Table of Content

18 April 2015, Volume 26 Issue 4

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Profile distribution and storage of soil organic carbon in a black soil as affected by land use types.

HAO Xiang-xiang1,2, HAN Xiao-zeng1, LI Lu-jun1, ZOU Wen-xiu1, LU Xin-chun1, QIAO Yun-fa1

2015, 26(4):  965-972. 

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Taking soils in a longterm experimental field over 29 years with different land uses types, including arable land, bare land, grassland and larch forest land as test materials, the distribution and storage of soil organic carbon (SOC) in the profile (0-200 cm) in typical black soil (Mollisol) region of China were investigated. The results showed that the most significant differences in SOC content occurred in the 0-10 cm surface soil layer among all soils with the order of grassland>arable land>larch forest land>bare land. SOC contents at 10-120 cm depth were lower in arable land as compared with the other land use types. Compared with arable land, grassland could improve SOC content obviously. SOC content down to a depth of 60 cm in grassland was significantly higher than that in arable land. The content of SOC at 0-10 cm in bare land was significantly lower than that in arable land. Although there were no significant differences in SOC content at 0-20 cm depth between larch forestland and arable land, the SOC contents at 20-140 cm depth were generally higher in larch forestland than that in arable land. In general, SOC content showed a significantly negative relationship with soil pH, bulk density, silt and clay content and an even stronger significantly positive relationship with soil total N content and sand content. The SOC storage in arable land at 0-200 cm depth was significantly lower than that in the other three land use types, which was 13.6%, 11.4% and 10.9% lower than in grassland, bare land and larch forest land, respectively. Therefore, the arable land of black soil has a great potential for sequestering C in soil and improving environmental quality.

Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China.

YI Bai-lu, HAN Ji, ZHOU Xiang, YANG Fang, MENG Xing, CAO Wu-xing, HUANG Lu-xia, XIANG Wei-ning

2015, 26(4):  973-980. 

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Yangtze River Delta region is the world’s sixth and China’s largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The “grain for green” policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the builtup land was much faster than the sprawl speed of urban builtup land, the  net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase.

Effects of different land-use types on soil organic carbon and its prediction in the mountainous areas in the middle reaches of Lancang River.

LIU Shi-liang1, AN Nan-nan1, YANG Jue-jie1, DONG Yu-hong2, WANG Cong1

2015, 26(4):  981-988. 

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Based on the analysis of 210 surface soil samples (0-20 cm) according to field investigation in 2011, soil organic carbon (SOC) content and its distribution under four different land-use types in the middle reaches of Lancang River were studied. Combining with the correlation analysis, relationships among SOC content, land-use type, topographical factors and NDVI were revealed. Furthermore, multiple linear regression and Kriging method were used to predict the SOC contents distribution in the mountainous areas in the middle reaches of Lancang River. The results exhibited that the rank order of SOC content under the four land-use types was forestland > scrubland > grassland > farmland. The important factors influencing the SOC content were land-use type, aspect, slope and curvature. Comparing the accuracy of these two models, we found that the multiple regression model performed better than geo-statistics in prediction of the SOC content in the mountainous region.

 

Impact of changes in land use and climate on the runoff in Liuxihe Watershed based on SWAT model.

YUAN Yu-zhi, ZHANG Zheng-dong, MENG Jin-hua

2015, 26(4):  989-998. 

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SWAT model, an extensively used distributed hydrological model, was used to quantitatively analyze the influences of changes in land use and climate on the runoff at watershed scale. Liuxihe Watershed’s SWAT model was established and three scenarios were set. The calibration and validation at three hydrological stations of Wenquan, Taipingchang and Nangang showed that the three factors of Wenquan station just only reached the standard in validated period, and the other two stations had relative error (RE)＜15%, correlation coefficient (R²)＞0.8 and NashSutcliffe efficiency valve (Ens)＞0.75, suggesting that SWAT model was appropriate for simulating runoff response to land use change and climate variability in Liuxihe watershed. According to the integrated scenario simulation, the annual runoff increased by 11.23 m³·s^-1 from 2001 to 2010 compared with the baseline period from 1991 to 2000, among which, the land use change caused an annual runoff reduction of 0.62 m³·s^-1, whereas climate variability caused an annual runoff increase of 11.85 m³·s^-1. Apparently, the impact of climate variability was stronger than that of land use change. On the other hand, the scenario simulation of extreme land use showed that compared with the land use in 2000, the annual runoff of the farmland scenario and the grassland scenario increased by 2.7% and 0.5% respectively, while that of the forest land scenario were reduced by 0.7%, which suggested that forest land had an ability of diversion closure. Furthermore, the scenario simulation of climatic variability indicated that the change of river runoff correlated positively with precipitation change (increase of 11.6% in annual runoff with increase of 10% in annual precipitation), but negatively with air temperature change (reduction of 0.8% in annual runoff with increase of 1 ℃ in annual mean air temperature), which showed that the impact of precipitation variability was stronger than that of air temperature change. Therefore, in face of climate variability, we need to pay attention to strong rainfall forecasts, optimization of land use structure and spatial distribution, which could reduce the negative hydrological effects (such as floods) induced by climate change.

Comparison on the methods for spatial interpolation of the annual average precipitation in the Loess Plateau region.

YU Yang1, WEI Wei1, CHEN Li-ding1, YANG Lei1, ZHANG Han-dan1，2

2015, 26(4):  999-1006. 

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Based on 57 years (1957-2013) daily precipitation datasets of the 85 meteorological stations in the Loess Plateau region, different spatial interpolation methods, including ordinary kriging (OK), inverse distance weighting (IDW) and radialbased function (RBF), were conducted to analyze the spatial variation of annual average precipitation regionally. Meanwhile, the mean absolute error (MAE), the root mean square error (RMSE), the accuracy (AC) and the Pearson correlation coefficient (R) were compared among the interpolation results in order to quantify the effects of different interpolation methods on spatial variation of the annual average precipitation. The results showed that the Moran’s I index was 0.67 for the 57 years annual average precipitation in the Loess Plateau region. Meteorological stations exhibited strong spatial correlation. The validation results of the 63 training stations and 22 test stations indicated that there were significant correlations between the training and test values among different interpolation methods. However, the RMSE (IDW=51.49, RBF=43.79) and MAE (IDW=38.98, RBF=34.61) of the IDW and the RBF showed higher values than the OK. In addition, the comparison of the four semivariagram models (Circular, Spherical, Exponential and Gaussian) for the OK indicated that the circular model had the lowest MAE (32.34) and the highest accuracy (0.976), while the MAE of the exponential model was the highest (33.24). In conclusion, comparing the validation between the training data and test results of the different spatial interpolation methods, the circular model of the OK method was the best one for obtaining accurate spatial interpolation of annual average precipitation in the Loess Plateau region.

Soil infiltration of snowmelt water in the southern Gurbantunggut Desert, Xinjiang, China.

HU Shun-jun1, CHEN Yong-bao1,2，3, ZHU Hai1，2

2015, 26(4):  1007-1015. 

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Soil infiltration of snowmelt water is an important income item of water balance in arid desert. The soil water content in west slope, east slope and interdune of sand dune in the southern Gurbantunggut Desert was monitored before snowfall and after snow melting during the winters of 2012-2013 and 2013-2014. According to the principle of water balance, soil infiltration of snowmelt in the west slope, east slope, interdune and landscape scale was calculated, and compared with the results measured by cylinder method. The results showed that the soil moisture recharge from unfrozen layer of unsaturated soil to surface frozen soil was negligible because the soil moisture content before snowfall was lower, soil  infiltration of snowmelt water was the main source of soil water of shallow soil, phreatic water did not evaporate during freezing period, and did not get recharge after the snow melting. Snowmelt water in the west slope, east slope, interdune and landscape scale were 20-43, 27-43, 32-45, 26-45 mm, respectively.


 

Using a modified remote sensing imagery for interpreting changes in cultivated saline-alkali land.

GAO Hui1,2, LIU Hui-tao1, LIU Hong-juan1, LIU Jin-tong1

2015, 26(4):  1016-1022. 

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This paper developed a new interpretation symbol system for grading and classifying salinealkali land, using Huanghua, a cosatal city in Hebei Province as a case. The system was developed by inverting remote sensing images from 1992 to 2011 based on site investigation, plant cover characteristics and features of remote sensing images. Combining this interpretation symbol system with supervising classification method, the information on arable land was obtained for the coastal saline-alkali ecosystem of Huanghua City, and the saline-alkali land area, changes in intensity of salinityalkalinity and spatial distribution from 1992 to 2011 were analyzed. The results showed that salinization of arable land in Huanghua City alleviated from 1992 to 2011. The severely and moderately saline-alkali land area decreased in 2011 compared with 1992, while the non/slightly saline land area increased. The moderately salinealkali land in southeast transformed to non/slightly salinealkaline, while the severely salinealkali land in west of the city far from the coastal zone became moderately salinealkaline. The center of gravity (CG) of severely and non/slightly salinealkali land moved closer the coastline, while that of the moderately salinealkali land moved from southwest coastal line to northwest. Factors influencing changes in arable land within the salinealkali ecosystem of Huanghua City were climate, hydrology and human activities.

Urban ecosystem services: A review.

MAO Qi-zheng1, HUANG Gan-lin1, WU Jian-guo1,2

2015, 26(4):  1023-1033. 

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Maintaining and improving ecosystem services in urban areas and human wellbeing are essential for sustainable development and therefore constitute an important topic in urban ecology. Here we reviewed studies on ecosystem services in urban areas. Based on the concept and classification of urban ecosystem services, we summarized characteristics of urban ecosystem services, including the human domination, high demand of ecosystem services in urban areas, spatial heterogeneity and temporal dynamics of ecosystem services supply and demand in urban areas, multiservices of urban green infrastructures, the socioeconomic dimension of ecosystem services supply and ecosystem disservices in urban areas. Among different urban ecosystem services, the regulating service and cultural service are particularly indispensable to benefit human health. We pointed out that tradeoffs among different types of ecosystem services mostly occur between supportive service and cultural service, as well as regulating service and cultural service. In particular, we emphasized the relationship between landscape design (i.e. green infrastructure) and ecosystem services supply. Finally, we discussed current gaps to link urban ecosystem services studies to landscape design and management and pointed out several directions for future research in urban ecosystem services.

 

Vegetation landscape health assessment in Changshan Archipelago, North Yellow Sea.

SUO An-ning, SUN Yong-guang, LI Bin-yong, LIN Yong, ZHANG Yong-hua

2015, 26(4):  1034-1040. 

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Island vegetation is an important component of island ecosystem. Multitargets of island ecosystem health integrated with landscape ecology theory were employed to construct the index system for island vegetation health assessment in terms of landscape vigor, landscape stressing intensity and landscape stability. The Changshan Archipelago in the North Yellow Sea was chosen as a case to apply the island vegetation health assessment index system. The results showed that the overall vegetation health status in Changshan Archipelago was good and had a big island variation. The vegetation health index for Haiyang Island and Zhangzi Island was above 0.80, belonging to first ecohealth level area, whereas that for Dachangshan Island, Xiaochangshan Island and Dawangjia Island ranged from 0.70 to 0.80, which could be categorized as the second ecohealth level area. Guanglu Island and Shichen Island could be termed as the third ecohealth level area with the vegetation health index below 0.70. The distance of island to mainland, area of island together with industrial structure were the main driving forces for the variation of vegetation landscape heath between different islands.

Measuring water ecological carrying capacity with the ecosystemservicebased ecological footprint (ESEF) method: Theory, models and application.

JIAO Wen-jun, MIN Qing-wen, LI Wen-hua, Anthony M. FULLER

2015, 26(4):  1041-1048. 

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Integrated watershed management based on aquatic ecosystems has been increasingly acknowledged. Such a change in the philosophy of water environment management requires recognizing the carrying capacity of aquatic ecosystems for human society from a more general perspective. The concept of the water ecological carrying capacity is therefore put forward, which considers both water resources and water environment, connects socioeconomic development to aquatic ecosystems and provides strong support for integrated watershed management. In this paper, the authors proposed an ESEFbased measure of water ecological carrying capacity and constructed ESEFbased models of water ecological footprint and capacity, aiming to evaluate water ecological carrying capacity with footprint methods. A regional model of Taihu Lake Basin was constructed and applied to evaluate the water ecological carrying capacity in Changzhou City which located in the upper reaches of the basin. Results showed that human demand for water ecosystem services in this city had exceeded the supply capacity of local aquatic ecosystems and the significant gap between demand and supply had jeopardized the sustainability of local aquatic ecosystems. Considering aquaproduct provision, water supply and pollutant absorption in an integrated way, the scale of population and economy aquatic ecosystems in Changzhou could bear only 54% of the current status.

Ecological footprint of farmers and herdsmen in Tibet Autonomous Region, China.

ZHAO Zhong-rui1, XIE Chuan-qi1, WU Tong1, XIANG Wen-hua2, FANG Jiang-ping1

2015, 26(4):  1049-1054. 

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Based on relevant statistical yearbook and with an integrated method, the ecological footprint and ecological carrying capacity of farmers and herdsmen during the period from 2000 to 2012 in Tibet Autonomous Region, China were studied. The results showed that the ecological status of farmers and herdsmen were in a surplus state during the study period, but the surplus amount exhibited a decreasing tendency. The ecological capacity decreased from 7.49 hm² in 2000 to 6.35 hm² in 2012, with a decrease of 15.3%, while the ecological footprint increased gradually from 1.03 hm² in 2000 to 1.26 hm² in 2012.

Socio-hydrology: A review.

DING Jing-yi, ZHAO Wen-wu, FANG Xue-ning

2015, 26(4):  1055-1063. 

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Socio-hydrology is an interdiscipline of hydrology, nature, society and humanity. It mainly explores the two-way feedbacks of coupled human-water system and its dynamic mechanism of co-evolution, and makes efforts to solve the issues that human faces today such as sustainable utilization of water resources. Starting from the background, formation process, and fundamental concept of socio-hydrology, this paper summarized the features of socio-hydrology. The main research content of socio-hydrology was reduced to three aspects: The tradeoff in coupled humanwater system, interests in water resources management and virtual water research in coupled humanwater system. And its differences as well as relations with traditional hydrology, eco-hydrology and hydro-sociology were dwelled on. Finally, with hope to promote the development of socio-hydrology researches in China, the paper made prospects for the development of the subject from following aspects: Completing academic content and deepening quantitative research, focusing on scale studies of socio-hydrology, fusing sociohydrology and eco-hydrology.

Influence of mulching management on the relationships between foliar non-structural carbohydrates and N, P concentrations in Phyllostachys violascens stand.

GUO Zi-wu1, HU Jun-jing1,2, YANG Qing-ping1, LI Ying-chun1, CHEN Shuang-lin1, CHEN Wei-jun2

2015, 26(4):  1064-1070. 

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To understand the physiological adaptive mechanism of Phyllostachys violascens  to intensive mulching management, the effect of mulching management (CK, 1, 3 and 6 years) on the concentrations and ratios of nonstructural carbohydrates (NSC), nitrogen (N) and phosphorus (P) in bamboo foliage, and their stoichiometry was investigated. The results showed the concentrations of NSC and soluble sugar increased, while the starch content and N/P decreased markedly in  bamboo stand with 1year mulching, compared to CK stand, which suggested the N limitation to bamboo growth was strengthened. Foliar soluble sugar content decreased significantly, while the starch content increased dramatically, and the NSC content by per unit mass of N and P reached the maximum in the bamboo stand with 3-year mulching, compared to all other treatments. Foliar NSC and soluble sugar contents decreased significantly, while foliar starch content and N/P increased dramatically in  the stand with 6-year mulching, which suggested the P limitation to bamboo growth was strengthened. Foliar NSC content was positively correlated with N and P concentrations in a shortterm mulching management stand (≤3 years), while showed negative relationship with N/P. The foliar starch content in the  stand with 6-year mulching was negatively correlated with N and P contents, while was positively correlated with N/P. The results indicated that shortterm mulching management accelerated the accumulation of soluble sugar and decomposition of starch in foliage, thus the growth and activity of Ph. violascens was enhanced greatly. Longterm mulching management promoted the starch accumulation, which led to the transition from N limitation to P limitation for bamboo growth. In summary, longterm (6 years) mulching management caused the decrease of growth and activity of Ph. violascens dramatically, thus enhancing the bamboo stand degradation. The utilization efficiency of N and P reached the highest in the stand with 3-year mulching, which implied 3-year was the best suitable period for intensive mulching management for maintaining bamboo stand quality.

Relationships between understory vegetation coverage and environmental factors in Pinus massoniana plantations from aerial seeding.

ZHAO Fang, OUYANG Xun-zhi

2015, 26(4):  1071-1076. 

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The relationships between understory vegetation coverage and environmental factors in Pinus massoniana plantations from aerial seeding were studied by using principal component analysis, redundancy analysis and variation partitioning. The selected environmental factors in total explained 74.2% variation of the understory vegetation coverage. At low altitude, stand characteristics were the key factor to influence the understory vegetation coverage. Stand characteristics, soil property and topographic factor were respectively explained 55.0% (including 29.1% for separateness and 25.9% for interaction with other factors), 38.9% (including 12.1% for separateness and 26.8% for interaction with other factors) and 9.0% (including 5.6% for separateness and 3.4% for interaction with other factors) of the total variation. Average diameter at breast height and canopy density affected mostly and positively correlated with the coverage of bryophyta, graminoid and shurb groups at significant level. Noncapillary porosity and soil water content showed a highly significant positive correlation to dicranopteris coverage, whereas average diameter at breast height, canopy density, soil nutrients and enzyme activity significantly negatively correlated with it. The coverage of graminoid, bryophyta and shurb groups showed the positive correlations, which indicated the three groups could promote each other, while the dicranopteris coverage had significant negative correlation with the three groups mentioned above.

Decomposition dynamics of leaf litter in logging residue of a secondary Castanopsis carlesii plantation and its chemical composition changes.

REN Wei-ling1,2, GUO Jian-fen1,2, WU Bo-bo1,2, WAN Jing-juan1,2, JI Shu-rong1,2, LIU Xiao-fei1,2

2015, 26(4):  1077-1082. 

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A field experiment was conducted to understand the decomposition rates and chemical composition changes of leaf litter in logging residues of a 35-year-old secondary Castanopsis carlesii plantation over a period of one year. Mass loss rate of leaf litter showed an exponential decrease with time from May 2012 to April 2013, with a total 80% loss of initial dry mass. Net potassium (K) release was observed during this period, with only 5% of initial K remained. Nitrogen (N) featured a pattern of accumulation at the early stage and release later, while phosphorus (P) exhibited a sequence of release, accumulation, and release. The remaining of N and P were 19% and 16% of their initial mass, respectively. The release rate was highest for K and the lowest for N. Decomposition of lignin indicated a trend of releaseaccumulationrelease from May 2012 to October 2012, with no further significant change from November 2012 to the end of the experiment. The concentration of cellulose nearly unchanged during the experiment. The N/P rate increased with decomposition, ranging from 18.6 to 21.1. The lignin/N rate fluctuated greatly at the early stage and then almost stabilized thereafter.

 

Light response characteristics of photosynthesis and model comparison of Distylium chinense in different flooding durations.

LIU Ze-bin1,2, CHENG Rui-mei1,2, XIAO Wen-fa1,2, GUO Quan-shui1,2, WANG Na1,2

2015, 26(4):  1083-1090. 

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The light responses of photosynthesis of two-year-old Distylium chinense seedlings subjected to a simulated reservoir flooding environment in autumn and winter seasons were measured by using a Li6400 XT portable photosynthesis system, and the light response curves were fitted and analyzed by three models of the rectangular hyperbola, nonrectangular hyperbola and modified rectangular hyperbola to investigate the applicability of different light response models for the D. chinense in different flooding durations and the adaption regulation of light response parameters to flooding stress. The results showed that the fitting effect of the nonrectangular hyperbola model for light response process of D. chinense under normal growth condition and under shortterm flooding (15 days of flooding) was better than that of the other two models, while the fitting effect of the modified rectangular hyperbola model for light response process of D. chinense under longerterm flooding (30, 45 and 60 days of flooding) was better than that of the other two models. The modified rectangular hyperbola model gave the best fitted results of light compensation point (LCP), maximum net photosynthetic rate (P_n_max) and light saturation point (LSP), and the nonrectangular hyperbola model gave the best fitted result of dark respiration rate (R_d). The apparent quantum yield (Φ), P_n_max and LSP of D. chinense gradually decreased, and the LCP and R_d of D. chinense gradually increased in early flooding (30 days), but D. chinense gradually produced adaptability for flooding as the flooding duration continued to increase, and various physiological indexes were gradually stabilized. Thus, this species has adaptability to some degree to the flooding environment.

Demography and spectrum analysis of Juglans cathayensis populations at different altitudes in the west Tianshan valley in Xinjiang, China.

ZHANG Wei1,2, JIAO Zi-wei1, SHANG Tian-cui1, YANG Yun-fei2

2015, 26(4):  1091-1098. 

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Juglans cathayensis is an endangered plant species and listed as a class Ⅱ protected species of the national government of China. In order to grasp the current state of J. cathayensis populations and predict the population dynamics in the future, a largesample investigation was conducted in the sample plots along different altitude gradients in four valleys in J. cathayensis conservation area. According to the diameter at breast height (DBH) class of the trees, the age class structures of the populations were analyzed, and static life tables for J. cathayensis populations in different habitats along the altitude gradient was constructed by smoothing out technique, and comparative fluctuations cycles of the populations in different habitats were carried out by spectral analysis. The results showed that DBH decreased gradually with the increasing altitude. The population was composed of 19 age classes in the lowaltitude habitat (1241-1380 m) with the maximum DBH of 91.7 cm, 18 age classes in the middlealtitude habitat (1381-1490 m) with the maximum DBH of 82.8 cm, and 13 age classes in the highaltitude habitat (1491-1670 m) with the maximum DBH of 58.9 cm. Life expectancies of J. cathayensis populations were fluctuant for the same age class at different altitudes and for different age classes at the same altitude. In the three altitudedifferent habitats, the survival curves of the populations trended toward Deevey-Ⅱ type and the age structures of the populations were expanding. The curves of mortality showed three peaks, and the mortality rates of 9 age classes at 1241-1380 m and 1491-1670 m above sea levels were the highest, being 55.9% and 89.8%, respectively, and the mortality rate of 12 age classes at 1381-1490 m above sea level was the highest (79.4%). The population dynamics was significantly affected by the fundamental wave of biological characteristic throughout the life cycle of J. cathayensis population, and small cycles of multiharmonic superposition with large cycles were presented. J. cathayensis is a long lifespan tree and a major dominant species in this conservation area. The natural regeneration of its current populations is good. If not strong anthropogenic disturbances or severe natural disasters, J. cathayensis would maintain the dominant position in the community.

Dynamics of carbon and nitrogen storage of Cupressus chengiana plantations in the arid valley of Minjiang River, Southwest China.

LUO Da1, FENG Qiu-hong2, SHI Zuo-min1, LI Dong-sheng3, YANG Chang-xu4, LIU Qian-li5, HE Jian-she5

2015, 26(4):  1099-1105. 

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The carbon and nitrogen storage and distribution patterns of Cupressus chengiana plantation ecosystems with different stand ages in the arid valley of Minjiang River were studied. The results showed that carbon contents in different organs of C. chengiana were relatively stable, while nitrogen contents were closely related to different organs, and soil organic carbon and nitrogen contents increased with the stand age. Carbon and nitrogen storage in vegetation layer, soil layer, and the whole ecosystem of the plantation increased with the stand age. The values of total carbon storage in the 13-, 11-, 8-, 6- and 4year-old C. chengiana plantation ecosystems were 190.90, 165.91, 144.57, 119.44, and 113.49 t·hm^-2, and the values of total nitrogen storage were 19.09, 17.97, 13.82, 13.42, and 12.26 t·hm^-2, respectively. Most of carbon and nitrogen were stored in the 0-60 cm soil layer in the plantation ecosystems and occupied 92.8% and 98.8%, respectively, and the amounts of carbon and nitrogen stored in the top 0-20 cm soil layer, accounted for 54.4% and 48.9% of those in the 0-60 cm soil layer, respectively. Difference in distribution of carbon and nitrogen storage was observed in the vegetation layer. The percentage of carbon storage in tree layer (3.7%) were higher than that in understory vegetation (3.5%), while the percentage of nitrogen storage in tree layer (0.5%) was lower than that in understory (0.7%). The carbon and nitrogen storage and distribution patterns in the plantations varied obviously with the stand age, and the plantation ecosystems at these age stages could accumulate organic carbon and nitrogen continuously.

Seasonal dynamics of soil net nitrogen mineralization under moss crust in Shapotou region, northern China.

HU Rui, WANG Xin-ping, PAN Yan-xia, ZHANG Ya-feng, ZHANG Hao, CHEN Ning

2015, 26(4):  1106-1112. 

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Seasonal variations of soil inorganic nitrogen (N) pool and net N transformation rate in mosscovered soil and in the bare soil were comparatively observed by incubating intact soil columns with parafilm capping in the field in a natural vegetation area of Shapotou, southeastern fringe of the Tengger Desert. We found pronounced seasonal variations in soil available N content and net N transformation rate in both mosscovered soil and bare soil, with significant differences among different months. In nongrowing season, soil available N content and net N transformation rate were significantly higher in March and October than in other months. Furthermore, immobilization was the dominant form of N mineralization, and no significant difference in net soil N mineralization rate was found between the two sampling soils. In growing season, soil available N content and net N transformation rate markedly increased and reached their peak values during June to August (17.18 mg·kg^-1 and 0.11 mg·kg^-1·d^-1, respectively). Both soil net nitrification and N mineralization rates in mosscovered soil were significantly higher than in bare soil. Soil ammonium and nitrate N content in April and May were higher in mosscovered soil (2.66 and 3.16 mg·kg^-1, respectively) than in bare soil (1.02 and 2.37 mg·kg^-1, respectively); while the tendency was the converse in June and September, with 7.01 mg·kg^-1 for soil ammonium content and 7.40 mg·kg^-1 for nitrate N content in bare soil, and they were 6.39 and 6.36 mg·kg^-1 in mosscovered soil, respectively. Therefore, the existence and succession of moss crusts could be considered as one of the important biological factors affecting soil N cycling through regulating soil available N content and promoting soil N mineralization process.

Nitrification of biological soil crusts and soil system during drought process and its response to temperature and moisture: A case study in the Shapotou region, Northwest China.

XU Bing-xin1,2, CHEN Yong-le1,2, HU Yi-gang1, ZHANG Zhi-shan1, LI Gang1,2, LI Meng-ru3, CHEN Dong1,2

2015, 26(4):  1113-1120. 

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Two types of soil covered by biological soil crusts (BSCs), i.e. moss and algae, and moving sand in the natural vegetation area at the southeast fringe of the Tengger Desert were collected intactly. They were incubated continuously for 20 days under two different temperatures (15 ℃ and 25 ℃) and moistures (10% and 25%) condition in the laboratory, and soil NO₃^--N contents were measured after 1, 2, 5, 8, 12, 20 days of incubation and net nitrification rate was evaluated during dehydration. The results showed that  NO₃^--N content of the mosscovered soil (2.29 mg·kg^-1) was higher than that of the algaecovered soil (1.84 mg·kg^-1) and sand (1.59 mg·kg^-1). Net nitrification rate of the three soil types ranged from -3.47 to 2.97 mg·kg^-1·d^-1. For the mosscovered soil and algaecovered soil at 10% and 25% moisture levels, the net nitrification rates at 15 ℃ were 75.1%, 0.7% and 99.1%, 21.3% higher than those at 25 ℃, respectively. Also, the net nitrification rates at 15 ℃ and 10% moisture levels were 193.4% and 107.3% higher than those at 25 ℃ and 25% moisture levels, respectively. The results suggested that regardless of soil moisture increasing or decreasing under the global warming senior, the net nitrification rate of BSCssoil system in the desert would probably be limited to some extent during drought process.

Phylogenetic diversity of airborne microbes in Qingdao downtown in autumn.

WANG Lin, SONG Zhi-wen, XU Ai-ling, WU Deng-deng, XIA Yan

2015, 26(4):  1121-1129. 

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To determine the community structure of airborne microbes in Qingdao downtown in autumn, the airborne bacteria and fungi were collected by the KC6120 air sampler and analyzed using the 16S/18S rDNA gene clone library method. Phylogenetic analysis of airborne bacteria showed that they belonged to six major phylogenetic groups: Proteobacteria (78.8%), Firmicutes (14.6%), Actinobacteria (4.0%), Planctomycetes (1.3%), Cyanobacteria (0.7%), and DeinococcusThermus(0.7%). The dominant genera of airborne bacteria included Acinetobacter (39.7%), Staphylococcus (11.3%), Sphingomonas (8.6%),  Paracoccus (6.0%) and Massilia
(5.3%). The main types of airborne fungi were Ascomycota (97.5%) and Basidiomycota (2.5%). Dominant genera of airborne fungi included Pyrenophora (76.5%), Xylaria (13.6%) and Exophiala (2.5%). The pathogens or conditioned pathogens, such as Acinetobacter, Staphylococcus, or Sphingomonas were detected in the airborne bacteria, whereas certain kinds of fungi, such as P. graminea, X. hypoxylon and Zasmidium angulare that could cause a variety of crop diseases were also detected.

Influence of different types of surface on the diversity of soil fauna in Beijing Olympic Park.

SONG Ying-shi1, LI Xiao-wen1,2, LI Feng1, LI Hai-mei2

2015, 26(4):  1130-1136. 

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Soil fauna are impacted by urbanization. In order to explore the stress of different surface covers on diversity and community structure of soil fauna, we conducted this experiment in Beijing Olympic Park. In autumn of 2013, we used Baermann and Tullgren methods to study the diversity of soil fauna in the depth of 0-5 cm, 5-10 cm, 10-15 cm under four different land covers i.e. bared field (BF), totally impervious surface (TIS), partly impervious surface (PIS) and grassland (GL). The results showed that the total number of soil fauna in 100 cm3 was in order of  GL (210)>PIS (193)>TIS (183)>BF (90), and the number of nematodes accounted for 72.0%-92.8% of the total number. On the vertical level, except for the TIS, the other three types of surface soil fauna had the surface gathered phenomenon. The Shannon diversity index and the Pielou evenness index of BF were lower, but the Simpson dominance index was higher than in the other land covers. The Shannon index and Margalef richness indes of GL were higher than those of the other land covers. The Shannon indexes of TIS and PIS were between the BF and GL. Except for the TIS and GL, the similarity indexes were between 0.4-0.5, indicating moderate nonsimilar characteristics. The diversity of soil fauna was significantly correlated with temperature, pH and available potassium.

Impacts of landscape patterns on heavy metal contamination of agricultural top soils in the Pearl River Delta, South China.

LI Cheng1, LI Fang-bai1, WU Zhi-feng2, CHENG Jiong1

2015, 26(4):  1137-1144. 

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Landscape patterns are known to influence many ecological processes, but the relationship between landscape patterns and soil pollution processes is not well understood. Based on 300 top soil samples, land use and cover map for the Pearl River Delta (PRD) of 2005, this study explored the characteristics and spatial pattern of heavy metal contamination of agricultural top soils and examined the impacts of landscape patterns on the heavy metal contamination in the buffers of soil samples. Research methods included geostatistical analysis, landscape pattern analysis, singlefactor pollution indices, and Pearson correlation analysis. We found that: 1) out of the 235 agricultural soil samples, 3.8%, 0.4%, 17.0% and 9.4% samples exceeded the GradeⅡ national standard for As, Pb, Cd and Ni concentrations respectively. High pollution levels were found in three cities, Guangzhou, Foshan and Zhongshan; 2) soils in the farmland were more polluted than those in the forest and orchard land, and there were no differences among different agricultural land use types in contamination level of each heavy metal (except Cd); and 3) the proportion, mean patch area as well as the degree of landscape fragmentation, landscapelevel structural complexity and aggregation/connectivity of water at the buffer zone were significantly positively correlated with the contamination level of each of the four heavy metals in agricultural top soils. Part of the landscape pattern of urban land in the buffer zone also positively correlated with Pb and Cd levels (P<0.05). On the contrary, the proportion, mean patch area and aggregation degree of forest land negatively correlated with soil Pb and Ni levels (P<0.05); and 4) the closer to the industry land were the soil samples, the more polluted the soils were for Pb, Cd and Ni. Only landscape diversity was found to be positively correlated with soil Cd contamination. The study results provide new information and scientific basis for heavy metal pollution control and remediation, especially for agricultural soils in the PRD.

Effects of methyl jasmonate treatments and endophyte infection on growth of Achnatherum sibiricum.

QIN Jun-hua, LU Yu, LI Xia, ZHOU Yong, REN An-zhi, GAO Yu-bao

2015, 26(4):  1145-1152. 

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We used Achnatherum sibiricum, a native grass as test material and application of methyl jasmonate (MJ) to simulate herbivory, and compared the growth and physiological characters of endophyteinfected (EI) and endophytefree (EF) plants. The results showed that MJ treatment significantly decreased the shoot growth, but significantly increased the concentrations of defensive substances such as total phenolic and lignin, and decreased the size of aphid population. Endophyte infection significantly increased the  tiller number, total phenolic and lignin contents in the shoot. As for shoot biomass and total phenolic in the root, they were affected by MJ treatment.
 Without MJ treatment, no significant differences were found in shoot biomass or root phenolic content whether the plants were infected by endophyte or not. With MJ treatment, the shoot biomass was significantly lower and  the shoot phenolic content was significantly higher in EI plants than in  EF plants. Endophyte infection significantly increased resistance of the host plant to aphids, and the beneficial effect was enhanced by MJ treatments, after three applications with MJ, there were no aphids on EI plants. Overall, endophyte infection could alter the allocation pattern of the host plant between growth and defense, and MJ treatments further strengthened the defensive ability of the host plant at the cost of growth.

 

Evaluating the response of yield and evapotranspiration of winter wheat and the adaptation by adjusting crop variety to climate change in HuangHuaiHai Plain.

HU Shi, MO Xing-guo, LIN Zhong-hui

2015, 26(4):  1153-1161. 

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Based on the multimodel datasets of three representative concentration pathway (RCP) emission scenarios from IPCC5, the response of yield and accumulative evapotranspiration (ET) of winter wheat to climate change in the future were assessed by VIP model. The results showed that if effects of CO₂ enrichment were excluded, temperature rise would lead to a reduction in the length of the growing period for wheat under the three climate change scenarios, and the wheat yield and ET presented a decrease tendency. The positive effect of atmospheric CO₂ enrichment could offset most negative effect introduced by temperature rising, indicating that atmospheric CO₂ enrichment would be the prime reason of the wheat yield rising in future. In 2050s, wheat yield would increase 14.8% (decrease 2.5% without CO₂ fertilization), and ET would decrease 2.1% under RCP4.5. By adoption of new crop variety with enhanced requirement on accumulative temperature, the wheat yield would increase more significantly with CO₂ fertilization, but the water consumption would also increase. Therefore, cultivar breeding, new irrigation techniques and agronomical management should be explored under the challenges of climate change in the future.

Effect of waterlogging on physical traits and yield of wheat in Sichuan, China.

WU Yuan-qi1, LI Chao-su2, FAN Gao-qiong3, WU Xiao-li2, TANG Yong-lu2

2015, 26(4):  1162-1170. 

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Following a twofactor split plot design, two popular varieties (Neimai836 and Chuanmai104) were used to study the effects of waterlogging at four growth stages (seedling, jointing, booting and anthesis) on wheat growth and yield formation during two growing seasons (2011-2012 and 2012-2013). The resulted showed that the greatest yield penalty occurred when waterlogging happened at the seedling stage (10%-15% decrease), and it was alleviated when waterlogging happened at the other stages. Waterlogging during the seedling stage significantly reduced SPAD of 2nd-6th leaves, tillers and spike number per plant, productive ears, dry matter accumulation after flowering and dry matter at maturity. Waterlogging during the jointing stage decreased SPAD of 4th-7th leaves, and waterlogging  during the booting stage reduced the SPAD of top 2nd, 3rd, 4th leaves. Waterlogging during the jointing and booting stages reduced the SPAD of flag leaf, the rate of grain filling during the gradual increase stage, the average filling rate and the 1000grain mass. Waterlogging during the flowering stage produced limited change in yield. Therefore, waterlogging during the seedling stage was identified to have the most critical influence on  wheat production under wheat/rice cropping rotations in Sichuan Province.

Physiological responses of different cucumber cultivars seedlings to iso-osmotic Mg(NO₃)₂ and NaCl stress.

CAO Qi-wei1, LI Li-bin1, KONG Su-ping1, QIU An1, CHEN Wei1, ZHANG Yun-nan2, SUN Xiao-lei1

2015, 26(4):  1171-1178. 

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In this study, the effects of isoosmotic solution of Mg(NO₃)₂ and NaCl on seedling growth, leaf lipid peroxidation, antioxidant enzyme activities, and osmotic adjustment substance accumulation were investigated using three cucumber cultivars with different ecotypes. Then salt tolerance was evaluated by membership function method. The results revealed that under the stress of 60 and 80 mmol·L^-1 Mg(NO₃)₂ solution and its isotonic 90 and 120 mmol·L^-1 NaCl solution, the seedling traits such as height, stem diameter, leaf area, fresh and dry mass of aerial part and underground parts, and antioxidant enzymes activity were obviously decreased with the increasing concentration of Mg(NO₃)₂ and its isotonic NaCl in the three cucumber cultivars. Moreover, the inhibitory effects became more obvious with the increasing concentration of either Mg(NO₃)₂ or NaCl solution. MDA content and membrane lipid peroxidation were enhanced in cucumber seedlings. Among the three cultivars, SJ31-1 changed less than the other two cultivars regarding  the reduced amplitudes of biomass, and activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the  increased amplitude of MDA. In addition, Mg(NO₃)₂ solution inhibited seedling growth more strongly than isotonic NaCl solution did, such difference was relatively significant with increasing the concentration of solution. The contents of proline, soluble amino acids, and soluble sugars varied depending on the cucumber genotype and salt type. The increased amplitude of proline content was the largest in SJ31-1, and that of soluble sugars was the largest in Lubai 19 when growing under salt treatment. The change of these parameters in Xintaimici was in between. Soluble sugars and soluble proteins were predominant osmolytes unde NaCl stress, whereas proline and soluble proteins were main osmolytes under Mg(NO₃)₂ stress. Comprehensive evaluation showed that salt tolerance of the three cucumber cultivars was in order of SJ31-1 > Xintaimici > Lubai 19.

Effects of different potassium fertilizer application periods on the yield and quality of Fuji apple.

LU Yong-li1,2, YANG Xian-long1,2, LI Ru3, LI Shui-li3, TONG Yan-an1,2

2015, 26(4):  1179-1185. 

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In order to ascertain the effects of potassium fertilizer application periods on apple production, we conducted a field experiment and analyzed the differences in apple yield, fruit quality, potassium fertilizer use efficiency, and nutrient concentrations in leaves and fruits among treatments with differences in timing of  potassium application. The results indicated that, compared with no potassiumapplied treatment (CK), all potassium fertilizer application treatments significantly increased the apple yield by 4.3%-33.2%, meanwhile, it also obviously improved the fruit quality. In comparison with the application of 100% potassium fertilizer as a base, the application of 50% or 100% of potassium fertilizer at the fruit enlargement stage (the remaining 50% applied as a base or after flowering) significantly increased the apple yield by 20.5%-27.7% and improved the fruit quality. Compared with the application 100% potassium fertilizer  at the stage of fruit enlargement, the evenly split application as base  flowering stage and  at the fruit enlargement stage not only contributed to a higher yield, better quality and higher potassium use efficiency, but also maintained a relatively stable potassium concentration level in leaves. However, the split potassium fertilizer application at the flowering and fruit enlargement stages resulted in the significant decrease in concentration of calcium in fruit, which would be negative to fruit quality. In conclusion,  our research suggested that evenly split application of potassium fertilizer as a base and  at the fruit enlargement stage was the suitable period for apple production in Fuji apple orchards in this region.

 

Influences of arbuscular mycorrhizal fungus and phosphorus level on the lateral root formation of tomato seedlings.

JIANG Xia1, CHEN Wei-li1, XU Chun-xiang1, ZHU Hong-hui2, YAO Qing1

2015, 26(4):  1186-1192. 

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To explore the influences of arbuscular mycorrhizal fungi (AMF) and P level on plant root system architecture, tomato seedlings were inoculated with AMF strain Rhizophagus irregularis BGC JX04B under two P levels, and the influences of AMF and P level on lateral root (LR) formation of tomato seedlings were studied. Results indicated that the promoting effect of AMF on plant biomass was not evident, but significantly decreased the root to shoot ratio of plants. AMF significantly increased the primary root length but decreased the 1^st order LR length and interacted with the mycorrhizal colonization period. AMF significantly lowered the 2^nd-3^rd order LR number and the ratio of 2^nd order LR number to 1^st order LR number, but did not significantly affect the 1^st-2^nd order LR density. High P level (50 mg·kg^-1 P) significantly promoted the plant growth and decreased the root to shoot ratio of plants. It had no significant effect on the primary root length and the 1st order root length, but significantly enhanced the 1^st-3^rd order LR number and the ratio of 2^nd order LR number to 1^st order LR number, increased the 1^st-2^nd order LR density. It suggested that AMF and P level did not share a common mechanism to influence the LR formation of tomato plants. The influence of high P level may depend on its promoting effects on nutrient uptake and plant growth, while the influence of AMF is more complex. Furthermore, the interaction between AMF and mycorrhizal colonization period implies the possible involvement of carbohydrate distribution (sugar signaling) in the regulation of root system architecture by AMF.

Effect of cadmium stress on physiological characteristics of garlic seedlings and the alleviation effects of exogenous calcium.

LI He, LIAN Hai-feng, LIU Shi-qi, YU Xin-hui, SUN Ya-li, GUO Hui-ping

2015, 26(4):  1193-1198. 

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In the experiment, the effects of exogenous cadmium (Cd²⁺) and calcium (Ca²⁺) in nutrient solution on growth, photosynthetic characteristics, enzymes activities, main mineral elements absorption of garlic seedlings were studied. The results showed that cadmium could obviously inhibit the growth of garlic seedlings, decrease the pigment contents and photosynthetic parameters (P_n, E, g_s) of leaves, reduced the enzymes (SOD, POD, CAT) activities and increase the MDA content of leaves, and also could reduce the N, P, K, Ca, Mg contents and increase the Cd content of roots. The growth was promoted after adding exogenous calcium to garlic seedlings under cadmium stress, which reflected that the morphological indexes were increased at first and then decreased with the increase of exogenous calcium concentrations, and were maximized when the exogenous calcium was 2 or 3 mmol·L^-1. At the same time, the pigment contents and photosynthetic parameters (P_n, E, g_s) of leaves showed a similar tendency with the morphological indexes, and they were the highest when the exogenous calcium was 2 or 3 mmol·L^-1. In addition, adding exogenous calcium to garlic seedlings under cadmium stress enhanced the enzymes (SOD, POD, CAT) activities and decreased the MDA content of leaves, also added the N, P, K, Ca, Mg contents and reduced the Cd content of roots, and the effect was best when the  exogenous calcium concentration was 2 or 3 mmol·L^-1.

Soil moisture dynamics of apple orchard in Loess Plateau dryland.

ZHAO Gang, FAN Ting-lu, LI Shang-zhong, ZHANG Jian-jun, WANG Yong, DANG Yi, WANG Lei, TANG Xiao-ming

2015, 26(4):  1199-1204. 

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The soil moisture of 0-500 cm soil layer in a dryland orchard at its full fruit period was measured from 2009 to 2013 to explore the soil moisture dynamics. Results indicated that soil water consumption mainly occurred in the soil layer of 0-300 cm in normal rainfall year and below the 300 cm soil layer when the annual rainfall was less than 400 mm. The soil moisture in the 200-300 cm soil layer fluctuated most and was affected by rainfall and apple consumption.  Seasonal drought usually happened between April and late June, while the accumulation of soil moisture mainly occurred in the rainy season from July to midOctober  to alleviate the drought effectively in next spring.

 

Control of continuous potato monoculture barrier via biological soil disinfestation method in Yellow River irrigation areas of central Gansu Province, Northwest China

LIU Xing1, ZHANG Shu-le1, LIU Guo-feng1, QIU Hui-zhen1, WANG Di2, ZHANG Jun-lian2, SHEN Qi-rong3

2015, 26(4):  1205-1214. 

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The potential of biological soil disinfestation(BSD) in control of continuous potato monoculture barrier was investigated in present study. BSD involves the induction of soil reduction conditions through incorporation of easily decomposed organic materials into soil, flooding the soil by irrigation, and covering the soil surface with plastic film. Control(CK) was left without cover and organic amendment as well as flooding. Field experiment was conducted for testing the effect of BSD approach on the control of continuous potato monoculture barrier, especially on tube yield, plant growth and development, suppression of soilborne pathogen, and soil microbial community and enzyme activities. Compared with CK, BSD treatment significantly increased tuber yield by 16.1% and plant biomass by 30.8%, respectively. Meanwhile, the incidence of diseased plant and the ratio of diseased tuber in BSD treatment also significantly decreased by 68.0% and 46.7% as compared to those in CK, respectively. BSD treatment significantly increased the content of chlorophyll and branch numbers per main stem of potato plants, improved the morphological characteristics of potato root system. In the course of BSD before potato sowing, soil pH value and bacteria/fungi significantly increased, but populations of fungi and Fusarium sp. significantly decreased compared with CK. There were no significant changes in populations of bacteria and actinomycetes between CK and BSD treatments. During potato growing stage,  the  populations of both soil fungi and Fusarium sp. were lower in BSD treatment than those of CK. With the advance of potato growth, the population of Fusarium sp. in BSD treatment gradually increased compared with CK. There were no significant changes in soil enzyme activities in the course of BSD  before potato sowing and the whole of potato growing stage. It was concluded that BSD has the potential to control continuous potato monoculture barrier and may be an important element in a sustainable and effective management strategy for potato soilborne diseases.

Effects of different straw-returning regimes on soil organic carbon and carbon pool management index in Guanzhong Plain, Northwest China

LI Shuo, LI You-bing, WANG Shu-juan, SHI Jiang-lan, TIAN Xiao-hong

2015, 26(4):  1215-1222. 

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A four-year (2008-2012) field experiment was conducted to investigate the effects of different strawreturning regimes on soil total organic carbon (TOC), labile organic carbon (LOC) and the ratio of LOC to TOC (LOC/TOC) as well as TOC stock (SCS) and soil carbon pool management index (CPMI) in a farmland with maizewheat double cropping system in Guanzhong Plain area, Shaanxi Province, China. The results indicated that soil TOC and LOC contents and SCS were significantly increased when wheat or maize straw was returned to field, and the increasing extent showed the rising order as follows: double strawreturning > single strawreturning > no strawreturning. Compared to no straw returning, a significant increase of TOC and LOC contents and SCS was found in the treatment of wheat straw chopping retention combined with maize straw chopping subsoiling retention (WCMM), and CPMI of WCMM was significantly higher than in the other treatments in 0-20 cm soil layer. Compared to no wheat straw  returning, soil CPMIs in 0-10 cm and 10-20 cm soil layer  increased by 19.1% and 67.9%  for the wheat straw chopping returning treatment, and by 22.6% and 32.4% for the  maize straw chopping subsoiling treatment, respectively. Correlation analysis showed that soil CPMI was a more effective index reflecting the sequestration of soil organic carbon in 0-30 cm soil layer than the ratio of LOC to TOC. This study thus suggested that WCMM regime is the best strawreturning regime for soil organic carbon sequestration.

Effect of conservation tillage on weeds in a rotation system on the Loess Plateau of eastern Gansu, Northwest China.

ZHAO Yu-xin, LU Jiao-yun, YANG Hui-min

2015, 26(4):  1223-1230. 

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A field study was conducted to investigate the influences of no-tillage, stubble retention and crop type on weed density, species composition and community feature in a rotation system (winter wheatcommon vetchmaize) established 12 years ago on the Loess Plateau of eastern Gansu. This study showed that the weed species composition, density and community feature varied with the change of  crop phases. Notillage practice increased the weed density at maize phase, while rotation with common vetch decreased the density in the notillage field. Stubble retention reduced the weed density under maize phase and the lowest density was observed in the notillage plus stubble retention field. Notillage practice significantly increased the weed species diversity under winter wheat phase and decreased the diversity under common vetch phase. At maize phase, a greater species diversity index was observed in the notillage field. These results suggested that no-tillage practice and stubble retention possibly suppress specific weeds with the presence of  some crops and crop rotation is a vital way to controlling weeds in a farming system.

Effects of bio-organic fertilizer and fungicide application on continuous cropping obstacles of cut chrysanthemum.

CHEN Xi1, ZHAO Shuang1, YAO Jian-jun2, YE Yan-ping2, SONG Ai-ping1, CHEN Fa-di1, CHEN Su-mei1, DONG Xue-na1

2015, 26(4):  1231-1236. 

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Fusarium wilt is a soil borne disease caused by plant continuous cropping in monoculture Chrysanthemum morifolium ‘Youxiang’ monoculture not only declines plant quality and yield but also decreases soil enzymes and soil microbial diversity over successive cultivation. In this article, the effects of fungicide (Carbendazim MBC), antifungal enhanced bio-organic fertilizer (BOF), and their combined application on the quality and soil enzymes activities of Chrysanthemum morifolium ‘Youxiang’ in continuous cropping systems were investigated. The results showed that both bioorganic fertilizer (BOF) and fungicide (MBC) single application could effectively prevent the occurrence of Fusarium wilt disease of cut chrysanthemum. Bio-organic fertilizer application was more effective on root activity, soil enzymes activities and quality(shoot height, stem diameter, leaf SPAD value, ray floret number, shoot fresh mass) improvement of cut chrysanthemum, while fungicide single application was responsible for soil enzymatic activities suppression to some extent. The combined application treatment (MBC+BOF) showed the best effects on quality improvement and soil enzyme activities promotion.

 

Adaptability of APSIM model in Southwestern China: A case study of winter wheat in Chongqing City.

DAI Tong1, WANG Jing1, HE Di1, ZHANG Jian-ping2, WANG Na1

2015, 26(4):  1237-1243. 

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Field experimental data of winter wheat and parallel daily meteorological data at four typical stations in Chongqing City were used to calibrate and validate APSIMwheat model and determine the genetic parameters for 12 varieties of winter wheat. The results showed that there was a good agreement between the simulated and observed growth periods from sowing to emergence, flowering and maturity of wheat. Root mean squared errors (RMSEs) between simulated and observed emergence, flowering and maturity were 0-3, 1-8, and 0-8 d, respectively. Normalized root mean squared errors (NRMSEs) between simulated and observed aboveground biomass for 12 study varieties were less than 30%. NRMSE between simulated and observed yields for 10 varieties out of 12 study varieties were less than 30%. APSIMwheat model performed well in simulating phenology, aboveground biomass and yield of winter wheat in Chongqing City, which could provide a foundational support for assessing the impact of climate change on wheat production in the study area based on the model.

 

Carbon, nitrogen, and phosphorus budgets of bottomcultured clam Ruditapes philippinarum.

ZHANG Sheng-li1, ZHANG An-guo2, YUAN Xiu-tang1, LIANG Bin1, LIU Shu-xi1

2015, 26(4):  1244-1252. 

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In order to elucidate the role of bottomcultured clams in the coastal nutrient cycle, the seasonal filtration, ingestion and biodeposition rates were in situ measured and carbon (C), nitrogen (N) and phosphorus (P) budgets of Ruditapes philippinarum among four seasons were modeled. The results showed that the scope for growth of R. philippinarum in carbon (SFG_C), nitrogen (SFG_N), and phosphorus (SFG_P) all varied significantly among seasons, with the highest values in spring. Meanwhile, SFG_C was negative in summer, SFG_N and SFG_P were always positive throughout the year. The seasonal variations of SFG_C, SFG_N and SFG_P were -3.94-49.82 mg C·ind^-1·d^-1, 0.72-9.49 mg N·ind^-1·d^-1, and 0.15-3.06 mg P·ind^-1·d^-1, respectively. The net growth efficiencies in carbon (K_C2), nitrogen (K_N2), and phosphorus (K_P2) also showed a distinct seasonal pattern among seasons, and ranked as K_P2> K_N2> K_C2. The C, N, and P budgets illustrated that the R. philippinarum population relatively used more N and P than C for growth and efficiently transferred the pelagic primary production to a higher trophic level. The current study suggested that R. philippinarum bottomcultured at large scale might play a dominant role in the nutrient cycle of the coastal ecosystem and should be considered as an important ecological component in coastal areas.

Ecosystem service  and  economic valuation in the upper reaches of Xin’an River, Anhui, China for mitigating phosphorus nonpoint source pollution.

HE Fang1, WU Nan2, FANG Xiang-long2, GAO Ji-xi3, ZHOU Xiao-tie2, FENG Chao-yang4

2015, 26(4):  1253-1262. 

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A model of phosphorus purification in a watershed was established based on the export coefficient and purification index of phosphorus in different types of land cover. The model was employed to simulate the economic value of the ecosystem service with the expected water quality standard and marginal cost of pollutant purification of the upper reaches of Xin’an River of Anhui, China. The results revealed that from 2000 to 2010, some farmland outside the Tunxi, Jixi, Shexian, Yixian and Xiuning was converted to builtup land. The total amount of phosphorus exported to the upper Xin’an River decreased a little, and the main source of phosphorus pollution was farmland and builtup land. More than half of the exported phosphorus was efficiently purified by different types of land cover via flow accumulation. The pattern of purification and export of highly concentrated phosphorus showed the same trend which occurred in the northern part of the watershed including the Yangzhi River, Fengle River and Hengjiang River. Forestland and grassland did not efficiently purify phosphorus in the watershed owing to the irrational distribution of existing land cover. The total service value was 3.80 and 3.31 million Yuan in 2000 and 2010, respectively.

 

Research advances in iron and zinc transfer from soil to plant in intercropping systems.

XIA Hai-yong1, XUE Yan-fang2, MENG Wei-wei1, YU Li-min1, LIU Ling-yan1, ZHANG Zheng1

2015, 26(4):  1263-1270. 

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Intercropping facilitates the efficient utilization of land, light, water and nutrients. It is, therefore, important to increase the biodiversity of farmland and to develop sustainable ecological agriculture in both theory and practice. Intercropping helps improve the mobilization and uptake of soil iron (Fe) and zinc (Zn) and corresponding nutritional status in the plants, thus achieving grain micronutrient biofortification. In this review, phenomena of the improvement of Fe and Zn nutrition in dicotyledonous plants as affected by intercropping with gramineous plants (e.g. maize/peanut intercropping) were summarized. Moreover, the possible mechanisms in relation to interspecific rhizosphere molecular and physiological processes, as well as the changes in interspecific root morphology and distribution and microorganisms in the rhizosphere were elucidated. The accumulation, transfer and distribution of Fe and Zn in the plants in intercropping systems were also reviewed. The possible affecting factors on nutrients of Fe and Zn were analyzed. Based on the present advances in the mobilization and acquisition of soil Fe and Zn, and their accumulation and distribution  in plants as well as the related  management and environment influence factors, some new research questions were pointed out. Quantitative analysis, dynamic and systemic researches and field studies on Fe and Zn transfer from soil to plant in intercropping systems should be strengthened in the future.

Factors affecting activation and transference of soil colloidal phosphorus and related analysis technologies.

ZHAO Yue1, LIANG Xin-qiang1, FU Chao-dong2, ZHU Si-rui1, JIN Yi1, ZHANG Yi-xiang1, JI Yuan-jing1

2015, 26(4):  1271-1278. 

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Colloids play a key role in the transference process of phosphorus (P) in soil. Activation and transference of soil colloidal phosphorus have great effect on soil P pool and the surrounding water quality. This paper summarized the current studies on soil colloidal P, discussing the effects of the various factors (e.g., soil physical and chemical properties, fertilization, rainfall and soil amendments) on the transference of soil colloidal P. Some advanced analysis technologies (e.g., flow fieldflow fractionation, transmission electron microscopeenergy dispersive Xray spectrometer, Xray absorption nearedge structure and nuclear magnetic resonance) and methods of reducing soil colloidal P were also involved. This review would provide important information on the mechanism of soil colloidal P transference.

Tobacco cadmium health risk assessment and reduction techniques: A review.

CAO Chen-liang1, MA Yi-bing1, LI Ju-mei1, WEI Dong-pu1, SHI Yi2

2015, 26(4):  1279-1288. 

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Tobacco is one of the cadmium accumulation and tolerance plants. Decreasing cadmium content of tobacco contributes to environmental safety and human health. Three aspects on tobacco cadmium research were reviewed in this paper, i.e. uptake and distribution of cadmium in tobacco, and health risk assessment of cadmium in tobacco and reduction measures. The current situations and existing challenges in the research field were discussed. The cadmium tolerance mechanisms of tobacco were reviewed, the factors on cadmium uptake were analyzed, and the general distribution of cadmium in tobacco was summarized. From the point of health risk assessment, the lack of cadmium limits in tobacco was identified, the recommended formula to calculate cadmium limits of tobacco based on atmosphere cadmium limits and digestion cadmium limits was provided and the cadmium limits of tobacco were estimated using each formula, and suggestions on cadmium limits in tobacco were presented. At last, we put forward several effective reduction measures to lower cadmium level in tobacco leaves.