Table of Content

10 February 2017, Volume 36 Issue 2

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Changes in microbial biomass carbon and nitrogen in forest floor litters and mineral soils along forest succession and altitude gradient in subtropical China.

LIU Yang1,2,3, HE Xian-jin1,2,3, HOU En-qing1,3*

2017, 36(2):  287-294. 

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Soil microbes play an important role in terrestrial carbon (C) and nitrogen (N) cycles via participating in litter decomposition and the turnover of soil organic matter. In this study, five subtropical forests along successional and altitudinal gradients were selected in Dinghushan Biosphere Reserve, China, including: (1) a pine forest (PF), a pine and broadleaved mixed forest (PBM) and a monsoon evergreen broadleaved forest (MEB) along a successional gradient; (2) a ravine evergreen broadleaved forest (REB), MEB (the same as along the successional gradient), and a mountainous evergreen broadleaved forest (MTEB) along an altitudinal gradient. In each forest, forest floor litters (separating into  undecomposed litter (L horizon) and a mixture of fragmented or humified litter (F/H horizon)) and underling mineral soils at 0-15 cm depth were selected in October, 2010. For each litter or mineral soil sample, microbial biomass carbon (MBC) and nitrogen (MBN) and the key associated edaphic properties (e.g. moisture content and the concentrations of total C, total N and total phosphorus (P)) were determined. Results showed that MBC, MBN, MBC/MBN ratio, total C, total N and total P all significantly decreased with the increasing extent of decomposition (L horizon →F/H horizon →mineral soil horizon). Both MBC and MBN in the F/H and mineral soil horizons significantly increased along the forest succession gradient (PF→PBM→MEB). MBC and MBN in the L horizon decreased in the order of PF>MEB>PBM. MBC and MBN of the L horizon but not of the F/H or mineral soil horizon significantly decreased with increasing altitude (RF→MEB→MTEB). Pearson correlation analysis showed that MBC was positively correlated with MBN in all horizons. Both MBC and MBN were positively correlated with moisture content in the L horizon, total P and dissolved organic N in the F/H horizon, and soil moisture content, total C, total N, and total P in the mineral soil horizon. Our results suggest that the relationships between soil microbial properties and edaphic properties depend on soil horizons, and are related to the different extents of organic matter decomposition, spatial location and nutrient availability of different soil horizons.

Contribution of nitrogen fixation by cyanobacteria to particulate organic nitrogen in a constructed wetland.

ZHANG Xiao-dong1,2, PAN Xu1,2, MA Mu-yuan1,2, LI Wei1,2, CUI Li-juan1,2*

2017, 36(2):  295-302. 

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Nfixing cyanobacteria can create extra nitrogen for aquatic ecosystems. Previous studies reported inconsistent patterns of the contribution of biological nitrogen fixation to the nitrogen pools in aquatic ecosystems. However, there were few studies concerning the effect of Nfixation by cyanobacteria on the nitrogen removal efficiency in constructed wetlands. This study was performed at Beijing Wildlife Rescue and Rehabilitation Centre, where a constructed lake for the habitation of waterfowls and a constructed wetland for purifying water from the lake are located. The composition of phytoplankton communities, the concentrations of particulate organic nitrogen (PON) and nitrogen fixation rates (R_n) in the constructed lake and the constructed wetland were compared throughout a growing season. We counted the densities of Anabaena and Microcystis cells, and explored their relationships with PON and R_n in water. The proportions of PON from various sources, including the ambient N₂, waterfowl faeces, wetland sediments and nitrates in water, were calculated by the natural abundance of ¹⁵N with the IsoSource software. The results revealed that the constructed lake was alternately dominated by Anabaena and Microcystis throughout the growing season, and the R_n was positively correlated with PON and the cell density of Anabaena (P<0.05). This implied that the fixed nitrogen by Nfixing Anabaena might be utilized by nonNfixing Microcystis, maintaining the fixed nitrogen with PON form. The contributions of ambient N₂ to the PON in the constructed lake and wetland were 0.5%-82.0% and 50.0%-86.0% respectively during the growing season. The proportions of PON from N₂ increased to more than 80% when the R_n reached the highest in September. The results demonstrated that the nitrogen fixed by Anabaena might be utilized by nonNfixing Microcystis, which formed water blooms in summer. Therefore, the decline of the removal efficiency of PON in the constructed wetland in summer might indirectly result from the nitrogen fixation, since the proliferated algae were difficult to sediment in surface flow wetlands.

Fractal dimension characteristics of soil particle size under different plant communities in ecological restoration area.

LIU Zhi-qiang1, GAO Ji-xi1,2*, TIAN Mei-rong2, LI Zhong-fei2, WANG Ya-ping1, TONG Ming-kun1

2017, 36(2):  303-308. 

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Soil particle size distribution and fractal dimension characteristics are important indicators of soil texture and fertility. This paper applied soil fractal theory and method to study fractal dimension of soil particles in the restored plant communities in a windprevention and sandfixation area in Duolun County, Inner Mongolia, as well as change patterns of soil particles in soil profile. Results showed that: (1) Soils under different plant communities had different particle size distribution characteristics, with fractal dimension ranging between 1.962-2.260. The fractal dimensions were in an ascending order in plant communities as unused grassland, Caragana microphylla forest, Betula platyphylla forest, poplar forest, Pinus sylvestris var. mongolica forest, mixed forest of Salix gordejevii and Salix matsudana, elm forest and Prunus sibirica forest. (2) The correlation between fractal dimension and the contents of different particle sizes showed significant difference. Fractal dimension had a significant positive correlation with the content of particle size <0.002 and 0.002-0.1 mm, a significant negative correlation with the content of particle size 0.25-0.5 mm, and no significant correlation with the content of particle size 0.1-0.25 and 0.5-2 mm. (3) Soil at depth of 0-20 cm in the study area had large fractal dimension, indicating that shallow soil texture had greatly improved; however, deep soil below 20 cm didn’t show obvious improvement. The study suggested that after a dozen years of ecological restoration in Duolun County’s windprevention and sandfixation area, the soil under different plant communities had different particle size distribution characteristics and larger fractal dimension compared to the unrestored grassland, indicating slight improvement in soil texture.

Surface energy balance of an arid desert wetland in Ebinur Lake basin, Xinjiang, China.

HE Xue-min1,2, QIN Lu3, LU Guang-hui1,2*, YANG Jian-jun2,4, GONG Yan-ming4,5, YANG Xiao-dong2,4

2017, 36(2):  309-317. 

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Based on the eddy covariance (EC) flux tower observation data drawn from the Ebinur Lake Wetland National Nature Reserve in Xinjiang from January to December of 2012, the diurnal seasonal characteristics of surface energy balance for desert wetland in the basin were compared. We analyzed variations in radiation, latent heat flux, sensible heat flux and soil heat flux and energy closure degree and residual energy accumulation characteristics for different seasons. The results showed that typical diurnal energy balance components for four seasons were high during the daytime, low at night, high at noon and low in the early morning, revealing a unimodal curve for the wetland of arid desert region in the Ebinur Lake Basin. Sensible heat flux was the main energyconsuming mechanism in the spring, while latent heat was higher than sensible heat in the summer, autumn and winter. As a whole, on a yearly scale, latent heat flux increased in spring and summer, declined in autumn and winter, and fluctuated considerably in summer. Moisture was a key factor affecting the ratio of sensible heat to latent heat flux. Diurnal variations in wetland surface residual energy in the desert area occurred over a long time period. Average diurnal residual energy levels for the four seasons were recorded as 17.77, 4.19, 171.99 and -12.81 W·m^-2, with the order of seasonal residual energy levels recorded as follows: winter < spring < summer < autumn. Compared to different underlying surfaces in arid area, the latent heat flux of wetland in desert area showed a higher proportion of energy expenditure (growing season, LE/R_n=0.803; entire year, LE/R_n=0.698), and the Bowen ratio was lower than the average level for arid area.

Combined analyses of MRT and DCCA on relationships between plant community distribution and ecological factors of Horqin Sandy Land.

CAO Wen-mei, LIU Xiao-yan*, WANG Guan-li, LUO Yan-yun, HE Tao, LIU Ting-xi

2017, 36(2):  318-327. 

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Based on the 12 habitat factors and the importance value of 48 plant species surveyed, the relationships between environmental factors and vegetation patterns in the semiarid desertification area were explored. A research area of Agula Ecohydrological Experimental Station which is located in the southern Horqin Sandy Land in China was selected to set up 19 plots along three lines of longitude. The types of plant community, the plant of main families and the plant of different lifeforms in this region were investigated in relation to environmental factors using MRT and DCCA. In order to eliminate redundant environmental variables, the environmental factors which significantly influ〖HJ*3〗ence plant community composition were chosen by forward selection and Monte Carlo tests. Results showed that: 1) The plant communities in this region could be divided into 4 types by MRT, which was in accordance with the spreaddimensional pattern on the DCCA ordination diagram. The four associations were Setaria viridis + Agriophyllum squarrosum-Artemisia halodendron association, A. sieversiana + Medicago ruthenica + Leymus chinensis association, Polygonum divaricatum-Hedysarum fruticosum + Caragana microphylla association, Juncus amplifolius+ Phragmites australis association; 2) Results of DCCA ordination indicated that Compositae and grasses were distributed in four communities in the study area, while legumes were more likely to be found in the better fixed dunes. With the improvement in the level of fixed dunes, the evolutionary process of the life forms about species was: the annual herb→ the annual and perennial herb→ the annual and perennial herb + shrubs, subshrub →the annual and perennial herb; 3) Four environmental variables were used in the species-environment correlation analysis. The first axis indicated that the dune community and the meadow community were discontinuously distributed, and the electrical conductivity and clay content of soil were important factors, while the second axis reflected that the soil organic matter and the capillary rise of water content play a decisive role in the community distribution of sand dunes under different fixed level status.

Niche of dominant plant populations in the water level fluctuation zone of canyon landform area of the Three Gorges Reservoir.

JIAN Zun-ji, MA Fan-qiang, GUO Quan-shui*, QIN Ai-li, XIAO Wen-fa

2017, 36(2):  328-334. 

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Based on the data of adjacent lattice method, vegetation characteristics such as species importance value, niche breadth, niche proportional similarity and niche overlap value were measured in the waterlevel fluctuation zone (WLFZ) and nonfluctuation zone (CK) of the canyon landform area of the Three Gorges Reservoir. The niche characteristics of dominant plants were studied and their forming mechanisms were discussed through the comparison between the WLFZ and the CK to provide a theoretical basis for optimal plant selection and scientific plant configuration of vegetation restoration and reconstruction in the WLFZ. The results showed that: (1) 10 dominant plant species appeared after experiencing many times of water level fluctuation in the WLFZ. Among them, Eclipta prostrate had the biggest niche breadth, followed by Digitaria chrysoblephara, Bidens pilosa, Setaria viridis, Echinochloa crusgalli, S. glauca, Xanthium sibiricum, Cynodon dactylon, Cyperus rotundus, and Polygonum hydropiper. The larger niche proportional similarities in the WLFZ were D. chrysoblephara vs. E. crusgalli, E. prostrata vs. X. sibiricum, B. pilosa vs. P. hydropiper, and the larger niche overlap values were B. pilosa vs. P. hydropiper, E. prostrata vs. X. sibiricum, C. dactylon vs. C. rotundus, D. chrysoblephara vs. E. crusgalli. These results suggested plants with larger niche breadth had larger niche proportional similarity and niche overlap value. (2) The proportion of niche proportional similarity and niche overlap value of more than 0.5 were 51% and 67% in the WLFZ, but 31% and 44% in the CK, respectively. The niche breadth, niche proportional similarity and niche overlap value of most dominant plants in the WLFZ were greater than those of the same plants in the CK, which indicated that the niche differentiation between different dominant plants was lower, the interspecific competition was more intense, and the stability of plant community was worse. (3) The biological characteristics of plants and their adaptabilities to  the environmental changes, and the habitat stability were the main reasons for the differences of niche characteristics between the WLFZ and the CK.

Intra and interspecific interactions of Larix principisrupprechtii plantation in Mt. Taiyue, Shanxi, China.

ZHOU Wen-song1, HAN Hai-rong1*, KANG Feng-feng1, CHENG Xiao-qin1, WU Ran1, YANG Jie2, TIAN Ping1, HUANG Liang-shuai1

2017, 36(2):  335-342. 

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In this study, the intraspecific and interspecific relationships of a 15-year-old Larix principisrupprechtii plantation were analyzed in Mt. Taiyue, Shanxi province, by using niche theory and Hegyi individual competitive index model. The results showed that: (1) niche breadth for L. principisrupprechtii and Betula platyphylla were larger than that of other tree species. There was a high proportion of niche similarity but low degree of overlap between L. principisrupprechtii and B. platyphylla, indicating the abundant environmental resources and the existence of low resource utilization competition. (2) By the calculation for Hegyi competition index, we found that the effect range of competition of L. principisrupprechtii in this area was 6 meters. The competition intensity to L. principisrupprechtii ranked as B. platyphylla > L. principisrupprechtii (intraspecific) > Picea koraiensis > Salix caprea. The competition intensity of L. principisrupprechtii decreased with increasing the diameter of breast height (DBH). (3) The nonlinear fitting result of the power function was optimum to predict the competition intensity of L. principisrupprechtii with different DBH. The model prediction showed that the community reached a stable stage and the competition intensity changed insignificantly at DBH of 60-70 cm for L. principisrupprechtii. (4) The Godron stability index was 39/61, which was far away from the stable point 20/80. This result manifested the high competition intensity in future; (5) A new partition method defining the effect range of competition was proposed, which could divide inside radius and outside radius accurately by calculating average competitive intensity of each tree in the unit area of competitive sample circle. The method would provide a more visual and precise result.

 

Effects of exclosure on species diversity and biomass allocation of understory vegetation of Savanna ecosystem in Yuanjiang dryhot valley, Yunnan, Southwest China.

JIN Yan-qiang1,3, LI Jing1,3, LIU Yun-tong1, ZHANG Yi-ping1*, FEI Xue-hai1,3, LI Pei-guang2, ZHANG Shu-bin2

2017, 36(2):  343-348. 

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Effects of exclosures on species diversity and biomass allocation were studied in a savanna ecosystem in Yuanjiang dryhot valley, Yunnan, Southwest China over two years. The response of understory vegetation to exclosure was compared with the free grazing area. We found that the average height, percentage cover and biomass of understory and its components increased significantly with exclosure compared to free grazing area. Herbaceous species diversity was significantly declined with exclosure. Compared to free grazing, the belowground/aboveground biomass ratio (B∶A ratio) of shrubs under exclosure varied insignificantly, while the branch/leaf biomass ratio for shrubs increased. However, the B∶A ratio of herbs was significantly decreased under exclosure treatments. This could be attributed to adaptation strategies in which plant changes in resource allocation pattern in response to adverse environmental conditions. In general, the exclosure was an effective approach of vegetation restoration and subsequent biomass accumulation. However, appropriate competition and intermediate disturbance (e.g., grazing) can buffer species richness, which is helpful for maintaining the ecosystem stability and functions per se.

Floristic composition and diversity of typical plant community in Zhoushan Archipelago, East China.

WANG Guo-ming*, YE Bo

2017, 36(2):  349-358. 

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The species composition and diversity of communities dominated by endemic species Cinnamomum japonicum var. chenii, Neolitsea sericea and Ilex integra in Zhoushan Archipelago were studied based on the investigation of typical plots. A total of 125 species of vascular plants, belonging to 62 families and 100 genera in seven plant communities were recorded. Among them, 16 endemic species to oceanfront belonging to 12 families and 14 genera were observed. The geographical elements were various, while tropical elements outweithed the temperate and subtropical elements. The dominant species were obvious in each layer. Species were dominated by Machilus thunbergii, C. japonicum var. chenii, I. integra and N. sericea in arborous layer, and by M. thunbergii and C. japonicum var. chenii in regeneration layer. The dominant species in shrub layer, herb layer and liana layer depended on community type and the environment. There was a large fluctuation of species richness (R), Shannon index (H) and Pielou index (J) between different layers of plant communities, which was related to the successional stage of community, the size of island, the distance from island to land, and human disturbance. The R and H indexes showed a consistent pattern of change trend. The R and H indexes in each layer of typical C. japonicum var. chenii community in Zhoushan were lower than those of other communities.

Species compositions and flora analysis of spermatophyta in Dianchi lakeside.

ZHANG Xue1, SHEN Shi-kang1*, WU Fu-qin1,3, YANG Guan-song1, DONG Wen-jing1, LIU Fang-li1, HE Shu-zhuang2, WANG Yue-hua1

2017, 36(2):  359-366. 

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Studies on species compositions, diversity and flora characteristics in lakesides can provide a scientific basis for lakeside plant community assembly, ecological restoration and reco-very. In this study, species composition, diversity and flora traits in Dianchi lakeside were studied through field investigation, plant identification, sample collection and literature review. Results indicated that 553 plant species belonging to 124 families and 371 genera were found in the investigated area. Of these plants, 370 species were indigenous and 183 species were alien. Furthermore, 11 dominant families such as Gramineae, Compositae, Rosaceae, Labiatae, and Papilionoideae, which included more than 10 plant species in Dianchi lakeside, were observed. The species composition of the flora was concentrated in the families with 1-10 species and in genera with 1-5 species. These findings indicated the abundant species diversity in Dianchi lakeside. Flora analysis showed that floristic types in the surveyed region exhibited complexity and an evolutionary trend of tropicaltotemperate type. The floristic types of spermatophyta mainly belonged to the families of tropical distribution types (47 families) and to the genera of tropical (151 genera) and temperate (165 genera) distribution types. A total of 27 invasive plants were characterized and they belonged to 6 families and 12 genera mostly from the tropics and subtropics. Based on above analysis, ecological restoration and reconstruction strategies for Dianchi lakeside were also proposed.

The properties of Pinus bungeana captured particulates from atmosphere with different diameters at breast height.

ZUO Na1, WANG Hui-xia1, YANG Zhen1, ZHONG Meng-ting1, SHI Hui1*, WANG Yan-hui2*

2017, 36(2):  367-373. 

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Urban vegetation is an effective way to remove the particulate matter in atmosphere. More attention of the previous studies focuses on microscale such as single leaf scale; however, the studies on single tree scale are scarce, which is key to select greening trees and evaluate their environmental benefits. Pinus bungeana trees with different diameters at breast height (DBH) at three differently polluted sites in Beijing were selected as research materials. The captured amounts of particulates were measured at the single leaf and single tree scale through collecting particulates on leaf surface, investigating the leaf surface microstructure by Scanning Electron Microscopy (SEM), and measuring the leaf area of each sample. For P. bungeana, the maximum amounts of PM_2.5, PM₁₀ and TSP capture per unit leaf area were 0.15, 0.29 and 0.97 g·m^-2. The DBH had no significant effects on the amount of captured particulates per unit leaf area (P>0.05). Among the sample trees with different DBH, the stomatal size and density on leaves were consistent, the grooveshaped projection distribution was evenness, and there were no marked differences for distribution groovelike projections. DBH had a marked impact on particulates retention on the tree scale (P<0.05), and the DHB with high particulate matter capture centered on 12.7-25.5 cm. The maximum amounts of PM_2.5, PM₁₀ and TSP capture were 5.77, 12.88 and 43.08 g per single tree, respectively. The DBH of P. bungeana had little effect on the microstructure of leaves, but a significant effect on crown radius and leaf area index. Thus, the DHB showed no significant effects on particulate matter retention at single leaf scale, but a significant impact on particulate matter retention on the single tree scale.

 

Biological characteristics, ecological adaptability, ornamentality, and invasion risk of Pennisetum species.

CHEN Chao1,2, YUAN Xiao-huan1,2, TENG Wen-jun1,2, YANG Xue-jun1,2, WU Ju-ying1,2*

2017, 36(2):  374-381. 

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With a field survey, we compared reproductive capacity, ecological adaptability and ornamental value of 12 Pennisetum species. Combined with available literature, we assessed the potential invasion risk for Pennisetum species using the Australia or New Zealand (WRA) weed risk assessment system and risk assessment system in central Europe (WG-WRA). The results showed that two risk assessment protocols had similar results. More than 50% of all species (including cultivars) had at least a moderate invasion risk (scores of more than 20 points), whereas P. alopecuroides had a high risk (32 and 29 points by the two protocols, respectively). Correlation analysis showed that Pennisetum species had a positive relationship between environmental adaptability and invasion risk, and presented a high risk of invasion with wide adaptability and strong resistance (cold resistance, drought resistance, disease and insect resistance). In addition, sexual reproductive capacity had a positive correlation with invasion risk. Higher seed yield meant a higher invasion risk for species, such as P. alopecuroides, while Pennisetum species with low seed production presented a less invasion risk, such as P. villosum and P. orientale. However, invasion risk of Pennisetum species was negatively correlated with the ornamental value.

Effect of exogenous hormones on germination and antioxidant enzyme activity of seeds of Cyclobalanopsis chungii.

LAI Hua-yan1, WANG You-feng1,2, WU Kai1, MA Xiang-qing1, WU Peng-fei1*

2017, 36(2):  382-388. 

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To solve the problems of quick seed germinating and artificial seedling difficulty of Cyclobalanopsis chungii, a precious timber species, the healthy, mature and nongerminating seeds were selected as experimental material. The antioxidant enzyme system activity in radicle and co-tyledon of the seeds was determined in 3, 5, 7, 9 and 13 days after treating with five different concentrations (0, 10, 20, 30, 40 mmol·L^-1) of two kinds of hormone (gibberellin acid and abscisic acid). The results showed that there were significant differences in germination rate and antioxidant enzyme activity among different hormone treatments. With the increase of the gibberellin acid concentration, the germination rate of seeds increased markedly, but there was no significant difference among the treatments. The abscisic acid with low concentration (10-20 mmol·L^-1) promoted the germination rate significantly, but not with high concentration (30-40 mmol·L^-1). With extension of the processing time of exogenous hormones, POD and SOD activities in the radicle and cotyledon showed a tendency of increase firstly then exhibited irregular changes. Under different concentrations of gibberellin acid, CAT activity in the radicle increased gradually with prolonging time, whereas CAT activity in the cotyledon demonstrated an inverted “N” pattern. Applying with 40 mmol·L^-1 abscisic acid could solve the problem of quick germinating by inhibiting PPO activity in the radicle and cotyledon.

The effects of Vitex negundo on seedlings of Cyclobalanopsis glauca and Delavaya toxocarpa with different moisture conditions. 

HUANG Fu-zhao, WEI Chun-qiang, LI Xian-kun, LU Shu-hua, LV Shi-hong*

2017, 36(2):  389-395. 

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In order to choose the appropriate species to improve and optimize the pioneer communities in Southwest China karst area, a pot experiment was conducted to test the effects of Vitex negundo on seedlings of Cyclobalanopsis glauca and Delavaya toxocarpa under the Vitex negundo canopy with different moisture conditions. The results indicated that relative growth rate of ground diameter and plant height of C. glauca and D. toxocarpa increased with soil moisture conditions. The relative growth rate of seedling under canopy of V. negundo was always lower than the open sites in the same water condition, and the difference increased with the soil moisture. SPAD of C. glauca in open site had no obvious changes in all moisture conditions, but increased with soil moisture under canopy of V. negundo. SPAD of D. toxocarpa in the open site increased with soil moisture, but showed no differences under canopy of V. negundo. SPAD of C. glauca and D. toxocarpa in the open site was always higher than under canopy of V. negundo in the same moisture condition. Relative neighbor effect of C. glauca and D. toxocarpa was negative in all moisture conditions and increased with soil moisture. The pioneer shrub V. negundo inhibited the growth of C. glauca and D. toxocarpa seedlings under canopy of V. negundo, and the inhibiting effect increased with soil moisture.

Wooddegrading enzymes and genetic diversity of Piptoporus betulinus in Northeast China.

PENG Mu, WANG Qiu-yu, YAN Shao-peng

2017, 36(2):  396-404. 

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Piptoporus betulinus is a parasitic fungus on Betula spp., and catalyzes wood fiber into carbohydrate using its secretory enzymes. However, wooddegrading enzymes by this brownrot fungus and its genetic diversity have been poorly studied. Here we collected fruiting bodies of P. betulinus from four sites in Northeastern China, detected their cellulase and hemicellulase activities, and then analyzed genetic diversity using target region amplified polymorphism (TRAP) marker. The results showed that enzymatic activities of strains collected from Maoershan and Dunhua were relatively higher than that from the other sites, and variance analysis result indicated that there existed significant differences between different sites and different treated days. All samples were divided into two groups by multidimensional scaling and heat map analysis, which basically coincided well with the pattern of geographic distance similarity, and found that a significant difference in enzyme production existed among different strains. In addition, based on analysis of molecular variance, genetic differentiation mainly occurred within population. These findings provide a technical support for rapidly developing enzyme system and engineering fungi, and lay a foundation for wood protection and the utilization of economic fungi in future.

Effects of different organicinorganic fertilizer combination ratios on rice yield and nutrient loss with surface runoff.

LIU Hong-jiang1, CHEN Yu-wen2, SUN Guo-feng1, CHEN Liu-gen1, ZHENG Jian-chu1*

2017, 36(2):  405-412. 

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A field experiment was conducted in 2015 to investigate the effects of different organicinorganic fertilizer combination ratios on nutrient loss with surface runoff and rice yield in a wheatrice double cropping system. The rice cultivar of Wuyunjing 29 was fieldgrown. Five treatments including single chemical fertilizer application (M1), and 25% organic fertilizer (M2), 50% organic fertilizer (M3), 75% organic fertilizer (M4), 100% organic fertilizer (M5) instead of chemical fertilizer with equivalent nitrogen substitution were designed. The results showed that the rice yield was the highest in M3 treatment, due to the obvious increase of spikelet number per panicle and the relative increase of effective panicles. Total surface runoff of farmland was 3.6× 10³ m³·hm^-2 in rice season. Total N loss from surface runoff was in gradual decline from M1 to M5 treatment; compared with M1 and M2 treatment, M3 treatment significantly decreased total N loss. However, total P and K losses were in gradual increase from M1 to M5 treatment; total P or K loss of M3 treatment was significantly lower than that of M4 and M5. Total N and K loss rates of surface runoff were in gradual decline, but total P loss rate was in gradual increase from M1 to M5 treatment, with average loss rates of different treatments being 4.52%, 1.13% and 5.68% for N, P and K, respectively. Compared with M1 treatment, M3 treatment ensured high rice yield, decreased surface runoff total N loss and loss rate, and slightly increased total P loss and loss rate. Therefore, M3 treatment was an appropriate ratio of organic fertilizer to replace chemical fertilizer.

Effect of spraying water to decrease leaf temperature at different time on the yield and quality of super rice Yuxiangyouzhan during grain filling stage.

WANG Hua1, DU Yao-dong1*, DU Xiao-yang2, TANG Xiang-ru3, SHEN Ping1, HUANG Zhen-zhu1

2017, 36(2):  413-419. 

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The paper aims to explore a technical approach, which can be used in agricultural production to reduce the damage of high temperature during rice grain filling stage. Taking Yuxiangyouzhan, the middle late maturity type super conventional Indica Rice, as the experimental material, a field experiment was conducted in the experimental farm of South China Agricultural University in 2014 and 2015. During the grain filling stage, the effects of three spraying schemes (S1: 11:00-12:00; S2: 13:00-14:00; S3: 15:00-16:00) on the yield and quality of Yuxiangyouzhan were compared. The results showed that, compared with the control, the three treatments all improved the paddy field microclimate (temperature and humidity), and S3 was the best scheme to decrease leaf temperature and increase humidity. Grain number per spike and 1000grain weight were significantly increased (P<0.05) due to decrease in leaf temperature by spraying water. S1 treatment resulted in the highest yield and number of grains per spike, and S2 treatment resulted in the highest  seed setting rate. The grain character was improved, the chalkiness rate was significantly lower than CK (P<0.05), and the chalkiness degree was slightly lower than that of CK. The rice filling rate was significantly enhanced (P<0.05), the organic matter accumulation was improved, and the 1000grain weight was increased. What’s more, decreased leaf temperature due to spraying water at different time significantly increased the peroxidase activity (P<0.05), thus enhancing resistance, rice yield and quality of Yuxiangyouzhan.

The competitive relationship of two oat varieties under different water and fertilization conditions.

DU Jing-qi1, YANG Wei-min1*, LI Gang2, SONG Li1, LIU Xu-li1, BAI Lian-mei1, LIU Qin-qin1

2017, 36(2):  420-427. 

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A de Wit replace series experiment was used to explore the competitive relationship of two oat varieties of Dingyan 1 and Jinyan 17 under different levels of water and fertilizer application. The results showed that Jinyan 17 had greater competitiveness than Dingyan 1 under a series of water and fertilization conditions. Under low water +  fertilization or sufficient water + fertilization, the aboveground biomass of Jinyan 17 was significantly higher than that of Dingyan 1. With the increasing levels of water and fertilization, the ratio of stem biomass to aboveground biomass of Dingyan 1 and Jinyan 17 increased, and the ratio of leaf biomass to aboveground biomass of both oat varieties decreased. In all treatments, grain yield in monoculture and harvest index of Jinyan 17 were greater than those of Dingyan 1. By simultaneous increase of aboveground biomass and harvest index, Jinyan 17 obtained higher grain yield. The synchronous improvement of competitive ability and harvest index is expected to become the focus of crop breeding in arid areas.

The influence of temperature and light intensity on Sargassum vachellianum detritus decomposition.

ZOU Min, ZHANG Shou-yu*, ZHOU Xi-jie

2017, 36(2):  428-435. 

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In this paper, light intensity and temperature gradients were simulated in a climate incubator, to measure the decomposition rate of Sargassum vachellianum detritus and the contribution of seaweed detritus to inorganic nutrients in seaweed field. The purpose of this study was to provide scientific support for exploring the ecological service effectiveness of large seaweed detritus. The results showed that temperature had no significant effect on mass remaining and the decomposition rate of seaweed detritus (P>0.05); however, the effect of light intensity was significant (P<0.05). The mass loss rate of seaweed detritus was over 60% under different temperature and light intensity conditions in twomonth experimental period, and seaweed detritus decomposed faster under conditions of 25.15 ℃ and 3200 lx. Temperature had no significant effect on the release of nitrogen and phosphorus nutrients during seaweed detritus decomposition (P>0.05). Light had no significant effect on the concentrations of ammonium, nitrate and nitrite under the same temperature (25.15 ℃) (P>0.05), but had a significant effect on the concentration of orthophosphate (P<0.05). Light intensity had a significant effect on the concentrations of ammonium nitrogen and orthophosphate (P<0.05), and had no significant effect on nitrate and nitrite nitrogen concentrations (P>0.05). The cumulative contribution of dissolved inorganic nitrogen to waters was 4.597 to 17.321 mg·L^-1 and the dissolved inorganic phosphorus was 27.989 to 76.304 mg·L^-1 according to the amount of S. vachellianum detritus in study field. In conclusion, the amount of ammonium nitrogen and orthophosphate released from S. vachellianum detritus decomposition was higher than that of nitrate nitrogen and nitrite nitrogen under different temperature conditions. Higher temperature was more favorable for ammonium nitrogen release, while orthophosphate release was more favorable at low temperature. The release of nitrogen and phosphorus nutrients declined with the increase of light intensity, and the release of orthophosphate was inhibited with the increase of light intensity.

Analysis of feeding habits in planarian Dugesia japonica.

DONG Zi-mei, SIMA Ying-xu, LI Xiao-yan, CHEN Guang-wen*

2017, 36(2):  436-441. 

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Feeding habits of the planarian Dugesia japonica and the influence of light intensity to their eating behavior were studied by disk method and flume method. The results showed that the sitotaxis of the worms to five kinds of food was in order of fish spleen > bovine liver > earthworm > chicken liver > cooked egg yolk. Light intensity less than 400 lx had no influence on the eating behavior of the worms. A significant effect occurred when light intensity reached 800 lx, under which 96.7% of the worms stopped eating. Under 1000 lx, all of the worms completely stopped eating. The data provided important clues for the further research of evolutionary biology and behavioral ecology of freshwater planarians.

Analysis of Sthenoteuthis oualaniens fishing grounds in Nansha sea area based on geostatistics.

FAN Jiang-tao, ZHANG Jun, FENG Xue, CHEN Zuo-zhi*

2017, 36(2):  442-446. 

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Based on data of underway survey with Nansha sea area collected by acoustic method in four seasons of 2013, we analyzed fishing grounds of Sthenoteuthis oualaniens in Nansha sea area. Acoustic detection of biomass was used as indicator of fishing grounds after normal transformation. The results showed that there was very strong spatial correlation of S. oualaniens fishing grounds in four seasons, and the nugget effect values of variation function were all less than 0.25. Using the variable function, different theoretical models were fitted respectively by different seasons. Exponential model was the best fitting model in summer and autumn, while spherical model in spring and Gaussian model in winter. The models fitted better for summer and winter than for the other two seasons, which also had stronger spatial correlation. The results of Kriging spatial interpolation analysis of different seasons showed that the higher biomass of fishing grounds was most centralized in the region near the island, which had obvious characteristics of patchy distribution. The fishing grounds of S. oualaniens had a tendency to move south gradually over time. According to the result of cross validation of theoretical value and observed value, the theoretical models and Kriging interpolation of different seasons are appropriate.

Effect of ambient temperature on body temperature and physiological thermoregulation ability of Takydromus amurensis.

XU Xiao-xiao, SUN Qing-lin, LIU Peng*, ZHAO Wen-ge

2017, 36(2):  447-451. 

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We used Heilongjiang grass lizards (Takydromus amurensis), which were collected from Changbai Mountain, as model animals. These lizards were housed to breed in the laboratory from April to June, 2014. In early October, adult and juvenile lizards were placed in the constant temperature incubator for measurement of body temperature. The effects of different temperature conditions (constant temperature and rapid warming) on body temperature and thermoregulation ability of T. amurensis were studied. The measuring time had significant impacts on the body temperature of T. amurensis from 11 to 39 ℃, and the lowest body temperature appeared at 07:00 a.m. The body temperature was significantly higher in juveniles than in adults from 11 to 19 ℃. There was no difference in the body temperature between juveniles and adults at 21 ℃; the body temperature was significantly lower in juveniles than in adults from 23 to 39 ℃. The body temperature of T. amurensis was linearly positively correlated with ambient temperature. The linear regression equations were as follows: y=0.72366x+7.1778 for the adults, and y=0.6508x+8.8039 for the juveniles, whose intersection point temperatures with isothermal line (y=x) were 25.97  and 25.21 ℃, respectively. The body temperature of T. amurensis increased in a short time with the ambient temperature increased rapidly from 10  to 30 ℃, but the heating rate gradually decreased. We concluded that the ambient temperature had a significant impact on body temperature of T. amurensis, and the thermoregulation ability of different aged lizards was different. Juvenile lizards had stronger thermoregulation ability, thus they could keep their body temperature stable more easily than adults.

Effect of stover mulching frequency on the community structure of soil macrofauna in notill systems in the black soil region of Northeast China.

JIANG Yun-feng1, MA Nan1, ZHANG Shuang1, CHEN Zhi-wen1*, XIE Hong-tu2

2017, 36(2):  452-459. 

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Soil macrofauna play an important role in nutrient cycling and energy flow in farmland ecosystems. To study the response of soil macrofauna communities to notillage stover mulch systems, a survey of soil macrofauna community was carried out at the Lishu site of the Chinese Academy of Sciences in April, July and October of 2015. On each sampling visit, soil macrofauna were collected by hand from five types of plot, namely notill for three years without stover mulch plot (NT0), notill for three years with one year of stover mulch (NT1/3), notill for three years with two years of stover mulch plot (NT2/3), notill for three years with three years of stover mulch plot (NT3/3), and a conventional tillage as the control. Within each plot, three subplots (25 cm×25 cm) were selected along the diagonal linetransect. Soil macrofauna were collected from three soil depths (0-5, 5-10, 10-15 cm) in each subplot. A total of 26 soil macrofauna groups belonging to 13 orders, 5 classes and 2 phyla were found during this study. The dominant macrofauna group was Enchytraeidae in the all treatment plots. The individual density, taxon richness, and diversity index of macrofauna were higher in the notillage stover mulch plots than those of conventional tillage plots. The highest individual density of soil macrofauna community was recorded in October for all study plots, whereas the highest of taxon and species diversity were recorded in July. The no tillage stover mulch system can increase the individual density for all soil macrofauna groups. Different soil macrofauna groups differed in response to the increased stover mulching frequency. Compared with conventional tillage, no tillage stover mulch could increase the individual density of saprophagous group.

Composition and distribution pattern of Littorinid snails in young rehabilitated mangroves.

CHEN Shun-yang1, CHEN Bin1, LIAO Jian-ji1, CHEN Gan-lin1, HUANG Yan2, CHEN Guang-cheng1*

2017, 36(2):  460-467. 

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Littorinid snails are common benthos in mangrove forests; their morphology, behavior and distribution characteristics are closely related to the vegetations. In this study, the composition and distribution patterns of Littorinid snails were investigated at rehabilitated mangroves under early stage (3 years old)； their variations with the tidal elevation and mangrove species were also studied. The results showed that Littorinid snails numerously occurred at the young mangrove forests, with a high density up to 32.67 ind·m^-2. Littoraria melanostoma was the dominant species in Kandelia obovata and Aegiceras corniculatum forests. The density and biomass of L. melanostoma was higher at the K. obovata forest with a tidal elevation of 1.8 m than those planted at 2.2 and 2.6 m. L. scabra was not collected at the forest with 2.2  and 2.6 m tidal elevations. The L. melanostoma snails at an A. corniculatum forest planted under a tidal elevation of 1.6 m had higher density and biomass than the K. obovata forest with the same tidal elevation, while their body size was smaller at the A. corniculatum forest. Neither the abundance nor the body size of L. scabra snail was different between the two mangrove species. These differences in the composition and distribution pattern of Littorinid snails may be owing to the different physicalenvironmental conditions resulted from the different morphology of mangrove vegetation, and the biological characteristics of the snails, such as the movement habit and the propagation pattern.

Vegetation characteristics and species diversity along the Yujing desert highway.

SONG Shao-peng1, DONG Zhi-bao1,2*, CHEN Hao1, CUI Xu-jia1, LI Chao1, XIAO Feng-jun1, LI Xiao-lan1, SHAO Tian-jie1

2017, 36(2):  468-475. 

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Based on the research of field vegetation, the calculation of species diversity and the determination of soil moisture content, the vegetation feature along Yujing desert highway, species diversity index and its relationship with soil moisture content were analyzed. The results indicated that: (1) there were mainly 16 families, 39 genera and 49 species living in the study area. Artemisia ordosica was the dominant species which was most widely distributed, and its community was the most common one among plant communities. Shrubs and semishrubs were dominant species among the field vegetation whose important value was larger than 0.1 in each region. (2) The average of Shannon index in twelve small study areas varied from 1.42 to 2.05. Among these small study areas, the highest average was in study area E, while the lowest was in study area G. Because of favorable soil nutrient content, wellgrown plants and high vegetation cover in loesscovered area (sample line 5), whose Shannon index and Sorenson similarity index were higher than other three study areas with three kinds of ecological conditions. (3) Pielou index was significantly correlated with the soil moisture content of soil profile in 0-10 cm, so did the richness of species to that of soil profile in 20-30 cm.

Lead content and its health risks of soils and vegetables along urban roadsides in Chongqing.

LIU Bin1*, WANG Lang1, HUANG Zeng-lin1, LIU Wei2, WANG Jia1

2017, 36(2):  476-482. 

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Twenty plots of typical urban roadside vegetable fields 1-10 m apart from the roads in Chongqing were randomly selected as the objects of study. A total of 102 soil samples and 132 vegetable samples were collected. Lead (Pb) contents in soil and vegetable samples were determined by atomic absorption spectrophotometry. The content Pb in soils ranged 13.30-152.80 mg·kg-1, with an average value of 33.85 mg·kg-1. Pb contents in all soil samples were lower than the secondary standard of Chinese Soil Environmental Quality Standard (GB 15618-1995). But the Pb contents of 86.29% of the samples were higher than that of the soil background value in Chongqing. The average pollution index of Pb in the roadside soils was 1.33, indicating that transportation caused some contamination to the roadside vegetable soils. The Pb contents of the edible parts of the vegetables were 0.059-2.363 mg·kg^-1, with an average value of 0.763 mg·kg^-1. Among them, the average Pb contents of the edible parts of beans, leafy vegetables and root vegetables were 1.037, 0.811 and 0.247 mg·kg^-1, respectively. Therefore, the Pb contents of the different kinds of vegetables generally showed a trend of leguminous vegetables > leaf vegetables > root vegetables. In addition, the longer the growth cycle of vegetables, the higher the Pb content of their edible parts. Compared with the Chinese Food Pollution Limits Standard (GB 2762-2012), the Pb contents of 96.2% of samples of the edible parts of vegetables planted on the roadside of Chongqing urban areas exceeded the national standard limit. The hazard quotients (HQs) of Pb in vegetables to children, adolescent and adults were 4.86, 6.29 and 4.83 respectively. It was concluded that the vegetables planted on the roadsides of Chongqing urban areas were seriously polluted and attention should be paid on their health risks.

Risk changes of storm flood disasters in southeast China under climatic warming.

WEN Quan-pei1,2, ZHOU Yue-hua1, HUO Zhi-guo2,3*, LI Lan1, WU Li4, ZHANG Lei5

2017, 36(2):  483-490. 

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Based on the meteorological disaster loss data of storm floods in nine provinces of southeast China from 1972 to 2013, the proportions of the disasteraffected areas and disasterdestroyed areas were integrated to establish relative storm flood disaster index, and storm flood risk assessment model was thereby constructed to analyze the risk change of storm flood disasters in southeast China before (1972-1992) and after (1993-2013) climatic warming, according to grey correlation method and normal information diffusion method. Storm flood disasters in the nine provinces showed a mutational change in the 1980s, which was earlier than climatic warming (1993). The maximum relative disaster index was detected in the 1990s in the nine provinces. The probabilities of severe and moderate disasters substantially increased, while the probabilities of light and small disasters showed an opposite tendency. In general, moderate disasters occurred with a high frequency (less than two years). The frequency of severe and oversevere disasters after climate warming was 2-8 times high as compared to that before climate warming in all provinces, except Jiangsu Province. Considering the effect of tropical cyclones on storm flood disasters, the relative disaster risk index in southeast China was generally increased after warming, except that there was a decrease of 7% in Jiangsu Province. The most significant increment was found in Guangxi Province (by 21%), and the high risk center moved from Guangdong Province to Guangxi Province after climate warming.

Simulation of nonpoint source pollution in a typical urban housing estate of Shenyang based on SWMM model.

WU Yi-lin1,2, ZHAO Ming-hua1, LIU Miao2*, LI Chun-lin2, HU Yuan-man2, SUI Jin-ling2, SUN Feng-yun3

2017, 36(2):  491-498. 

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The proportion of urban nonpoint source (NPS) pollution in watershed NPS pollution is increasing with urbanization. Urban NPS pollution is becoming research hotspot. In this study, rainfallrunoff model was validated in a typical housing estate of Shenyang based on the measured data with the distributed hydrological model method (SWMM) to analyze the trends of rainfall runoff and urban NPS pollution under different recurrence intervals and rainfall types. The results indicated that the accuracy of runoff simulation was greater than 0.7. The total simulation accuracies of TSS, TN, TP, and COD loads were acceptable; however, the simulation accuracy of heavy metal was lower than that of nutrient pollution. Increased rainfall had a great influence on pollutant discharge. The runoff increased by 274.13% with the increase of recurrence interval of rainfall intensity from 0.25 years to 5 years. At the same time, the total emission of TSS, TN, TP and COD increased by 83.18%, 119.37%, 103.15% and 78.07%, respectively. For different types of rainfall, the earlier the rainfall peak appeared, the greater the peak concentration of pollutants happened. Our results provide a scientific support for urban NPS pollution estimation and sponge city construction.

Changes of architectural landscape in renewal of old industrial zone in Tiexi District, Shenyang.

XU Yan-yan1,2,3, LIU miao1, HU Yuan-man1*, LI Chun-lin1, XIONG Zai-ping1

2017, 36(2):  499-507. 

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China is in the process of rapid urbanization and urban renewal. The research of urban expansion has mostly focused on the border expansion, while that of the pattern changes caused by the internal transformation of the city is insufficient. With the aid of remote sensing and GIS technology, this paper analyzed the characterization of landscape changes of the architectural landscape in old industrial zone in Tiexi District, Shenyang, from the indicators of architectural landscape, statistical analysis, architectural landscape renewal pattern as well as the spatial autocorrelation of building average height. The results showed that from 1997 to 2011, the major buildings were multistory ones. The number of single storey buildings and low layer ones decreased, but the number of multistory, highrise and super highrise ones increased. The architectural landscape expanded in the vertical direction, and the building capability was improved. The building energy consumption was reduced. The renewal of architectural landscape was related to regional transportation, the distance from the center of the city and the type of land use. The spatial distribution of the average height of buildings was related to the land use type and the distance from the city center. In this process, understanding the change pattern of the old industrial zone can provide a useful reference for the urban planning and architecture renewal of the old industrial area.

Dynamic changes of hemeroby degree based on the land cover classification: A case study in Beijing. 

FENG Zhi-xian1,2, ZHANG Ji-xian3, HOU Wei4, ZHAI Liang4*

2017, 36(2):  508-516. 

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Based on hemeroby theory, this paper used the high precision land cover data to establish a classification system of human disturbance to environment. All land cover types were classified into seven disturbance levels (no human disturbance, weak human disturbance, moderate human disturbance, moderatestrong human disturbance, strong human disturbance, severe human disturbance, and complete human disturbance). Then, Beijing was taken as a test site in this study and its land cover maps in 2007, 2015 were manually extracted from high resolution remote sensing images (spatial resolution better than 2.5 m). An areaweighted hemeroby index (HI) had been adopted for analyzing the dynamic relationship between ecological environment and human activities by using different types of reporting units, i.e. grid cell, administrative-unit, and main functional area. Our results showed that during the period from 2007 to 2015 in Beijing: (1) Area of strong human disturbance decreased by 5.14%; while others hemeroby types of area all increased. Typically, the areas of moderatestrong and complete human disturbance had increased by 1.97% and 1.44%, respectively. (2) The spatial distribution of HI in Beijing showed a diffusion pattern from the city center to its periphery and high HI areas were mostly located in the southeast part of Taihang Mountain. (3) HI index of whole Beijing decreased during this period, but with regional differences, e.g. HI index of Shijiangshan district had increased 0.14, and Daxing and Tongzhou districts had decreased 0.15 and 0.11. (4) The descending order of HI for each main functional area in Beijing was: capital core area, functional urban area, urban developing area, ecological conservation area, and forbidden development area. The HI variations in main functional areas from 2007-2015 were in accordance with the main functional area planning of Beijing.

Research progress on cyanobacterial toxins and the cyanotoxin synthetase gene.

WANG Yang, LI Yue, FENG Yue, ZHANG A-mei, XIA Xue-shan, LIU Li*

2017, 36(2):  517-523. 

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With the aggravation of water eutrophication and continuing outbreak of cyanobacteria blooms, the harmful algal bloom could not only break the structure and the balance of hydrophy-tic ecosystem, but also pose serious health threats on animals and human due to cyanobacteria-toxin production. This paper reviews the progress of research on the secondary metabolites of cyanobacteria bloom toxins and cyanotoxin synthetase gene. The types of cyanotoxins, toxicology of cyanobacterial toxin, cyanotoxin synthetase gene and molecular biology identification for detecting the toxic cyanobacteria were described. Some suggestions on disadvantage of present research about cyanotoxin were put forward. The purpose of this review is to provide a theoretical basis and technological support on scientific evaluation of ecological and environment hazards of toxinproducing cyanobacteria and instituting earlywarning system of cyanotoxins.

Research advances in the mechanisms of plant root systems disturbance in rhizosphere micro-environment.

CHEN Zhi-yu1,2,3, MA Jing1,2,3, LAI Hua-yan1,2, MA Xiang-qing1,2, WU Peng-fei1,2*

2017, 36(2):  524-529. 

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Rhizosphere micro-environment is the bridge of communication between plant and soil, and the priority area that responds to the environmental stress. Changes in root architecture, type and quantity of exudates may impact rhizosphere microorganisms and soil fauna structure and diversity, as the roots are main regulators of rhizosphere. However, there are complicated interactions between plant roots, microorganisms and soil animals in the rhizosphere. Soil animals’ disturbance and microbial decomposition can improve rhizosphere soil properties, and enhance plant stress and nutrient use efficiency, thereby promoting the growth of plant roots. Based on the studies of the physical and chemical disturbances of external microenvironment of root rhizosphere, interactive disturbance of roots and microbes of internal rhizosphere, physical disturbance of roots and soil animals, chemical disturbances with root exudates as the medium, we clarified the interaction mechanisms of disturbance in internal and external environment of rhizosphere, and made prospects for further research in this field.

A review on the ecomorphology of turtles.

XIAO Fan-rong1, KONG Fei1, WANG Ji-chao1, SHI Hai-tao1,2*

2017, 36(2):  530-540. 

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Turtles with different morphology occupy a wide range of habitats from aquatic to highly terrestrial, making them an ideal species group for ecomorphological study. Current studies indicate that niche divergence, including dietary and habitat shift, may be correlated with morphological differences of turtles. This review outlines the research progress on the ecomorphology of turtles, with the focus on the definitions, the relationships between ecomorphological characteristics (body size and morphology of shell, head, limbs and tail), feeding habits and habitat use. Meanwhile, the comparative analysis of phylogenetic systematics and ecomorphology of turtles was addressed in this paper. In addition, current issues in ecomorphological research were pointed out and some suggestions for the further work were made.

 

Elevational patterns of species richness and their underlying mechanism.

LIU Kai-ming1, ZHENG Zhi2,3, GONG Da-jie1*

2017, 36(2):  541-554. 

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Elevational patterns of species richness and their underlying mechanism have long been one of significant issues in macroecology. Species richness along the elevation gradients shows four patterns, the common pattern of which is unimodel with midelevation peak. Multiple hypotheses were proposed to explain the patterns, including four aspects: climate, spatial effect, interaction among species, and evolutional history. These hypotheses were used to explain the species richness elevational patterns from different aspects. This article reviewed the history of research on elevational pattern of species richness, the methodology and the potential mechanisms for elevation patterns. These hypotheses mainly included waterenergy dynamic hypothesis, metabolic theory of biodiversity, productivity hypothesis, relationship between species and area, middomain effect, habitat heterogeneity and static evolutionary models. The review introduced the distributional pattern of species richness along elevation gradient and the ecological evolution process affecting the pattern. At present, most of studies focused on the role of modern climate, but the parameters used as modern climate were so strongly collinear with each other that it was difficult to distinguish the absolute contribution of certain climate factor. Combined modern climate with phylogenetic analysis, the phylogenetic characters of species in different elevational bands were compared to help to further understand the elevation patterns of species richness, their underlying mechanisms and effect of modern climate fluctuation on vegetation community.

Estimation of chlorophyll content of Eremurus chinensis based on optimization support vector regression machine.

TAN lin1,2,3, HE Bing-yu1,2,3, LIU Wei-guo1,2,3*, PANG dong1,2,3

2017, 36(2):  555-562. 

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Spectral reflectance and chlorophyll content of the leaves were determined in the seedling stage and flowering stage of Eremurus chinensis in Gurbantunggut desert located in the center of the Junggar basin. Relationship was developed between 24 kinds of spectral index and chlorophyll, and estimation model was established by support vector regression (SVR) using the optimal spectral index which had high interrelationship. The results showed that (1) the chlorophyll content in flowering stage was higher than that in seedling stage, which was mainly related to the photosynthesis of vegetation, and the spectral reflectance of the flowering stage was lower than that of seedling stage. The spectral reflectance of two phases was consistent with the spectral reflectance of common plants. (2) The GNDVI and chlorophyll content showed the highest correlation with coefficient of determination (R²) values of 0.664, among all the spectral indices. In the flowering stage, the correlation coefficient between GM-2 and chlorophyll content showed the highest correlation with R² values of 0.711. According to the rankings of correlation coefficients (R²), the first 7 of the spectral index were the same in the two periods. (3) Seven sensitive spectral indices were used as input factors, and the optimal SVR estimation model was established by selecting the optimal parameters (c,g) from 3 kinds of optimization algorithms. The model accuracy was high during both the seedling stage and flowering stage. The model accuracy was ranked as, PSO-SVR>GA-SVR>GS-SVR, with the PSO-SVR coefficient being the highest and the root mean square error (RMSE) the least. In the seedling stage, the PSOSVR and coefficient was 0.812 with the RMSE being 0.728. In the flowering stage, the PSOSVR coefficient was 0.841 with the RMSE being 0.247. The results showed that the SVR model based on PSO-SVR algorithm had high precision with low error, which can estimate the chlorophyll content accurately. Moreover, the estimation of chlorophyll content in the flowering period was better than that in the seedling stage. The result would provide scientific basis and technical support for monitoring and estimating ecological characteristics of desert vegetation, spatial and temporal distribution of desert vegetation, and biochemical parameter inversion.

Removing nitrogen, phosphorus, and PPCPs from cropland drainage using permeable reactive barrier materials.

WU Bing-xing1,2, SHI Ya-nan1, MU Wen-yan1, ZENG Xiang-feng1, CHEN Xi-juan1, ZHUANG Jie1*

2017, 36(2):  563-568. 

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Agricultural nonpoint pollution is a main contamination source of groundwater, which contains numerous phosphorus and ammonia, leading to the eutrophication of rivers and lakes. Permeable reactive barrier (PRB) is an insitu remediation technology, which has been developed in the last decade for remediation of groundwater. In this research, zerovalent iron (ZVI) and biochar, which are known as effective material in PRB, were used in the remediation of phosphorus, ammonia and PPCPs in simulated cropland drainage. Under the flow rate of 1 mL·min^-1, pH 7, and phosphorus concentration 11.73 mg·L^-1, ZVI reacted with phosphorus at rate of 88.7 mg·kg^-1, while no significant removal of phosphorous by biochar was observed. How-ever, under the same condition, the sorption capacity for cambamazipine, ibuprofen and bisphenolA by biochar was detected as 328.0, 99.8, 385.4 mg·kg^-1, respectively, which was 57.5, 66.5, 83.8 times higher than ZVI. The interception effect of different PRB materials on pollutants was different. Therefore, selection and combination of various materials should be taken into consideration when dealing with cropland drainage in the actual field.

Mechanisms of nitrogen and organic matter removal from water bodies by aerobic denitrifiers enhanced ecological floating bed.

TANG Yin-qi1, LI Yang2, CHANG Su-yun1, SUN Jing-mei1*

2017, 36(2):  569-576. 

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The ecological floating bed was enhanced by aerobic denitrifiers and aeration, which improved the removal of nitrogen and organic matter from eutrophic water. The results showed that 54.5% of NH₄⁺-N, 100% of NO₃^--N, 59.8% of TN and 56.3% of COD_Cr were removed by the aerobic denitrifiers enhanced ecological floating bed in seven days at COD_Cr/TN=1.7-2.9 inflow, and the removal efficiencies of TN and COD_Cr were 47.1% and 36.3% higher than in the traditional floating bed, respectively. Additionally, the aerobic denitrifiers enhanced ecological floating bed removed 55.4% of NH₄⁺-N, 100% of NO₃^--N, 48.9% of TN and 65.6% of COD_Cr in seven days at COD_Cr/TN=3.3-5.0 inflow, and the removal efficiencies of TN and COD_Cr were 21.0% and 20.0% higher than in the traditional floating bed, respectively. In the aerobic denitrifiers enhanced ecological floating bed, aeration benefited the removal of organic matter and aerobic denitrifiers would enhance the denitrification under the high level of DO, avoiding the poor performance of the NO₃^--N removal by the aerated ecological floating bed. Monod kinetic model was used to predict the initial removal of TN and COD_Cr by the aerobic denitrifiers enhanced ecological floating bed, with correlation coefficients of about 0.9, suggesting that this model had a good prediction on the initial removal of nitrogen and organic matter.