exceeded the threshold of the environmental quality standards of soil (500 mg·kg^-1). The total petroleum hydrocarbons concentration of the polluted soil was significantly positively correlated with the contents of organic carbon, total nitrogen and available potassium, respectively. The microbial diversity index in the soil around the old oil well decreased with the increasing total petroleum hydrocarbons concentration, however, it was reversed for the soil around the new oil well. Sequence analysis of the prominent bands in DGGE profiles showed that some dominant species existed in the petroleumcontaminated soils around the oil wells and mostly were oilassociated and hydrocarbon degrading bacteria, including Microbacterium, Streptomyces, Dietzia, Flavobacterium, αProteobacteria, and γProteobacteria.

Spatial distribution of sulfur dioxide around a tobacco bulk-curing workshop cluster.

HE Fan1, WANG Mei2, WANG Tao3, SUN Jian-feng4, HUANG Wu-xing1, TIAN Bin-qiang1, GONG Chang-rong1

2014, 25(3):  857-862. 

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In order to manifest lower energy consumption and less labor employment, and provide the theoretical basis for constructing environmentally friendly modern tobacco agriculture, this paper analyzed gas composition of the chimney from a  bulk-curing barn and the dispersion of sulfur dioxide (SO₂) around the workshop cluster using ecom-J2KN flue gas analyzer and air sampler. During curing, the concentrations of carbon dioxide (CO₂) and SO₂ in the chimney were both highest at 38 ℃, while the concentration of nitrogen oxides (NO_x) was highest at 42 ℃. The emission concentration of SO₂ from the chimney was 1327.60-2218.40 mg·m^-3. Average SO₂ emission would decrease by 49.7% through adding 4.0% of a sulfur-fixed agent. The highest concentrations of SO₂ in the surface soil appeared at the yellowing stage. SO₂ concentration in horizontal direction localized at 43-80 m exceeded 0.5 mg·m^-3. The highest concentration of SO₂ (0.57 mg·m^-3) was observed at 50 m. At 50 m in the downstream wind direction of the workshop cluster, SO₂ concentration in vertical direction localized at 0.9-1.8 m exceeded 0.5 mg·m^-3, and the highest concentration of SO₂ in vertical direction was 0.65 mg·m^-3 at 1.6 m. During curing, the average concentration of SO₂ was decreased by 0.43 mg·m^-3 by using the sulfur-fixed agent. The polluted boundary was localized at 120 m in the downstream wind direction of the workshop cluster.

Spatial distribution, mechanism and  management strategies of carbon source and sink of urban residential area: A case in Guanzhong Region, China.

WEI Shu-wei1.2, WEI Shu-jing3, WANG Ya-mei2, WEN Zheng-min3

2014, 25(3):  863-874. 

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Urban residential area is an important component of urban ecosystem. Its carbon process will have an important impact on carbon cycle and carbon balance of urban ecosystem. In this paper, the data of CO₂ emission and absorption in Guanzhong area were collected by case analysis, literature consulting and questionnaires and surveys to analyze its sources and the spatial distribution characteristics. The results showed that building materials production and renovation of residential area had the most CO₂ emission, and building materials had much larger CO₂ emission compared with everyday means of subsistence. Only 40%-52% of total carbon emission occurred within the residential area, while the rest was in the peripheral area. The spatial distance variation of carbon source, the spatial differences of carbon component and the spatial distribution by spheres and zoning were observed. As for CO₂ absorption, only 9%-17% CO₂ emission could be absorbed in the residential area, and the others had to be imposed to the outer space, showing hierarchical grading rules and spatial variation. Some space management techniques and intervention measures were put forward.

 

Identification of coupling relationship between urbanization and ecological environment in Jilin from entropy change perspective.

SUN Ping-jun1,2, XIU Chun-liang1, ZHANG Tian-jiao3

2014, 25(3):  875-882. 

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By using the entropy change equation of the second law of thermodynamics, entropy method and PSE model, this article made an analysis on coupling relationship between urbanization and ecological environment in Jilin Province from 2001 to 2011. In the study period, the urbanization development had been out of normal evolution track: The economic urbanization and space urbanization dominated the whole urbanization process, while population urbanization was neglected too seriously, with an apparent characteristic of extensive and inefficient input of resources (especially land resource). According to the levels of ecological environment on the basis of PSE model, not only the pressure index, sensitivity index and the elasticity index, but also the comprehensive index showed considerable growth with obvious stage characteristics: ascendingdescendingascending. The total entropy values of the urbanization were less than zero during the time, which meant an unstable rising curve. While the total trophy values of the ecological environment varied below and above zero, and 2003, 2006, 2010 and 2011 were the “turning points”, reflecting the instability of the ecological environment. The coupling total entropy values between urbanization and ecological environment had the same characteristics with the ecological environment: the same “turning points” and shape of the curve, in which, the “turning points” corresponded to the type of antagonistic evolution pattern, while the rest of years responded to the type of coordination evolution pattern.

Spatio-temporal dynamics of ecosystem service value in Wuhan Urban Agglomeration.

ZENG Jie1, LI Jiang-feng2, YAO Xiao-wei2

2014, 25(3):  883-891. 

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Based on the land use vector data of Wuhan Urban Agglomeration in the years 1990, 2000 and 2009, this paper used Costanza’s evaluation formula to estimate the ecosystem service value (ESV) of the study area according to “equivalent value per unit area of ecosystem services in China” and analyze its spatio-temporal characteristics. Then the correlation analysis was applied to explore the association between the ESV evolution and the land use changes. The results showed that due to the substantial growth of water area, the ESV of Wuhan Urban Agglomeration increased by 9.5% during the study period, which showed an overall rising trend. The ESV of water regulation and waste treatment increased obviously. Furthermore, the ESV changes showed obvious regional differences, which were most significant in Xiantao, Xinzhou and Yunmeng. The ESV was higher in the southeast and lower in the northwest. Over time, a Wuhancentered “low-high-low” hierarchically distributed structure of ESV was formed in the eastern, western and northern parts. The ecologic dominance of the northern mountainous and hilly region was gradually abated, while a structural expansion with a highESV cluster had taken place in the southern part of the region in 2009. During the research period, the temporal change of ESV in Wuhan Urban Agglomeration was positively correlated with the area changes of forestland, water, grassland and cultivated land. However, the spatially balanced distribution of ESV was negatively correlated with the dispersion degrees of the cultivated land and unused land.

Review on the main microorganisms and their metabolic mechanisms in enhanced biological phosphorus removal (EBPR)systems.

SUN Xue, ZHU Wei-jing, WANG Liang, WU Wei-xiang

2014, 25(3):  892-902. 

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Enhanced biological phosphorus removal (EBPR) process is applied widely for removing phosphorus from wastewater. Studies on functional microorganisms and their metabolic mechanisms are fundamental to effective regulation for stable operation and performance improvement of EBPR process. Two main types of microorganisms in EBPR systems, polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were selected to summarize their metabolic mechanisms such as substrate uptake mechanisms, glycogen degradation pathways, extent of TCA cycle involvement and metabolic similarity between PAOs and GAOs. Application of mole
cular biology techniques in microbiology and metabolic mechanisms involved in the EBPR system was evaluated. Potential future research areas for the EBPR system and process optimization were also proposed.

 

Metabolism and interaction of C and N in the arbuscular mycorrhizal symbiosis.

LI Yuan-jing1,2, LIU Zhi-lei1,2, HE Xing-yuan3, TIAN Chun-jie1

2014, 25(3):  903-910. 

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The arbuscular mycorrhiza (AM) is the symbiont formed by the host plant and the arbuscular mycorrhizal fungi (AMF). The transfer and metabolism of C and N in the symbiosis plays an important role in keeping nutrient balance and resource reallocation between the host plant and the fungi. The carbohydrates produced by plant photosynthesis are transferred to the fungi, where they are metabolized as materials and energy used for fungal spore germination, mycelium growth and uptake of nitrogen and other nutrients. At the same time,  N is transferred and reallocated from the fungi to the host plant, where the final released ammonium is used for plant growth. Accordingly, we reviewed the current progress in C and N transfer and metabolism in the AM symbiosis, and the crosstalk between them as well as some key issues to elucidate the mechanism of the interaction between C and N transport in the symbiosis, so as to provide the theory foundation for the application of AM in sustainable agriculture and ecosystem.

 

Urban ecological risk assessment: A review.

WANG Mei-e， CHEN Wei-ping, PENG Chi

2014, 25(3):  911-918. 

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With the development of urbanization and the degradation of urban living environment, urban ecological risks caused by urbanization have attracted more and more attentions. Based on urban ecology principles and ecological risk assessment frameworks, contents of urban ecological risk assessment were reviewed in terms of driven forces, risk resources, risk receptors, endpoints and integrated approaches for risk assessment. It was suggested that types and degrees of urban economical and social activities were the driven forces for urban ecological risks. Ecological functional components at different levels in urban ecosystems as well as the urban system as a whole were the risk receptors. Assessment endpoints involved in changes of urban ecological structures, processes, functional components and the integrity of characteristic and function. Socialecological models should be the major approaches for urban ecological risk assessment. Trends for urban ecological risk assessment study should focus on setting a definite protection target and criteria corresponding to assessment endpoints, establishing a multipleparameter assessment system and integrative assessment approaches.

 

A review of the role and function of microbes in coral reef ecosystem.

ZHOU Jin1,2, JIN Hui3, CAI Zhong-hua1,2

2014, 25(3):  919-930. 

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Coral reef is consisted with several kinds of reef-associated organisms, including coral, fish, benthos, algae and microbes, which is an important marine ecosystem. Coral reef lives in the oligotrophic environment, has very highly primary productivity and net productivity, and is called “tropical rain forest in ocean”. In corals, diverse microorganisms exert a significant influence on biogeochemical and ecological processes, including food webs, organism life cycles, and nutrient cycling. With the development of molecular biology, the role of microorganisms in a coral system is becoming more outstanding. In this article, we reviewed current understanding on 1) the onset of coral-bacterial associations; 2) the characteristics of microbes in coral (specificity, plasticity and co-evolution); 3) the role and signal regulation of microbes in the health and disease of coral; and 4) the response mechanism of microbes for global climatic change and consequent effects, such as temperature rise, ocean acidification and eutrophication. The aims of this article were to summarize the latest theories and achievements, clear the mechanism of microbial ecology in coral reefs and provide a theoretical reference for better protection and maintaining the coral’s biodiversity.