Table of Content

10 April 2018, Volume 37 Issue 4

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Effects of canopy structure on the net photosynthetic rate in endangered plantTaxus chinensisvar.mairei.

TIE Jun, WANG Xia, LIU Bei-bei

2018, 37(4):  967-973. 

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To investigate the relationship between diurnal variation of net photosynthetic rate and canopy structure, we measured net photosynthetic rate (P_n) and canopy structure parameters \[leaf area index (LAI), mean leaf inclination (MTA), and radiation coefficient (τd)\] ofendangered plantTaxus chinensis var.mairei by Li-6400 Portable Photosynthesis System and CI-110 Canopy Analyzer. The results showed that P_n was the highest at 10:00, being 10.58 μmol·m^-2·s^-1 (female) and 8.21 μmol·m^-2·s^-1 (male) respectively. It was the lowest at 14:00, being 1.03 μmol·m^-2·s^-1 (female) and 1.54 μmol·m^-2·s^-1 (female) respectively. Thediurnal variations ofP_n was not significantly different between male and female (P>0.05). The diurnal variation of P_n in both male and female had a bimodal pattern, with a clear middaydepression. P_n differed among canopy positions. In sunny side, P_n of female was descended inorder of: distal part of upper layer>basal part of upper layer>basal part of middle layer>distal part of lower layer>distal part of middle layer>basal part of lower layer. For males,P_n followed the order: distal part of middle layer>distal part of lower layer>distal part of upper layer>basal part of upper layer>basal part of middle layer>basal part of lower layer (male). In rear side,P_n of female was descended as: distal part of upper layer>basal part of upper layer>distal part of middle layer>basal part of middle layer>basal part of lower layer>distal part of lower layer. For males,P_n followed the order: distal part of upper layer>distal part of middle layer>distal part of lower layer>basal part of middle layer>basal part of upper layer>basal part of lower layer (male). The diurnal variations of P_n were not significantly different between sunny side and rear side (P>0.05).P_n of both male and female was significantly negatively correlated withLAI (r=-0.732,P=0.000) and positively correlated with MTA (r=0.602, P=0.001) andτd  (r=0.659, P=0.000).

Effects of clonal integration on the growth of the invasive speciesMikania micrantha in habitats with heterogeneous light availability.

LI Xiao-xia, SHEN Yi-de, FAN Zhi-wei, WANG Ya, LIU Yan, HUANG Qiao-qiao

2018, 37(4):  974-980. 

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Mikania micrantha is native to Central and South America. In 1919, M. micrantha appeared as a weed in Hong Kong, China. Since then, it has spread rapidly. At present, it can be found in many provinces of China, posing serious threats to forests, farmlands and orchards. It is one of the top 100 worst weeds in the world. A greenhouse experiment was conducted to examine the effects of clonal integration on the performance of the stoloniferous herbM. micrantha in habitats with heterogeneous light availability. The results showed that when light availability was heterogeneous, clonal integration increased biomass of ramets grown in patches with low light availability, reduced biomass of those grown in patches with high light availability, and did not significantly change the biomass accumulation of the whole clonal fragments. Clonal integration reduced the differences in root/shoot ratio among ramets, increased the difference in photosynthetic rate among ramets, and tended to increase the specific leaf area in the ramets grown under high light conditions. These results suggest that clonal integration did not affect the biomass accumulation of the whole clonal fragments of M. micrantha stolons grown under heterogeneous light conditions, but it would enhance the growth of the ramets grown under low light availability. Consequently, clonal integration would enhance the invasion of M. micrantha from open habitats to habitats with low light availability (e.g., forests, weed communities). Our results indicated that clonal integration is one of the important strategies for M. micrantha to adapt to habitats withheterogeneous light availability.

Spatial distribution of fine roots and underground competition inCamellia oleifera-Vulpia myuros intercropping system.

DING Yi-fei, CAO Yong-qing, YAO Xiao-hua, WU Peng-fei, GONG Hong-en, FU Song-ling, ZHANG Ping-an

2018, 37(4):  981-986. 

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Using methods of field stratified excavation and image scanning, the spatial distribution of biomass and morphology of fine root (≤1 mm) ofCamellia oleiferaand Vulpia myuros in Camellia oleifera-Vulpia myuros intercropping system was examined. The underground competition between those two specieswas quantified by the niche overlap formula proposed by Levins. The results showed that  the fine root biomass ofC. oleiferawas 1.37 times as high as that of V. myuros, with average fine root biomass ofC. oleifera andV. myuros being 0.52 and 0.38 mg·cm^-3,respectively.  In the horizontal direction, fine root biomass of C. oleifera decreased with increasing distance from trees, while the root length density and specific root length of C. oleifera increased with theincreases of distance from trees. Fine root biomass ofV. myuros decreased with the increases of distance from trees, and the root length density and specific root length showed an even distribution. The root length density ofV. myuros was greater than that ofC. oleifera at different distances from trees, whereas fine root biomass and competition index of C. oleifera were greater than that ofV. myuros except for the distance 90 cm.  In the vertical direction, fine root biomass ofC. oleifera first increased and then decreased with the deepening of soil layer, and the root length density increased with the soil layer, while the specific root length was evenly distributed. The fine root biomass and root length density ofV. myuros decreased with the deepening of the soil layer, while the specific root length increased with the soil layer. Except for the 0-10 cm layer, the fine root biomass and competition index of C. oleifera was greater than that ofV. myuros. Our results indicated that fine roots ofC. oleifera had higher plasticity to avoid competition and maximize uptake of soil resources in the intercropping system.

Fine root biomass, productivity and turnover ofAbies faxoniana primary forest in sub-alpine region of western Sichuan, China.

LIU Shun, LUO Da, YANG Hong-guo, SHI Zuo-min, LIU Qian-li, ZHANG Li, KANG Ying, MA Qing

2018, 37(4):  987-993. 

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Primary forests play an important role in the global carbon budget. Fine roots in the forests are an integral component of ecosystem carbon cycling. The seasonal dynamics of fine root (≤2 mm) biomass were investigated by sequential soil coring method from May to November in 0-30 cm soil layer ofAbies faxoniana primary forest in sub-alpine region of western Sichuan. Furthermore, fine root productivity and turnover rate were estimated by decision matrix method. The results showed that living fine root biomass and annual production in 0-30 cm soil layer ofA. faxoniana primary forest were 286.89 g·m^-2 and 168.94 g·m^-2·a^-1, respectively. The average fine root turnover rate was 0.56 a^-1. Fine root biomass, productivity and mortality had substantial seasonal variation during the growing season. Living fine root biomass and productivity showed an overall unimodal seasonal trend, peaking in September. Fine root necromass and the ratio of necromass to living biomass of fine root showed a “U” trend, while mortality exhibited an upward trend during the growing season. Soil depth was a significant factor affecting fine root dynamics. Living fine root biomass, fine root necromass, productivity and turnover rate decreased, whereas the ratio of necromass to living fine root biomass slightly increased along soil depth.

Genetic variation and niche differentiation ofAllium forrestiiand Allium changduense.

ZHONG Yan, YU Yan, XIE Deng-Feng, XIE Chuan, HE Xing-Jin

2018, 37(4):  994-1002. 

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In this study, genetic variation and niche differentiation of two closely related speciesAllium forrestii Diels andA. changduense J. M. Xu were investigated based on three chloroplast DNA regions (atpI-atpH,trnL-trnF and ndhC-trnV). Fresh leaves from 232 individuals of 16 natural populations were collected. Field investigation showed that the distributions of the two species were discontinuous, with substantial differences in their habitats. According to the results from analysis of genetic variation, neither shared haplotype nor obvious gene flow was detected between those two species, indicating the independent evolution of the two species. The results of ecological niche modeling showed that the optimum ecological niche of both species were overlapped, except for the temperature seasonality and the mean temperature of coldest season. Our results indicated that the extreme temperature seasonality, lower mean temperature of coldest season, and highly specific habitat may be the major reasons for the differentiation of A. forrestiiandA. changduense.

Effects of stand structure and terrain factors on seedling regeneration of Pinus tabuliformis forest in the Songshan National Nature Reserve, Beijing.

HUANG Ping, LIU Yan-hong

2018, 37(4):  1003-1009. 

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To investigate the natural regeneration of Pinus tabuliformis, thirtytwo plots wereselected inP. tabuliformisforests in Songshan National Nature Reserve. The effects of terrain factors (altitude, slope, aspect, and slope position) and forest stand structural indicators (crown index, proportion of large trees, stand density, shrub coverage and herb coverage) on the natural regeneration ofP. tabuliformis were examined. The results showed that the regeneration density ofP. tabuliformiswas significantly negatively correlated with altitude. The regeneration density of seedlings at different slope positions followed the pattern: bottom slope > middle slope > upper slope. The regeneration density ofP. tabuliformis was negatively correlated with the magnitude of slope. The relationship between the regeneration density and the proportion of large trees could be explained by a parabolic model. The regeneration density was the lowest when the proportion of large trees reached about 50%. Furthermore, the regeneration of seedlings was positively correlated with stand density and herb coverage.

Effects of water level on intra and inter specific relationships ofSpartina anglica and Scirpus triqueter. 

MU Ya-nan, AN Shu-qing, ZHI Ying-biao, ZHANG Ming-xiang, LI Hong-li

2018, 37(4):  1010-1017. 

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Tidal action can change the water level of marsh habitats, with consequence on plant growth and interspecific relationships. A controlled greenhouse experiment was carried out toexamine the effects of water level on the relationship between the alien, clonal speciesSpartina anglica and native speciesScirpus triqueter. Three water levels (flooding with 5 cm over substrate surface; flooding with 0 cm over substrate surface; drain away water from 5 cm under substrate surface) were crossed with five planting arrangements (two alien plants per pot, two native plants per pot, four alien plants per pot, four native plants per pot, four plants per pot with two alien and two native plants) to explore the effects of water level on inter and intra specific relationships ofS. anglica andS. triqueter. The results showed that water level had significant effects on root biomass and leaf number of S. anglica andS. triqueter. The planting pattern had significant effects on the growth and reproduction of both species. The inter and intraspecific relative neighborhood effect indices of both species were negative in all water levels. The intra specific relative neighborhood effect index of S. anglica was significantly higher than that at interspecific level. There was no significant difference between the inter and intra specific relative neighborhood effect indices ofS. triqueter. In conclusion, water level altered intra and inter specific relationships of S. anglica andS. triqueter. The distribution ofS. anglica could be effectively controlled by proper regulation of water level and restoration of native species in Chinese coastal zone.

Nitrogen and phosphorous characteristics of canopy rainfall of eight dominant tree species in secondary forests of Shennongjia Mountain.

YANG Lin, WANG Ming, WANG Chuan-hua

2018, 37(4):  1018-1025. 

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Variation of N and P characteristics induced by hydrologic process of forest canopy rainfall plays an important role in nutrient cycling, community succession and biodiversity conservation in forests. In 2015, eight dominant tree species in secondary forests of Shennongjia Mountain were selected. Rainfall in open area, throughfall and stemflow of each species were collected monthly. The N and P characteristics of water samples, including nitrate, nitrite, ammonium,total nitrogen, total P and pH, were measured. Intensities of N and P deposition and the impacts of speciesspecific canopy hydrology on N and P concentrations and pH were analyzed. Ourresults showed that  N and P depositions in Shennongjia Mountain were 11.89 kg N·hm^-2·a^-1 and 1.98 kg P·hm^-2·a^-1, respectively. Nitrate, nitrite and ammonium accounted for 40.75%, 15.19%, and 44.08% of the total N in rainfall, respectively.  Annual mean concentrations of N and P in throughfall and stemflow of eight species were significantly higher than those of the atmospheric rainfall, indicating that N and P leaching occurred when rainfall dropped through tree canopy and stem. Meanwhile, we observed significant interspecific differences of N and P in both stemflow and throughfall. Interestingly, nitrate, ammonium, total N and total P of stemflow and throughfall of native speciesAbies fargesii were the highest among the eight species.  pH of stemflow and throughfall were slightly higher than that of atmospheric rainfall. Specifically, pH of stemflow of eight species ranged from 5.42 to 6.82, and those of throughfall varied from 6.23 to6.83. Furthermore, pH of stemflow and throughfall of introduced species was significantly lower than that of the native ones. In contrast, there were no significant differences of N and P between introduced and native tree groups. Therefore, more attention should be paid on the impacts of secondary forest succession on forest N and P cycling in Shennongjia Mountain.

Carbon and nitrogen stoichiometry of plant community and its influencing factors in a northern Tibet alpine grassland.

MA Bai-bing, SUN Jian, ZHU Jun-tao, LUO Guang-xiang

2018, 37(4):  1026-1036. 

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Both carbon (C) and nitrogen (N) are essential nutrients for plants. Their interaction and relationships with habitats influence growth, development, and nutrition status of plants. C∶N ratio of vegetation reflects growth rate of plants. Plant C and N concentrations, C∶N ratios and their relationships with environmental factors were analyzed based on the investigation of 58 sampling sites in a northern Tibet alpine grassland. The results showed that: (1) The coupling relationships between plant C and N varied in the alpine grassland. Plants could be divided into two groups: one with higher C∶N and another with lower C∶N. (2) The mean values of plant C concentration, N concentration and C∶N ratio in northern Tibet were 382.64 mg·g^-1, 17.76 mg·g^-1 and 22.24, respectively, with coefficients of variation (CV) in order of N concentration > C∶N ratio > C concentration. (3) For the plants with high C∶N ratio, different environmental factors explained by variance to plant C concentration, N concentration and C∶N ratio were in order of soil organic carbon (SOC) (48.91%) > soil total nitrogen (STN) (30.50%) > temperature (27.47%) > precipitation (16.66%). For plants with low C∶N ratio, the explanation variance was in order of precipitation (18.78%) > longitude (16.32%) > aridity index (AI, 14.35%) > plant species richness (12.58%). (4) For plants with high C∶N ratio, SOC concentration was negatively correlated with plant C and N concentration, and C∶N ratio was not significantly affected by other environmental factors. In contrast, for plants with low C∶N ratio, precipitation, longitude, AI and richness had significant negative effects on plant C concentration and C∶N ratio. This study provided scientific basis for sustainable utilization and ecological conservation and restoration of alpine grasslands in northern Tibet.

Distribution of habitat suitability for different sources of Fritillariae Cirrhosae Bulbus.

ZHAO Wen-long, CHEN Hong-gang, LIN Li, CUI Zhi-jia, JIN Ling

2018, 37(4):  1037-1042. 

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Using Maxent model and GIS technology, in combination with ecological environment data and actual geographical distribution of four different sources of Fritillariae Cirrhosae Bulbus, the spatial distribution of suitable habitats for different types of Fritillariae Cirrhosae Bulbus was predicted and the grade of habitat suitability was classified. The results showed that altitude was the most important ecological factor driving the habitat suitability of Fritillariae Cirrhosae Bulbus with different sources. The contribution rates of altitude to the habitat suitability of Fritillaria cirrhosaD. Don, Fritillaria przezvalskiiMaxim.,Fritillaria delavayiFranch., andFritillaria unibracteata Hsiao were 38.8%, 44.9%, 51.1%, and 52.6%, respectively. The suitable habitats for Fritillaria cirrhosa D. Don mainly distributed in areas with an altitude of 1850-4550 m, and the suitable habitats for the other three types were in the alpine areas with an altitude of over 2800 m. The most suitable habitats for different sources of Fritillariae Cirrhosae Bulbus were concentrated in Sichuan, Tibet, Gansu, Qinghai, and Yunnan provinces. However, the distribution area and spatial pattern in each province were different. It is necessary to distinguish different sources of Fritillariae Cirrhosae Bulbus when they are introduced, domesticated, and artificially planted.

Effects of low temperature in Japonica rice flowering stage on seed setting based on a mountain temperature gradient.

MA Shu-qing, QUAN Hu-jie, DENG Kui-cai, LIU Xiao-hang, XI Zhu-xiang, TONG Li-yuan, CHAI Qing-rong, YANG Jun, YANG Ru, PAN Chang-hong, JIN Long-fan, YANG Huan-yu

2018, 37(4):  1043-1050. 

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Given the fact that air temperature decreases with altitude, a lowtemperature experiment was conducted on the north slope of Changbai Mountain to understand the responses of rice seed setting to low temperature in flowering stage. The experimental setup included seven altitudes (temperature), three durations, and three flowering periods. The results showed that seed setting was sensitive to low temperature in flowering stage. The empty abortion rate was higherunder conditions of lower temperature and longer duration. The relationship between rice emptyabortion rate and 2-day average temperature followed linear function, but the influence coefficient of temperature was small. The relationship between empty abortion rate and ≥3 days average temperature followed logarithmic function, and the influence coefficient was greater. There were significant differences for the influence of low temperature among different flowering periods, with the biggest influence presenting in the fullflowering period, followed by the middle and earlyflowering periods. The influence coefficient of temperature in fullflowering period was three times as large as that in the earlyflowering period. On average, under the two, three, and four days lowtemperature treatments, the empty abortion rate increased by 0.4, 1.5 and 3.1 percentage points, respectively, with 1 ℃ decrease of daily temperature. The empty abortion rate increased by 0.4, 1.9 and 3.5 percentage points, respectively, with 1 ℃ decrease of daytime temperature. The relationships between the empty abortion rate and daytime temperature or the highest temperature were significantly stronger than that between the empty abortion rate and night temperature or the lowest temperature. The combined effect of the lowtemperature duration and the strength of lowtemperature on the empty abortion rate followed a binary linear equation. For example, the empty abortion rate raised 4.5 percentage points with the extended one day of the duration and raised 1.7 percentage points with 1 ℃ decrease of the temperature. In northeast China, shortterm lowtemperature (≤2 days) in flowering stage caused slight chilling injury and three days or more lowtemperature could cause moderate and severe chilling injury. Therefore, the daytime temperature and maximum temperature would be more effective than the daily average temperature and minimum temperature as chilling injury index of rice in flowering stage.

Responses of photosynthesis in leaves of  Japonica rice to light intensity at elevated CO₂ concentration.

LIU Xiao-meng, YU Ling-fei, HUANG Yao, SUN Wen-juan, LIU Chao, CHEN Jian, HU Zheng-hua

2018, 37(4):  1051-1057. 

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To investigate the responses of photosynthesis in leaves of rice to light intensity atdifferent levels of elevated CO₂ concentration, Japonica rice (Oryza sativa L.) ‘Nanjing 9018’ was grown at three levels of CO₂ concentration,i.e., ambient (CK), ambient + 40 μmol·mol^-1 (T1), and ambient + 200 μmol·mol^-1  (T2) in opentop chambers (OTC), with four OTCs as replicates for each treatment. We measured leaf net photosynthesis rate (P_n) and nitrogenconcentration at different light intensities at jointingbooting, headingflowering, and milking stages. Non-rectangular hyperbola function was used to fit P_n against light intensity. P_n in T1 was slightly higher than CK at jointingbooting stage and milking stage when light intensity was low (PAR=400 μmol·m^-2·s^-1), and no significant difference was detected for all other light intensities at the three developmental stages.P_n at different light intensities and light saturated net photosynthesis (P_{n max}) in T2 was 34%-40% higher than those in CK at jointing-booting and heading-flowering stages, while there was no significant difference at milking stage. Leaf nitrogen concentrations tended to be lower in T2, while photosynthetic nitrogen use efficiency (PNUE) was significantly higher than that in CK and T1. The PNUE was enhanced with the increases of light intensity. In addition, elevated CO₂ 200 μmol·mol^-1  was beneficial to improvement of the apparent quantum efficiency at jointing-booting and heading-flowering stages.

Effects of glaucocalyxin A on four phospholipases inArabidopsis thaliana. 

YANG Peng-jun, CHEN Lu, QIU Yi-zhi, AN Yan-huang, ZHAO Min, YANG Ning

2018, 37(4):  1058-1064. 

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The effects of different concentrations of diterpenoids glaucocalyxin A (0, 20, 100 μmol·L^-1) on membrane permeability and osmotic adjustment of fiveArabidopsis thaliana lines (the ColombiaArabidopsis thaliana, and pla₁-1, pla₂-1, plc₁-1 and pldδ₂ phospholipase mutants) were examined. The results showed that the relative electrolyte leakage and malondialdehyde (MDA) contents were significantly increased by the application of glaucocalyxin A in five lines of A. thaliana. The contents of proline and soluble protein first increased and thendecreased, with a peak at 24 h. Different types of phospholipases played different roles in thephysiological regulation process. Our results suggest that the effects of glaucocalyxin A areassociated with the four types of phospholipids and that its allelopathic effects can be exerted byregulating phospholipases.

The effects of crab herbivory on the growth ofPhragmites australisseedlings in a high marsh of the Yellow River delta.

ZHANG Li-wen, WANG An-dong, ZHAO Ya-jie, SONG Jian-bin, HAN Guang-xuan

2018, 37(4):  1065-1070. 

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Bottom-up and top-down effects as well as intra and inter specific interactions drive plant growth and reproduction in the salt marsh. Compared to the bottom-up effect, however, the top-down effect has been largely overlooked. Phragmites australis is a dominant species, whose populations living in the high marsh are important and unique in the Yellow River Delta. To reveal the impacts of the top-down factor on the growth ofP. australisseedlings in the high marsh， we investigated the effects ofHelice tientsinensis herbivory on their growth by establishing 24 plots with a size of 2 m×2 m. The seedlings ofP. australis were heavily grazed and damaged by crab. In all plots, 52.41% of seedlings were not consumed by crabs, 27.04% of seedlings were mildly fed, and heavy herbivory by crab accounted for 20.54%. The growth of seedlings was significantly influenced by crab herbivory. Heavy herbivory by crab strongly reduced the height, leaf number and leaf length of seedlings. The top-down effects should be considered in the protection and management of P. australis vegetation in the Yellow River Delta.

Effects of moss mat on soil CO₂, CH₄ and N₂O fluxes inCunninghamia lanceolataplantation in mid-subtropical region. 

CHEN Nai-shou, YANG Zhou-ran, YANG Yu-sheng, CHEN Shi-dong, XIE Jin-sheng

2018, 37(4):  1071-1080. 

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No data are available on greenhouse gas flux characteristics of biological soil crust (BSCs) in subtropical forests, which brings great uncertainty for estimating the regional greenhouse gas fluxes. In this study, we investigated the patterns of CO₂, CH₄ and N₂O exchange of BSCs and soils in condition of light or dark in a mid-subtropical Cunninghamia lanceolata plantation. Equal pressure sampling method was used to minimize the disturbance of soils. The gas samples were analyzed with gas chromatography (GC) (Shimadzu). Random forest algorithm was used to compare the effects of light and BSCs on the fluxes of greenhouse gases. The results showed that BSCs, light and their interaction significantly affected CO₂ flux (P<0.001). BSCs and light had significant effects on CH₄ absorption flux (P<0.001). Light and its interaction with BSCs exerted significant effects on the N₂O flux (P<0.001). Our results indicated that BSCs and light played important roles in soil greenhouse gas emissions in the study site. BSCs restrained soil CO₂ emission under dark condition. BSCs slightly increased N₂O flux and significantly increased CH₄ absorption flux (P<0.01). Moreover, CO₂, CH₄ and N₂O fluxes of BSCs were significantly decreased under light condition. Light had greater effect on CO₂ and N₂O flux than on BSCs, whereas BSCs had greater effect on CH₄ flux than light. Such a result indicated that the CO₂ and N₂O fluxes were associated with the photoautotroph of BSCs while chemoautotroph played a great role in CH₄ flux.

Effects of combined biochemical inhibitors on ammonia volatilization and cumulation in yellow clayey soil.

ZHOU Xuan, WU Liang-huan, DONG Chun-hua

2018, 37(4):  1081-1088. 

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We investigated the effects of urease inhibitorN(n-butyl) thiophosphoric triamide (NBPT), nitrification inhibitor 2-chloro-6-(trichloromethyl) pyridine (CP), and their combined application on NH₃ volatilization rate, NH₃ accumulation and dynamics of yellow clayey soil in an incubation experiment. Results showed that NH₃ volatilization rate peaked after three days of urea application and then leveled off. CP treatments with different application doses promoted soil NH₃ volatilization and increased the peak value of NH₃ volatilization rate by 10.9%. NBPT treatments with different application doses delayed the peak time of soil NH₃ volatilization and significantly reduced the peak value of NH₃ volatilization rate by 35.0%. NBPT significantly inhibited soil NH₃ volatilization. On the 24th day after incubation, soil NH₃ volatilization amount was reduced by 37.2% in NBPT treatments as compared with urea treatment, while it was increased by 2.1% in CP treatments. Compared with application of CP alone, combined application of CP with NBPT showed synergistic inhibition effect on NH₃ loss. NBPT+CP treatments effectively delayed urea hydrolysis in early time, and thus reduced NH₃ loss by 14.2% (day 24) as compared with urea treatment. However, NH₃ volatilization increased with the increases of CP dose. Furthermore, the dynamics of the cumulative amount of NH₃ volatilization could be quantitativelydescribed by Elovich equation (q_t=a+blnt). Additionally, CP treatments increased the slopeb value, which increased with the increasing dose. NBPT treatments reduced the slope b value, which decreased with the increasing dose. NBPT+CP treatments reduced the slopeb value. Soil NH₃ volatilization rate was significantly positively correlated with soil pH. In conclusion, application ofNBPT or combined with CP could significantly reduce soil NH₃ volatilization rate and soil N loss, and thus improve fertilizer utilization in yellow clayey soil.

 

Responses of seed germination and seedling growth of Medicago sativa andLeymus chinensis to soil moisture.

YANG Kun, MA Hong-yuan, WEI Ji-ping, YANG Fan, ZHAO Dan-dan, DONG Li-qin, LI Jing-yu

2018, 37(4):  1089-1094. 

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Soil moisture is a key environmental factor affecting seed germination and seedling growth. To investigate the effects of soil moisture on seedling emergence and growth of Leymus chinensis andMedicago sativa under natural conditions, a simulation study was conducted with six soil moisture levels (2.5%, 5%, 7.5%, 10%, 20% and 30%). The results showed that the seedling emergence rate and seedling growth of both species were significantly affected by soil moisture. With increasing soil moisture, the seedling emergence rate was first increased and then decreased. ForM. sativa, the seedling emergence rate was the highest (up to 93%) when the soil moisture was 10%-20%; the lowest seedling emergence rate was 2% at 30% soil moisture level. For L. chinensis, the highest seedling emergence rate was 76% when the soil moisture was 5%; the lowest rate was 9% at 30% soil moisture. With the increases of soil moisture, root length and seedling height first increased but then decreased, which was consistent with the pattern of seedling emergence rate. The optimal soil moisture level was 7.5%-10% for seedling emergence and growth of M. sativa, and 5%-7.5% for that ofL. chinensis seeds. In conclusion, soil moisture at 7.5%-10% would be suitable to the sowing and seedling growth of M. sativa, and 5%-7.5% for L. chinensis.

The relationship between transpiration rate and leaf traits of Phragmites australis in response to soil moisture in Zhangye wetland.

LI Qun, ZHAO Cheng-Zhang, YAO Weng-Xiu, WANG Jian-Liang, ZHANG Wei-tao

2018, 37(4):  1095-1101. 

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The response of the relationship between transpiration rate and leaf traits to environmental factors is important for clarifying ecophysiological coupling mechanism between carbohydrate metabolism and constructing modes of leaf traits. In this study, we investigated the relationships between transpiration rate (T_r) and leaf area and leaf thickness ofPhragmites australis under different soil moisture levels along a transect from the central to the edge of the wetland in Zhangye National Wetland Park, Gansu Province, China. Four plots were established withdifferent soil moisture levels as Ⅰ (95.70%), Ⅱ (67.50%), Ⅲ (50.70%) and Ⅳ (30.17%). The results showed that the height, coverage, and aboveground biomass of the wetland community showed an increase and then decrease trend with the decreases of soil moisture. The leaf area and T_r presented an increase and then decrease trend, while the leaf thickness displayed an increasing trend from plots Ⅰ to Ⅳ. T_r was significantly positively correlated with leaf area in plots Ⅰ and Ⅳ (P<0.01) and leaf thickness in plot Ⅰ (P<0.01), but negatively correlated with leaf thickness in plot Ⅳ (P<0.01). Meanwhile, positive correlations between T_r and leaf area, leaf thickness were found in plots Ⅱ and Ⅲ (P<0.05). In plots with saturated soil moisture (Ⅰ) andserious soil water deficit (Ⅳ), Phragmites australis built up through a small thin leaf mode, and a small thick leaf mode, respectively, to keep lowerT_r. In the moderate soil water condition (Ⅱ, Ⅲ), they built up through a large thin leaf resource investment strategy to achieve higher T_r. All these changes in plants reflect the phenotypic plasticity of plant adaptation to heterogeneous habitats.

Spatial variations of soil carbon and nitrogen contents inPhragmites australisandCyperus malaccensis marsh in the Minjiang River estuary.

WANG Hua, SUN Zhi-gao, LI Jia-bing, HE Tao, GAO Hui, WANG Jie, LIN Peng-zuo, WU Xin-tong

2018, 37(4):  1102-1110. 

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To clarify the spatial variations of soil carbon and nitrogen contents of different wetlands in Shanyutan of the Minjiang River estuary,Phragmites australismarsh (PM), Cyperus malaccensismarsh (CM) and their ecotonal marsh (P. australis-C. malaccensismarsh, PCM) were investigated. In the horizontal direction, the contents of soil total nitrogen (TN) and soilorganic carbon (SOC) in different marshes were in the order of PCM>PM>CM. At the verticaldirection, a decrease trend was observed in soil profiles of the three marshes. Compared with PM and CM, the contents ofNH₄⁺-N in surface soil of PCM decreased by 15.78% and 0.84%, while that of NO₃^--N decreased by 13.04% and 44.00%, respectively. In bottom soil layers, soil NH₄⁺-N increased by 30.00% and 6.06%, while soil NO₃^--N increased by 43.75% and 23.91%, respectively. The NH₄⁺-N contents of PM soils were mainly controlled by organic matter contents, while the contents of TN in CM soils were influenced by electric conductivity (salinity). Soil particle composition and moisture were the key driving factors for the contents of NH₄⁺-N and NO₃^--N in PCM soils. The competition of P. australisandC. malaccensis significantly increased the contents of SOC and TN and altered the spatial distributions of NH₄⁺-N and NO₃^--N in PCM soils, probably due to the alteration of fine particle composition and nitrogen mineralization and nitrification.

Effects of planting duration of Chinese prickly ash orchard on soil organic carbon minerali zation and chemically stable organic carbon.

LONG Jian, LIAO Hong-kai, LI Juan, ZHANG Wen-juan, ZHAO Chang, ZHANG Ming-jiang

2018, 37(4):  1111-1119. 

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With 5-, 17-, 30-year-old Chinese prickly ash orchards (designated as PO₅, PO₁₇, PO₃₀ respectively) and a forest land (FL, about 60 years) as control in a demonstration area of desertification control in southwestern Guizhou as our research objects, the dynamics of soil organic C mineralization were assessed by fitting equation methods. The effects of planting Chinese prickly ash orchards on soil organic C mineralization and chemically stable organic C were analyzed. The results showed that the double exponential equation fit well for the variation of soil organic C mineralization, with a correlation coefficient of >0.95. The correlation of soil slowacting C with cumulative C mineralization was significant (R=0.792,P<0.01). The concentration of Na₂S₂O₈resistant organic C at all soil layers was highest in the forest compared to the three Chinese prickly ash orchards, whereas its proportion to SOC was the lowest. The concentration and proportion of H₂O₂resistant organic C at 0-15 cm soil layer were the highest in thePO₃₀, and those at 30-50 cm were the highest in the PO₁₇. The concentration and proportion of HF soluble organic C at all soil layers were the highest in the PO₁₇. Soil organic C concentration of the four forest types accounted for only 1.6%-29.3% of the slowacting C, the concentration of which was close to the cumulative mineralization amount of soil organic C after 92 days. The mineralization rate of slowacting C (k_s) fluctuated slightly (0.013-0.025), and the k_s values of PO₃₀ were the highest at 0-15 cm and 15-30 cm layers. With the increases of cultivation duration, soilactive organic C and slowacting C concentrations showed increasing and decreasing trend,respectively. In conclusion, reasonable cultivation duration of Chinese prickly ash orchard can improve soil quality and C sequestration.

Soil microbial communities, enzyme activities and the affecting factors in coal waste piles with different reclamation durations.

YU Ya-jun, WANG Ji-ping

2018, 37(4):  1120-1126. 

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Soil microbes and enzymes could respond to environmental change and stress, which have indicative effects for the recovery of soil ecological function. To investigate the indicative effects of soil microbial community and enzyme activities on changes of reclaimed soil quality in coal waste piles, we collected soil samples from reclaimed coal mine land (3-, 5- and 7-year-old orchards) in Caocun, Huozhou, Shanxi Province. Soil microbial community composition and the activities of four enzymes were measured. The influences of soil physicochemical properties on those parameters were analyzed by path analysis. The results showed that: (1) Soil organic matter, nitrogen and phosphorus concentrations increased with the increases of reclamation years in the three orchards, but the water content and clay content only increased remarkably in 7-year-old orchard. Compared with the local ordinary orchard (CK), soil quality was lower in the three reclaimed orchards. (2) The PLFAs concentrations of different microbial communities andenzyme activities in the three reclaimed orchards increased with reclamation duration. Bacteria, fungi, alkaline phosphatase and urease activities in 0-10 cm and 10-20 cm soil layers increased with the increases of reclamation duration. Both Gram negative bacteria and dehydrogenase activity in 0-10 cm soil layer and actinomycetes and catalase activity in 10-20 cm soil layer significantly increased. Generally, the PLFAs concentrations of microorganisms in different communities and enzyme activities in the three reclaimed orchards were lower than those in the controlorchard. (3) Bacteria, fungi, actinomycetes, Gram positive bacteria, catalase, urease, dehydrogenase and alkaline phosphatase activity all had significant indication for changes of soil properties in reclaimed orchards in coal waste piles, which could be used as microbial indicators for changes in soil quality.

Leaching of soil salt with different leaching water volumes in aquaculture ponds of Jiaozhou Bay.

LI Qi-fei, KONG Fan-long, XI Min, LI Yue

2018, 37(4):  1127-1134. 

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Serious salinization often occurs in aquaculture ponds. To ensure the effective utilization of land and water resources, the leaching dynamics of soil salinity in aquaculture ponds in Jiaozhou Bay was examined with indoor soil column experiment. Another aim of our experiment was to explore the optimum water consumption. The results showed that the salt content of soil and its leaching solution exponentially decreased with the increases of leaching water volume. Taking the leaching effect and water saving into account, the 1∶1 ratio of water and soil couldachieve better improvement effect. In the process of desalting, the concentrations of Ca²⁺, Mg²⁺, K⁺, Na⁺, and Cl^- in soils decreased, the concentration of SO₄^2- first increased and then decreased, but the concentration of CO₃^2- and HCO₃^- showed an upward trend. The concentration of each salt ion in leaching solution was similar to that of soil salt ion. The desalination rates of soil salt ions were in order of Cl^->Na⁺>K⁺>Ca²⁺>Mg²⁺>SO₄^2->HCO₃^-. With the increases ofleaching water volume, the soil ion composition changed from Cl^- and Na⁺, to Na⁺, K⁺, and SO₄^2-, and finally to Na⁺, HCO₃^- and K⁺. More attention should be paid on the alkalizationphenomenon occurred during soil desalting.

Establishment and fine-tuning of nature reserve networks based on minimum cumulative resistance model: A case study of Mountain Qinling region.

FU Meng-di, LUO Jian-wu, TIAN Yu, ZHAO Zhi-ping, LI Jun-sheng

2018, 37(4):  1135-1143. 

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Constructing nature reserve networks and optimizing their performance in conservation have become a hot topic in the research area of biodiversity conservation. This study aims todevelop and fine tune a spatially clear nature reserve network, in which conservation gaps are analyzed, ecological corridors are defined, and ecological nodes are identified, on the basis ofcurrent nature reserve system by applying minimum cumulative resistance model (MCR model) in Mountain Qinling region. The MCR model was used to calculate the minimal cumulative resistance surface of ecological source areas. The selected areas were grouped into multiple categories, taking into account ecological vulnerability, the significance of ecosystem services, biodiversity richness and climate change patterns. Eight ecological restraint factors, including altitude, slope and land use pattern, were selected to develop the ecological resistance surface. The results showed that the ecological source area in Mountain Qinling region was 25088.84 km², accounting for 24.66% of the total area. The area of minimum resistance accounted for 25.06% of the regional area. A nature reserve network was developed with interwoven points, lines and surfaces, including 38 eco-nodes, 40 eco-corridors, one relatively large eco-source area and few small eco-source areas. Our findings would contribute to the planning of biodiversity conservation and nature reserve construction.

Spatial heterogeneity of water quality and its response to land use in Puhe River Basin.

FAN Zhi-ping, LIU Jian-zhi, ZHAO Yue, FENG Kai-bin, WANG Qiong, LI Fa-yun, TU Zhi-hua

2018, 37(4):  1144-1151. 

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Spatial variation of water quality factors, including TN, TP, NH₄⁺-N, COD_cr, pH, DO and TDS, were analyzed by using GIS technique and geo-statistics method based on water sampling data collected in the Puhe River Basin from August to September 2012. Responses of water quality to land use changes were investigated. Results showed that the spatial distributions of NH₄⁺-N, DO and TDS were highly variable, and significantly affected by structural factorsincluding climate, topography, and hydrology. TP, COD_cr and pH showed weak spatial variations, and were significantly affected by random factors such as human activity. TN showed a weak spatial variation and was jointly affected by structural and random factors. TN and NH₄⁺-N were negatively related to the proportion of forest lands and positively related to the proportions of agricultural lands and construction lands. Moreover, pH and DO were negatively related to the proportions of water area and unused land. Our results indicated that forest, agricultural lands and construction lands were the dominant factors driving the spatial heterogeneity of TN and NH₄⁺-N, and that water area and unused land were the dominant driving factor for the spatial variation of pH and DO. Results from this study provide support for environment management of river basin.

Spatial and temporal evolution of eco-environmental quality in the oasis of Shiyang River Basin based on RSEDI.

SHI San-e, WEI Wei, YANG Dong, HU Xin, ZHOU Jun-ju, ZHNAG Qiang

2018, 37(4):  1152-1163. 

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We assessed the eco-environmental quality in Wuwei and Minqin oases of Shiyang River Basin based on the Landsat TM/OLI images in 1995, 2006, and 2016. Remote sensingecological distance index (RSEDI) was used to assess the eco-environmental quality, which was calculated by several indices, including desertification index (DI), generalized difference vegetation index (GI), salinization index (SI), and wetness index (WI). The results showed that the ecological quality of Wuwei and Minqin oases was enhanced from 1995 to 2016, with the mean RSEDI increasing from 5.3 in 1995 to 14.8 in 2016. The area of ecological restoration was larger than that of ecological degradation. Spatially, the eco-environmental quality of Minqin oasis was overall in recovering mode. In contrast, the Wuwei oasis exhibited the recovering mode in the northwest region but the degrading mode in the southeast region. Among the three years examined here, the eco-environmental quality of the two oases in 1995 was poor based on the changes in profile map, with a significant spatial discrepancy. In 2006, the eco-environmental quality was the worst among the three years and its discrepancy was the least. The eco-environmental quality was the best in 2016, with significant spatial discrepancy. In general, the eco-environmental quality in the two oases of Shiyang River Basin has been significantly improved by the environmental rehabilitation in the recent decade.

Characters of aquatic N₂O concentrations in agricultural watershed of Jurong Reservoir.

BIAN Hang, HU Zheng-hua, FENG Fang, XIAO Qi-tao, XIE Yan-hong, XU Zu-fei, LEE Xu-hui

2018, 37(4):  1164-1171. 

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To clarify spatial and temporal dynamics of N₂O concentration in agricultural watershed, water samples in the Jurong Reservoir watershed were collected from October 2015 to September 2016. By measuring the headspace gaseous N₂O concentration using the method of headspace balance-gas chromatography, the N₂O concentration in water was calculated. In combination with parameters of water quality, factors influencing aquatic N₂O concentration were analyzed. Results showed that the water N₂O concentration in Jurong Reservoir watershed varied from 5.04 to 61.83 nmol·L^-1. The concentrations of N₂O in rivers, ponds, and the reservoir peaked in winter, with values being （30.26±12.33）, （21.28±5.98）, and （18.56±2.27） nmol·L^-1, respectively. The average N₂O concentrations in different water types were in order of rivers (25.93±11.60） nmol·L^-1, ponds (20.03±9.57） nmol·L^-1, and the reservoir (16.17±4.72） nmol·L^-1. The aquatic N₂O concentration was significantly positively correlated with dissolved oxygen (DO), redox potential (ORP), ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N), nitrite nitrogen (NO₂^--N), and dissolved inorganic nitrogen (DIN), and negatively related to water pH.

Assessment of temporal and spatial dynamics of agricultural drought in Shaanxi Province based on vegetation condition index.

LI Xin-yao, YANG Lian-an, NIE Hong-mei, REN Li, HU Sheng, YANG Yu-cen

2018, 37(4):  1172-1180. 

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Drought is frequent and severe in Shaanxi Province because of the special geographical location and climate. Thus, it is critically needed for efficient agricultural drought monitoring and drought impact analysis using remote sensing technology. Here, we used vegetation conditionindex (VCI) as the monitoring indicator of agricultural drought at growing season to explore the applicability of VCI in agricultural drought monitoring in Shaanxi Province and its correlation with precipitation. Then VCI was adopted to identify and analyze the temporal and spatial dynamics of agricultural drought from March 2002 to May 2016. The results showed that VCI had some advantages in monitoring agricultural drought in Shaanxi Province. VCI did not show good correlation with precipitation on monthly scale, which indicated that precipitation was just one of many factors affecting vegetation coverage and growth. VCI had lag response to precipitation change, with about one month lag in Guanzhong plain and southern Shaanxi, less than one month lag in northern Shaanxi. Over the past fifteen years, agricultural drought events of Shaanxi Province mainly occurred in March, followed by October and November. While continuous agricultural droughts mainly occurred in spring or autumn, the overall drought condition had been alleviated. Theproportion of drought area was the largest in autumn and smallest in summer. The droughtfrequency was the highest in autumn and lowest in summer. Most of the region in northern Shaanxi was prone to spring drought and autumn drought, while some areas of Guanzhong plain and southern Shaanxi were prone to spring drought and autumn drought. The drought frequency was the highest in northern Shaanxi, followed by Guanzhong plain and lowest in southern Shaanxi.

Assessment of the trophic level of main fishery species in coastal waters of Daling River and Yalu River based on stable isotope technique.

TIAN Jia-shen, LI Duo-hui, WANG Bai, ZHOU Zun-chun, LU Zhi-chuang, YOU Guang-ran, WU Ying-chao

2018, 37(4):  1181-1186. 

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We measured the abundance of carbon and nitrogen stable isotopes in the dominant fishery species in the coast of the Daling and Yalu rivers in spring with stable isotope technique, calculated the trophic levels, and established the continuous nutritional spectrum of the majorbiological groups. The results showed that the δ¹⁵N and δ¹³C of the dominant species ranged from8.2‰ to 14.1‰ and from -22.9‰ to -16.6‰, respectively in Daling River, while ranged from 7.9‰ to 13.2‰ and from -20.6‰ to -16.1‰ in Yalu River, respectively. The trophic level of the major biological groups in Daling River was between 2.8 and 3.9, with the crustacean, gastropod, bivalve and fish ranging 2.9-3.5, 2.8-3.1, 2.9-3.4 and 3.4-3.9, respectively. The trophic level of the major biological groups in Yalu River was between 2.8 and 3.7, with the crustacean, cephalopod, gastropod, bivalve and fish ranging 3.0-3.6, 3.4-3.5, 2.8-3.0, 2.9-3.2 and 3.1-3.7, respectively. The continuous trophic spectrum demonstrated thatBullacta exarataand Mactra veneriformis were the primary consumers in both rivers. Crustacean was the secondary consumer, and fishes were the senior consumers. This study established the continuous trophic spectrum of the major fishery species in the coast in Daling and Yalu rivers, and thus provided basic data for the conservation and development of fisheries resources.

Variations of macrobenthic community structure in the intertidal zone of Xiaoqing River estuary in spring from 2004 to 2015.

LIU Yi-ting, LIU Xin-yu, LENG Yu, XU Zhao-dong, WANG Zhen-zhong, WEN Ruo-bing

2018, 37(4):  1187-1196. 

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To reveal the variations of the structure of macrobenthic communities in the intertidal zone of Xiaoqing River estuary and the effects of coastal protection dam and sea ice, annual samplings of macrobenthos were carried out in each spring from 2004 to 2015. Species composition, biomass, abundance, and biodiversity indices of macrobenthos were analyzed. The results showed that a total of 108 species were identified in the past 12 years. The whole collections were divided into five main groups based on cluster analysis. Samples in 2004 before dam construction and samples in 2013 which were less affected by the dam construction and sea ice disaster, were identified as two separate groups. Macrobenthic communities were significantly affected during the dam construction in 2005-2008, the samples from which were identified as a group. Samples in the period of 2009-2012 after the dam construction were identified as a group, during which macrobenthic communities were mainly influenced by sea ice. Samples in 2014 and 2015 were merged into one group, in which the communities tended to be stable. The abundance and biomass ranged from 218 to 1522 ind·m^-2 and 31.83 g·m^-2 to 123.41 g·m^-2, respectively. Species richness index (d), evenness index (J) and Shannon diversity index (H) were 3.12, 0.51 and 2.55, respectively. Abundance/biomass curves showed that the macrobenthic assemblages were under moderate to severe disturbance due to the construction of coastal protection dam and sea ice disaster.

Community structures of crustacean zooplanktons and their correlation with environmental factors during spring and summer in Junshan, Qingshan and Yaohu lakes.

ZHAO Hui, ZHANG Kun, PENG Shui-xiu, ZHANG Meng, DENG Dao-gui

2018, 37(4):  1197-1203. 

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The community structure of crustacean zooplanktons in three lakes (Junshan, Qingshan and Yaohu) in Nanchang, Jiangxi Province was investigated from March to August 2016. The results showed that 14 species of crustacean zooplanktons were identified in the three lakes, eight species out of which belonging to Cladocera and six species belonging to Copepoda. The density of crustacean zooplankton in Lake Junshan, Lake Qingshan and Lake Yaohu ranged 0.8-24.9, 0.3-18.7, and 5.9-47.9 ind·L^-1, respectively. The density of crustacean zooplanktons in Lake Yaohu was significantly higher than that in Lake Junshan (P=0.003) and Lake Qingshan (P<0.001). The eutrophic species,Diaphanosoma sp.,Moina micrura, and Bosminasp., were the dominant ones in the three lakes in summer, whereasDaphnia galeatawas the dominantspecies in Lake Junshan in spring. Results from redundancy analysis showed that water temperature, chlorophylla, and pH determined the community structure of crustacean zooplanktons in the three lakes. In addition, the community structure of crustacean zooplanktons in Lake Qingshan and Lake Yaohu located on the outskirts of the city were closely related to nitrogen and phosphorus concentrations.

Adaptive changes of digestive organ size and percentages of different subtypes of leukocyte before and after metamorphosis in tadpoles of Mongolian toads, Pseudepidalea raddei.

LIAN Li-yan, GAO Hui-qing, SUN Jia-luo, SUN Si-qi, ZHANG Qiong-wen, ZHANG Zhi-qiang

2018, 37(4):  1204-1210. 

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The developments of body size and digestive organ size in wild tadpoles of Mongolian toads (Pseudepidalea raddei) during the Gosner stages 28, 38, 42, 44, 45, and 46 (G28, G38, G42, G44, G45, and G46) were recorded following Gosner staging table (Gosner, 1960). Blood samples were collected by cutting tail or cardiac puncture. The percentages of different subtypes of leukocyte and the ratio of neutrophils to lymphocytes (ratio of N/L) were measured. The results showed that body mass, total body length, and tail length initially increased, and then gradually decreased over the developmental stages. Body length and the ratio of body mass to body length were increased over all the developmental stages. The length and wet mass of small intestine reached the peak in G38, with the wet mass being higher than that in G42. Liver wet mass increased from G28 to G45 tadpoles, but decreased in G46. Percentage of neutrophils in G45 was greater than in G38. Percentage of eosinophils was greater in G44 than that in G42 and G45. Percentages of lymphocytes, basophils and monocytes, as well as the ratio of N/L did not change across different developmental stages. These results indicate that the sizes of energy acquisition and energystorage organs reach the maximum value at metamorphic peak and before landing, respectively. The changes of the proportions of neutrophils and eosinophils are beneficial to the transition from aquatic to terrestrial environment, as well as to the completion of metamorphosis development.

The response of swimming behavior of juvenileAristichthys nobilisto turbulence intensity.

SONG Ji-quan, WANG Ji-bao, HUANG Wei, WU Huan, JIN Zhi-jun, SHI Xiao-tao, CHEN He-chun, YANG Pan, XIANG Chen-guang

2018, 37(4):  1211-1219. 

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Turbulence, a complex flow regime, exists universally in nature. It has importantinfluences on the survival of fish. Turbulence is closely related to the swimming behavior of fish, which has received extensive attention. In this study, with juvenileAristichthys nobilis (10.10±0.54 cm of body length) as experimental objects, a ball (10 cm in diameter) was put in a tank to generate a nonuniform turbulence field, and turbulence intensity was chosen as the characteristic magnitude of turbulence. We analyzed the relationship between the responses of swimming behavior of A. nobilisand turbulence intensity when the fish migrated upstream, with the spatial distribution of turbulence being overlapped with typical trajectories of juvenileA. nobilis. Theresults showed that the upstream swimming behavior ofA. nobilis was affected by the turbulence intensity. The sensitive turbulence intensity of juvenileA. nobilis ranged 8.7-9.2 cm·s^-1 when the flow velocity was 14, 26 and 34 cm·s^-1, and the preferred turbulence intensity was 5.25-8.4 cm·s^-1. The results would improve our understanding of the relationship between fish behavior and turbulence and provide guidance for the conservation ofA. nobilis.

Effects of tea tree cultivar on community structure of soil fauna.

YU Lin-fei, LI Ting-xuan, WANG Sheng-qiang, LIU Xuan-you, YU Xue-lian

2018, 37(4):  1220-1226. 

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Soil fauna is one of the significant biological indicators of soil environment. Understanding the differences of community structure of soil fauna under tea plantations of different cultivars can provide scientific basis for the selection of advantageous tea cultivars in the process of returning croplands to tea gardens. Soil samples from tea plantations with four major tea tree cultivars (Fuding Dabaicha, Chuancha No. 3, Chuanmu No. 217 and Chuannong Huangyazao) were collected from Zhongfeng Ecological Tea Garden in Mingshan Township, Yaan City, Sichuan Province. Soil fauna from 0-15 cm soil layer was extracted by three different methods: handsorting approach, modified Tullgren method, and Baermann’s method. Results showed that the soil fauna belonging to five groups, 10 classes, and 23 phyla were observed in the tea garden. The plantation of Fuding Dabaicha had significantly higher abundance of soil fauna, compared with other three tea cultivars. Nematoda were the dominant group in the plantations of all the four tea cultivars. There was higher richness of soil fauna groups in the plantations of Chuanmu No. 217 and Chuannong Huangyazao than those of Fuding Dabaicha and Chuancha No. 3. The Shannon index and Simpson evenness index of soil fauna in the plantations of Chuancha No. 3 were significantly higher than those of the other three tea cultivars. Soil fauna richness index was positively correlated with soil organic C and available P content, while Simpson evenness index was negatively correlated with available K. Therefore, enhancing soil organic C and available P contents would increase the richness of soil fauna community.

Species diversity of terrestrial birds in forests of northern Guangdong.

ZOU Fa-sheng, LU Xue-li, WANG Xin-cai, GONG Yue-ning, SONG Xiang-jin, CHEN Zhi-hong, ZHANG Min

2018, 37(4):  1227-1232. 

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Forest birds are difficult to be detected because of their cryptic behaviors. In this study, camera trapping technology was used to monitor such birds in three forest sites of northern Guangdong. At Nanling National Nature Reserve, Chebaling National Nature Reserve, and Nanxiong Provincial Nature Reserve, 124, 66, and 29 cameras respectively were set up to monitor forest birds between January 2011 and March 2017. A total of 2659, 1063, and 769 photographs were produced, respectively. In total, 54 species were cameratrapped at the three sites, with 47species at Nanling, 27 species at Chebaling, and 21 species at Nanxiong. Lophura nycthemera and Garrulax pectoralis were the dominant species in those forests. The mean number of species recorded per camera was four. There were significant differences in species richness among the three sites, with the highest species richness in Nanling and the lowest in Nanxiong. No significant differences were found among the three sites for the mean number of individuals recorded per camera. Species richness in northern Guangdong appeared to be much higher than that at nearby sites, such as at Badakongshan in Hunan, and Huaping in Guangxi. Such differences might be related with the use of a larger number of cameras over a longer period. Syrmaticus ellioti andPucrasia macrolopha were not detected during cameratrapping at the three northern Guangdong sites and in other transect survey in northern Guangdong in past decades. We speculated that bothspecies may have been locally extinct.

A systematic review on the methods of ecosystem services value assessment.

LI Li, WANG Xin-yuan, LUO Lei, JI Xin-yang, ZHAO Yan, ZHAO Yan-chuang, Nabil Bachagha

2018, 37(4):  1233-1245. 

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The status of researches in ecosystem services value assessment (ESVA) wasreviewed. The methods of ESVA could be classified into two categories from the aspect of evaluation process: direct and indirect, which are further classified into several subcategories. After analyzing the concept connotation, calculation, and application of each classified method, we put forward ten problems in ESVA. Finally, by summarizing the theory, methodology, and resultsexpression form of ESVA, we proposed three suggestions to strengthen the future research ofESVA:  comparative and comprehensive application of different methods for the assessment ofecosystem services value;  ecosystem services value assessment of the areas with sparse or novegetation;  the assessment of service value of complex ecosystems and the evaluation of ESVA at fine scale.

Ecological function of promoting microorganisms associated with ectomycorrhizal fungi.

XU Man, FU Wan-qiu, DAI Chuan-chao, JIA Yong

2018, 37(4):  1246-1256. 

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Numerous studies have demonstrated that a lot of microorganisms, named mycorrhization helper bacteria, play an important role in driving mycorrhizal formation and function. Ectomycorrhizae is a key factor in forest ecosystem. Some ectomycorrhizal macrofungi are abundant and with medicinal and economic value. In this review, we summarized the effects of promoting microorganisms associated with ectomycorrhizal fungi on its functions and the underlying mechanisms for promoting mycorrhization, growth of fungal hyphae, and formation of fruitbody. We also explored the colonization mechanism of promoting microorganisms and its contextdependence as well as ecological function. Meanwhile, we reviewed the interaction between ectomycorrhizal fungi and these microorganisms. Then, we outlined the prospects of promoting microorganisms forfurther research and presented some new ideas for the research on growth, development, and ecological function of ectomycorrhizal fungi.

 

Fish social hierarchy and its application in aquaculture and stock enhancement.

ZHANG Zong-hang, GUO Hao-yu, ZHANG Xue-mei, ZHANG Xiu-mei

2018, 37(4):  1257-1264. 

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Social hierarchy is an important part in the research of fish behavioral ecology. It refers to a certain sequence of hierarchy formed by intraspecific competition in a population of social fish, with consequence on fish physiology and behavior. In the processes of aquaculture and artificial seedling, fish social hierarchy may result in more attack, pressure and growth variation, and thus lead to poor animal welfare. We reviewed the literatures on fish social hierarchy and its driving factors including selfconditions such as gene, personality trait, metabolism, body size, and social experience, and the environmental factors such as density, food and shelter. We described the experimental design and identification for the study on fish social hierarchy, discussed the deficiencies in previous research on social hierarchy, and proposed the possible directions forfurther research. This review aimed to provide referential information for the research on social behavior of fish, and for its application in aquaculture and artificial seedling to avoid the deficiencies of social hierarchy and improve fish welfare.

Salivary glands and water management in termites.

WANG Yi, JI Bao-zhong, LIU Shu-wen, XU Li-jun, JIN Ming-xia, WANG Ya-zhao

2018, 37(4):  1265-1275. 

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Salivary glands and water management are the basis of termite social behavior and their ecological function. Salivary glands of termites consist of labral glands, mandibular glands, and labial glands. Labral glands in few termite species have been reported, but the generality for their existence in termites is questionable. Mandibular glands, a pair of smallsized glands located at the base of each side of the head cavity, are widely presented in different termite species. The secretions of the mandibular glands may be related to defense, caste differentiation and protection of the mandibular from abrasion. Labial glands, which are widespread in each caste individuals of various termite species, have the most complex function among all the external secretion glands of termites. Labial glands consist of labial glandular acini, labial gland reservoirs, and relevant ducts. The secretions of labial glands are composed of multiple chemicals, which play important roles in nutrition, defense, and water management. We reviewed the progresses in the anatomy, ultrastructure, chemical compositions and functions of the secretions, and water management of termite salivary glands. A potential mechanism underlying water management in termites wasproposed in this review.

Detection of grain protein content in winter wheat based on near infrared spectroscopy.

ZHANG Song, FENG Mei-chen, YANG Wu-de, WANG Chao, SUN Hui, JIA Xue-qin, WU Gai-hong

2018, 37(4):  1276-1281. 

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Grain protein content (GPC) is a major index for evaluating the quality of winter wheat. To assess the influences of calibrated methods on the detection of GPC in winter wheat by using near infrared spectroscopy, original spectra reflectance was firstly pre-processed with S-G smoothing, baseline correction, and multiple scattering correction. The successive projectionalgorithm (SPA) method was used to extract the important spectral bands of grain GPC in winter wheat. Multivariate statistical methods of partial leastsquares regression (PLSR), principalcomponent regression (PCR), support vector machine (SVM), and multivariable linear regression (MLR) were used to establish a spectral prediction model of GPC, and the model accuracy was evaluated. The following wavelengths extracted by the SPA method were highly related to the GPC: 1801, 1010, 1109, 2219, 2239, 871, 1361, 2284, 1925, 1849 and 1456 nm. Wecompared the performance of models established with different multivariate methods. The results showed that the model of GPC constructed with SVM+SPA outperformed other calibrated models withR²=0.9760 and 0.9581, RMSE=0.2481 and 0.3587 for calibrating model and validated model, respectively. Our results indicated that the combination of SPA and SVM method might be a fast and non-destructive one to measure the grain protein of winter wheat.

The simulation of fish migratory trajectory in a vertical slot fishway based on multihydraulic indices.

JIANG Yong-qiang, YANG Zhong-yong, SHI Xiao-tao, WU Lei, NIE Long-feng, WEI Yong-cai

2018, 37(4):  1282-1290. 

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To explore the fish adaptability under various hydraulic factors during the process of fish tracing in a vertical slot fishway, it is necessary to simulate the fish migratory trajectory. In this study, a numerical model was used to calculate the flow field and the field of turbulentkinetic energy and its dissipation rate in a vertical slot fishway. An influence coefficient for each hydraulic factor was endowed by the degree of fish preference on them. With this method, themigratory trajectory of a fish was modeled and adjusted by results from previous laboratory experiment. The results showed that the field structure of turbulent kinetic energy influenced the fish trajectory most profoundly since most the tracing points appeared nearby a threshold value ofturbulent kinetic energy. The influence of centripetal velocity was limited but not negligible, because it is a key factor in the process of continuous fish traceability. The influence of the turbulence dissipation rate could be negligible.