Table of Content

10 July 2013, Volume 32 Issue 7

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Decomposition and nitrogen- and phosphorus release of leaf litters from main tree species in a mid-subtropical forest.

ZHONG Mi-cai1，2,3, WANG Qing-kui1,2**, GAO Hong2, YU Xiao-jun2

2013, 32(7):  1653-1659. 

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By using the standard litter-bag method, an experiment was conducted to study the decomposition rate and the nitrogen (N) and phosphorus (P) release processes of leaf litters derived from Pinus massoniana, Alnus cremastogyne, Schima superba, and Cycloblanopsis glauca in a 21-year-Cunninghamia lanceolata forest. By the end of the experiment (13 months incubation), C. glauca litter had the highest decomposition rate, with 33.5% of mass loss, followed by A. cremastogyne and S. superba, and P. massoniana had the lowest decomposition rate, with 29.9% of mass loss. The time for 50% and 95% of the mass loss of the litters from the four tree species ranged from 21 to 26 months and from 94 to 112 months, respectively. During the decomposition, the N concentration in A. cremastogyne litter decreased, whereas that in the other tree species litters increased. The P concentration in the litters decreased rapidly at the first three months of decomposition, and then varied insignificantly. During litter decomposition, the ratio of carbon (C) to N decreased, while the ratio of C to P increased. C. glauca, A. cremastogyne, and S. superba litters had net N release, but P. massoniana litter had N sequestration. In terms of P, the litters from the four tree species had net release during decaying. Among the four tree species, A. cremastogyne was more appropriate to be mixed planted with C. lanceolata.

 

Dynamic changes of biomass and its allocation in Cunninghamia lanceolata plantations of different stand ages.

YU Yue-feng1,2,3, SONG Tong-qing1,2**, ZENG Fu-ping1,2, PENG Wan-xia1,2, WEN Yuan-guang4, HUANG Cheng-biao4, WU Qing-biao4, ZENG Zhao-xia1,2, YU Yang1,2,3

2013, 32(7):  1660-1666. 

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Based on the investigation data from a total of 15 plots (20 m×50 m) in Cunninghamia lanceolata plantations of different stand ages (6, 16, 23, 32, and 50 years old) in Guangxi of South China, and by using the data of 15 sample trees of different ages and diameter at breast height (DBH), the biomass regression equation with DBH as the single variable was established. The biomass in the tree layer and in the shrub, herb, and litter layers of the plantations was calculated by regression analysis and quadrat harvest method, respectively, and the change trends of the biomass and its allocation in the plantations of different stand ages were analyzed. Except that the stands of 16 and 23 years old had a slight decrease in biomass due to intermediated thinning, the total biomass of the other stands increased with stand age. The biomass of the stands of 6, 16, 23, 32, and 50 years old was 62.73, 172.51, 141.65, 192.30, and 247.32 Mg·hm^-2, respectively, of which, living biomass made up 95.76%-98.39%. Tree layer predominated in biomass, occupying 89.77%-96.55% of the total biomass, and the change trend of tree layer biomass with stand age was as the same as that of the total biomass. The biomass of litter layer was the second, occupying 1.61%-4.24%; while the biomass of shrub and herb layers was the least, accounting for 0.01%-4.26% and 0.27%-4.07%, respectively. The biomass in shrub layer was the largest in 6 years old stand, while that in herb layer was the largest in 23 years old stand. In tree layer, trunk had the greatest proportion of biomass, accounting for 54.89%-75.97%, followed by root, accounting for 11.91%-12.66%. The biomass of both trunk and root was increased with stand age. The proportion of branch and leaf biomass was 11.86-15.19%, and 4.80%-13.17%, respectively, and decreased with stand age. In shrub layer, the biomass allocation was in the order of branch > root > leaf, except for leaf > branch in 50 years old stand, and root > branch in 23 and 50 years old stands. In herb layer, as compared with underground part, aboveground part had greater biomass in 6 and 23 years old stands, but was the opposite in other age stands. The biomass of tree organs and in different layers as well as the whole biomass could be well fitted by growth models. As compared with other plantations, 32 years old C. lanceolata plantation had a mediumhigh level total biomass, suggesting that C. lanceolata would be a fast-growing and high-yielding forestation tree species with high photosynthetic efficiency and high carbon sequestration potential.

 

Species diversity of forest communities in Pangquangou Nature Reserve, Shanxi of China.

LI Xu-hua1, DENG Yong-li2, ZHANG Feng1,2**, DONG Gang1,2, LI Shi-guang3

2013, 32(7):  1667-1673. 

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Based on the numerical classification of the forest communities in Pangquangou Nature Reserve of Shanxi by  Two-Way Indicator Species Analysis (TWINSPAN), and by using the indices of richness, species diversity, and evenness, this paper studied the species diversity of the forest communities within the Reserve, and by using Spearman’s rank correlation coefficient, analyzed the relationships among the species diversity in the tree, shrub, and herbaceous layers of the communities. The richness, species diversity, and evenness indices of the 15 associations of the communities well reflected the diversity differences of all the associations. Overall, the richness and species diversity indices of most associations presented the sequence of herbaceous layer > shrub layer > tree layer, and the evenness index was the lowest in herb layer but had less difference in tree and shrub layers. There existed significant differences (P<0.01) among the Patrick index, Simpson index, and Shannon index and between the Pielou index and Alatalo index. In Ass. 3 (Larix principisrupprechtii-Spiraea pubescens+Rosabella-Fragaria orientalis), there was a significant negative correlation (r=-0.643, P<0.05) between shrub and herbaceous layers; in Ass. 8 (Betula platyphylla+Populus davidiana-Cotoneaster acutifolius+R.bella-Carex stenophylloides), shrub layer had a significant negative correlation (r=-0.458, P<0.05) with tree layer but a significant positive correlation (r=0.404, P<0.05) with herbaceous layer; in Ass. 11(Picea meyeri-C. stenophylloides+Carpesium cernuum), tree layer was significantly negatively correlated with herbaceous layer (r=-0.949, P<0.05).

Biomass model and carbon storage of Pinus yunnanensis on Tibet Plateau of China.

YANG Yang1,2, RAN Fei1**, WANG Gen-xu1, ZHU Wan-ze1, YANG Yan1, ZHOU Peng1,2

2013, 32(7):  1674-1682. 

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Pinus yunnanensis forest is an important component of coniferous forest ecosystems on Tibet Plateau. To accurately estimate the carbon storage of the P. yunnanensis forest ecosystem is of significance to understand the carbon sequestration of forest ecosystems in Tibet, and also, to provide basic data for estimating the carbon sequestration potential of forest ecosystems on Tibet Plateau and in China. In this paper, an investigation was conducted on the biomass and carbon storage of the P. yunnanensis forest of different ageclasses. Based on the data from twelve sampling plots and forty seven sample trees, the biomass regression equations of each organ (leaf, branch, stem, and root) of P. yunnanensis based on tree height and diameter at breast height were established. Then, the biomass and carbon storage of young, middle age, premature, and mature P. yunnanensis forests were calculated. The results showed that the exponential model was an appropriate regression model for estimating the biomass of each organ based on the tree height and the diameter at breast height of P. yunnanensis (R²>0.90). The total vegetation biomass of the young, middleage, premature, and mature P. yunnanensis ecosystems was (63.80±9.21), (134.76±12.69), (142.91±13.02), and (316.72±42.57) t·hm^-2, of which, the biomass of tree layer was (49.48±10.32), (120.57±9.37), (124.70±12.92), and (304.76±32.47) t·hm^-2, the biomass of shrub and herb layer was (13.09±3.02), (12.81±2.54), (11.88±3.12), and (3.47±0.98) t·hm^-2, and the biomass of litter layer was (1.23±0.24), (1.38±0.31), (0.72±0.11), and (1.13±0.39) t·hm^-2, respectively. The carbon storage of the young, middleage, premature, and mature P. yunnanensis  forost ecosystems was (30.67±7.13), (67.63±19.06), (71.00±4.15), and (159.32±39.95)
t·hm^-2, respectively. The carbon storage of the P. yunnanensis forest increased significantly with its increasing stand age, indicating that Tibetan P. yunnanensis forest had great potential in carbon sequestration.

Spatial heterogeneity of soil nitrogen and phosphorus under different land use patterns in depressions between karst hills.

TANG Cheng1,3, DU Hu1,2, SONG Tong-qing1,2**, PENG Wan-xia1,2, ZENG Fu-ping1,2, YANG Gai-ren1,3, LIANG Zhi-xia1,3, LU Cheng-yang1,3

2013, 32(7):  1683-1689. 

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Soil samples were collected from the depressions between karst hills by grid sampling method (5 m×5 m), and the spatial heterogeneity of soil nitrogen and phosphorus in surface layer (0-20 cm) under different land use patterns (burned land, mowing land, grassland, and fenced land) were investigated by classic statistics and geo-statistics. In the study area, the soil total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) under the four land use patterns showed a moderate variation, with the contents being 5.40-6.26 g·kg^-1, 1.24-1.44 g·kg^-1, 365.87-507.32 mg·kg^-1, and 3.91-8.04 mg·kg^-1, respectively. The soil quality of fenced land and burned land was superior to that of grassland and mowing land. The soil AN of burned land, AP of burned land, AN of mowing land, and TN of fenced land were fitted well by spherical model; the soil TN of burned land, TN of mowing land, and AP of mowing land were fitted well by exponential model; and the other soil nutrient variables were fitted well by Gaussian model. A strong spatial autocorrelation occurred for the soil TP of mowing land, TP of burned land, TP of grassland, and TN of mowing land, AP of burned land, AP of grassland, and TN of fenced land, while a moderate spatial autocorrelation existed for the other variables. The soil TN and AN as well as the soil TP and AP under the four land use patterns showed the similar spatial distribution pattern. The soil TN and AN of burned land and mowing land presented a concave distribution, while the TP and AP showed a unimodal distribution. The soil TN, TP, AN, and AP in grassland all decreased with slope position, while these soil nutrients in fenced land presented concave distribution. Land use pattern changed the soil nutrient quality in the depressions between karst hills, and caused different spatial patterns of soil nutrients. Therefore, in the ecological restoration and reconstruction of karst region with broken landform and shallow soil, it should adopt rational land use pattern, protection, and moderate development to improve the soil quality of degraded ecosystems.

Effects of N and P addition on soil nitrogen mineralization in a subtropical evergreen broadleaved forest.

ZHAO Yang, ZHANG Chi, ZHAO Hong-fei, XU Xiao-niu**

2013, 32(7):  1690-1697. 

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Three treatments (no nutrient addition, CK; N addition, 100 kg N·hm^-2·a^-1; and N+P addition, 100 kg N·hm^-2·a^-1 + 50 kg P·hm^-2·a^-1) were installed in an evergreen broadleaved forest in  northern subtropics to study the effects of nutrient addition on the soil nitrogen dynamics and mineralization in the forest. The annual mean inorganic N concentrations (NH₄+-N + NO₃^--N) in 0-10 cm and 10-20 cm soil layers for the treatments CK, N addition, and N+P addition were 7.27 and 6.80 mg·kg^-1, 13.94 and 8.92 mg·kg^-1, and 11.20 and 7.13 mg·kg^-1, respectively, among which, the percentages of NH₄⁺-N to total inorganic N were 90.66% and 91.15%, 65.78% and 72.85%, and 84.64% and 85.08%, respectively. The net ammonification, nitrification, and N mineralization rates in the 0-10 cm and 10-20 cm soil layers of the three treatments showed the similar seasonal patterns, with the maximum in summer and the minimum in winter. There were no significant differences for the net rates of N transformation in spring and autumn. Nutrient addition (N and N+P) decreased the annual average net rates of nitrogen mineralization. N addition decreased the net nitrification rate but increased the net ammonification rate, whereas N+P addition increased the net nitrification rate but decreased the net ammonification rate. Due to the long-term dynamic processes of forest ecosystems in response to nutrient addition, it would be necessary to conduct a long-term observation on the nitrogen dynamics in forest ecosystems under scenario of increasing N deposition.

Profile distribution characteristics of dissolved organic carbon in different types of subtropical paddy soils.

SHENG Hao1, ZHOU Ping2, YUAN Hong1, LIAO Chao-lin1, HUANG Yun-xiang1, ZHOU Qing1, ZHANG Yang-zhu1**

2013, 32(7):  1698-1702. 

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Five subtropical paddy soils developed from different parent materials (reddish yellow clayey soil I, reddish yellow clayey soil II, granitic sandy soil, red clay soil, and alluvial sandy soil) were chosen, and samples were collected according to soil genetic horizons, aimed to investigate the profile distribution characteristics of dissolved organic carbon (DOC) in subtropical paddy soils, and to approach the profile shift patterns of DOC and related affecting factors. In the test soils, the DOC content in the profiles ranged from 13.61  to 90.34 mg·kg^-1. Plough layer had the highest DOC content (72.33 mg·kg^-1 on average), whereas the below layers showed relatively lower DOC content. Except for alluvial sandy soil, the DOC content in the other four soils did not decrease gradually with increasing depth, while had a higher distribution in some horizons (e.g., percogenic horizon, waterloggogenic horizon, and parent rock horizon) than in upper horizon, which could be related to the special leaching and deposition processes of DOC, its biological degradation, mineral phase adsorption, and the regimes of redox throughout the whole profile. The percentage of DOC to soil organic carbon (SOC) (DOC/SOC) in the whole profiles ranged from 0.21% to 1.31%, with the lowest value in plough layer and relatively higher values in below layers. It was suggested that the SOC in below layers could be more active and more sensitive to human disturbances (e.g., ploughup) than that in plough layer. Correlation analysis showed that there was a significant positive correlation between DOC and SOC, suggesting the decisive effect of SOC level in the profiles on the profile distribution of DOC. From the viewpoints of maintaining soil quality, sequestrating soil C, and mitigating soil CO₂ emission, it would be necessary to take different cultivation and management modes for different kinds of subtropical paddy soils.

Nitrous oxide emission rates of saline soils in Yellow River Delta of China under different water and N amendment conditions.

ZHANG Jin-feng1, 2**, LI Zeng-jia3

2013, 32(7):  1703-1709. 

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A laboratory incubation was conducted to investigate the N₂O emission rates of saline soils collected from the Yellow River Delta of China under different water and N treatments. For the soils with the salinity from ECe = 6.4 mS·cm^-1 to ECe = 126.5 mS·cm^-1, their N₂O emission rates under different water conditions (50% WHC, 80% WHC, and 4 cm water depth) and without N amendment were very low, often below the detection limit. After applying 0.4 mg N·g^-1 soil of NH₄NO₃, the N₂O emission rate of sandy moderately saline soil at 50% WHC and at 4 cm water depth was 41.0 μg N₂O·kg^-1 soil·d^-1 and 364.6 μg N₂O·kg^-1 soil·d^-1, respectively, being comparable to that of non-saline soils under the similar conditions, and the N₂O emission rate of sandy strongly and extremely saline soils was 43%-65% and 23%-48% of that of sandy moderately saline soil, respectively. By contrast, the N₂O emission rate of Namended loamy saline soils was very low, from 0.91 to 37.1 μg N₂O·kg^-1 soil·d^-1. The  high potential of N₂O production and its strong dependence on nitrogen amendment and soil texture in saline soils suggested that the effects of soil salinity on N₂O emission were mainly controlled by the limitation of C and N supply rather than the microbial factors.

Differentiation characteristics of soil nutrients in temperate steppe under different vegetation types.

LI Yi-kang1,2, ZHANG Fa-wei1, LIN Li1, DU Yan-gong1, CAO Guang-min1, GUO Xiao-wei1,2, ZHOU Guo-ying1, HAN Fa1**

2013, 32(7):  1710-1716. 

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Taking the temperate steppe under four vegetation types around the Qinghai Lake of Northwest China as test objects, this paper studied the distribution patterns of soil nutrient heterogeneity under natural condition and grazing disturbance. There existed obvious layering characteristics in the soil available N, P, and K, being the highest in surface layer (0-10 cm) and decreased with soil depth. In degraded Stipa purpurea steppe, the available nutrient contents in different soil layers were lower than those in Poe steppe, Elymus nutans steppe, and Leymus secalinus steppe. The Poe steppe which was restored for a longer time and experienced exotic substance input had higher contents of soil available nutrients. The soil total N content in degraded S. purpurea steppe and E. nutans steppe was higher in 0-20 cm layer, but decreased sharply below 20 cm depth. In contrast, both Poe steppe and L. secalinus steppe showed a higher soil total N content at each depth. The soil total P content had no significant correlation with soil depth (P>0.05), but was significantly lower at the depths 0-10 cm, 10-20 cm, 20-30 cm, and 30-40 cm in degraded S. purpurea steppe than in other three steppes (P<0.05). The soil total K and organic matter contents in degraded S. purpurea steppe  were also lower than those in other three steppes. Soil organic matter content had significant correlations with soil total and available N, P, and K (P<0.01). Soil bulk density increased with soil depth. Degradation resulted in the increase of soil pH value. After 6 years recovery of degraded temperate steppes, the soil could be basically recovered. It was suggested that both grazing disturbance and natural factors could affect the soil nutrient status in temperate steppe.

Effects of soil inherent and exogenous organic carbon on carbon dioxide flux of paddy soil.

ZHANG Lei, YIN Li-chu**, YI Ya-nan, GAO De-cai, FU Wei-wei

2013, 32(7):  1717-1722. 

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Soil inherent and exogenous organic carbon are the carbon sources of soil respiration, but rarely distinguished in the previous studies about the effects of different fertilization modes on the carbon emission from paddy soils. In this study, three original treatments in a 30-year fertilization experiment of paddy soil were adjusted to seven treatments, i.e., original high organic material treatment (HOM), high organic material treatment changed from original normal organic material treatment (N-H), original normal organic material treatment (NOM), normal organic material treatment changed from chemical fertilizer (C-N), chemical fertilizer treatment changed from high organic material treatment (H-C), chemical fertilizer treatment changed from normal organic material treatment (N-C), and original chemical fertilizer treatment (CF). The CO₂ fluxes of the three original and four changed treatments were measured to study the effects of different fertilization modes on the CO₂ emission and to illuminate the effects of soil inherent and exogenous organic carbon on the CO₂ fluxes. The average CO₂ fluxes of the seven different fertilization treatments were 85.34, 69.10, 51.27, 49.15, 14.89, 12.92, and 11.59 mg C·m^-2·h^-1, respectively. In the treatments of inorganic fertilization and normal organic fertilization, the level of soil inherent organic carbon had no significant effects on the average CO₂ flux; while in the treatments of high organic fertilization, high level of soil inherent organic carbon promoted the average CO₂ flux. The relationship between the CO₂ flux (Y) and the exogenous carbon content (x) met the exponential equation Y=13.33e^1.719x (R²=0.967, n=21), indicating that the exogenous organic carbon had significant effects on the soil CO₂ flux. About 14% of the exogenous organic carbon was decomposed and released as CO₂-C during rice growth season, and this decomposition rate was less affected by soil organic carbon content and the added amount of organic material.

Sustainability of agro-ecoeconomic system in reclamation area of Heilongjiang, Northeast China based on emergy analysis.

FU Shi-cong1, WANG Da-qing2, ZHANG Yang1， WANG Jiang-li3, ZHAO Wei1, TANG Zhe-qing2, ZHANG Li1, WANG Hong-yan

2013, 32(7):  1723-1729. 

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Based on the theories and analytical methods of emergy, and adopting the indices such as net energy yield ratio, environmental loading ratio, energy density, energy consumption per capita, production cost ratio, sustainability index, system stability index, and dominance index, an analysis was made on the emergy structure of agroecoeconomic system in the reclamation area of Heilongjiang in 2002-2011. In the study area, all the indices mentioned above were maintained at a high level, the investment in industrial auxiliary energy was increased substantially, the production capacity of agroecosystem was continued to enhance, and the economic development level and the workers’ living standards were improved significantly. However, these improvements also induced the decline of agroecosystem sustainability, the irrational planting structure, and the low energy efficiency issues, which should be solved in the future development.

Water quality of cropland drainage ditches in the Yellow River irrigation regions of Ningxia and Inner Mongolia, China.

HU Yi-gang1, WU Pan2,3, ZHAO Yang1, ZHANG Zhi-shan1**, XU Bing-xin1,3

2013, 32(7):  1730-1738. 

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The agricultural non-point source pollution in the upper reaches of Yellow River is becoming the main pollution source of Yellow River, which threatens the safe use of water resources in the lower reaches of Yellow River basin. Through the investigation on the soil and water characteristics of cropland drainage ditches in the Yellow river irrigation regions of Ningxia and Inner Mongolia, it was found that there existed significant differences in pH and TN, TDS, and NO₃^--N concentrations of drained water among different drainage ditches and within different levels of drainage ditches. The TN, TP, NH₄⁺-N, and COD concentrations of drained water were significantly affected by the drainage time, levels of drainage ditches, and their interactions. The total salt content in the bottom soil of the drainage ditches was obviously lower than that in the side slope soil, whereas the TN and TC contents in the side slope soil of the drainage ditches were 1.2 times higher than those in the bottom soil. The increased proportion of TN, TP, and TC contents in the bottom soil of the ditches relative to that in the side slope soil in Inner Mongolia irrigation region was 1.6, 3.8, and 6.3 times higher than the increased proportion in Ningxia irrigation region, respectively. The TN, TP, NH₄⁺-N, and COD concentrations of drained water in Inner Mongolia in August were 3.2, 2.5, 2.8, 10.0, and 1.5 times more than those in Ningxia irrigation region, respectively. The nitrogen concentration in drained water was higher than the State Surface Water Standard of China, especially in the subfeeder and main drainage ditches in Ningxia and Inner Mongolia irrigation regions. The phosphorus concentration in drained water was relatively low, which hardly cause any pollution. During the main drainage periods in the irrigation region of Inner Mongolia, the nitrogen pollution of subfeeder and the nitrogen and phosphorus pollution of main drainage ditches were most serious in August.

Composition and ecological benefits of street trees in Shinan District of Qingdao City, Shandong Province based on i-Tree Model.

ZHANG Yu-yang1, ZHOU Chun-ling1**, Dong Yun-zhai2, WANG Yuan-sen1

2013, 32(7):  1739-1747. 

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In this paper, the i-Tree Model was applied to analyze the composition of the street trees in Shinan District of Qingdao, and to quantify the economic value of the street trees’ ecological benefits in storm water interception, CO₂ absorption and sequestration, air quality improvement, and energy saving in 2012. On the main roads of the District, there were 12322 individuals of 43 street tree species, among which, the top 10 species such as Platanus spp. and Ginkgo biloba accounted for 84.4% of the total. Mediumsized (DBH: 15-30 cm) and smallsized (DBH<15 cm) trees dominated the street trees, occupying 53.54% and 29.06%, respectively. Overall, the street trees were in good health condition, and the healthy trees occupied 97.4% of the total. The annual economic value of the street trees’ ecological benefits was 23032 thousand yuan, and the weighted average benefit of an individual tree was 1869 yuan. This study could offer helpful and scientific references on the planning and planting of urban street trees and the management of urban landscape.

Species composition and diversity of herb communities in Dongtan reclamation areas of Chongming Island, Shanghai.

YANG Jie1,2, YU Hua-guang1,2, XU Feng-jie1,2, MA Ming-rui1,2, YOU Wen-hui1,2**

2013, 32(7):  1748-1755. 

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The study of species composition and diversity of plant communities in reclamation area can provide references in understanding and protecting the biodiversity in reclamation area. In this paper, an investigation was conducted on the herb communities in the reclamation areas with different reclamation history in Dongtan of Chongming Island, aimed to understand the variation characteristics of species composition and diversity of herb communities during the succession. In the investigation area, a total of 49 herb species were recorded, belonging to 20 families and 45 genera, among which, Compositae and Gramineae occupied about 45% of the total. Annual herbs dominated in the herb communities. With the increasing duration of reclamation, the species richness and diversity decreased after an initial increase, with the peak value in the 50 years of reclamation. The Jaccard index and Cody index all decreased after an initial increase with the increasing duration of reclamation, and the communities changed intensely in the 20-40 years of reclamation. Conductivity (salinity) was the main soil factor affecting the species diversity of the communities.

Intra- and inter-specific competition of rare and endangered plant Ulmus lamellosa in Shanxi Province of China.

WANG Xiao-xia, ZHANG Qin-di**, BI Run-cheng, BAI Yu-fang

2013, 32(7):  1756-1761. 

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Based on the field investigation data of 128 Ulmus lamellosa target trees and 1093 competing species individuals in a 100 m×100 m sampling plot in Taiyue Mountain of Shanxi, this paper analyzed the intra- and inter-specific competition intensities of U. lamellosa by using Hegyi’s competition index (CI). The intraspecific competition intensity of U. lamellosa decreased gradually with its increasing DBH. In the plot, there were many other species, but their individual number was fewer than that of U. lamellose, and thus, the interspecific competition intensity of U. lamellosa was relatively weaker than its intraspecific competition. The order of the intra- and inter-specific competition intensities was U. lamellosa-U. lamellosa > Carpinus cordata-U. lamellosa > Acer elegantulum-U. lamellosa> other species-U. lamellosa. The relationships between the competition intensity and the DBH of U. lamellosa followed the equation CI=AD-B. When the DBH of U. lamellosa reached 25 cm, the competition intensity had less change, and the model could well simulate and predict the intra-and inter-specific competition intensities of U. lamellosa.

Population structure and its dynamics of wild Prunus divaricata in Xinjiang, Northwest China.

LIU Ying1, ZHANG Xiang-feng1, ZHAO Yu1**, GAN Yu-ping2

2013, 32(7):  1762-1769. 

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In order to understand the structure of the wild population and analyze its current survival situation, an investigation was conducted in the natural distribution region of Prunus divaricata population. Adopting space as a substitute for time, a comparative analysis was made on the ageclass, heightclass, and crown widthclass of the population, and the dynamics of the age structure of the population was described according to the static life table. The results showed that the structure of the crown widthclass and heightclass showed a certain degree of decline, and there was an overall logarithmic decline in crown widthclass. Due to the effects of different microenvironments among the plots, the population structure had definite difference. The survival curve fitted the B1 type (steptype curve), indicating that the seedlings had a high mortality rate, and there were significant differences in the death rate at different life stages. The natural population of wild P. divaricata in Xijiang showed some unstable characteristics. Therefore, it is urgently needed to supplement seedlings or young individuals and to prohibit felling adult individuals so as to provide guarantee for the conservation and recovery of wild P. divaricata population.

Responses of canopy stomatal conductance of Schima superba stand to vapor pressure deficient in southern China.

CAO Qing-ping1,2, ZHAO Ping1**, NI Guang-yan1, ZHU Li-wei1, NIU Jun-feng1, ZENG Xiao-ping1

2013, 32(7):  1770-1779. 

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Canopy stomatal conductance (G_s) is an important parameter quantifying the stomatal performance at canopy level, being able to characterize the exchange dynamics of vapor and energy of forest canopy. In this paper, the sap flow in a Schima superba stand in southern China was continuously monitored with Granier’s thermal dissipation probes, and the canopy transpiration of the stand was obtained through data upscaling methodology. In combining with the microclimatic observations, the G_s was estimated by using PenmanMonteith equation, and the responses of the G_s to vapor pressure deficit under different soil water conditions (wet season vs. dry season) were compared. The estimated G_s based on the sap flow measurement was in the same order of magnitude as that of the leaf stomatal conductance (g_s) determined by gaseous exchange method, and similar patterns of the diurnal variations of both G_s and g_s were observed. The responses of the G_s to vapor pressure deficit in wet and dry seasons had obvious difference. In wet season (soil water content θ> 33%), the G_s was more sensitive to vapor pressure deficit (partial coefficient -0.316); in dry season (θ< 23%), the G_s was more sensitive to photosynthetically active radiation (PAR) (partial coefficient 0.885). The decoupling coefficient (Ω) of stand canopyatmosphere was close to 1 (maximum value) in wet season but substantially smaller in dry season, indicating that vapor pressure deficit had little effects on G_s in wet season probably due to the thicker boundary layers on leaves, while PAR was the main environmental factor controlling G_s.

Effects of exogenous salicylic acid on the physiological characteristics recovery of longan seedlings under acid rain stress. 

LIU Jian-fu**, WANG Ming-yuan, WANG Qi-zhi, TANG Yuan-jiang, YANG Chen, ZHONG Shu-chun, ZHU Ai-jun

2013, 32(7):  1780-1786. 

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This paper studied the effects of exogenous salicylic acid (0, 0.1, 0.5, 1.0, and 2.0 mmol·L^-1) on the physiological characteristics of longan (Dimocarpus longana ‘Fuyan’) seedlings under acid rain (pH 3.0) stress. Under the stress of the acid rain, the seedling’s leaf superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities as well as the leaf total chlorophyll, soluble protein, and soluble sugar contents decreased obviously, and the leaf malondialdedyde content had a remarkable increase, suggesting the toxic effect of the acid rain on the longan seedlings. Applying 0.1-1.0 mmol·L^-1 of exogenous salicylic acid improved the SOD, POD, and CAT activities and the total chlorophyll, soluble protein, and soluble sugar contents significantly, and decreased the malondialdedyde content. Low concentrations of exogenous salicylic acid reduced the oxidative damage caused by the acid rain stress, and 0.5 mmol·L^-1 of salicylic acid had the best effect. As compared with the acid rain stress alone, applying 0.5 mmol·L^-1 of salicylic acid improved the SOD, POD, and CAT activities by 144%, 440%, and 132%, and increased the total chlorophyll, soluble protein, and soluble sugar contents by 62%, 105%, and 177%, respectively, and decreased the malondialdedyde content by 35%. It was suggested that low concentrations of exogenous salicylic acid (0.1-1.0 mmol·L^-1) could alleviate the toxic effect of acid rain stress on longan seedlings via activating the seedlings leaf antioxidant enzyme activities and reducing oxidative stress, while high concentration of exogenous salicylic acid (2.0 mmol·L^-1) lowered the mitigation effect.

Responses of antioxidative enzymes and phytochelatins in Lolium perenne to Cd²⁺ stress.

LIU Jun-xiang, XU Xin-qiao, QIAN Yong-qiang, JU Guan-sheng, HAN Lei, SUN Zhen-yuan**

2013, 32(7):  1787-1793. 

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A hydroponics experiment was conducted to study the Cd accumulation in Lolium perenne and the effects of the accumulated Cd on the activities of antioxidative enzymes and the concentrations of phytochelatins under Cd²⁺ stress. The ^{L. perenne} plants with three fully expanded leaves were cultured in 1/2 Hoagland’s nutrient solution for 2 weeks, and then treated with 5 mg·L^-1 of Cd²⁺. The Cd concentration, antioxidative enzymes activities, and thiol compounds concentrations in both roots and leaves were measured on the day 0, 0.25, 1, 3, and 6 after treatment. After 6 days, the Cd concentration was 2588 mg·kg^-1 in roots and 240 mg·kg^-1 in leaves. The Cd transport index from root to leaf was 0.093, and the Cd bioconcentration index of leaf was 48, indicating that L. perenne had a high Cd accumulation capacity, and could be applied in phytoremediation. After exposed to Cd²⁺ stress, the MDA content in L. perenne leaves and roots and the SOD and CAT activities in L. perenne roots had less change, but the root APX was highly sensitive to Cd²⁺, with the activity on day 6 decreased significantly by 67%, as compared with that on 0 day. Within 1 day Cd²⁺ exposure, the SOD, APX and CAT activities in leaves decreased significantly. On day 3, the antioxidative enzyme system in leaves had a positive feedback to the increase of leaf Cd content, and the SOD, APX, and CAT activities increased significantly by 14%, 77%, and 99%, respectively, as compared with day 1. On day 6, the SOD activity decreased significantly by 19%, as compared with day 3, but the APX and CAT activities had no significant change. On day 6, the concentrations of Cys, GSH, PC₂, PC₃, PC₄, PC₅, and PC₆ in roots were 2.19, 1.57, 2.06, 16.08, 5.73, 6.03, and 4.31 times higher, and the concentrations of Cys, GSH, PC₂, PC₃, and PC₄ in leaves were 0.69, 3.21, 1.64, 5.73, and 0.27 times higher than those on day 0, respectively. PC₃ thiol had the greatest proportion to total thiol in roots, whereas GSH thiol had the greatest proportion to total thiol in leaves, suggesting that PC₃ thiol and GSH thiol were the main existence forms of thiol in roots and leaves, respectively. With the increasing time of Cd²⁺ treatment, the total thiol concentration both in roots and in leaves increased significantly, and the total PCs-SH concentration in roots and leaves was significantly positively correlated with the Cd concentration in roots and leaves. It was suggested that L. perenne could rapidly synthesize thiol compounds to decrease the proportion of Cd²⁺ to total Cd in leaves and roots, which played a key role in protecting the antioxidative enzymes in roots and leaves, and indirectly maintained the balance of reactive oxygen metabolism.

Role of nitric oxide in improving cadmium tolerance of microwave-pretreated wheat seedlings.

QIU Zong-bo**, ZHANG Man-man, GUO Jun-li, LEI Meng-yun

2013, 32(7):  1794-1799. 

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To approach whether nitric oxide (NO) in microwave pretreatment can improve wheat seedling’s cadmium tolerance, wheat seeds were pretreated with microwave radiation (126 mW·cm^-2)  for 10 s, and the seedlings were treated with 150 μmol·L^-1 of CdCl₂ and 0.5% (w/v) of cPTIO (a NO scavenger), aimed to study the effects of NO on the lipid peroxidation, antioxidant enzyme activities, photosynthesis pigment concentrations, and growth of microwavepretreated wheat seedlings under cadmium stress. The 10 s microwave pretreatment could significantly decrease the malondialdehyde content, while increase the superoxide dismutase, peroxidase, catalase activities, the concentrations of nitric oxide, chlorophyll a, chlorophyll b, and carotenoid, and the plant height, root length, and shoot and root dry weight of the seedlings under cadmium stress. The amelioration effect of the microwave pretreatment on the cadmium stress was effectively reversed by the addition of cPTIO, suggesting that NO was involved in the microwave pretreatment-induced cadmium tolerance of wheat seedlings, and microwave pretreatment did trigger NO production which could lead to the cadmium tolerance of wheat seedlings.

Effects of soil burial depth and duration on the seed germination of Quercus wutaishanica.

ZHOU Li-biao1, YAN Xing-fu1**, ZHANG Qiang1, QIU Zhi-hu2, LI Jing1

2013, 32(7):  1800-1806. 

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Quercus wutaishanica seeds were collected from Liupan Mountains of Ningxia, Northwest China to study their germination under effects of different soil burial depths (0, 30, and 50 cm) and durations (2, 4, 6, 8, 10, and 12 weeks), aimed to explore the safe storage condition and long storage potential of the seeds and to provide reference for the seedling reproduction of Q. wutaishanica and the recovery of degraded Q. wutaishanica shrubs. During the early period (two weeks) of soil burial, the seed germination of Q. wutaishanica was inhibited, but with the extending of burial duration, the germination percentage increased, germination rate accelerated, and germination index and vigor index presented a fluctuated increase. After burial for 12 weeks, the germination percentage of the seeds buried under 30 cm and 50 cm soil depths was 90.1% and 96.8%, respectively. The seed rot rate was increased with increasing burial depth and extending burial duration. After buried for 2 weeks, the seeds germinated spontaneously. After 12 weeks burial, the germination percentage of the seeds buried under 30 cm and 50 cm depths was 24.5% and 43.0%, respectively.

Effects of storage condition on the seed germination of four Solanaceae species in Hexi Corridor, China.

WANG Ju-hong1,3, CHEN Wen2**, MA Rui-jun1

2013, 32(7):  1807-1812. 

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The storage condition of plant seeds after their dispersal is critical to the seed germination.  This paper studied the effects of four storage conditions (dry-stored at room temperature, and placed on litter, covered with litter, and covered with soil in winter) on the seed germination of four Solanaceae species (Lycium ruthenicumr, L. barbarum var. auranticarpum, Solanum alatum, and Darura stramonium) in Hexi Corridor, aimed to better understand the seed germination characteristics of these species and how these species adapting to their habitats. Covering seeds with soil (1 cm) and litter in winter could significantly increase the germination percentage of L. ruthenicumr and L. barbarum var. auranticarpum seeds up to 96.5% and 75.5%, and 65.3% and 53.7%, respectively, and accelerate the germination. In the meantime, the nongerminated seeds of L. ruthenicumr and L. barbarum var. auranticarpum could still keep higher viability. Placing on litter in winter and dry-storing at room temperature could increase the germination percentage of L. ruthenicumr seeds by 57.5%, while the non-germinated seeds could loss their viability by 47.5% and 31%, respectively. Placing on litter in winter made the germination percentage of L. barbarum var. auranticarpum seeds being 39.3%, and partial non-germinated seeds (38%) lost their viability. After stored under the four storage conditions, the germination percentage of S. alatum seeds was more than 90% while that of D. stramonium seeds was less than 10%, but the non-germinated seeds of D. stramonium still kept 50.5%-81.5% viability. Both L. ruthenicumr and L. barbarum var. auranticarpum displayed the consistency in the responses of seed germination to various storage conditions, i.e., the seeds of the two species under soil and litter cover in winter had a significantly higher germination percentage, the germination was accelerated, and the germination duration was shortened, as compared with those under placed on litter in winter or drystored at room temperature, which indicated that covering seeds with soil and litter in winter could break the dominancy of L. ruthenicumr and L. barbarum var. auranticarpum seeds and keep their viability, whereas the colddry environment in winter could make some seeds lost their viability, being unfavorable for the establishment and natural regeneration of population. The demand of seed germination to cold-wet environment reflected the natural mechanisms of reproducing race of temperate plants, which ensured the maximization of seedling survival and population establishment.

Chlorophyll fluorescence characteristics of Amaranthus tricolor L. under high temperature stress.

CHEN Mei, TANG Yun-lai**

2013, 32(7):  1813-1818. 

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Amaranth (Amaranthus tricolor L.) plants were exposed to several temperature levels (25, 30, 35, 40, and 45 ℃) for 1 h, and then, the characteristic parameters of chlorophyll fluorescence and the rapid light response curves of photosynthesis were measured, aimed to understand the effects of high temperature stress on the photosynthesis process of amaranth. High temperature stress (>40 ℃) decreased the maximum fluorescence (F_m), potential photochemical efficiency (F_v/F_o), and maximum photochemical efficiency of PSⅡ (F_v/F_m). Simultaneously, the electron transport rate (ETR), actual photochemical efficiency of PSⅡ (Yield), and photochemical quenching coefficient (q_P) also had some decrease. In contrast, the initial fluorescence (F_o) and nonphotochemical quenching coefficient (NPQ) were increased significantly. The initial slope rate (α), maximum apparent electron transport rates (ETR_max), and halfsaturation light intensity (Ik) under high temperature stress also had some decline. These results indicated that the photosynthesis of A. tricolor plants was very sensitive to high temperature stress. High temperature (>40 ℃) disturbed the A. tricolor plant’s light energy absorption and conversion, photosynthetic electron transport efficiency, and endurance against strong light.

Effects of environment and genotype on phenotypic variation and growth of young sea cucumber (Apostichopus japonicus).

CUI Shen-kun, CHANG Ya-qing**, SONG Jian, CHENG Long

2013, 32(7):  1819-1824. 

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In this study, six genotypes of young sea cucumber (Apostichopus japonicus) were exposed to three laboratory environments (high stocking density and natural light cycle, E1; low stocking density and dark, E2; and low stocking density and natural light cycle, E3) for 60 days, and a model was established to investigate the effects of environment, genotype, and their interaction on the survival rate and the specific growth rate (SGR) and coefficient of variation of growth traits (body length and body weight) of the young sea cucumbers. Environment, genotype, and their interaction had no significant effects on the survival rate of the sea cucumbers (P>0.05). Environment had significant effects on the SGR, but less effects on the coefficient of variation of growth traits, whereas genotype had significant effects on the SGR and the coefficient of variation of growth traits. No significant effects of genotype-environment interaction were recorded for the SGR and the coefficient of variation of growth traits (P>0.05). The SGR of the body length and body weight was the highest in the E3, with the average SGR being 0.03% and 1.58%, respectively. It was suggested that genotype × environment (light cycle and stocking density) interaction could be ignored when planning a breeding program for sea cucumber under laboratory conditions. This study provided theoretical basis for the family breeding of A. japonicus and the construction of healthy aquaculture mode.

Cannibalism and intraguild predation of phytoseiid mites Neoseiulus barkeri and Neoseiulus cucumeris. 

PENG Yong-Qiang, MENG Rui-Xia**, ZHANG Dong-Xu, ZHANG Peng-Fei, HAN Yu-Hua

2013, 32(7):  1825-1831. 

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Phytoseiid mites Neoseiulus barkeri and N. cucumeris are the generalists mainly preying on spider mites and thrips, and widely used in agricultural biocontrol. In this paper, the cannibalism and intraguild predation of N. barkeri and N. cucumeris and the female aggressiveness on larvae (quantified as attack probability) in intraguild predation  were studied, aimed to elucidate the interrelationships between these two species of predatory mite to reasonably establish a combination of different natural enemies in biological control. The results showed that the phytoseiid mites consumed more con and heterospecific larvae, lesser protonymphs, and seldom con and heterospecific eggs. The adult females of the two species mites exhibited higher predation rates on heterospecific larvae and protonymphs than on conspecific larvae and protonymphs, suggesting that the two  species of mites preferentially engaged in intraguild predation in absence of other food sources. The predation rate of N. barkeri on heterospecific larvae and protonymphs was higher than that of N.  cucumeri. Moreover, N. barkeri was more aggressive to heterospecific larvae than N. cucumeri in intraguild predation. Therefore, N. barkeri was most probably a potential intraguild predator of N. cucumeris, whereas N. cucumeri was a potential intraguild prey when the intraguild predation occurred between N. barkeri and N. cucumeris.

Effects of bacterial-feeding nematodes on soil functional stability under heat or copper stress.

FENG Yun, ZHU Dong, LIU Man-qiang, CHEN Xiao-yun**, LI Hui-xin, HU Feng

2013, 32(7):  1832-1837. 

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A microcosm experiment was conducted to study the effects of inoculating bacterial-feeding nematodes on the soil ecological functional stability under persistent Cu²⁺ stress or transient heating stress (40 ℃ for 18 h), with the shortterm decomposition of barley leaf power as the representative of soil function. In the treatments without any stress (blank control) and with Cu²⁺ stress, soil bacterialfeeding nematodes could promote soil microbial activities to some extent. On the 15th day of Cu²⁺ stress, the soil basal respiration in nematodesinoculated treatments increased significantly, and the soil functional resistance was significantly higher than that in the treatments without nematodes inoculated. However, under heating stress, inoculating bacterialfeeding nematodes had less effect on the soil basal respiration and microbial activities, and the soil functional resistance was lower than that in treatments without nematodes inoculation. It was suggested that under the two stresses, inoculating bacterial-feeding nematodes could decrease soil functional resilience.

Effects of different management modes of grassland after returned from cropland on meso and microfaunal communities in Wuchuan County of Inner Mongolia, North China.

MING Fan-bo1, MEN Li-na2, LIU Xin-min1**

2013, 32(7):  1838-1843. 

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In May-September 2006, soil cores were sampled from the grasslands returned from cropland and under different management modes in Wuchuan County of Inner Mongolia by using soilcutting ring (50 mL), and the meso- and micro-fauna were isolated by dry- and wet funnel methods to study the effects of different management modes of grassland after returned from cropland on the meso- and micro-faunal communities, aimed to provide references for the evaluation of returning cropland to grassland. A total of 19845 meso and micro-fauna were collected, belonging to 6 phylum, 8 classes, and 8 groups. The dominant groups were Nematode and Enchytraeidae, accounting for 81.37% and 15.68% of the total individual numbers of the meso- and micro-fauna, respectively. As compared to that in cropland, the individual number of Nematode in the grasslands returned from cropland and under different management modes increased significantly (P<0.05), especially in the grassland planted with Helianthus tuberosu +Artemisia sp. However, the individual number of Enchytroidae, Acarina, and Collembola had less increase. After returning to grassland, no significant differences were observed in the vertical distribution of meso- and micro-faunal communities, but the Acarina in the grassland planted with Medicago sativa had an increase in surface gathering. Our results suggested that in the study area, all the management modes of grassland after returned from cropland were beneficial to the restoration of Nematode. In the management of the grasslands returned from cropland, more attentions should be paid to the reservation and accumulation of ground litters to promote the restoration of Acarina and Collembola.

Effects of ration level and feeding frequency on the growth and biochemical components of juvenile turbot (Scophthalmus maximus).

LI Hua-hua, WU Li-xin**, JIANG Zhi-qiang, A Rong, CHEN Wei, LI Hong-yu, DONG Yi-yi

2013, 32(7):  1844-1849. 

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Taking juvenile Scophthalmus maximus (initial wet weight 7.56±0.03 g) as test object, an experiment was conducted on its growth and biochemical components under effects of different ration level (1.0%, 1.5%, 2.0%, and satiation) and feeding frequency (once a day, twice a day, and three times a day) at 17-19 ℃. With increasing ration level, the juvenile final weight, relative rate of body weight gain, and feeding rate all increased significantly (P<0.05). The specific growth rate had a linear increase with ration level; the feed conversion efficiency in wet weight, dry matter, protein, and energy decreased after an initial increase with increasing ration level; whereas the juvenile biochemical components and the apparent digestibility among groups were less affected by ration level (P>0.05). With increasing feeding frequency, the juvenile final weight, relative rate of body weight gain, specific growth rate, and feed conversion efficiency decreased after an initial increase, with the maximum at the feeding frequency of twice a day. No significant differences were observed in the apparent digestibility and biochemical composition among different feeding frequencies (P>0.05).

Fish species composition in Shibing of Guizhou, Southwest China, a candidate World Heritage Site.

LIU Yun, HOU Xiu-fa, ZHOU Jiang**

2013, 32(7):  1850-1856. 

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As a karst area of southern China, the Shibing in Guizhou Province is a second-batch candidate site nominated for the list of World Heritage Sites. In this paper, a threeyear survey was conducted on the fish species composition in Shibing. A total of 46 species of freshwater fishes were collected, belonging to 39 genera, 15 families, and 7 orders, among which, Cypriniformes had 28 species, accounting for 61% of the total. In species composition, native fishes dominated, with 40 species and occupying 87% of the total, whereas alien species had 6 species, occupying 13% of the total, and including 1 known invasive species (Gambusia affinis) and 5 artificial feeding species (Protosalanx hyalocroaniah, Ctenopryngodon idellus, Hypophthalmichthys molitrix, Aristichthys nobilis, and Megalobrama amblycephala).

Carbon  and nitrogen stable isotopes composition and its relationships with trophic levels of arthropods in smelting areas.

ZHENG Dong-mei**, SUN Li-na, LI Hui-ying, LI Xin-xin

2013, 32(7):  1857-1861. 

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By measuring the δ¹³C and δ¹⁵N ratios of plants and their main consumers in different habitats of Huludao Zinc Plant, Liaoning Province of Northeast China, this paper studied the relationships between the carbon  and nitrogen stable isotopes composition of different consumers and the consumers. In the study area, the δ¹³C and δ¹⁵N values of arthropods had a greater variation range, being -12.61‰--29.63‰ and 1.73‰-9.94‰, respectively. The C3 plants were dominant, which led to the lower δ¹³C values of the animals in different habitats. The δ¹⁵N values of Argiope bruennichii and Paraten odera sinensis were higher than those of the other animals. According to the trophic model, herbivores (Locusta migratoria manilensis and Acrida chinensis) were at the second trophic level, i.e., the primary consumers, whereas A. bruennichii and P. odera sinensis were at the third trophic level, i.e., the secondary consumers.

Enrichment characteristics and sources of heavy metals in surface sediments of Qinghai Lake, Northwest China.

ZHU Yang-chun1,2, CHEN Xue-min2**, FU Xiao-yong2

2013, 32(7):  1862-1869. 

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Aiming at the distribution characteristics of heavy metals in surface sediments of Qinghai Lake, 99 surface (0-20 cm) sediment samples were collected from 11 plots to measure the heavy metals (Zn, Cu, Pb, Ni, Cr, and Fe) contents. Geo-accumulation index and potential ecological risk index were adopted to evaluate the enrichment status of these heavy metals, and correlation analysis and factor analysis were conducted to approach the sources of these heavy metals. At tourist sites (dock 151 and Jiangxigou dock), surface sediments were slightly polluted by Zn and Cu; in Buha River, surface sediments were slightly polluted by Cr; while in the other plots, no pollution was observed. All the plots had a slight potential ecological risk. There existed significant positive correlations between the Cr, Fe, and TOC in the sediments. The Cr and Fe played significant roles in factor one (endogenous factor), and were mainly from sedimentary parent materials. The river water into the Lake also played an important role in Cr input. Both Pb and Zn had weak correlations with the other heavy metals, which represented the transferring and transformation patterns of factor two (agricultural activity) and factor three (tourist and traffic emission factors). The Pb and Zn were mainly affected by human activities. The Cu accumulation in surface sediments was related with endogenous, agricultural, and tourism emission factors. The Ni distribution was mainly affected by endogenous factors and tourist and traffic emission factors. Our results suggested that the heavy metals pollution and its potential ecological risk of surface sediments in Qinghai Lake were slight. In addition to endogenous factor, the agricultural activities around the Lake and the tourist and traffic emissions contributed to the pollution sources of the heavy metals.

Characteristics of heavy metals pollution of fishes in Daning River of Three Gorges Reservoir Area during initial impoundment.

YU Yang1,2, WANG Yu-chun1,2, ZHOU Huai-dong1,2**, GAO Bo1,2, ZHAO Gao-feng1,2

2013, 32(7):  1870-1876. 

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There exists spatial heterogeneity in the water environment in different areas of the Three Gorges Reservoir Area (TGRA) after impoundment. In order to explore the effects of different water environmental conditions on the heavy metals concentrations in the fishes in TGRA, we selected the river mouth (Wushan) and backwater area (Dachang) of Daning River, a typical tributary in central TGRA, as the study areas. Eleven fish species were collected from each of the two sites, and the Cr, Cd, As, Pb, Ni, Cu and Zn concentrations in the muscle tissue of all fish samples were determined. The food sources and nutrition levels of the fish samples were evaluated by using stable isotope analysis (δ¹³C and δ¹⁵N). It was found that the fishes in Dachang had greater range of δ¹³C values (-28.8‰--22.5‰) than those in Wushan (-26.2‰--23.1‰), while the δ¹⁵N values of the fishes in Dachang were lower than those in Wushan. There were no significant differences in the heavy metal concentrations in the fishes in Dachang and Wushan, but the heavy metal concentrations in demersal fishes in Dachang were significantly higher than those in corresponding species in Wushan. As compared with other fishes, the demersal fishes in backwater water area had more contact with sediments, which could be an important reason for the higher heavy metal levels in the demersal fish tissues.

Intra-annual inhomogeneity of precipitation and its prediction in Shaanxi Province of Northwest China in 1960-2011.

LIU Wen-li, ZHANG Ming-jun**, WANG Sheng-jie, WANG Bao-long, LI Xiao-shou, MA Xue-ning

2013, 32(7):  1877-1887. 

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Based on the daily precipitation data from 19 stations in Shaanxi Province during 1960-2011, and by using the methods of inverse distance weighted interpolation, climate tendency coefficient, MK mutations inspection, Morlet wavelet analysis, correlation analysis, synthetic analysis, and R/S analysis, this paper analyzed the variation characteristics of intraannual precipitation concentration degree and concentration period and their variation tendency in the Province. In 1960-2011, the intraannual precipitation concentration degree in the Province ranged from 0.44 to 0.66, and presented the spatial distribution characteristics of being higher in the south and north but lower in the middle part. The intraannual precipitation concentration period ranged from 18.32-22.37 ten days, and showed comparatively small regional difference. The intraannual precipitation concentration degree presented an increasing trend, while the intra-annual precipitation concentration period displayed an advanced tendency. The variation trends of the intra-precipitation concentration degree and concentration period all existed obvious regional differences. A decreasing abrupt variation in the intraannual precipitation concentration degree occurred in 1974, while the postponed abrupt variation of the intra-annual precipitation concentration period happened in 1962. The variations of the intra-annual precipitation concentration degree and concentration period did not have a fixed cycle, but various cycle scales nested each other, showing stronger partial characteristics of time and frequency. In the whole province, the annual precipitation was positively correlated with intra-annual precipitation concentration degree, and also, positively correlated with intra-annual precipitation concentration period except in Hengshan of northern Shaanxi. Both in waterish and in water deficient years, the spatial distribution of intra-annual precipitation concentration degree displayed the characteristics of being higher in the south and north but lower in the middle part, while the spatial distribution of intra-annual precipitation concentration period had a greater difference. The variation tendency of the intra-annual precipitation concentration degree and concentration period in the future would keep the same with that in the past 52 years.

Simulation of the effect of forest harvest mode on forest landscape: A case study in Huzhong forest region of Daxing’anling
 Mountains, China.

CHEN Hong-wei, HU Yuan-man**, CHANG Yu, BU Ren-cang, LI Yue-hui, LIU Miao, XIONG Zai-ping

2013, 32(7):  1888-1895. 

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The effect of disturbances on the changes of forest landscape is a long-term process. Traditional observation methods are hard to explore the long-term effect of disturbances on forest landscape at large spatial scale, while model simulation is a commonly used method at present. In this paper, a spatially explicit landscape model, LANDIS, was used to simulate the longterm (300 years) dynamics of forest landscape under four different forest harvest scenarios, i.e., no cutting, clear cutting, gradual cutting, and selective cutting, in the Huzhong forest region of the Daxing’an Mountains. We analyzed the mean patch area, aggregation index, percent cover, and age structure of the two typical forest types, larch and white birch. The results showed that forest harvest reduced the percent cover of larch forest while increased that of white birch forest, and there were no significant differences among the various forest harvest scenarios. As compared with other forest harvest scenarios, clear cutting decreased the aggregation level of larch forest while increased that of white birch forest significantly. During the early-stage of the simulation, forest harvest reduced the mean patch area of larch forest while increased that of white birch forest. Clear cutting increased the percent cover of the saplings and middle-aged cohorts of larch and white birch forests significantly, as compared to other forest harvest scenarios. It was concluded that forest harvest, especially clear cutting, promoted the fragmentation of forest landscape, and thus, under the same forest harvest intensities, selective cutting should be adopted as far as possible to reduce the effect of forest harvest on forest ecosystems, and further, to promote the healthy and sustainable development of forest ecosystems.

Cold-damage risk analysis and division of banana production in Hainan Province of South China based on yield.

CAI Da-xin1**, WANG Chun-yi1, ZHANG Jing-hong2, LIU Shao-jun2

2013, 32(7):  1896-1902. 

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Based on the banana production data of Hainan Province in 1990-2010, and by using the methods of linear moving average, regression analysis, and information diffusion, a model for calculating the theoretical harvest area of banana was developed, which could distinguish the relative contribution of cold weather hazard to the reduction rate of banana yield from other weather hazards. Then, the model of the colddamage risk assessment for banana production was developed, and the risk division of banana production in Hainan Province was conducted. The results showed that the higher dangerous regions of banana cold-damage were located in the north, middle, and west parts of Hainan Island, and the danger rank was the highest in Danzhou. The lower hazard areas were mainly located in the south, southeast, and southwest parts. However, banana was widely planted in the northern and western coastal cities/counties. In most parts, the cold-damage risk was at low level. The risk was the highest in Wuzhishan, followed by in Chengmai, Haikou and Changjiang, and the lowest in east coastal areas and Sanya, where the banana production was almost not affected by cold weather hazard.

Evolution of cultivated land in center region of the Three Gorges Reservoir Area based on terrain factors: A case study of Caotangxi watershed.

WANG Yong-yan1,2, LI Yang-bing1,2**, GAN Cai-hong1,2, LI Yuan1

2013, 32(7):  1903-1911. 

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Based on the remote sensing images in 1990, 2000, 2004, and 2007 and the 1∶50000 DEM, and by using software ArcGIS 9.3 and Fragstas 3.3, this paper studied the evolution of cultivated land in Caotangxi watershed, a center region of Three Gorges Reservoir Area. The database of the cultivated land in Caotangxi watershed was established, and the slope, elevation, and terrain niche index were produced. Then, the slope gradient, elevation gradient, and terrain niche gradient were calculated with the database of the cultivated land so as to discuss the distribution characteristics of the cultivated land at different terrain gradients according to the dimensionless distribution index. The results showed that the cultivated land in the watershed was mainly distributed in the slope gradient range of 15°-35°, elevation range of 500-1000 m, southeast and south slopes, and in middle and high terrain gradient. An obvious change in the area and spatial distribution of cultivated land took place in the study area in 1990-2007. With the increasing terrain gradient index, the distribution area of cultivated land increased first and decreased then. The remarkable reduction in the aggregation index of cultivated land was mainly in the fourth and fifth terrain niche gradients (1.2-1.5 and 1.5-2.0, respectively), showing that the aggregation of cultivated land in middle and high terrain gradient decreased, the cultivated land was fragmented, and the ecological environment was becoming well.

Micro-topographic spatial differentiation pattern and coexistence mechanism of relict deciduous broadleaved trees: A review.

SHANG Kan-kan1,2, DA Liang-jun2,3**

2013, 32(7):  1912-1919. 

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Climatic conditions in a long history have far-reaching effects on the modern distribution pattern of biodiversity, while analyzing the distribution pattern, regeneration type, and adaptation strategy of relict species-dominated populations can reveal their remnant mechanism under climate change. From the perspective of relict species community ecology, this paper reviewed the connotation of relict deciduous broad-leaved tree species, their distribution and habitat characteristics, inter-species relationship, population regeneration and community maintenance, plant traits, and functional response. It was proposed that in the studies on the diversity of regional relict species, it should start with the relationships between micro-landform and vegetation, and then, analyze the habitat characteristics, population structure, community dynamics, and plant traits of relict species communities at micro-topographic scale, reveal the spatial differentiation pattern among micro-landforms and the coexistence mechanism of many relict deciduous broad-leaved tree species in local area, and elucidate the remnant mechanism of relict species communities by the analysis of community phylogenetic structure, which would enrich the researches on the biodiversity of subtropical mountainous areas and the theory of protection ecology in China.

Monitoring and simulation forecasting on crop chilling damage in China: Research progress.

TAN Yan-jing1, ZHANG Jia-hua1,2**, YAO Feng-mei3, Vijendra BOKEN4

2013, 32(7):  1920-1927. 

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Chilling damage is one of the important disasters impacting grain production in China. Climate change makes chilling damage often occurred in China, especially Northeast China. In the central part of Northeast China, chilling damage occurs once every 8 years. To study the chilling damage is of significance to Chinese food security. According to the formation mechanisms of chilling injury, chilling damage can be divided into delayedtype, obstacletype, and mixed-type, and their chilling indices differed with crop type. Based on the small spatial scale of sitebased monitoring, the precise temperature indicators provided by the new technologies such as geographical information system (GIS) can be used for regional crop chilling damage monitoring. Remote sensing technology can estimate the obstacle chilling damage via monitoring land surface temperature (LST) and vegetation index (e.g., NDVI). The prediction methods of crop chilling damage, such as the coupling of mathematical statistics with climate model and crop model and the crop development states and yield forecast based on weather forecast, have been applied in meteorological operation and service system. Crop model can be used for assessing chilling damage loss according to crop development process and yield loss, and applied to make regional damage assessment through combing with remote sensing information. The further development directions of chilling damage monitoring and forecasting technologies as well as the better services for crop chilling damage prevention and mitigation are also discussed in this paper.

 

Invasion mechanisms of Bromus tectorum L.: A review.

LIU Yao-bin1,2, ZHANG Yuan-ming1**, Liliya DIMEYEVA3

2013, 32(7):  1928-1936. 

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Bromus tectorum L. distributes widely around the world, and is a severely invasive species in North America, giving great influence on the local plant community structure and ecosystem function. This paper reviewed the research progress in the invasion mechanisms of B. tectorum from the aspects of habitat, spreading route, biological characteristics of B. tectorum, interactions among B. tectorum and its new neighbors, and effects of changing ecological factors in new habitats on B. tectorum. According to the recent studies, there are multiple factors affecting the invasion of B. tectorum. To clarify the invasion mechanisms would be essential in developing ecological theories and in controlling the massive invasion of B. tectorum.

Application of red mud in the remediation of heavy metals pollution: A review.

YANG Jun-xing1, CHEN Shi-bao2, GUO Qing-jun1**

2013, 32(7):  1937-1944. 

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The application of red mud in the remediation of heavy metals-polluted environment has raised great concerns. This application does make a breakthrough in the remediation of heavy metals-polluted environment, but brings about environmental risks at the same time. In the present studies on the application of red mud in the remediation of heavy metalspolluted environment, more attentions focus on the remediation effectiveness or remediation process, but few focuses on the deactivation mechanisms of heavy metals by red mud. The environmental riskassessment of red mud remediation is still at the beginning. This paper reviewed the research progress in the application of red mud in the remediation of heavy metalspolluted environment, and gave comments to the future studies on the application of red mud in the management of heavy metals pollution: 1) to further study the deactivation mechanisms of heavy metals by red mud, 2) to approach the effective safety assessment means of red mud application, and 3) to integrate the red mud remediation and bio-remediation (plants or microorganisms) to remediate the heavy metals and organic compound pollution.