Chinese Journal of Applied Ecology

Effects of soil warming and nitrogen addition on the length distributions of different diameter class fine roots of Chinese fir seedlings.

CHEN Yun-yu , XIONG De-cheng, DENG Fei, XU Chen-sen, FENG Jian-xin, SHI Shun-zeng, ZHONG Bo-yuan, CHEN Guang-shui

2016, 27(4): 1009-1014. doi:10.13287/j.1001-9332.201604.024

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In order to determine how the diameter class length distribution (DCLD) of fine roots of Chinese fir (Cunninghamia lanceolata) would be affected by soil warming, nitrogen addition and their interaction, a factorial experiment of soil warming (ambient, +5 ℃) and nitrogen addition (ambient, +4 and +8 g N·m^-2·a^-1) was carried out in the Chenda State-owned Forest Farm in Sanming, Fujian Province. An expanded extreme value model fitted the DCLD of roots of all the six treatments very well (R²=0.97). The model parameters showed that soil warming reduced the total root length, but its effect on root diameter was not significant. Nitrogen addition decreased both total root length and root diameter. The interaction of soil warming and nitrogen addition had significant effects on total root length, but had no significant effects on root diameter. DCLD of fine roots under the six treatments could be fitted well by the extreme value function (R²>0.98). The correlation analysis showed that specific root length for roots of 0-1 mm diameter was significantly negatively correlated with the parameter c, and the actual total root length was significantly positively correlated with the parameter b. It was concluded that the root morphology of Chinese fir seedlings would respond to both soil warming, nitrogen addition and their interaction, and these responses could be reflected by the changes in parameters of the extreme value model.

Plant and soil nutrient characteristics in the karst shrub ecosystem of southwest Hunan, China

LI Yan-qiong, DENG Xiang-wen, YI Chang-yan, DENG Dong-hua, HUANG Zhi-hong, XIANG Wen-hua, FANG Xi, JING Yi-ran

2016, 27(4): 1015-1023. doi:10.13287/j.1001-9332.201604.015

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This research was conducted in light (LRD), moderate (MRD, abandoned land) and intense (IRD) rocky desertification shrub ecosystems in Shaoyang, Hunan Province. We collected plant samples and soil at 3 layers (0-15, 15-30, 30-45 cm), and analyzed the distribution patterns of soil and plant nutrients and the relationships among them. Our results showed that the contents of soil organic carbon (SOC) and total N in different soil layers were various and decreased with soil depth, while the contents of total P, K, Ca and Mg had no obvious variation among the different soil layers. The contents of total N, P, Ca and Mg in soil were significantly different among the 3 rocky desertification shrub ecosystems, and the SOC, total N and total P in MRD were relatively higher than in the others. The rank of macroelement contents in soils for LRD and IRD was SOC>total K>total Ca>total Mg>total N>total P, while it was SOC>total K>total Ca>total N>total Mg>total P for MRD. The rank of macroelement contents in plants from the 3 rocky desertification shrub ecosystems was Ca>N>K>Mg>P, and the contents of N and P in plants were significantly positively correlated with the corresponding contents of total N and total P in soils. Soil nutrients were closely related to vegetation growth. According to the soil nutrient status of desertification plots of different grades, we should integrate the forest reservation with artificial afforestation and targeted fertilization methods for managing karst rocky desertification.

Species composition and population structure of plant communities on semi-fixed dunes of the Gurbantongut Desert, China.

SHI Ya-fei, ZHANG Zhi-shan, HUANG Lei, HU Yi-gang, LI Jun, YANG Yu-guang

2016, 27(4): 1024-1030. doi:10.13287/j.1001-9332.201604.013

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The objective of this study was to investigate species composition, and predict future development of dominant species on semi-fixed sand dunes in the Gurbantongut Desert. Using the plant height, crown area and volume instead of age structure, the growth and development condition of dominant shrub populations were analyzed. The results showed that totally 23 species were observed, of which Chenopodiaceae occurred the most with 6 genera 8 species, followed by Asteraceae with 5 genera 6 species. The vegetation community of Gurbantunggut Desert was characterized by few species, and simple structure. As a dominant species, Haloxylon persicum was distributed mainly on the top of the dunes and was a stable increasing population. However, the number of H. ammodendron was small. Artemisia ordosica, as an exotic species introduced by vegetation restoration after construction, covered mainly in the windward and the top of dunes. The po-pulation of A. ordosica had an increasing age structure with a strongly increasing potential, which has affected local species composition. The populations of Calligonum leucocladum and Ephedra distachya were lack of seedlings and had few saplings, resulting in the declining age structure. Due to the same distribution habitat, C. leucocladum might be replaced by A. ordosica in the future.

Effects of forest types on soil dissolved organic carbon and nitrogen in surface and deep la-yers in subtropical region, China.

XIAO Hao-yan, LIU Bao, YU Zai-peng, WAN Xiao-hua, SANG Chang-peng, ZHOU Fu-wei, HUAGN Zhi-qun

2016, 27(4): 1031-1038. doi:10.13287/j.1001-9332.201604.029

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Forest types have significant effects on the availability and dynamics of soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). By now the impacts of forest types on soil DOC and DON were mainly focused on surface soil (0-10 cm). Based on the comparisons between natural forest, Phyllostachys pubescens, Castanopsis kawakamii and Cunninghamia lanceolata plantations, we investigated the effects of forest types on soil DOC and DON pools in top (0-10 cm) and deep soils (40-60 cm). Cold water, hot water and KCl solutions were used to extract soil DOC and DON from surface and deep soils. Results showed that the effects of forest types on soil DOC, DOC/TOC, DON and soil microbial biomass carbon were only significant in the surface soil. The concentrations of DOC and DON varied with extract methods and hot water extracted the largest amounts of DOC and DON, and cold water the least. Correlations among hot water, KCl and cold water extracted DOC and DON were significant, suggesting that the organic C and N released by these three solutions might be at least partly from similar pools. The concentrations of DOC and DON and DOC/TOC in surface soil under natural forest and P. pubescens were greater than under C. kawakamii and C. lanceolata. It indicated that the concentrations of DOC and DON were greater under the natural forest and P. pubescens than under the C. kawakamii and C. Lanceolata, and more beneficial to improve soil fertility.

Element concentration in leaves and nutrient resorption efficiency on dry-red soil and vertisols in dry and hot valley in Yuanmou, China.

YAN Bang-guo, HE Guang-xiong, SHI Liang-tao, FAN Bo, LI Ji-chao, PAN Zhi-xian, JI Zhong-hua

2016, 27(4): 1039-1045. doi:10.13287/j.1001-9332.201604.002

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By performing a pot experiment, the study compared leaf and litter element concentration between the dry-red soil and vertisols, and analyzed the interactive effects of soil types and species on leaf nutrient concentration and nutrient resorption efficiency. The results showed that the soil type significantly affected the concentrations of N, P, Ca, Mg, Cu, Zn, Fe and N:P in leaves as well as the concentrations of N, P, Mn and N:P in leaf litters. Concentrations of N, Mn and N:P in leaves and litters derived from the dry-red soil were significantly higher than those from the vertisols. In contrast, concentrations of P, Ca, Mg, Fe, Cu and Zn in leaves and concentration of P in litters derived from the dry-red soil were significantly lower than those from the vertisols. Leaf N concentration was 34.8% higher, and leaf P concentration was 40.0% lower from the dry-red soil compared with those from the vertisols. N, P and K showed net resorption while the other elements showed accumulating patterns when leaf was senesced. Accumulation of Ca, Mg and Mn of senesced leaves was significantly higher on the dry-red soil than on the vertisols. Species identities only significantly affected leaf N concentration. Interactions of species and soil taxonomy significantly affected nutrient concentration neither in leaves nor in leaf litters, indicating that soil taxonomy influenced plant nutrient concentration in a similar way across multiple species. The influences of soil types on plant element concentration could have further effects on litter decomposition, plant-soil nutrient feedback and biogeochemical cycle in this dry and hot valley.

Effects of gel made by super absorbent polymers and urea on fine root growth and nitrogen use efficiency of Platycladus orientalis bareroot seedlings.

JING Da-wei, XING Shang-jun, LIU Fang-chun, MA Hai-lin, DU Zhen-yu, MA Bing-yao, YU Xue-dou, ZHU Ya-ping

2016, 27(4): 1046-1052. doi:10.13287/j.1001-9332.201604.001

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A pot experiment including five treatments, i.e., CK (neither fertilizer nor super absorbent polymers), U (urea alone), S [super absorbent polymers (SAP) alone], SUM (SAP mixed with urea) and SUG (gel made of SAP and urea) was conducted to evaluate their effects on fine root morphological characteristics, fine root absorption area, fine root nitrogen metabolism and nitrogen use efficiency of Platycladus orientalis bareroot seedlings. Results showed that compared with U treatment, the SUG treatment significantly increased the biomass, length, specific root length, surface area and volume of fine root. The total absorption area and active absorption area of fine root were also increased remarkably under the SUG treatment. The specific root length in the SUG treatment was increased by 34.7%, 37.9%, 41.1% and 12.4% compared with the treatments of CK, U, S and SUM, respectively. Compared with the U treatment, the activities of nitrate reductase, glutamine synthase, glutamate synthase and glutamate dehydrogenase in fine root of the SUG treatment was improved by 41.2%, 76.6%, 30.7% and 125.8%, respectively, while the ratio of GS to GDH decreased. Not only the ground diameter and plant height, but also the dry matter accumulation of aboveground and underground parts was remarkably enhanced under the SUG treatment. The nitrogen use efficiency was 40.7% in the SUG treatment, being 118.8% and 44.5% higher than the U and SUM treatments, respectively. Gel made of SAP and urea was able to significantly increase the nitrogen use efficiency, promote the growth and enhance the ability of drought resistance by improving the morphological characteristics, enhancing the absorption area and key enzymes activities of nitrogen metabolism in the fine root of P. orientalis bareroot seedlings.

Analysis of water sources of plants in artificial sand-fixation vegetation area based on large rainfall events.

WANG Yan-li, LIU Li-chao, GAO Yan-hong, LI Gang, ZHAO Jie-cai, XIE Min

2016, 27(4): 1053-1060. doi:10.13287/j.1001-9332.201604.005

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Water is a major limiting factor for plant growth in arid and semi-arid regions. To find out the main sources of water for two artificial sand-fixation plants (Caragana korshinskii and Artemisia ordosica), we analyzed the characteristics of hydrogen and oxygen stable isotopes in water molecules of rainfall, soil water and xylem water. To analyze water sources of these two plants, we used a direct comparison method and a multi-variate mixed linear model. The results showed that an equation of local meteoric water line in Shapotou was δD=7.83δ¹⁸O+5.64 (R²=0.91). The value for rainfall δ¹⁸O varied during plant-growing season, which was higher in the beginning and end of growing season, and lower in the peak of growing season. The value for soil water δ¹⁸O in the upper layers changed dramatically. The change range became smaller in the deeper soil layer. C. korshinskii had a greater efficiency (56.1%) in utilizing soil water in 40-80 cm soil layer. A. ordosica had a utilizing efficiency of 56.4% in 20-60 cm soil layer. A week after rain event, C. korshinskii and A. ordosica showed a higher efficiency in upper soil water. C. korshinskii showed an increase of 12.5% in utilizing soil water in 0-40 cm soil layer and A. ordosicas showed an increase of 10% in utilizing soil water in 0-20 cm layer. These results suggested that C. korshinskii and A. ordosica changed their water use strategy after large rainfall events, which might enable them to more easily adapt to arid environment.

Ecological effects of soil salinity regulation through saline water irrigation and subsurface drainage in high water table level area.

YU Shu hui, HAN Li pu, GAO Hui, LIU Jin tong

2016, 27(4): 1061-1068. doi:10.13287/j.1001-9332.201604.009

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In high water table level area, saline water irrigation in crucial drought periods has been confirmed to have a positive effect to increase crop yield while it may cause soil salt accumulation to have a potential negative effect on next season crop growth. It was supposed that eliminating or reducing this kind of negative effect could ensure a sustainable increase of crop yield under saline water irrigation. Field experiments were completed in a 2year period in Nandagang district in coastal area of Hebei Province. We investigated the dynamic changes of soil salt accumulation under saline water irrigation in dry season, and analyzed the ecological effect of removing soil salt storage by subsurface pipe drainage system in rainy or proper season. The results showed that the soil salinity experienced accumulation-desalinization-secondary accumulation under saline water irrigation in dry season. In the early stage of irrigation, under 1 g·L ^-1 concentration saline water irrigation treatment, the soil salt load was obviously removed in the layer of 0-50 cm, the soil salinity went up with soil depth, HCO₃^- content increased whereas other ions contents decreased; under 6 g·L^- and 13 g·L^-1 concentration saline water irrigation treatments, the soil salt accumulated in the layer of 0-50 cm, the soil salinity went down with soil depth, HCO₃-content decreased whereas other ions contents increased. Leaching effect of soil salt under subsurface pipe drainage system during rainy or proper season was significant. The soil desalinization ratio increased with the rainfall strength, ranging from 16.0% to 45.7%. On a yearly scale, the soil salt accumulation under saline water irrigation was lower than that in control area. The wheat yield under saline water irrigation was significantly higher than that in control area, and the yield in the treatment of 1 g·L^-1 was highest.

Evolution pattern of impervious surface in the Yuqiao Reservoir Watershed, Tianjin, China during the process of urbanization.

XIE Hui-jun, LI Chong-wei, ZHANG Ya-juan, SONG Ai-yun

2016, 27(4): 1069-1076. doi:10.13287/j.1001-9332.201604.004

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Imperviousness in watershed is a key index to measure urbanization status which exerts an important impact on both eco-hydrological process and spatio-temporal pattern. Taking Yuqiao Reservoir Watershed as a case study area, based on the ENVI 5.1 software, the basic impervious surface information was extracted from remote sensing images taken in 1984, 1994, 2004 and 2013. The linear spectral mixture analysis (LSMA) model was applied to extract the impervious surface area (ISA) in nine coverage classes of watershed in order to analyze its spatio-temporal varying trend in terms of the landscape pattern metrics. Results showed that the RMSE and IS pixel accuracy of all samples were 0.005 and 85.4% respectively, which indicated that the method of extracting impervious surface on a basin scale was feasible. The average of ISA showed a linear growth, from 0.16 to 0.23, the impervious surface area increased by 4.9% in the whole watershed, and the total impervious surface area increased by 1 time. In the sub-basin road network, the impervious surface area increased gradually with the density of the road network, and its expansion pattern was of infilling growth. The patch shape of the middle coverage degree was irregular, and its fragmentation degree was the highest. The fragmentation degree and diversity of the landscape in the whole river basin increased year by year due to increasing human disturbance.

Geo-spectrum characteristics of land use change in Jiangsu Province, China.

LYU Xiao, SHI Yang-yang, HUANG Xian-jin, SUN Xiao-fang, MIAO Zhi-wei

2016, 27(4): 1077-1084. doi:10.13287/j.1001-9332.201604.006

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This paper studied the spatial-temporal characteristics and rules of land use change in Jiangsu Province using theories and methods of geo-spectrum. Based on the land use data translated from remote sensing images of 1990, 2000 and 2010, we synthesized the geo-spectrum of the mode of arable land use change and that of land use change in two corresponding phases, 1990-2000 and 2000-2010, in Jiangsu using ArcGIS 10.0. The results showed that in the phase of 1990-2000, the major characteristics of land use change were swaps between the geo-spectrum unit of arable land and urban-rural construction land, arable land and water body, and arable land and grassland. Specifically, the patterns of “arable land → urban-rural construction land” and “arable land→ water body” were highly significant. We also found the reduction of arable land area and the concentration of its spatial distribution. In the phase of 2000-2010, the “arable land → urban-rural construction land” pattern was still the most salient characteristic. In addition, the patterns of “grassland → water body” and “urban-rural construction land → water body” became more spatially concentrated and tended to expand. Compared with the previous phase, the area of the land use in the phase of 2000-2010 had been changed expanded and became more scattered. Overall, the geo-spectrum of arable land use change in Jiangsu was mainly shaped by the anaphase change type and partially by the prophase change type, with a tiny influence of the repeated and continuous change.

Connotation characterization and evaluation of ecological well-being based on ecosystem service theory.

ZANG Zheng, ZOU Xin-qing

2016, 27(4): 1085-1094. doi:10.13287/j.1001-9332.201604.003

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China is advocating ecological civilization construction nowadays. Further researches on the relation between ecosystem service and humanity well-being are full of theoretical and practical significance. Combining related researches, this paper defined the concept and connotation of ecological well-being based on ecosystem service theory. Referencing theory of national economic accounting and relative researches, the evaluation indicators of ecological well-being supply and consumption were established. The quantitative characterization and evaluation method of red line of regional ecological well-being was proposed on the basis of location quotient. Then the evaluation of ecological well-being in mainland China in 2012 was set as an example for empirical research. The results showed that the net product values of 6 ecosystems, includingcultivated land, forest land, grassland, wetland, water area and unused land, were respectively 1481.925, 8194.806, 4176.277, 4245.760, 3177.084 and 133.762 billion CNY. Spatial heterogeneity of ecosystem net product in different provinces was distinct. Ecological well-being per capita of forest land, grassland, wetland, cultivated land and unused land in eastern and middle provinces were under the red line and less than the national average. The spatial distribution of 9 kinds of ecological well-being per capita split at Hu’s line with high value in northwest and low value in southeast, and was aggravated by differences in density of population and land resources gift.

Optimization and evaluation of key photosynthesis parameters in forest ecosystems based on FLUXNET data and VPM model.

JIA Wen-xiao, LIU Min, SHE Qian-nan, YIN Cai, ZHU Xi-yang, XIANG Wei-ning

2016, 27(4): 1095-1102. doi:10.13287/j.1001-9332.201604.010

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Gross primary productivity (GPP) plays an important role in global carbon cycle. Vegetation maximum light use efficiency (ε_max) is the key parameter for GPP simulation of terrestrial ecosystem. Based on the vegetation photosynthesis model (VPM) and the eddy covariance flux data at 40 stations from FLUXNET (179 site-years of data), we identified the key model parameters influencing the simulation of GPP with VPM through one-at-a-time (OAT) method. The cross validation method was employed to optimize the key model parameters and evaluate the model perfor-mance for global forest ecosystems. The results showed that the prediction of GPP was mostly affec-ted by ε_max, maximum temperature for photosynthesis (T_max), and optimum temperature for photosynthesis (T_opt). There were distinguishable differences for the key optimized parameters among different forest ecosystems. The optimized ε_max ranged from 0.05 to 0.08 μmol CO₂·μmol^-1PAR (evergreen broad-leaved forest>evergreen coniferous forest>mixed forest>deciduous broad-leaved forest). The optimized T_max ranged from 38 to 48 ℃,while T_opt ranged from 18 to 22 ℃. With the optimized key parameters based on ecosystem types, the VPM was able to simulate the seasonal and inter-annual variations of GPP in four forest ecosystems.

Feeding habitats and trophic levels of Rhopilema esculentum Kishinouye in Liaodong Bay based on analyzing carbon and nitrogen stable isotopes.

SUN Ming, WANG Bin, LI Yu long, WANG Ai yong, DONG Jing, MA Tian yu, BAN Yan li

2016, 27(4): 1103-1108. doi:10.13287/j.1001-9332.201604.007

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By using stable isotope techniques, we analyzed the carbon and nitrogen stable isotope ratios of Rhopilema esculentum Kishinouye and its potential feed materials in Liaodong Bay of Bohai Sea, aiming to identify potential food sources and trophic levels of R. esculentum . The results showed that the δ¹³C and δ¹⁵N values for R. esculentum ranged from -20.27‰ to -23.06‰ (ave raged at -21.33‰), and from 6.82‰ to 10.03‰ (averaged at 8.25‰), respectively. The main food sources for R. esculentum included suspended materials, phytoplankton, fish eggs, zooplankton (≤1000 μm), zooplankton (1000-1500 μm), zooplankton (>1500 μm), among which, zooplankton (≤1000 μm) was the most important food source and contributed 71%-88% of the total food sources, followed by zooplankton (>1500 μm) (6%-19%), zooplankton (1000-1500 μm) (0%-22%), suspended materials (0%-10%), phytoplankton(0%-8%) and fish eggs (0%-2%). A Pearson correlation test indicated that there was significant negative relationship between the diameter and δ¹³C value of R. esculentum (P<0.05), while no significant correlation was found between its diameter and δ¹⁵N value (P>0.05). The trophic level of R. esculentum ranged from 2.79 to 3.88 depending on diameter classes,with a mean valu of 3.28 These results indicated that R. esculentum plays a key role in controlling microzooplankton in the Liaodong Bay, which is significant for providing deeper understanding into the tropic structure of biological communities as well as into the material cycles and energy flow of entire ecosystem in the Liaodong Bay.

Effect of cadmium stress on root vigor and accumulation of elements Ca, Mg, Mn, Zn, Fe in Salix variegate.

LIU Yuan, MA Wen-chao, ZHANG Wen, ZENG Cheng-cheng, CHEN Jin-ping, WEI Hong

2016, 27(4): 1109-1115. doi:10.13287/j.1001-9332.201604.008

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In order to explore the effect of cadmium stress on root vigor and accumulation of five kinds of conventional metal elements in Salix variegata, a hydroponic experiment with different cadmium treatments were conducted. The cadmium treatments included 0 mg·L^-1(CK), 2 mg·L^-1 (T₁), 10 mg·L^-1 (T₂), 20 mg·L^-1(T₃) and 50 mg·L^-1(T₄). The root vigor and distribution of cadmium and five kinds of conventional metal elements (including Ca, Mg, Mn, Zn and Fe) in S. variegata were tested. The results showed that: 1) The root vigor of S. variegata decreased with increasing cadmium stress gradually. Compared to control, the root vigor decreased significantly in treatments with the cadmium concentration reaching and exceeding 10 mg·L^-1. 2) With increasing the cadmium concentration, the abilities of S. variegata to absorb and accumulate Fe in leaves were inhibited significantly; the abilities to absorb and accumulate Mg, Mn and Fe in phloem were inhi-bited significantly; the abilities to absorb and accumulate Ca, Mg, Mn, Zn and Fe in xylem had no significant differences; and the abilities to absorb and accumulate Ca, Mg, Mn, Zn and Fe in root were inhibited significantly. It could be concluded that cadmium had antagonistic effect on the accumulation of the other metal elements, especially Zn in plant root. 3) With increasing concentrations of cadmium, the translocation factors of Ca, Mg, Mn and Zn increased significantly when compared to control, while there was no significant influence on Fe. 4) Under cadmium stress, there was a significantly negative correlation between the accumulations of cadmium and Ca in S. variegate root, and a very significantly negative correlation between the accumulations of cadmium and the other four kinds of conventional metal elements, indicating that the change of conventional metal elements in S. variegate root could be one of the indices of the degree of cadmium stress.

Edge effects of forest gap in Pinus massoniana plantations on the decomposition of leaf litter recalcitrant components of Cinnamomum camphora and Toona ciliata.

ZHANG Yan, ZHANG Dan-ju, LI Xun, LIU Hua, ZHANG Ming-jin, YANG Wan-qin, ZHANG Jian

2016, 27(4): 1116-1124. doi:10.13287/j.1001-9332.201604.025

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The objective of the study was to evaluate the dynamics of recalcitrant components during foliar litter decomposition under edge effects of forest gap in Pinus massoniana plantations in the low hilly land, Sichuan basin. A field litterbag experiment was conducted in seven forest gaps with different sizes (100, 225, 400, 625, 900, 1225, 1600 m²) which were generated by thinning P. massoniana plantations. The degradation rate of four recalcitrant components, i.e., condensed tannins, total phenol, lignin and cellulose in foliar litter of two native species (Cinnamomum camphora and Toona ciliata) at the gap edge and under the closed canopy were measured. The results showed that the degradation rate of recalcitrant components in T. ciliata litter except for cellulose at the gap edge were significantly higher than that under the closed canopy. For C. camphora litter, only the degradation of lignin at the gap edge was higher than that under the closed canopy. After one-year decomposition, four recalcitrant components in two types of foliar litter exhibited an increment of degradation rate, and the degradation rate of condensed tannin was the fastest, followed by total phenol and cellulose, but the lignin degradation rate was the slowest. With the increase of gap size, except for cellulose, the degradation rate ofthe other three recalcitrant components of the T. ciliata at the edge of medium sized gaps (400 and 625 m²) were significantly higher than at the edge of other gaps. However, lignin in the C. camphora litter at the 625 m² gap edge showed the greatest degradation rate. Both temperature and litter initial content were significantly correlated with litter recalcitrant component degradation. Our results suggested that medium sized gaps (400-625 m²) had a more significant edge effect on the degradation of litter recalcitrant components in the two native species in P. massoniana plantations, however, the effect also depended on species.

Carbon storage and allocation in Cunninghamia lanceolata plantations with different stand ages.

LAN Si-an, DU Hu, ZENG Fu-ping, SONG Tong-qing, PENG Wan-xia, HAN Chang, CHEN Li, SU Liang

2016, 27(4): 1125-1134. doi:10.13287/j.1001-9332.201604.020

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Based on survey of 45 plots (1000 m² each) of five different stand ages, i.e., young, middle-aged, pre-mature, mature, and over-mature plantations, in the main production area of Cunninghamia lanceolata in the north of Guangxi, China, carbon (C) storage and its allocation in vegetation and soil were studied. The results showed that total carbon storage of C. lanceolata plantations changed in the order of over-mature plantation (345.59 t·hm^-2) > mature plantation (331.14 t·hm^-2) > pre-mature plantation (299.11 t·hm^-2) > young plantation (187.60 t·hm^-2) > middle-aged plantation (182.81 t·hm^-2). For all the stand ages, soil stored the greatest amount of carbon, C pool in vegetation layer was the second, while C storage in the litter layer was lowest. On average, C storage in belowground layer was greater than that in aboveground layer. Carbon storage in aboveground vegetation layer ranged from 34.80 to 134.55 t·hm^-2, which contributed 18.6% to 38.9% to the total ecosystem carbon storage and increased with ages. Carbon storage in the litter layer ranged from 1.26 to 2.07 t·hm^-2, which only contributed 0.4%-1.1% to the total ecosystem carbon storage. Carbon storage in the soil layer ranged from 149.24 to 206.02 t·hm^-2 and represented 61.9%-80.0% of ecosystem carbon storage. Canopy layer stored the highest amount of carbon (33.51-133.7 t·hm^-2) and comprised 92.8%-98.9% of aboveground vegetation carbon storage. Within the canopy layer, carbon storage differed with compartments. Stems stored the highest amount of carbon (20.98-95.68 t·hm^-2) by accounting for 62.6%-72.6% of carbon storage in the canopy layer, which increased with ages. The branches and leaves accounted for 4.8%-11.0% and 11.1%-14.2% of C stored in the canopy layer, respectively, which all decreased with ages, while increased to some extent in the over-mature plantation. Roots occupied 11.3%-12.3% of carbon storage in the canopy layer with small fluctuation with the stand age.

Effects of exogenous nitrogen on N₂O production processes in wetland soils of different restoration phases in the Yellow River estuary.

SUN Zhi-gao, SUN Wen-guang

2016, 27(4): 1135-1144. doi:10.13287/j.1001-9332.201604.030

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The effects of exogenous nitrogen on N₂O production processes in the soils of un-restoration wetland (R₀), restoration wetland since 2007 (R₂₀₀₇) and restoration wetland since 2002 (R₂₀₀₂) of the Yellow River estuary were studied, and the contributions of different processes in N₂O production were determined. Results showed that the N₂O production of restoration wetland soils (R₂₀₀₂ and R₂₀₀₇) with NO₃^--N addition was much higher than that with NH₄⁺-N addition, but both NH₄⁺-N and NO₃^--N additions demonstrated inhibition on the N₂O production of soils in R₀. Although the effect of NO₃^--N addition on the total N₂O production of topsoil in R₂₀₀₂ was significantly higher than those in R₂₀₀₇, the values in R₂₀₀₂ and R₂₀₀₇were greatly increased with increasing NO₃^--N addition. The denitrification and nitrifier denitrification processes in restoration wetland soils (R₂₀₀₂ and R₂₀₀₇) were greatly affected by NO₃^--N addition, but no significant influence on the non-biological processes of soil in R₀ was observed. Although NH₄⁺-N addition did not produce significant effects on the total N₂O production of wetland soils, the nitrifier denitrification process in R₀ soil, the nitrification process in R₂₀₀₇ soil and the non-biological process in R₂₀₀₂ soil were generally stimulated. In R₀ and R₂₀₀₂ soils, the N₂O produced by non-biological processes was generally eleva-ted with NH₄⁺-N addition, while with NO₃^--N addition, the non-biological processes generating N₂O in R₀, R₂₀₀₂ and R₂₀₀₇ soils were generallyinhibited, which was closely correlated with the regulation of soil pH caused by the import of exogenous nitrogen. This study found that the enrichment of NO₃^--N greatly enhanced the total N₂O production of wetland soils and significantly altered the original contribution patterns of biological and non-biological processes to N₂O production. Thus, special attention should be paid on the influences of nutrient import (particularly NO₃^--N enrichment) induced by ecological restoration project on N₂O production of wetland soils.

Effects of Spartina alterniflora invasion on methane emission in coastal salt marsh.

PAN Xiao-cui, GUAN Ming, ZHANG Chong-bang

2016, 27(4): 1145-1151. doi:10.13287/j.1001-9332.201604.026

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To investigate the effects of Spartina alterniflora invasion on methane emission from coastal salt marsh, three S. alterniflora invasive levels were established nearby Taizhou City of Zhejiang Province, including native community, mixed community with S. alterniflora and native weeds, and mono-community of S. alterniflora. The results showed that the CH₄ flux in the three communities ranged from 0.68 to 5.88 mg·m^-2·h^-1, and CH₄ flux increased significantly with S. alterniflora invasion. CH₄ flux in the mono-community of S. alterniflora being 8.7 and 2.3 times as that in the native and mixed communities, respectively. S. alterniflora invasion increased significantly methanogens number, methane production potential, methanotrophs number, methane oxidation potential, plant biomass, soil organic carbon content and soil pH, but decreased significantly soil total nitrogen content. The correlation analysis showed that the CH₄ flux was positively related to methanogens number, methane production potential, methanotrophs number, methane oxidation potential, plant biomass and soil pH, but negatively related to soil total nitrogen content. Overall, our results suggested that S. alterniflora invasion improved plant biomass production and soil pH, resulting in the increases in methanogens number and methane production potential to further drive soil CH₄ emission.

Simulation of rice yield response to elevated carbon dioxide and temperature for different cultivars in the cold region of China.

ZHANG Na, YAO Feng-mei, ZHANG Jia-hua

2016, 27(4): 1152-1162. doi:10.13287/j.1001-9332.201604.036

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This paper was aimed to assess the potential impacts of rising temperature and CO₂ concentration on the production of different rice cultivars in the cold region of China, Heilongjiang Province. Total three representative rice varieties with different maturity types were selected to conduct the simulation experiments according to the required accumulated temperature. Daily weather data and open top chamber (OTC) test yield data for year 2013 were used to initialize CERES-Rice model parameters. CERES-Rice model was executed to simulate the influence of climate change on early-mature, mid-mature and late-mature rice production under fixed weather scenarios, which consisted of three CO₂ concentrations (i.e. 390, 450 and 550 μmol·mol^-1) and four temperature rise levels (i.e. 1, 2, 3 and 4 ℃). Results showed that with the increase in concentration of CO₂, the rice yield would increase. With the rise in temperature, early-mature rice yield would decline significantly. However, mid-mature and late-mature rice yield would increase at first and then gra-dually decline. Without considering the effect of CO₂ fertilization, except that the medium and late varieties under 1 ℃ warming would slightly increase the yield by 3.1% and 0.27% respectively, yield under the other treatments would reduce. The most serious reduction occurred to early-mature rice, which decreased up to 57.7% when the temperature increased by 4 ℃, while mid-mature rice and late-mature rice yields decreased about 10%. Considering the effect of CO₂ fertilization, mid-mature and late-mature rice yields would even increase by 0.75% and 3.2% at 450 μmol·mol^-1 CO₂ under 2 ℃ warming, respectively. Mid-mature rice yield would still increase 4.5% under 3 ℃ warming and late-mature rice yield would also increase 0.39% under 4 ℃ warming at 550 μmol·mol^-1 CO₂. However, it was identified that early-mature rice yield would always sharply decrease with temperature increasing regardless of the effect of CO₂ fertilization. Similarly, CO₂ fertilization effects could improve rice yield to certain extent with temperature increasing. However, the diffe-rence among the varieties in response to CO₂ fertilization effect was not significant. The contribution rate of CO₂ fertilization effect on rice yield was less than 10%.

Effects of nitrapyrin-nitrogen (N) fertilizer application rates on N utilization and N₂O emission in summer maize field.

WEI Shan-shan, WANG Yan-qun, LI Ying-chun, SHU Xiao-xiao, PENG Zheng-ping, SHI Xin-li, ZHOU Ya-peng

2016, 27(4): 1163-1168. doi:10.13287/j.1001-9332.201604.034

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To reduce the N₂O emission from soil and enhance N utilization by crop, a field experiment was carried out to study the effects of nitrapyrin-N fertilizer application rates (0, 180, 270, 360 kg N·hm^-2) on soil N₂O emission and N apparent loss, grain yield and N utilization of summer maize. Results showed that the soil N₂O emission under different N fertilizer treatments mainly occurred in periods from sowing to seedling, and from jointing to tasseling. Soil N₂O emission peaks were observed after basal and top dressing events. Maize yield increased with N fertilizer rates but there was no significant difference between 270 and 360 kg N·hm^-2, and the net income of these two treatments was 5209 and 5426 yuan·hm^-2, respectively. Compared with no N fertilizer treatment, the N uptake in the N fertilizer treatments was increased by 109.6%-134.1%. The treatment of 270 kg N·hm^-2 had the highest agronomic N efficiency and N use efficiency, but the N apparent loss was low. The treatment with nitrapyrin-N fertilization rate of 270 kg N·hm^-2 appeared to be the optimal rate to obtain high maize yield and N use efficiency, and low soil N₂O emission and N apparent loss.

Effects of nitrogen application on yield and nitrogen use efficiency of rapeseed (Brassica napus)

ZOU Xiao-yun, LIU Bao-lin, SONG Lai-qiang, GUAN Chun-yun

2016, 27(4): 1169-1176. doi:10.13287/j.1001-9332.201604.021

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A greenhouse pot experiment was conducted to study the effects of nitrogen application on the yield and nitrogen use efficiency of rapeseed under post anthesis waterlogging condition. Two high nitrogen use efficiency rapeseed genotypes ‘Monty’ and ‘Xiangyou 15’ and two low nitrogen use efficiency rapeseed genotypes ‘R210’ and ‘Bin270’ were treated with 3 nitrogen levels (0.05, 0.2, 0.3 g N·kg^-1soil) under waterlogging or normal water condition. The results showed that compared with the normal water condition, rapeseed pods per plant, 1000-seed mass, seed number per pod and seed yield decreased significantly under post anthesis waterlogging condition. Under the normal water condition, yield increased significantly along with the increment of nitrogen fertilizer, while under waterlogging condition the contribution of increment of nitrogen fertilizer was not significant. Compared with the low nitrogen use efficiency rapeseed genotypes, the high nitrogen use efficiency rapeseed genotypes stimulated seed filling under post anthesis waterlogging condition. Under the same water treatment, nitrogen use efficiency, nitrogen partial factor productivity, agronomic nitrogen use efficiency, nitrogen uptake efficiency and N harvest index of nitrogen fertilizer decreased significantly as the results of post anthesis waterlogging, nitrogen uptake and utilization capability of different rapeseed genotypes were affected significantly by waterlogging. Compared with the low nitrogen use efficiency rapeseed genotypes, the high nitrogen use efficiency rapeseed genotypes were more conducive to nitrogen translocation and redistribution of nitrogen to the pods under waterlogging condition, thus improving the seed production efficiency. Significant water and nitrogen interaction effects existed in rapeseed yield performance parameters, and the effects of water, nitrogen fertilizer and their interaction on rapeseed yield and yield performance parameters varied among diffe-rent genotypes.

Characteristics of photosynthesis and light energy partitioning in Amorphophallus xiei grown along a light-intensity gradient.

FU Zhong, XIE Shi-qing, XU Wen-guo, YAN Suo, CHEN Jun-wen

2016, 27(4): 1177-1188. doi:10.13287/j.1001-9332.201604.035

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The objective of the present study was to examine the adaptation strategy of Amorphophallus xiei, a shade-demanding species, grown under different levels of light intensity. The responses of leaf to photosynthetic active radiation, CO₂ and simulated sunflecks were analyzed in A. xiei grown under 100% (high light), 32.6% (moderate light) and 5.98% (low light) of full sun. Meanwhile, chlorophyll a fluorescence parameter and light energy partitioning were also recorded and calculated in the above-mentioned responsive process. The results showed that in most cases, the maximum photosynthetic rate (P_max), dark respiration rate, apparent quantum yield and carboxylation efficiency in A. xiei significantly decreased with increasing the light level, however, the light compensation point, CO₂ compensation point significantly increased. The photosynthetic induction was quicker in individuals grown under moderate light (P<0.05), and the initial stomatal conductance (g_s-i) during dark adaptation increased significantly with increasing the light level. There was a ne-gative correlation between g_s-i and the time required to reach 30%, 50% and 90% of P_max during the process of photosynthetic induction. Moreover, the values of actual photochemical efficiency of PSⅡ (ΔF/F_m′) in the light, phototochemical quenching of chlorophyll fluorescence (q_P) and photosynthetic electron transport rate (ETR) were higher and non-photochemical quenching (NPQ) recorded in photosynthetic induction was also higher in individuals grown under high light, nevertheless, the maximum photochemical efficiency of PSⅡ in the light (F_v′/F_m′) was higher in individuals grown under low light. The proportion of light energy allocated to non-photochemical quenching (Ф_NPQ) was lower in individuals grown under high light, and, correspondingly, it was higher in ones grown under low light. The results obtained here suggested that, when exposed to high light stress, moderate- and low-light-grown A. xiei would activate the mechanism of energy dissipation to protect itself from injury. Correspondingly, high-light-grown individuals would employ the strategy of increasing heat dissipation and forming quenching complex to cope with high light stress, which, however, might be one of reasons for the sensitivity of A. xiei to high light environment.

Effects of two phenolic acids on root zone soil nutrients, soil enzyme activities and pod yield of peanut

LI Qing-kai, LIU Ping, TANG Zhao-hui, ZHAO Hai-jun, WANG Jiang-tao, SONG Xiao-zong, YANG Li, WAN Shu-bo

2016, 27(4): 1189-1195. doi:10.13287/j.1001-9332.201604.039

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In order to investigate the relationship between the accumulation of phenolic acids in peanut continuous cropping soil and the continuous cropping obstacle of peanut, the effects of p-hydroxy benzoic acid and cinnamic acid on peanut root zone soil nutrients, soil enzyme activities and yield of peanut were studied by pot experiment at three stages of peanut, i.e. the pegging stage of peanut (45 days after seedling), the early podding (75 days after seedling) and the end of podding (105 days after seedling) stages. The results showed that the peanut root zone soil nutrients and enzyme activities changed obviously under the two phenolic acids treatment, especially at the pegging stage of peanut. The soil alkali-hydrolyzable nitrogen, available phosphorus, available potassium, and soil enzyme activities (urease, sucrose, neutral phosphatase) were decreased significantly. At the early and end of podding stages of peanut, the effects of the two phenolic acids on peanut root zone soil nutrients and soil enzyme activities were under a weakening trend. The allelopathy of cinnamic acid was stronger than that of p-hydroxy benzoic acid at the same initial content. The pod yield per pot was reduced by 45.9% and 52.8%, while the pod number of per plant was reduced by 46.2% and 48.9% at higher concentration (80 mg·kg^-1 dry soil) of p-hydroxy benzoic acid and cinnamic acid treatments, respectively.

Effects of straw returning combined with medium and microelements application on soil organic carbon sequestration in cropland.

JIANG Zhen-hui, SHI Jiang-lan, JIA Zhou, DING Ting-ting, TIAN Xiao-hong

2016, 27(4): 1196-1202. doi:10.13287/j.1001-9332.201604.022

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A 52-day incubation experiment was conducted to investigate the effects of maize straw decomposition with combined medium element (S) and microelements (Fe and Zn) application on arable soil organic carbon sequestration. During the straw decomposition, the soil microbial biomass carbon (MBC) content and CO₂-C mineralization rate increased with the addition of S, Fe and Zn, respectively. Also, the cumulative CO₂-C efflux after 52-day laboratory incubation significantly increased in the treatments with S, or Fe, or Zn addition, while there was no significant reduction of soil organic carbon content in the treatments. In addition, Fe or Zn application increased the inert C pools and their proportion, and apparent balance of soil organic carbon, indicating a promoting effect of Fe or Zn addition on soil organic carbon sequestration. In contrast, S addition decreased the proportion of inert C pools and apparent balance of soil organic carbon, indicating an adverse effect of S addition on soil organic carbon sequestration. The results suggested that when nitrogen and phosphorus fertilizers were applied, inclusion of S, or Fe, or Zn in straw incorporation could promote soil organic carbon mineralization process, while organic carbon sequestration was favored by Fe or Zn addition, but not by S addition.

Spatial-temporal variation of fraction of absorbed photosynthetically active radiation (FPAR) in Beijing during 2010-2012.

XIE Jun-fei, GUO Jia

2016, 27(4): 1203-1210. doi:10.13287/j.1001-9332.201604.016

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In this study, the spatial distribution of fraction of absorbed photosynthetically active radiation (FPAR) of vegetation in Beijing during 2010-2012 was analyzed based on the MODIS-FPAR data with a resolution of 1 km and the functional classification of vegetation. The yearly dynamics of FPAR of different vegetation types were also investigated. Furthermore, the correlation between FPAR and leaf area index (LAI) was explored. The results showed that, there was a spatially descended trend from the northeast mountains to the central urban area of Beijing. The annual average FPAR of different vegetation types changed little during 2010-2012. These values varied in the ranges of 0.42-0.44, 0.38-0.39, 0.32-0.33, and 0.21-0.22 for coniferous forest, broadleaf forest, grassland, and crop, respectively. However, the range of variation was big for each vegetation type within the year. There was significant linear or logarithm relationship between FPAR and LAI of each vegetation type. Additionally, the smooth time series of MODIS-FPAR of vegetation types could better reflect seasonal variation, which was generated by Savitzky-Golay filtering in software Timesat.

Spatial variation of soil phosphorus in flooded area of the Yellow River based on GIS and geo-statistical methods: A case study in Zhoukou City, Henan, China.

JIA Zhen-yu, ZHANG Jun-hua, DING Sheng-yan, FENG Shu, XIONG Xiao-bo, LIANG Guo-fu

2016, 27(4): 1211-1220. doi:10.13287/j.1001-9332.201604.012

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Soil phosphorus is an important indicator to measure the soil fertility, because the content of soil phosphorus has an important effect on physical and chemical properties of soil, plant growth, and microbial activity in soil. In this study, the soil samples collecting and indoor analysis were conducted in Zhoukou City located in the flooded area of the Yellow River. By using GIS combined with geo-statistics, we tried to analyze the spatial variability and content distribution of soil total phosphorus (TP) and soil available phosphorus (AP) in the study area. Results showed that TP and AP of both soil layers (0-20 cm and 20-40 cm) were rich, and the contents of TP and AP in surface layer (0-20 cm) were higher than in the second layer (20-40 cm). TP and AP of both soil layers exhibited variation at medium level, and AP had varied much higher than TP. TP of both layers showed medium degree of anisotropy which could be well modeled by the Gaussian model. TP in the surface layer showed strong spatial correlation, but that of the second layer had medium spatial correlation. AP of both layers had a weaker scope in anisotropy which could be simulated by linear model, and both soil layers showed weaker spatial correlations. TP of both soil layers showed a slowly rising change from southwest to northeast of the study area, while it gradually declined from northwest to southeast. AP in soil surface layer exhibited an increase tendency firstly and then decrease from southwest to the northeast, while it decreased firstly and then increased from southeast to the northwest. AP in the second soil layer had an opposite change in the southwest to the northeast, while it showed continuously increasing tendency from northwest to the southeast. The contents of TP and AP in the surface layer presented high grades and the second layer of TP belonged to medium grade, but the second layer of AP was in a lower grade. The artificial factors such as land use type, cropping system, irrigation and fertilization were the main factors influencing the distribution and spatial variation of soil phosphorus in this area.

Spatial scale effect of land use landscape pattern in Yongdeng County, Gansu Province, China.

LIU Yuan-yuan, LIU Xue-lu

2016, 27(4): 1221-1228. doi:10.13287/j.1001-9332.201604.017

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Based on “patch-corridor-matrix” pattern, spatial scale effect of landscape pattern was studied in Yongdeng County of Lanzhou City, Gansu Province, China. The results showed that the grassland was the matrix of landscape structure in the studied area, road and river played the corridor role, and the other landscape elements (cultivated land, forest land, garden land, residential land, industrial and mineral land, public management and service land, and the other land) acted as patches. The patch level index and the landscape level index all showed obvious dependence on spatial extent. The scale effect of patch index of different landscape elements existed differently in different extent intervals, so did the scale effect of the landscape level index. Within the extent of 1-20 km, the scale effect showed the most obvious difference between the element types and the index types, while it became smaller in 21-90 km, and disappeared beyond 90 km. 90 km×90 km might be the effective extent to study the dependence of spatial extent of landscape structure.

Agro-household livelihood vulnerability and influence factors of ethnic villages under different geomorphology backgrounds.

HAN Wen-wen, LIU Xiao-peng, PEI Yin-bao, AN Qiong, LI Yong-hong

2016, 27(4): 1229-1240. doi:10.13287/j.1001-9332.201604.031

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The vulnerability and influence factors of agro-household livelihood in Haiyuan County, Ningxia were empirically analyzed utilizing set pair analysis and obstacle degree model, based on field survey data of impoverished agro-households in 2014. Results showed that vulnerability of agro-household livelihood in Haiyuan County was high in general while it exhibited geomorphological and ethnical differences. Vulnerability of agro-households livelihood in plain areas, valleys and intermountain depression areas were lower than that in earth-rock areas, loess ridge areas and moderately high mountain landform areas. Moreover, vulnerability of agro-household livelihood was higher in mixed Hui and Han ethnic villages than in mono Hui or Han ethnic villages. The villagers’ lacking of necessities and the stress of sensitive external geographical environment were considered to be the fundamental reasons of vulnerability of agro-household livelihood. The unreasonable livelihood structure and the unvariant livelihood strategy caused the long-term accumulation of livelihood vulnerabi-lity. The nature of the local environment, which was not easy to change, decreased the accessibility of poverty alleviation resources. Building a clear village water rights allocation system, the implementation of counterpart-assistance to educate impoverished families, increasing investment in improving the diversities of means of living, developing the chains of comprehensive commodity market among villages, were necessary to improve the response capability of agro-household livelihood. The management of vulnerability of agro-household livelihood should put the ‘Extending Roads to Every Village Project’ on a more prominent position in the ‘Extending Radio and TV Broadcasting Coverage to Every Village Project’. Furthermore, the combination of meteorological disaster prevention and insurance enterprise disaster reduction should be sought, and the agricultural production insurance system should be developed.

Effects of future climate change on climatic suitability of flue-cured tobacco plantation in Yunnan, China.

HU Xue-qiong, XU Meng-ying, HE Yu-qin, ZHANG Ming-da, JI Wen-juan, ZHU Yong

2016, 27(4): 1241-1247. doi:10.13287/j.1001-9332.201604.037

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The climatic suitability distribution of flue-cured tobacco planting in Yunnan will be profoundly affected by climate change. According to three key factors influencing climatic suitability of flue-cured tobacco planting in Yunnan, namely, average temperature in July, sunshine duration from July to August, precipitation from April to September, the variations of climatic suitability distribution of flue-cured tobacco planting in Yunnan respectively in 1986-2005, 2021-2040 and 2041-2060 under RCP4.5 and RCP8.5 climate scenarios were investigated by using the climatic simulation data in 1981-2060 and the meteorological observation data during 1986-2005. The results showed that climatic suitability region would expand northward and eastward and plantable area of flue-cured tobacco would gradually increase. The increment of plantable area was more in 2041-2060 than in 2021-2040, and under RCP8.5 scenario than under RCP4.5 scenario. The optimum climatic area and sub-suitable climatic area were expanded considerably, while the suitable climatic area was not much changed. In the future, the north-central Yunnan such as Kunming, Qujing, Dali, Chuxiong, Lijiang would have a big increase in both the optimum climatic area and the cultivable area, meanwhile, the southern Yunnan including Wenshan, Honghe, Puer and Xishuangbanna would have a big decrease in both the optimum climatic area and the cultivable area.

Quantitative evaluation of resource and environment pressure in Qinghai Province, China based on footprint family

MA Cai-hong, ZHAO Jing

2016, 27(4): 1248-1256. doi:10.13287/j.1001-9332.201604.019

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In order to effectively evaluate the influence of human activities on the resource and environment, this paper constructed an resource and environment pressure evaluation system based on footprint family, and calculated the ecological footprint, carbon footprint, water footprint, and resource and environment pressure in Qinghai Province. The results showed that from 1990 to 2013, the ecological footprint per capita in Qinghai Province increased from 1.32 hm² to 3.32 hm², and biological capacity per capita decreased from 2.33 hm² to 2.07 hm². Since 2006 there was ecological deficit. However, the biomass surplus existed during 1990-2013. The carbon footprint per capita increased from 5.82 t to 15.85 t, which had been more than 7.93 times of the target to address climate change. The water footprint per capita decreased from 967.67 m³ to 732.05 m³. Since 1990, the ecological pressure was at low grade (Ⅰ_b), greenhouse gas (GHG) emissions pressure was enhanced from low grade (Ⅰ_b) to above-average grade (Ⅱ_b), the water pressure was at very low grade (Ⅰ_a), the resource and environment pressure increased from very low grade (Ⅰ_a) to low grade (Ⅰ_b). The rate of contribution of ecological pressure and water resource pressure to resources and environment pressure gradually decreased, whereas, the rate of contribution of GHG emission pressure to resources and environment pressure gradually increased. The resource and environment pressure had spatial heterogeneity. In 2013, it was at very high grade (Ⅲ_b) in Xining City, at above-average grade (Ⅱ_b) in Haidong City, at below-average grade (Ⅱ_a) in Haixi State and atvery low grade (Ⅰ_a) in the rest regions. The main resource and environment pressure source also had obvious spatial heterogeneity. In future, differentiation strategies should be taken in the decompression progress.

Effects of altitudes on soil microbial biomass and enzyme activity in alpine-gorge regions.

CAO Rui, WU Fu-zhong, YANG Wan-qin, XU Zhen-feng, TAN Bo, WANG Bin, LI Jun, CHANG Chen-hui

2016, 27(4): 1257-1264. doi:10.13287/j.1001-9332.201604.018

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In order to understand the variations of soil microbial biomass and soil enzyme activities with the change of altitude, a field incubation was conducted in dry valley, ecotone between dry valley and mountain forest, subalpine coniferous forest, alpine forest and alpine meadow from 1563 m to 3994 m of altitude in the alpine-gorge region of western Sichuan. The microbial biomass carbon and nitrogen, and the activities of invertase, urease and acid phosphorus were measured in both soil organic layer and mineral soil layer. Both the soil microbial biomass and soil enzyme activities showed the similar tendency in soil organic layer. They increased from 2158 m to 3028 m, then decreased to the lowest value at 3593 m, and thereafter increased until 3994 m in the alpine-gorge region. In contrast, the soil microbial biomass and soil enzyme activities in mineral soil layer showed the trends as, the subalpine forest at 3028 m > alpine meadow at 3994 m > montane forest ecotone at 2158 m > alpine forest at 3593 m > dry valley at 1563 m. Regardless of altitudes, soil microbial biomass and soil enzyme activities were significantly higher in soil organic layer than in mineral soil layer. The soil microbial biomass was significantly positively correlated with the activities of the measured soil enzymes. Moreover, both the soil microbial biomass and soil enzyme activities were significantly positively correlated with soil water content, organic carbon, and total nitrogen. The activity of soil invertase was significantly positively correlated with soil phosphorus content, and the soil acid phosphatase was so with soil phosphorus content and soil temperature. In brief, changes in vegetation and other environmental factors resulting from altitude change might have strong effects on soil biochemical properties in the alpine-gorge region.

Effect of land consolidation on soil microbial community diversity.

YE Jing, HE Li-ping, LI Dong-bin, YU Min-fen, WU Jia-sen

2016, 27(4): 1265-1270. doi:10.13287/j.1001-9332.201604.011

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Land consolidation has become a main means of achieving the intensive use of land resources, which ensures the dynamic equilibrium and requisition-compensation balance of the total cultivated land in China. However, the intensive disturbance during the land consolidation may affect the soil quality. In order to investigate the effect of land consolidation on soil microbial diversity, we studied the changes of soil microbial community diversity after 1-year and 4-year land conso-lidation by using PLFA method. The results indicated that compared with no consolidation (Z0), for land consolidation after 1a (Z1a), the soil pH value increased by 14.6%, the soil organic carbon content decreased by 65.4%, the phospholipid fatty acids content and relative abundance of all the microflora decreased significantly (P<0.05) by 43.4%-63.7% and 25.2%-53.9%, respectively, and the ratio of fungi/bacteria (F/B) decreased significantly by 35.9% (P<0.05), while the ratio of Gram-positive bacteria/Gram-negative bacteria (G⁺/G^-) increased significantly by 56.1%. These were significantly related to the increased pH value and the decrease of organic carbon content. The Shannon index and evenness index (E) of soil microbial diversity were significantly decreased, with significant differences observed among Z0 and Z1a, Z4a. After 4-year land consolidation, the indices characterizing soil microbial community diversity were improved compared with those after 1-year land consolidation. In summary, the land consolidation could significantly affect the composition of soil microbial communities, and decrease the stability of the soil ecosystem.

Effect of nutrient status on the kinetics of cyanophage PP infection in Phormidium.

SHANG Shi-yu, MA Hui, ZHAO Yi-jun, CHENG Kai

2016, 27(4): 1271-1276. doi:10.13287/j.1001-9332.201604.028

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In this study, the cyanobacterium Phormidium was grown under six different nutrient concentrations, ranging from standard AA medium to a 600× dilutions of that media. After incubation at 25 ℃ and 2000 lx for 8 months, the growth curve for each treatment was measured by direct counting of cell numbers. Additionally, the lytic cycle and mortality rate were determined by monitoring the lytic effect of the host cells using microscopy. The adsorption rate of cyanophage PP was measured using the centrifugation method, where the burst size and lytic cycle were confirmed by measuring the one-step growth curve. Results indicated that elevated TN and TP could significantly promote the growth of Phormidium. Statistical analysis showed that during the mid-log phase (day 6th) cell densities were significantly higher under high nutrient conditions. Additionally, the adsorption rate in standard AA medium was significantly higher than that in the other five dilution media. Although nutrient conditions did not affect mortalityrate significantly, the latent period and lytic cycle of cyanophage PP were obviously shortened. Moreover, the average burst size of cyanophage PP increased significantly with increasing the nutrient concentration. These results not only proved that high nutrient concentration could promote cyanophage infectivity, but also implied that cyanophage might play an important ecological role in adjusting the succession of algal populations in the progress of eutrophication.

Predicting the potential suitable distribution area of the apple snail Pomacea canaliculata in China based on multiple ecological niche models.

ZHANG Hai-tao, LUO Du, MU Xi-dong, XU Meng, WEI Hui, LUO Jian-ren, ZHANG Jia-en, HU Yin-chang

2016, 27(4): 1277-1284. doi:10.13287/j.1001-9332.201604.027

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The high-risk invasive apple snail Pomacea canaliculata has greatly threatened the agriculture, ecosystem integrity and public health. In order to provide scientific evidence for effective prevention and control of P. canaliculata, a most suitable ecological niche model was selected to predict the potential suitable distribution areas of P. canaliculata in China. Based on 377 reported occurrence points and 19 bioclimatic variables, four ecological niche models, MaxEnt, GARP, BIOCLIM, and DOMAIN, the potential geographic suitable distribution areas were predicted for the invasive snail. Then, the results of different models were analyzed and compared with two statistical criteria, the area under the Receiver Operating Characteristic curve (AUC) and Kappa value. The results showed that all of the four ecological niche models could simulate the snail’s distributions very well. More specifically, the MaxEnt model outperformed the others in all aspects of predicting the snail’s potential distribution (AUC=0.955±0.004, Kappa=0.845±0.017), followed by GARP and DOMAIN. Although BIOCLIM offered the lowest prediction accuracy, its AUC was 0.898±0.017 and its Kappa value was 0.771±0.025. Based on the MaxEnt model, the prediction results showed that the potential suitable distribution areas of P. canaliculata were mainly located in the south of 30° N in China, but there was some regions spreading over the north of 30° N. The potential areas accounted for 13.2% of the national land in area. Notably, Guangdong, Guangxi, Hunan, Chongqing, Zhejiang and the coastal areas of Fujian were potentially high-risk areas. In conclusion, this study would be an important reference for the prevention and control of the invasive apple snail P. canaliculata and it also would be an example of predicting the potential distribution of aquatic alien species on large scale.

Eco-hydrological impacts of Three Gorges Reservoir’s operation on three outfalls of Chingjiang River

LI Jing-bao, LUO Zhong-hai, YE Ya-ya, YANG Bo

2016, 27(4): 1285-1293. doi:10.13287/j.1001-9332.201604.023

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Based on the measured daily flow prototype sequence of five hydrologic stations in the three outfalls of Chingjiang River from 1990 to 2014, its hydrological characteristics and its changing trend was analyzed by using the Mann-Kendall statistical test and the cumulative anomaly method, while the effect of the operation of the Three Gorges on the variation of the 33 indexes of ecological hydrology was also analyzed by the index system of ecological hydrology and range of variability approach. The results showed an obvious decreasing trend in annual mean discharge with the confidence degree of 95% with a decrease rate of 19% during 1990-2014. The jump point appeared in 2003, with the annual mean discharge being 1981.1 m³·s^-1 before 2003 but 1603.25 m³·s^-1 after. There was an obvious increase in monthly mean discharge from January to April (the degree of deviation was 1.58, 1.86, 0.83 and 0.62 respectively), an obvious increase in the late May and the early June, a slight decrease in July and August (the degree of deviation was -0.12 and -0.10 respectively), and a significant decrease in October (the degree of deviation was -0.40). There was a great change in annual minimum flows while a slight change in most of the annual maximum flows and a moderate decrease in 1-day and 3-day maximum flow. It also had a great change in duration and frequency of the low-flow pulse and slight change in high-flow pulse.

Effects of elevated N availability on anatomy, morphology and mycorrhizal colonization of fine roots: A review.

WANG Wen-na, WANG Yan, WANG Shao-zhong, WANG Zheng-quan, GU Jia-cun

2016, 27(4): 1294-1302. doi:10.13287/j.1001-9332.201604.032

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Increase of nitrogen (N) availability can greatly affect the structure and function of forest ecosystems. Fine root is critical to belowground ecological processes, thus its response to elevated N availability has become a focus of ecological researches. This article reviewed the trend and under-lying mechanism of fine root response to elevated N availability, including root anatomy, morphology and mycorrhizal colonization. We found that cross-sectional areas of root stele and xylem and the diameter, number and wall thickness of xylem vessel (tracheid) all increased, however, cortex thickness, the number of cortical cell layer, diameter of cortical cell and number of passage cell in exodermis decreased with higher N availability. The response of root anatomy was closely related to plant hormones. In addition, mycorrhiza colonization rate decreased after N fertilization, while specific root length (root length per unit root mass) generally decreased in arbuscular mycorrhizal species, while increased in ectomycorrhizal species. By contrast, the root diameter and tissue density varied widely among species under higher N status. These findings based on individual roots and species provided deeper understanding of carbon and nutrient cycles in terrestrial ecosystems. In addition, we discussed some knowledge gaps and proposed several research outlooks for guiding future researches.

Overview of organic agriculture development.

LIU Xiao-mei, YU Hong-jun, LI Qiang, JIANG Wei-jie

2016, 27(4): 1303-1313. doi:10.13287/j.1001-9332.201604.040

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This paper introduced the concepts of organic agriculture as defined by different international organizations, origin and theoretical development of organic agriculture, as well as its developing trajectory in China (i.e. a late start followed by rapid growth compared to developed countries). The differences between domestic and international organic agriculture were illustrated by scale, crop types, production standards, inputs and planting techniques. Constraints limiting improvements to organic agriculture in aspects of standards, technology, marketing, certification, environmental pollution, enterprise reputation, and national policies were discussed. Future directions and strategies for developing healthy organic agriculture in China were provided.

Research progress on the dual-mulching of ridge and furrow technology in dry farming regions of northern China: A review.

LI Rong, HOU Xian-qing, WANG Xiao-min, JIA Zhi-kuan, HAN Qing-fang

2016, 27(4): 1314-1322. doi:10.13287/j.1001-9332.201604.038

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The precipitation exiguity and water deficiency are the major factors limiting crop growth in dry farming regions of northern China. Dual-mulching of ridges and furrows, which have been widely concerned both domestically and internationally, could increase the utilization efficiency of precipitation and crop yield. In this paper, we reviewed the concept and model of dual-mulching of ridges and furrows, its supporting farm machinery and implements as well as its ecological effects on soil and crops. Based on the current research progress of cultivation techniques using harvested rainfall in ridge and furrow, priority of future research aspects of the dual-mulching of ridges and furrows were suggested as follows: 1) to establish the suitable ridge-furrow ratios for different crops in different types of dry farming regions of northern China; 2) to pay more attention to the study of coupling effects of soil moisture with temperature, fertility and other factors; 3) to explore better environment-friendly mulching materials; 4) to enhance the research on technical evaluation and popularization, and the design of supporting farm machinery and implements.

Effects of intercropping on soil CO₂ and N₂O emissions from upland: A review.

TANG Yi-ling, WANG Jian-wu, YANG Wen-ting

2016, 27(4): 1323-1330. doi:10.13287/j.1001-9332.201604.033

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Greenhouse gases (GHGs) emission from arable field is a hot topic recently, adopting appropriate cropping systems is an effective way to reduce GHGs emission. This paper reviewed the impacts and mechanisms of intercropping on soil CO₂ and N₂O emissions in upland field. Rational intercropping systems could increase soil organic carbon (SOC), promote the transformation of straw to SOC, slow down mineralization rate of SOC, and hence reduce soil CO₂emissions. The Poaceae intercropping with legume could maintain the stability of yield while reducing synthetic N inputs, formation of inorganic N by residue decomposition and soil mineral N, and further reducing soil N₂O emission. In addition, crop interactions in intercropping system and filed microclimate were important factors on GHGs emission as well. It is necessary to extent the period of researches in field GHGs emission in order to fully understand the underlying mechanisms of GHGs emission in farm land, especially the function of soil microorganisms at molecular level. It would provide theoretical knowledge in building environment-friendly agricultural system in the future.

Formation mechanism and assessment method for urban black and odorous water body: A review

WANG Xu, WANG Yong-gang, SUN Chang-hong, PAN Tao

2016, 27(4): 1331-1340. doi:10.13287/j.1001-9332.201604.014

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Black and odorous (B&O) water body reflects very typical serious water pollution related to organic pollution, sediment re-suspension and thermal pollution. Also, the insufficiency of water cycle is one of the most important hydrodynamic factors for formatting B&O water body. The blackening substances mainly include suspended particles, Fe- and S-containing substances; the odour causing substances include the small molecule gases such as H₂S, NH₃and some compounds such as VOSCs, Geosmin and 2-MBI. Evaluation methods of B&O water were summarized from the evaluation index, B&O index, multiple linear regression model and comprehensive evaluation method in this paper. Correspondingly, the relative research direction in the future was discussed. All these works not only defined the identifying technology for urban B&O water body, but also would further support the water environment improvement and ecological recovery in urban region.

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