Table of Content

10 October 2017, Volume 36 Issue 10

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Spatial distribution pattern and association of Kobresia humilis and Polygonum vivipurum under different slope aspects in a subalpine meadow of Gannan.

LIU Min-xia*, LI Li-rong, CHE Ying-di, XIAO Wei, JIAO Jiao

2017, 36(10):  2685-2691. 

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The spatial distribution and correlation of population can reflect the adaptation strategy under the conditions of population succession and environmental change. Kobresia humilis and Polygonum vivipurum are the main species in the subalpine meadow of Gannan. Through field community investigation and by using Ripley’s K function, the distribution pattern and interspecific association of K. humilis and P. vivipurum on different slopes (northerly, westerly, and southerly) were analyzed. The results showed that the distribution of K. humilis and P. viviparum showed a significant difference on the three slopes. The number, coverage and biomass of K. humilis showed an increasing trend, and the P. viviparum showed a decreasing trend from northerly to westerly to southerly slope. On northerly slope, the population of K. humilis showed an aggregated distribution at 0-2.2 m scale, and the aggregation intensity decreased and tended to randomly distribute with the increase of scale; P. viviparum was in aggregated distribution. On westerly slope, K. humilis and P. vivipurum showed aggregated distribution at 0-0.8 m scale, and random distribution at >2.3 m scale. The distribution pattern of K. humilis and P. vivipurum showed a random distribution on southerly slope. The two species showed a positive correlation at 0-1 m scale on northerly slope, and a negative correlation at 0-1.3 m scale on westerly slope. Interspecific associations tended to be uncorrelated with increasing scales on these two slopes, and these two species also showed no correlation on southerly slope. The spatial patterns and associations of K. humilis and P. vivipurum are helpful for us to understand the intraspecific and interspecific competition processes, the diversity of ecological strategies and the community succession trend in the subalpine meadow.

 

Root distribution and interaction in a Nitraria tangutorum-Achnatherum splendens (shrub-grass) community in arid Northwest China.

CHEN Bin1,2*, LIU Mao-song3*, HUANG Zheng4, ZHANG Ming-juan5, XU Chi3

2017, 36(10):  2692-2698. 

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This study aims to better understand the underlying mechanisms of the coexistence of shrub and grass species in arid environments. A typical shrubgrass community, Nitraria tangutorum-Achnatherum splendens community, was selected near the Shahu Lake in Ningxia Hui Autonomous Region, Northwest China. To characterize the heterogeneity of the habitat, we partitioned the community into three microhabitats, namely under-canopy, transitional and open microhabitats, from the canopy areas of plant clumps to the inter-clump barren areas. With trenching methods, roots were collected and the distributions of root biomass densities and root extinction coefficients of the two species were compared in the soil profiles of the three microhabitats. The results showed that both Nitraria and Achnatherum produced most of their roots in under-canopy microhabitats; however, the extent of decline in root biomass density from undercanopy to open microhabitats was more intensive in Achnatherum. The layers with highest root biomass density of Nitraria were continuously deepened from undercanopy to open microhabitats, while that of Achnatherum re-increased in open microhabitats. Nitraria had its highest fine root biomass density in 10-30 cm layer in the undercanopy microhabitat, while the highest fine root biomass density of Achnatherum was in 0-10 cm layer. There were significant (or marginally significant) differences in root extinction coefficients between the two species in all microhabitats, indicating that there was belowground niche segregation between Nitraria and Achnatherum. Taking into account of the patchy clumpstyle aboveground distribution pattern, we suggest that aboveground aggregation together with belowground segregation might be the coexistence strategies of Nitraria and Achnatherum to cope with arid environments.

 

The quantitative characteristics of plant germplasm resources in Horqin grassland.

SUN Rui1,2, XU Wen-duo1, CHEN Wei1*, ZHANG Yue1

2017, 36(10):  2699-2706. 

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In this paper, the quantitative characteristics of plant germplasm resources in Horqin grassland of Tongliao area were studied by using samplingplot method. The results show that it is quite abundant and complicated for species composition of plants in Horqin grassland with 42 families, 163 genera, and 276 species, of which the finepasture species accounted for 35.15%. The types of grassland can be divided into 5 categories, 7 subcategories and 17 grassland groups. Among them, the community in which Leymus chinensis is the constructive species is most widely distributed. The aboveground biomass of L. chinensis community significantly increases with the increase of species diversity. Meanwhile, the aboveground biomass of L. chinensis community varies with the geographical factors, i.e. the grassland aboveground biomass increases with the increase of longitude and decreases with the increase of latitude. Our results provide some important insights for increasing the yield of highquality pasture, improving degraded grassland and developing grassland animal husbandry. Furthermore, this study provides an important reference for the restoration and reconstruction of Horqin grassland, and thus the local economic development of the study area.

 

Phenotypic diversity of wing fruits and seeds in natural populations of Acer truncatum Bunge in China.

QIAO Qian1, FENG Zhen1*, REN Hong-jian1, AN Kai1, ZHANG Lin2, SUN Zhong-kui3

2017, 36(10):  2707-2715. 

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Acer truncatum is an endangered plant endemic to China. Our objectives were to determine the variations in phenotypic traits of A. truncatum populations and their spatial patterns. We used nested variation, coefficient of variation, multicomparison, correlation analysis and UPGMA cluster analysis to analyze 13 phenotypic traits of fruits and seeds for 150 individuals in 15 populations of A. truncatum. The results showed that there were extremely significant differences among and within populations. The mean coefficient of phenotypic differentiation between populations was 19.87%, which was lower than that within populations (80.13%), indicating that the variance within population was the main source of the phenotypic variation of the species. The coefficient of variance (CV) of the 13 traits was 8.98%-21.45%, with an average of 13.34%. The CV of seeds among populations (11.46%) was lower than that of wing fruits (14.52%), which means that the seeds have higher stability than the fruits. Principal component analysis (PCA) showed that the main variation source of A. truncatum came from the fruits. Correlation among traits showed that the larger the fruits, the larger the seeds. The angle of the fruits was independent of the fruits and seed sizes. The fruit morphology mainly presented longitudinal variations, while the seeds had no significant variation patterns. The 15 populations of A. truncatum could be clustered into three groups according to the UPGMA cluster analysis. The multiple variations among and within populations provided insights and guidelines for genetic conservation and utilization of A. truncatum germplasm resources.

Population structure and regeneration of Emmenopterys henryi in different patches in  mountainous area of southern Jiangsu.

PENG Xian-li1, REN Xiao-jie2, ZHANG Guang-fu1*, LI Li2, YANG Ting1, XIAO Si-yu1, WANG Xue-feng2, SHI Ya-jiang2

2017, 36(10):  2716-2724. 

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Habitat fragmentation results in isolated and patched small populations. At present, however, little is known about population structure and regeneration mode of rare and endangered tree species in different patches. The static life table of Emmenopterys henryi population was compiled based on population life table and theory of survival analysis by applying age class structure represented by DBH class and smoothing out technique. Meanwhile, sizeclass structure and sprouting ratio of this species in five patches were also examined. The results showed that there was a fluctuation in the structure of E. henryi populations across the five patches. Overall, the survival curve of the population tended to follow the type of Deevey Ⅱ, and the individuals at juvenile stage were abundant. The mortality rate and disappearance rate in the lifespan had similar variation trend, with the peaks in the 1st and 5th age class periods. The survival rate of the population decreased monotonically, whereas the cumulative mortality rate increased monotonically. Nevertheless, the two rates began to be flat from the 5th age class. Additionally, sprouting ratio and Magini index differed markedly across the five patches. Despite longterm persistence by virtue of sprouting regeneration, some patches of small populations have been so seriously threatened that the local populations are on the edge of extinction due to human disturbance.

Distribution and impact factors of rattan in lowland secondary rain forest in Hainan-Island， China.

PENG Chao1, FAN Shao-hui1*, LIU Guang-lu1, XU Rui-jin2, HU Xuan1, SU Hao-ran1

2017, 36(10):  2725-2733. 

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Taking 6 kinds of natural rattan in Ganzhalin of Hainan Island as the research objects, the dominant environmental factors affecting the distribution of rattans were screened out by Detrended Correspondence Analysis (DCA) and Redundancy Analysis (RDA). Meanwhile, the variations of rattan population density with environmental factors were analyzed. Calamus rhabdocladus and C. faberii had higher population density, Daemonorops jenkinsiana and C. tetradactylus took second place, while Plectocomia microstachys and C. simplicifolius had lower density. There were five major factors affecting rattan density, with the order of effect being TP > slope > TN > terrain > rock coverage rate. These five factors explained 33.5% of the information of the speciesenvironment relationship on axis 1, and 73.7% information was explained with 4 axes. Some differences existed among the six rattans along five environmental gradients. C. tetradactylus adapted to the lower slope with relatively high soil TP content and low rock coverage rate, C. faberii was mainly found at middle and upper sites with relatively low TN and TP contents and low rock coverage, and C. simplicifolius was more likely to distribute at hollow sites of middle slope with relatively low TN and TP contents. C. rhabdocladus was mainly found in lower valley with low TP content, D. jenkinsiana grew at lower TP sites with high rock coverage, and P. microstachys seedlings more likely to live at slopes with high N and P contents. In conclusion, C. rhabdocladus and D. jenkinsiana have a stronger ability to adapt to habitats in the study region and the response of rattans to habitats is also different among species. Moreover, the response of rattan seedlings to habitats has obvious differences relative to other growing stages. Therefore, in the process of rattan resource protection and recruitment, different measures should be taken for different species and growing stages.

 

Diversity and community structure of arbuscular mycorrhizal fungi in desert and steppe ecosystems.

LI Xue-jing1,2, XU Tian-le1,2, CHEN Bao-dong1,2*, XU Li-jiao1,2, ZHAO Ai-hua1,2

2017, 36(10):  2734-2743. 

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Arbuscular mycorrhizal fungi (AMF) are ubiquitous soil fungi in natural and agricultural ecosystems, which can form symbiotic associations with the majority of terrestrial plants and have important ecological functions. To compare the AMF communities between desert and steppe ecosystems, and to reveal the key influencing factors for AMF diversity, we collected rhizosphere soil samples from both zonal and non-zonal desert and steppe in Inner Mongolia, Gansu and Qinghai provinces, China. The community structure of the soil AMF was investigated using Illumina Miseq sequencing platform. In total, 159 AMF operational taxonomic units (OTUs) were detected, belonging to 1 class, 3 orders, 5 families and 8 genera, among which, Glomus was the dominant genus in both desert and steppe ecosystems. The AMF richness, Shannon diversity, phylogenetic diversity in steppe was higher than those in desert (both zonal and non-zonal vegetation regions). A remarkable difference in AMF community structure between desert and steppe ecosystems was noted in zonal vegetation region. However, there was no significant difference in AMF community structure between non-zonal desert and steppe. Correlation analysis clearly reflected the relationship between environmental factors and AMF community structure and diversity, and variation partitioning showed that soil properties and climate factors were more important than plant community and geographic distance in determining AMF community structure. In summary, the soil AMF communities of desert and steppe were mainly shaped by soil properties and climate factors. This study provided support for the potential use of AMF for ecological control of grassland desertification.

Effects of light conditions on the growth characteristics and photosynthetic traits of Quercus mongolica seedlings.

LI Dong-sheng1,2, BAI Qing-hong1, LI Yong-jie1, XU Zhong-qi2*, YU Hai-tao3

2017, 36(10):  2744-2750. 

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In order to study the growth process of Quercus mongolica seedlings under different light conditions, a controlled experiment was conducted under four light intensity treatments, including full sun light (FS), light shade (LS), medium shade (MS) and severe shade (SS). The morphological characteristics, photosynthetic traits and biomass allocation of Q. mongolica seedlings were measured. The results show that: (1) Specific leaf area under medium shade and severe shade was significantly greater than that under full sun light and light shade. No significant differences in seedling height were found among the different light conditions. The basal diameter under full sun light was significantly greater than that under medium shade and severe shade. The main root length was similar to the root diameter; both were bigger under full sun light than under the other three shade conditions, and were bigger under light shade and medium shade than under severe shade. (2) The maximum net photosynthetic rate under four light conditions showed a pattern of light shade > full sun light > medium shade > severe shade. The apparent quantum efficiency under full sun light and light shade were significantly higher than that under medium shade and severe shade. There was no significant difference in the dark respiratory rate among different light conditions. (3) Both total biomass and root biomass were the highest under full sun light, followed by under light shade and medium shade, and lowest under severe shade. There were little differences in leaf biomass and stem biomass; the biomass of different organs was in order of root > leaf > stem, and the proportions of root biomass ranged 68%-76%. The rootshoot ratio under full sun light, light shade and medium shade were bigger than that under severe shade.

Foliar physiological characteristics of Schima superba along a vertical canopy gradient. 

HUANG Ke-chao, HE Wen, ZHOU Cui-ming, HUANG Yu-qing*, GU Da-xing, XU Guang-ping, ZHOU Long-wu

2017, 36(10):  2751-2758. 

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We investigated leaf morphology, diurnal variation of photosynthesis, and chlorophyll content of Schima superba along different positions of canopy (top, middle and bottom layers) to determine its eco-physiological response to spatial variation. The results showed that specific leaf area of S. superba from the top layer was significantly lower than that from the middle and bottom layers. Leaf length and maximum width were significantly different among the three layers (P<0.01), being bottom layer > middle layer > top layer. Compared with the middle and bottom layers, photosynthetically active radiation was the highest at the top canopy. Leaves from the top layer had significantly higher net photosynthesis rate (P_n), stomatal conductance (g_s), carboxylation efficiency (V_c), transpiration rate (T_r) and stomatal limitation (L_s) than that from either the middle or bottom layer. Conversely, leaves from the bottom layer had the highest intercellular CO₂ concentration (C_i). Photosynthetically active radiation from each layer had a significant positive correlation with P_n, g_s, V_c, T_r and L_s, and was negatively correlated with C_i. The highest contents of chlorophyll a+b (Chl-a+b) and carotenoid (Car) of leaves were found from the middle and bottom layers, while the top layers had much higher chlorophyll a/b (Chl-a/b). The results indicated that illumination was the primary driver of variation in leaf morphological and physiological characteristics of S. superba along the vertical space of canopy.

Effects of different salinity levels on the growth and physiological characteristics of roots of Tamarix chinensis and T. austromongolica.

SONG Xiang-jing, LI Sheng-nan*, WEI Wei, GUO Jia, YU Yi-lei, LIU Zhi-wei

2017, 36(10):  2759-2767. 

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Tamarix species are dominant shrubs in the Yellow River Delta region, and they can adapt to saline environment well. Roots can directly sense soil salinity change. Therefore, studying the effects of differing salinity on the eco-physiological characteristics of roots of Tamarix species is important for the ecological restoration of coastal wetlands. In the present study, we studied the effects of different salinities (0, 0.4%, 0.8%, 1.2%, 2.4% and 3.6% NaCl solutions) on the growth and eco-physiological characteristics of roots of 1-yearold T. chinensis and T. austromongolica cuttings. We determined the rooting rate of Tamarix cuttings, root lifespan, root number, root length, root biomass, hydrogen peroxide enzyme (CAT) activity, adenosine triphosphate (ATP) synthase activity, and abscisic acid content. The cuttings of the two Tamarix species were suitable for cultivation at solutions with a salt content of lower than 0.8%. The rooting rate of the two species decreased significantly when salt content was more than 0.8%, and T. austromongolica cuttings did not produce roots when salt content was at 3.6%. The root growth of both Tamarix species was significantly inhibited when the salinity increased to more than 1.2%, especially for T. chinensis. Both Tamarix species could relieve the harm of salt to their roots by increasing the proportion of root biomass allocation under high salt conditions. The activities of ATP synthase and CAT of T. chinensis roots increased when the salinity was less than 0.8%, and the activities decreased when the salt content was more than 0.8%. The content of abscisic acid (ABA) of T. chinensis roots increased with the increasing salinity, and then decreased when the salinity was higher than 1.2%. The activities of ATP synthase and CAT and the content of ABA of T. austromongolica roots decreased gradually with the increasing salinity.

The response of endogenous hormones to storage and their effects on seed germination of Halenia elliptica.

XIA Yu-bin, BU Hai-yan*, GE Wen-jing, ZHANG Yan-ming, ZHAO Di, XU Dang-hui, LIU Kun, QI Wei

2017, 36(10):  2768-2776. 

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Endogenous hormones are considered as a main internal cause to regulate germination and dormancy of seeds, which have been highly concerned. However, no theory or hypothesis on the change patterns of endogenous hormones with environmental changes and their regulation mechanisms on seed germination has been generally accepted. In this study, seeds of Halenia elliptica which is widely distributed in the alpine meadow of northeastern QinghaiTibet Plateau were used to test the dynamics of endogenous hormone content and germination under different storage temperatures and durations. The contents of endogenous hormones of seeds varied with storage duration under different storage temperatures. Under room temperature, the effects of storage duration on the absolute contents of endogenous hormones and the ratios of promoters to inhibitors (except IAA/ABA) were significant. Under cold storage, the effects of storage duration on the contents of GAs, IAA, ABA and total promoters were significant. Storage duration and storage temperature significantly influenced the germination percentage. The seed germination percentage under room temperature was about 4 times as high as that under cold storage, and seed germination showed a dormancy cycle. Seed germination of H. elliptica was not controlled by the contents of promoters or inhibitors. Seed germination correlated positively with the content of GAs and negatively with the content of IAA, while the germination percentage would be higher only when the CTK content was higher. Therefore, the relationships among endogenous hormones in this study might be consistent with the “threefactor” hypothesis proposed by Khan, that is, CTK antagonized ABA, to relieve or eliminate the role of ABA and promote the role of GAs.

Effect of nitrogen on growth and photosynthesis of Populus euphratica seedlings under drought stress.

ZHONG Xiao-li1, MA Xiao-dong1,2*, Lü Hao-hao1, ZHU Chen-gang2, YANG Yu-hui1

2017, 36(10):  2777-2786. 

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Populus euphratica is an important stressresistant germplasm resource for desert riparian forests in Tarim River Basin. The survival and growth of P. euphratica seedlings are always limited by water and nitrogen. In this experiment, we studied the effect of nitrogen supply on the early morphogenesis of P. euphratica seedlings under drought stress. Four water treatments (D₁, D₂, D₃and D₄ with soil relative water contents of 20%-25%, 40%-45%, 60%-65% and 80%-85%, respectively) and three nitrogen application levels (N₀, N₁, N₂: 0, 3, 6 g·pot^-1) were used to determine the growth index, chlorophyll fluorescence and photosynthetic parameters of P. euphratica seedlings. The results showed that under slight drought stress (D₃), P. euphratica seedlings had a higher capacity of growth and photosynthesis when N₁ was applied. Under severe drought stress (D₁), the root/shoot ratio of seedlings was the lowest, and significantly increased when the nitrogen level increased. Under the conditions of drought (D₁, D₂, D₃), the effect of N₁ on seedling growth was higher than that of N₂. Under severe drought stress (D₁), nitrogen application significantly increased the fluorescence parameters and photosynthetic rate. Therefore, P. euphratica seedlings had the best growth performance when soil relative water content was 60%-65% (D₃) and nitrogen application level was 3 g·pot^-1 (N₁). The root growth and photosynthetic capacity of seedlings was significantly increased by nitrogen fertilization under different drought stresses, indicating that nitrogen had a compensatory effect on drought stress. So, nitrogen fertilization can promote the early morphogenesis of P. euphratica seedlings and help the seedlings survive during the vulnerable period of growth.

Preliminary revision of the avifauna of Heilongjiang Province.

XING Xiao-ying, LI Xiang, LI Feng, MA Jian-zhang*

2017, 36(10):  2787-2794. 

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Heilongjiang (northeastern extreme of China) is located between the temperate and the boreal zone, harboring a high diversity of birds. The Avifauna of Heilongjiang was published in 1992 and included 19 Orders, 57 Families and 343 bird species, which represented 29% of 1186 bird species nationwide. However, after more than two decades, there is a need to update the list of birds of Heilongjiang because during this time period more and more new records have been added, and studies on bird taxonomy have developed rapidly. We checked references of new records and compared them with the second edition of A Checklist on the Classification and Distribution of the Birds of China. We added 2 Orders, 8 Families and 51 species, deleted 1 Order, 1 Family and 11 species. We also revised 2 families, 14 genera, Latin names of 14 species and 16 subspecies, and 38 Chinese names. Additionally, 21 subspecies were updated to species. After these modifications, there are 20 Orders, 64 Families and 384 species in Heilongjiang, representing 28% of 1371 bird species nationwide. We found 21 species not previously recorded in Heilongjiang according to A Checklist on the Classification and Distribution of the Birds of China. This revision is an important contribution to updating both Heilongjiang and Chinese avifauna.

Spatial patterns of fish assemblages based on classification strengths in the rivers of  Chaohu basin.

QIAN Hong1, CHU Ling1, ZHU Ren1, CAI Yong-jiu2, YAN Yun-zhi1*

2017, 36(10):  2795-2802. 

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Identifying the spatial pattern of fish assemblages is essential for the conservation and management of fish species diversity. Based on the data collected from 66 stream segments within the Chaohu basin in October 2013, we examined how stream fish assemblages varied spatially and assessed the classification strengths of three spatial schemes (i.e., subbasin, stream order and ecoregion) and fish taxonomic clusters in classifying fish assemblages. Our results showed that fish assemblages did not vary significantly among subbasins and stream orders but differed significantly among ecoregions. For the spatial schemes of subbasin and stream order, the mean withingroup similarity of fish assemblages was not significantly different from the mean betweengroup similarity, and thus the two spatial schemes presented very low classification strength for classifying fish assemblages. But for the spatial scheme of ecoregion, the mean withingroup similarity of fish assemblages was significantly higher than the mean betweengroup similarity, and thus its classification strength was relatively high. However, compared with the scheme of taxonomic clusters, the classification strength of the ecoregion scheme was relatively low. The results indicated that the spatial pattern of fish assemblages depended on the landscape conditions to a certain extent in the Chaohu basin, and also on the local environmental factors. In future research, it is necessary to further clarify the main environmental factors affecting the spatial pattern of fish assemblages in the Chaohu basin and the spatial distribution of these key factors, so as to provide scientific basis for the conservation and management of fish species diversity in the Chaohu basin.

Spatial-temporal distribution of fishing ground for Antarctic krill fishery in the South Georgia Island during the austral winter and its drivers.

CHEN Guang-wei1, CHEN Lv-feng1,2, ZHU Guo-ping1,2,3*, XU Yu-cheng4, TIAN Jing-huan1, Ding Bo1

2017, 36(10):  2803-2810. 

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Based on the data collected by scientific observers onboard Chinese Antarctic krill fishing vessel, the present study analyzed the effect of month, bottom depth and fishing depth on catch per unit effort (CPUE) of Antarctic krill fishery operated in the South Georgia Island during the austral winter 2013-2016 using geographically weighted regression (GWR) model and further revealed the drivers of the spatialtemporal differences. The results indicated that higher CPUEs were distributed in the first 10 days of July to the last 10 days of August. The highest mean CPUE was 20.5±21.1 t·h^-1 in 2014, and the lowest mean CPUE was 10.4±10.5 t·h^-1 in 2015. A significant difference was also found in average CPUE values among months. Fishing ground was concentrated in 53°00′S-54°30′ S, 35°15′W-38°30′W. The goodness of fit for GWR model was the highest in 2015, but the lowest in 2016. The spatial effect (positive correlation) of fishing depth on CPUE of Antarctic krill fishery was strengthened increasingly from south to north, but no consistent trend was observed for the spatial effect of bottom depth on CPUE. The goodness of fit for GWR model was higher than that of ordinary least square (OLS) model, indicating that GWR model was more suitable to present the spatial effect of drivers on CPUE. The results derived from the present study can provide effective references for studying forming mechanism of fishing ground and fishery management of Antarctic krill fishery in the South Georgia Island.

Feeding habits of Japanese Spanish mackerel (Scomberomorus niphonius) larvae and juveniles in Xiangshan Bay.

LIN Nan1, WANG Yu-tan1,2, CHEN Yuan-ge1, JIANG Ya-zhou1, YUAN Xing-wei1, LI Sheng-fa, LING Jian-zhong1*

2017, 36(10):  2811-2816. 

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The present study explored the feeding ecology of the larvae and juveniles of Japanese Spanish mackerel (Scomberomorus niphonius) collected from Xiangshan Bay between April 3th and June 10th in 2015. In order to obtain sufficient quantity of individuals in different development stages, larvae and juveniles were sampled weekly by frame net (1 m×2 m, 1.0 mm mesh size). A total of 1108 individuals were collected across the study, having body length of 4.0-41.1 mm; 587 intact specimens among them were used to investigate the feeding ecology of the larvae and juveniles by gut content analysis. A total of 11 prey species were found in guts, and fish larvae were the dominant preys (98.6%), which mainly consisted of Konosirus punctatus, Gobiidae and Chelon haematocheilus. Except yolksac larvae, the feeding incidences were 62.0%, 81.3%, 80.0%, and 86.8% in pre-flexion, flexion, postflexion larval and juveniles, respectively. The gapesize of larvae and juveniles significantly correlated with its body length, and the rate of the gapesize relative to body length ranged from 16.4% to 25.1%. The mean size of the prey increased accordingly as the predator S. niphonius grew, which also showed significant correlation with body length and gapesize. The average length for prey ranged from 2.6 mm in yolksac larval to 11.2 mm in juveniles. There were three peaks for the density of dominant prey items in Xiangshan Bay, and S. niphonius mainly appeared in the second peak of prey abundance during the study period. The variation of S. niphonius was synchronized with that of prey item density.

Distribution and habitat character of Schizothoracinae fishes in the middle Yarlung Zangbo River.

ZHU Ting-bing1, CHEN Liang1,2, YANG De-guo1*, MA Bo3, LI Lei3

2017, 36(10):  2817-2823. 

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The distribution and habitat characters of Schizothoracinae fishes in the middle Yarlung Zangbo River were investigated in April and October, 2015. The results showed that there were six Schizothoracinae fishes distributed in the middle Yarlung Zangbo River, including Schizothorax oconnori, Ptychobarbus dipogon, Schizothorax younghusbandi, Schizothorax waltoni, Schizothorax macropogon, and Oxygymnocypris stewarti. Oxygymnocypris stewarti was only found above Renbu section of the Yarlung Zangbo River, while S. oconnori and S. younghusbandi were found at all sampling sites of the middle Yarlung Zangbo River. RDA model showed that river width, flow velocity and pH were the main factors affecting the distribution of Schizothoracinae fishes in the middle Yarlung Zangbo River. In consideration of overfishing, alien species invasion and cascade hydropower development in the middle Yarlung Zangbo River, the management departments should take actions such as defining conservation regions, forbidding fishing by law and promoting the release of native fish to sustain the effectiveness of habitat of Schizothoracinae fishes.

Genetic diversity of Leptobotia microphthalma in the upper Yangtze River inferred from mitochondrial DNA.

SHEN Shao-Yi2, TIAN Hui-Wu1, LIU Shao-Ping1, CHEN Da-Qing1, LV Hao3, WANG Deng-Qiang1*

2017, 36(10):  2824-2830. 

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Leptobotia microphthalma is a small freshwater fish, endemic to the Upper Yangtze River, and its distribution is limited. In this study, mitochondrial DNA cytochrome b (cyt-b) and control region sequences were used to investigate the genetic diversity and structure of L. microphthalma populations. A total of 108 fishes were collected from Yibin and Jiangjin stations in the upper Yangtze River. In spite of limited distribution, the population exhibited a high level of genetic diversity; the average haplotype diversity (H_d) and average nucleotide diversity (P_i) were 0.889 and 0.00382 in cyt b and 0.958 and 0.00420 in control region, respectively. Hierarchical analysis of molecular variance (AMOVA) showed no significant genetic differentiation among sampled populations (F_ST<0.05). The high average gene flow (N_m) value revealed frequent genetic exchange between populations. Three haplotype groups with distinguishing mutant steps were identified from network diagram, and great genetic differentiation (F_ST>0.25) existed among them, suggesting genetic divergence within population. Nucleotide mismatch distribution and the neutral test (Tajima’s D) result showed that there probably existed no population expansion of L. microphthalma in history.

Growth, mortality and recruitment pattern of Coilia nasus at Jingjiang section of the Yangtze River.

GUO Hong-yi1, LIU Dong1, ZHANG Xu-guang1, TANG Wen-qiao1,2*, LI Hui-hua1, SHEN Lin-hong3, ZHANG Ya1

2017, 36(10):  2831-2839. 

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Coilia nasus (Japanese grenadier anchovy) is a commercially important fishery resource in the middle and lower reaches of the Yangtze River. A total of 1878 C. nasus were caught by a stow net from coastal waters at Jingjiang section of the Yangtze River during three periods of January 2003 to December 2004, January 2008 to December 2009, and January 2012 to December 2013. The present study aimed to determine the growth and population parameters of C. nasus at Jingjiang section of the Yangtze River. Based on length frequency data collected from the surveys, growth, mortality and recruitment pattern of C. nasus were estimated by utilizing FiSAT II software developed by the Food and Agriculture Organization of the United Nations (FAO). The body length (L) distribution of C. nasus ranged from 34.7-258.0 mm, and the weight (W) distribution from 0.11-71.50 g. Growth equations were calculated as W=2.72×10^-6L_3.030 (r=0.974, n=218) for 2003-2004, W=3.75×10^-6L_2.961(r=0.925, n=823) for 2008-2009 and W=2.27×10^-6L_3.061 (r=0.936, n=837) for 2012-2013. The von Bertalanffy growth parameters were L_∞=282.5 mm, K=0.56 year^-1, t₀=-0.49 years, t_i=1.49 years for 2003-2004, L_∞=295.0 mm, K=0.54 year^-1, t₀=-0.50 years, t_i=1.51 years for 2008-2009, and L_∞=296.0 mm, K=0.55 year^-1, t₀=-0.49 years, t_i=1.54 years for 2012-2013. These results indicated that growth parameters were quite close among three survey periods, and C. nasus population along the coast water collected at the Jingjiang section of the Yangtze River was mainly comprised of larvae and juveniles with rapid growth rate and young inflection point age. Our results also showed that the estimated fishing mortality (F) and exploitation rate (E) were lower in 2012-2013 than in 2003-2004. However, the analysis of the BevertonHolt dynamic model suggested that C. nasus at the Jingjiang section of the Yangtze River was still overexploited. The recruitment pattern was continuous, displaying a major recruitment period from April to September annually. In order to effectively protect C. nasus population along the coastal water, longerterm fishing ban (from April to September) in the coastal region might acquire better protective effects.

Butterfly diversity of different interference habitats in Nanniwan wetland.

TAN Can1, WANG Ting-yi1, WANG Lu1, FAN De-miao1, MA Juan1, LIU Chang-hai1,2*

2017, 36(10):  2840-2846. 

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From 2015 to 2016, we chose different interference habitats to collect butterfly in Nanniwan wetlands: Naniwancun (YGS), Houjiulongquan (TGS), Mengjiagou (THS), Danangou (WTS). We collected a total of 329 specimens which belong to 36 species in 27 genera under 5 families. Pieridae was the dominant family and Pieris rapae was the dominant species in the four habitats. The analysis of fauna revealed that the individual percentages of widely distributed species (W), Palaearctic species (P) and Oriental species (O) were 55.6%, 39.2% and 5.2%, and the species number percentages of P, W and O were 50.0%, 36.1% and 13.9%, respectively. The four habitats had the same tendency in genus number, species number, and individual number, with WTS having the highest ones of 23, 27, and 132 respectively, followed by THS, TGS, and YGS in sequence. They had the same tendency in species richness, diversity index and evenness index, with WTS having the highest ones of 5.3248, 0.4393, and 0.1333 respectively, followed by THS, TGS, and YGS in sequence. YGS had the highest dominance index of 0.3265, followed by TGS, THS, and WTS in sequence. The habitat complexity of the four habitats decreased gradually with the increase of interference, being in the order of WTS, THS, TGS, and YGS. Viewed from the butterfly resources of the four habitats, ecological succession of Nanniwan wetland had not reached the climax community, and butterfly resources were not abundant.

Effects of rubber plantation on structure and diversity of termite community.

LIN Xiao-bing1,2, LIU Sheng-jie1, XIAO Hai-feng1, XIA Shang-wen1, YANG Xiao-dong1*

2017, 36(10):  2847-2854. 

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In this study, we investigated the termite community in natural forests (tropical rain forest and evergreen broadleaved forest) and rubber plantation in Nabanhe Natural Reserve in Xishuangbanna, and explored the effects of rubber plantation on termite community structure, feeding group composition and diversity. The results are as follows: (1) A total of 397 samples of termites were collected in the three forest types, and 20 species of termites were identified belonging to 2 families and 10 genera. The dominant species were tropical termites; (2) Season was an important factor affecting the termite community, and the diversity of termites in the rainy season was higher than that in dry season; (3) The abundance, richness and diversity index of termites in the natural forests were significantly higher than that of rubber plantation. For feeding groups, the proportion of soilwood feeding termites in the rubber plantation was significantly lower than that in the natural forests, while the proportion of wood feeding termites in the rubber plantation was higher. Our results suggested that large areas of monocluture rubber plantations in tropical region have negative impacts on termite community structure and diversity. We recommend that polyculture rubber plantations as the alternative monoculture rubber plantations should be developed to protect termite diversity.

Diversity of flower-visiting insects in typical steppe with different enclosure durations in Inner Mongolia.

TENG Yue, Lu Kai-liang, Ge Xin-yu, Li Jun-lan*

2017, 36(10):  2855-2865. 

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We studied the diversity, timing characteristics and frequency of flower-visiting insects on a degraded typical grassland with three enclosure durations in Xilinguole, Inner Mongolia. Experimental treatments included plot A (enclosed in 1983), plot B (enclosed in 1996) and plot C (free grazing). A total of 2131 individuals, 183 species belonging to 7 orders and 71 families were collected from the 3 plots. 1133 individuals of 154 species belonging to 7 orders and 60 families were from plot A, 847 individuals of 158 species belonging to 6 orders and 158 families were from plot B, and 151 individuals of 21 species belonging to 3 orders and 13 families were from plot C. Plot A had the greatest individual number of the flower-visiting insects, plot B had the highest richness, while plot C had both the lowest individual number and richness. The Shannon diversity index (3.12), Pielou evenness index (0.86) and Margalef richness index (7.16) were the highest in the plot B in July. The BergerParker dominance index (0.15) was the highest in plot C in June. The change trend of Shannon diversity index in different months was consistent with that of Pielou evenness index, but contrary to that of BergerParker dominance index. The Jaccard community similarity was the highest between the plot A and plot B (0.25) and the lowest between the plot A and plot C (0.16). The dominant flowervisiting insect species varied with plots and months and in flower-visiting frequency.

 

Effects of rice and water spinach intercropping on the growth, yield, and pest control of rice.

NING Chuan-chuan1，2, CHEN Quan-yang1, HU Hong-jie1, LUO Shi-ming1，2, CAI Kun-zheng1，2*

2017, 36(10):  2866-2873. 

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Intercropping is a good cropping practice to efficiently utilize light, heat, water and soil. However, most previous studies of intercropping have focused on upland crops. The present study was carried out to explore the effects of rice and water spinach intercropping on growth, dry matter accumulation, pest control and yield of rice by field trials of continuous two years (2014-2015)/four seasons. The experiment included five treatments: Rice monoculture, water spinach monoculture, rice and water spinach intercropping at three ratios (2∶2, 3∶2 and 4∶2). The results showed that rice and water spinach intercropping had no significant effect on plant height and chlorophyll content of rice, but significantly increased the number of tiller and aboveground biomass of rice. Intercropping significantly increased rice yield per unit area mainly by increasing effective panicles, total grains and even seed setting rate. Rice yield advantage of the three intercropping patterns was shown as 2∶2 > 3∶2 > 4∶2. In addition, rice and water spinach intercropping reduced the incidence levels of rice sheath blight by 39.8%-68.8% and leaf folders by 36.7%-56.0%. Our results suggested that rice and water spinach intercropping is a feasible ecological agriculture model in controlling diseases and pests through enhancing biodiversity and increasing rice crop yields.

Photoperiodic induction of sexual morph differentiation of Acyrthosiphon pisum (red morph).

ZHANG Ting-wei, CHEN Wan-bin, LIU Chang-zhong*, SUN Qian

2017, 36(10):  2874-2879. 

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The differentiation of sexual morphs of the pea aphid, Acyrthosiphon pisum (red morph) in the 3rd generation after 2 continuous generations under different photoperiods (8L∶16D, 10L∶14D, 12L∶12D and 14L∶10D) was observed in lab. The results showed that the ovipara of red pea aphid in Lanzhou were wingless, while males were winged. Photoperiod had a significant influence on the differentiation of sexual morphs of pea aphid (P<0.05). No sexual morph was produced under 14L∶10D photoperiod, but the sexual morphs were produced under the other photoperiods (8L∶16D, 10L∶14D and 12L∶12D). The percentage of male sexual morphs gradually diminished, while the percentage of ovipara remained unchanged in the 3rd generation with decreasing illumination time. The percentages of males and sexual morphs were the highest (15.03% and 91.43% respectively) under 12L∶12D photoperiod, but the percentage of vivipara was the lowest (8.57%). Under 10L∶14D photoperiod, the percentage of vivipara was the highest, but the percentage of sexual morphs was the lowest. Under 8L∶16D photoperiod, the percentage of ovipara was the highest (78.88%), but was not significantly different from those of the other treatments (P>0.05). The reproductive period of the 1st generation also had a significant influence on the differentiation of sexual morphs in the 3rd generation under the same short illumination conditions (P<0.05). Meanwhile, there was a certain time sequence to produce sexual morphs of pea aphid (first ovipara and last males) with some vivipara in the process of sexual morph transition. Hence, the critical photoperiod of red pea aphid was between 12 to 14 hours of illumination. Relatively longer illumination was advantageous to produce males, while the male differentiation time was delayed and the male differentiation days were shortened with decreasing illumination time. The results suggested that the photoperiodic change was a critical factor of reproductive plasticity and sexual morph differentiation of red pea aphid. The illumination length by which maternal pea aphid experienced influenced sexual differentiation of offspring.

Effects of nitrogen sources on the growth and toxicity of Alexandrium tamarense.

SI Ran-ran1, GUAN Wan-chun1, CAI Jing-bo2, CHEN Shao-bo1*

2017, 36(10):  2880-2885. 

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In order to understand the effect of nitrogen sources on the growth and toxicity of harmful dinoflagellate Alexandrium tamarense, four nitrogen sources (nitrate, ammonium, urea and glycine) were added into artificial seawater enriched with F/20 and cells were batchcultured at 20 oC and 200 μmol photons·m^-2·s^-1. Cells of A. tamarense at exponential phase were collected to test the acute toxic effect on zebrafish embryo in 48 hours. The results showed that four nitrogen sources were all utilized by A. tamarense, but the growth rate was different, being ammonium (0.25 d^-1) > nitrate (0.20 d^-1) > urea = glycine (0.12 d^-1). However, the pigment contents were not influenced. Compared with the control group (embryo medium), the rude extract of A. tamarense at 2 ×10⁴ cells·mL^-1 had significantly teratogenic effects on the zebrafish embryos, resulting in embryo coagulation, developmental retardation, vitelline membrane rupture, yolk sac edema and tail bending. When the cell density increased to 8×10⁴ cells·mL^-1, the toxicity increased accordingly, moreover, a significant difference was found among the four nitrogen sources, showing nitrate > urea = glycine > ammonium. In summary, A. tamarense can maintain relatively high growth rate and make algal blooms outbreak continuously regardless of environmental changes, which threatens the ecological environment in coastal areas.

 

Change of culturable bacterial quantity in different types of degraded permafrost in the upstream region of Shule River Basin.

ZHANG Bao-gui1, LIU Xiao-jiao2, LIU Min1， ZHANG Gao-sen3,4, ZHANG Wei3,4, WU Xiu-kun3,4, CHEN Tuo3,4, LIU Guang-xiu3,4*

2017, 36(10):  2886-2893. 

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Owing to climate change and human activities, evident degradation of permafrost has happened in the upstream regions of the Shule River Basin, such as increasing depth of active layer and vegetation degradation. However, little is known about the effects of permafrost degradation on soil microbes. In this study, we investigated the effects of soil properties on bacterial community during the process of permafrost degradation by analyzing the culturable bacterial quantity of 12 soil samples from four permafrost types \[i.e., substable permafrost (SSP), transition permafrost (TP), unstable permafrost (UP) and extremely unstable permafrost (EUP)\] in different seasons (April, June and September). The results showed that the quantity of culturable bacteria varied between 0.4×10⁷-5.3×10⁷ CFU·g^-1, and the quantity of culturable bacteria decreased significantly during the process of permafrost degradation in each season, and the bacterial quantity reached the highest level for each permafrost type in June. However, the seasonal variation of the bacterial quantity in the different types of permafrost did not exhibit the same trend. Correlation analysis showed that soil bacterial quantity was significantly positively correlated with soil moisture, total nitrogen, and organic carbon contents. These results indicated that there existed huge environmental heterogeneity such as heterogeneity in soil moisture, organic carbon and total nitrogen content between different permafrost types during retrogressive succession of vegetation along with permafrost degradation, and this heterogeneity may further affect the microbial quantity. The results provide a reference for the comprehensive evaluation of ecological environment of different types of permafrost in QinghaiTibet Plateau.

Effects of different fertilizer applications on microbial metabolic activity and community structure in tea rhizosphere soil.

JIANG Yu-hang1,2, LIN Sheng1,2*, LIN Wei-wei1,2, CHEN Ting1,2, Yasir Arafat1,2, WEI Xiao-ya1,2, LIN Wen-xiong1,2*

2017, 36(10):  2894-2902. 

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A field trial was conducted in tea garden where tea plants had been continuously monocultured for 20 years, located in Taozhou, Anxi of Fujian Province, with four treatments including no fertilization (CK), nitrogen fertilizer (NF), goat manure (GM) and leguminous green manure (LF), to investigate physicochemical properties, microbial metabolic activities and phospholipids fatty acid (PLFA) in tea rhizosphere soil. The results showed that pH, organic matter and available K were improved by 0.47%, 17.56% and 56.10% under NF, 2.36%, 27.48% and 63.41% under GM, and 2.13%, 54.96% and 73.17% under LF, respectively. The alkalytic N and available phosphorus were significantly decreased by 9.10% and 335.00% under NF, while increased by 17.06 and 211.00% under GM, and 16.70% and 388.00% under LF, respectively. Meanwhile, the activities of urease, sucrase, polyphenol oxidase and peroxidase were improved by NF, GM and LF, with the effect of improvement being in order of LF> GM> NF. Acid phosphatase activity and microbial P use rate were significantly decreased by 70.04% and 249.00% under NF, while increased by 24.74% and 180.00% under GM, and 34.28% and 251.00% under LF, respectively. Furthermore, microbial community abundance and bacterial diversity were dramatically improved under GM and LF. In conclusion, both GM and LF can improve soil fertility and promote microbial metabolic activities in tea rhizosphere soil, being meaningful to enhance economical and ecological efficiency of tea gardens.

Effects of continuous application of biochar-based fertilizer and biochar on organic nitrogen fractions in brown soil.

LI Yue, YU Ya-lin, ZHANG Xin, YANG Qing-cheng, ZENG Yu-qing, HAN Xiao-ri, YANG Jin-feng*

2017, 36(10):  2903-2909. 

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To clarify the change of organic nitrogen fractions with continuous fertilization, a sitespecific plot experiment was used to study the effects of continuous application of biocharbased fertilizer and biochar on the fractions of organic nitrogen in brown soil. Five treatments were employed, including the control without fertilization (CK); low application level of biochar; high application level of biochar; nitrogen, phosphorus and potassium combined fertilization; and biocharbased fertilizer. Soil samples were collected in 0-20 and 20-40 cm soil layers after the harvest of peanut in 2014. An organic N fractionation method by Brenmer was used to determine soil organic nitrogen fractions. The results showed that after 4 consecutive years of fertilization treatments, total soil nitrogen increased for all the treatments. The total soil nitrogen of biocharbased fertilizer treatment was significantly higher than that in the original soil and CK group, with increases of 69.8% and 4.8% respectively. The contents of soil organic nitrogen fractions in different fertilization treatments were in the order of ammonium N > amino acid N > nonhydrolysable N > hydrolysable unidentified N > amino sugar N. The input of biocharbased fertilizer significantly increased the contents of ammonium N and amino acid N in acid hydrolysable organic nitrogen of soil. Compared with the original soil, the input of biochar-based fertilizer increased the contents of ammonium N and amino acid N by 65.9% and 128.0% respectively. As the application rate of biochar increased, ammonium N content showed an increasing trend, but such increment in the biochar treatments was far lower than that in the biocharbased fertilizer treatment. The applications of biochar, NPK fertilizers and biocharbased fertilizer increased the content of hydrolysable unidentified N, and the total content of non-hydrolysable organic nitrogen, but the differences among the treatments were not significant. Overall, continuous application of biochar-based fertilizer or biochar significantly increased the contents of ammonium N and amino acid N from acid hydrolysable organic nitrogen in soil, promoted the activation of nitrogen, and benefited the uptake and transport of nitrogen of low-and middleyield peanut field.

Effects of low-molecular-weight organic acids on potassium release from different K-bearing minerals using kinetic models.

ZHU Dan-dan, WANG Jin, CONG Ri-huan, LI Xiao-kun*

2017, 36(10):  2910-2916. 

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Effects of low-molecular-weight organic acids (tartaric acid and oxalic acid) on potassium (K) release from different K-bearing minerals (biotite, muscovite, and microcline) were studied with the continuous flowing method to explore an optimal model for describing K⁺ release kinetics and provide theoretical evidence to further evaluate plant available K of soil. Results showed that the amounts of K release from biotite, muscovite and microcline extracted by tartaric acid were 2.2, 3.3 and 2.6 times as high as that by water, respectively, while the amounts of K release extracted by oxalic acid were 2.7, 4.5 and 10.1 times as high as that by water, respectively. The amount of K release from Kbearing minerals with different extractions in continuous flow method was in order of biotite > muscovite > microcline. Parabolic diffusion, power function, Elovich equation and first order equation were used to describe the release of K from K-bearing minerals, and the result shows that the determination coefficients (R²) of the kinetic equations were from 0.591 to 0.999, showing significant correlations for biotite and muscovite. The effect of low-molecular-weight organic acids on microcline K release kinetics under the first order equation reached extremely significant level. Under the condition of continuous flow, lowmolecularweight organic acids can significantly improve K release in different K-bearing minerals.

Habitat quality and its relationship with socioeconomic activity in Taizi River Basin.

WANG Qiong1, LU Chong1,2, HAN Qing1,2, FAN Zhi-ping1,3*, LIU Jie4, LI Fa-yun1, TU Zhi-hua1, WANG Shan-Xiang1,2, ZHAO Yue1,2

2017, 36(10):  2917-2925. 

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Combined with principal component analysis and entropy methods, the paper assessed the habitat quality of Taizi River Basin. Correlation analysis and redundancy analysis were used to identify the effects of socioeconomic development and land use pattern on habitat quality. Results indicated that habitat quality across all reaches of Taizi River Basin was 4.35% in good condition, 91.30% in fair condition, and 2.17% in poor condition. The reaches with good habitat quality were mainly located in the upstream of the Taizi River, and those with fair quality in the midstream, and poor quality in the downstream in Anshan. Socioeconomic development and land use pattern were the main factors affecting habitat quality. Habitat quality was negatively correlated with population density, regional GDP per capita, the first and second industry outputs and the ratio of land area for cultivation to construction, whereas it was positively correlated with forest area percentage. Socioeconomic development and land use pattern explained 45.7% and 39.5% of the characteristics of habitat quality, respectively. Our results suggest that the habitat quality in Taizi River Basin may be improved by rationally adjusting industrial structure and optimizing land use pattern.

Groundwater risk simulation of water erosion sand amended with municipal sewage sludge.

HUANG Dian-nan, TAN Jie, FU Jin-xiang*, LIU Jun, ZHANG He-kai, ZHAO Yu-jun, LI Lin, CHANG Sha

2017, 36(10):  2926-2932. 

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To explore groundwater environmental risk of watererosion sandy soil amended with municipal sewage sludge and further verify the feasibility of municipal sewage sludge as ameliorant to sandy soil, a saturated leaching test in simulated soil columns was carried out based on the improvement effect of sewage centrifugal dewatering sludge on sandy soil. Sewage centrifugal dewatering sludge was mixed with the sandy soil at a portion of 15% (wet weight) to prepare 0-20 cm soil layer. The quality of exudate was analyzed by means of saturated leaching, and its environmental risk to groundwater was assessed with the improved sandy soil as the surface soil. The results showed that nitrogen had a big, persistent risk. The proportion of nitrate nitrogen in total nitrogen was high. TN content was positively correlated with nitrate nitrogen content (r=0.997, P<0.01). Nitrosation happened in deep soil, greatly increasing the risk of nitrite nitrogen pollution of groundwater. Furthermore, the peak value of TP in exudate was 0.18 mg·L^-1, being about 2.6 times the control. The COD content was positively correlated with nitrite nitrogen and TP (r=0.630, P<0.05; r=0.677, P<0.05). The carbon source represented by COD was the main limiting factor affecting the risk of nitrite nitrogen and TP in groundwater; however, sludge hydrolysis and acidification reduced the pH of exudate and increased the exudate COD content, which further increased the risk to the groundwater. The peak value of COD in exudate was 46 mg·L^-1, being about 2.5 times the control. There was a positive correlation between pH and COD (r=-0.760, P<0.01). The risk of heavy metals to groundwater was higher at the end of the experiment, showing a certain delayed effect. The sandy soil improved with 15% proportion of municipal sewage sludge would have a somewhat environmental risk to the groundwater during the oversaturated leaching process. Thus, some certain pollution prevention and control measures should be taken to control the risk.

Risk assessment of harmful elements in rural road surface dust in vicinity of a coal mining area in southwest Guizhou, China.

Lü Ya-chao1, WANG Zhi-kang2, QIN Fan-xin1*, LI Ying-ju1, LI Xin-li1, Li Gang1

2017, 36(10):  2933-2942. 

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To evaluate the pollution of harmful elements (Cr, Cu, Zn, As, Cd, Pb and Ni) from road dust in vicinity of the coal mining area near rural area in southwest Guizhou Province, China, 36 dust samples in rural roads were collected. The leaching contents of harmful elements were quantitatively extracted by the method of toxicity characteristic leaching procedure (TCLP). Nemerow comprehensive pollution index (P) and Hkanson index were subsequently calculated to assess the ecological risk. The results showed that the TCLP leaching contents of the total harmful elements were in the range of 1.73%-21.12%. Nemerow comprehensive pollution index (P) results indicated that Pb was at heavy pollution level, As at moderate pollution level, Cr and Cu at mild pollution level, Cd and Zn at the alert level, and Ni at safety level. The potential ecological risk index (E_i) results manifested that Cd achieved strong ecological risk level, As was at the medium level, and other elements belonged to the slight ecological risk level. The total potential ecological risk index (RI) value reached 321.85, which indicated a strong potential of ecological risk. Furthermore, the SBET (simple bioaccessibility extraction test) method was used to evaluate bio-accessibility of harmful elements in the road dust samples, and human exposure risk assessment method adopted by the United States Environmental Protection Agency (USEPA) was used to estimate their health risk after oral intake. The results showed that the average bioavailability of harmful elements in dust were in the range of 7.32%-31.06%. For human health, total carcinogenic risk (TCR) indexes for children and adults were 5.91×10^-5 and 2.15×10^-5, respectively. The potential non-carcinogenic risk (HQ) index of the human body was not significant except for As. The total noncarcinogenic risk (HI) indexes of the harmful elements in road dusts for children and adults were 1.30 and 0.16, respectively, which may pose a potential non-carcinogenic hazard to children. In conclusion, the risk level of Pb, As and Cd in road dusts in rural areas investigated by this study was significant, and should be highly concerned.

Ecological relevance of the endpoints: A perspective of ecotoxicology from dissipative structure and hierarchy theory.

WANG Chang-you1,4*, WANG Zi-Yang2, ZHENG Jiang-peng3

2017, 36(10):  2943-2950. 

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In this paper, the dissipative structure and hierarchy theory are used to comprehend the endpoint of ecotoxicological effect. The hierarchical stability of dissipative structure produces the hierarchical structure of the life system, which is represented by a series of life levels. The pollution causes the fluctuation of the dissipative structure of the life system and interferes with the stability of a series of life organization, displaying a series of toxic effects on the organizations of life. The toxic effects at low levels provide a functional and developmental mechanism for that at high levels, and toxic effects at high levels are compatible with that at low levels. The endpoint at a certain life level that characterizes the toxicity of pollutants can be constructed from the endpoints at the low level, including the response of components at the low level and the response of their interactions to the pollutants. It also directly reflects the changes in components and their interactions. Furthermore, an endpoint can be involved in the construction of endpoint at a high level, becoming the toxic mechanism of life organization at the high level. However, it is difficult for an endpoint to reflect directly the changes of relationships among constituents at a high level. Therefore, the endpoint of the toxic effect has a hierarchical nature, and the endpoint at different levels has different ecological relevance. In order to characterize the effects of ecological toxicity at community level, we need to find the endpoint at the community level. Considering the discrete characteristics of complex system, we can divide the biological community into several holons that can be readily studied and observed following the principle of hierarchical decomposition. A multiscale hierarchical mechanism model that links the ecological toxicity mechanism of holons at community level to the ones at population level and below should be established. This model can provide a new way to establish the quantitative relationship between pollutant concentration and community effect, and can provide a more comprehensive and accurate way to understand and evaluate the ecological and environmental impacts of pollutants.

Process technologies and chemical-physical properties of seaweed extracts as well as their application in agriculture.

GENG Yin-yin, YIN Yuan-hong, SHEN Hong*

2017, 36(10):  2951-2960. 

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In order to adapt to marine environmental stresses, such as high salinity, high pressure, low temperature and less sunshine, seaweed plants accumulate many kinds of functional active substances in their tissues during growth process. These active substances play important roles in promoting crop growth and improving fruit quality, and enhancing the resistance to environmental stresses. In this paper, the advantages and disadvantages for the methods of physically ultrasonic crushing, chemical acid/alkaline hydrolysis, and complex enzymatic hydrolysis or microbial hydrolysis are discussed in detail according to the extraction technologies of seaweed extracts. It is pointed out that the combination of physical, chemical and biological hydrolysis is the best process for obtaining specific functional substances in seaweed. Meanwhile, the physiological functions of polysaccharides, polyphenols, phytohormones, and amino acid derivatives in seaweed are analyzed so as to explain the internal mechanism of seaweed extracts to promote crop growth. On this basis, the effects of seaweed extracts on soil remediation, root growth, flowering/fruit setting and stress resistance are emphatically discussed. Finally, some problems in the research and application as well as research directions regarding seaweed extracts are put forward.

Review on the structure and influencing factors of aquatic invertebrates in wetland ecosystems.

LU Kang-le1,2, WU Hai-tao1*, Lü Xian-guo1, CHEN Zhan-yan1,2, GUAN Qiang1

2017, 36(10):  2961-2970. 

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Wetlands are a special ecological complex with a variety of functions between terrestrial and aquatic systems. Aquatic invertebrates are an important group of biotic communities in wetland ecosystems and are important participants in wetland material cycling and energy flow. Their community characteristics and spatial distribution can reflect many characteristics of wetland. In this paper, we summarized the structure and influence factors of aquatic invertebrates, as well as the aquatic invertebrate composition, and the structural characteristics of aquatic invertebrates in different types of wetlands. We also discussed the influences of environmental factors including abiotic factors (e.g. sediment, temperature, hydrology, dissolved oxygen, pH, phosphorus and nitrogen, etc.), biotic factors (e.g. vegetation, competition and predation) and anthropogenic disturbances on community structure of aquatic invertebrates. Finally, we outlined the problems and the prospects of aquatic invertebrate research in wetland ecosystems.

Potential distribution modeling and analysis of Quercus phillyraeoides.

LI Ying1,2, JIANG Xiao-long2*, DENG Min2, LI Qian-sheng1*

2017, 36(10):  2971-2978. 

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Understanding the distribution characteristics and dynamics of the regional keystone species is important for biodiversity conservation and ecosystem recovery. Quercus phillyraeoides is a widespread woody species in East Asia subtropics evergreen broadleaved forest with important ecological functions and economic values. In this study, the current (1950-2000) and future (2060-2080) potential distribution patterns were analyzed using MaxEnt based on the 134 distribution sites of Q. phillyraeoides and 9 environmental variables. We also tested the effects of climate variables on the potential distributions of Q. phillyraeoides using percent contribution, permutation importance and Jackknife test. The current potential distribution of Q. phillyraeoides is mostly overlapped with its natural distribution. The most suitable areas are mainly located in East China, Southwest China and Japan. The precipitation in the warmest quarter and the maximum temperature of the warmest month are the two key factors of the potential distributions of Q. phillyraeoides. Its suitable distribution areas will decrease sharply when CO₂ concentration increases in future, especially those located in southeast coastal areas. The results could provide important information on future biodiversity conservation and ecosystem recovery of the evergreen broad-leaved forest under the background of global climate change.

Refined early-warning of tea frost disaster: A case study in Songyang county of Zhejiang.

LI Shi-rui1,2, WANG Zhi-hai1, JIN Zhi-feng1*, QIU Xin-fa2, SUN Rui3

2017, 36(10):  2979-2987. 

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Frost is one of the major climate disasters in tea production, affecting sustainable development of tea production. Based on the meteorological data of 70 basic weather stations in Zhejiang Province and 25 regional automatic stations in Songyang County, as well as Optimized Consensus Forecast  fine grid numerical prediction products and 30m resolution DEM data, a minimum air temperature model was established by GIS and mixed interpolation method. Taking daily minimum air temperature as tea frost damage warning index, combined with the map of tea plantation extracted from fineresolution ZY-3 satellite remote sensing data, a refined earlywarning method of tea frost disaster was studied. Results showed that the daily minimum air temperature model was of high accuracy with an absolute error of 0.35 ℃ and a relative error of 2.83%. The frost damage warning effectiveness was 8 days in advance and the spatial resolution was 30 m×30 m. Taking the tea frost disaster warning on March 15, 2017 as an example, the preestimated area of affected tea plantation was 2340.0 ha, accounting for 30.6% of the total tea area in the county. The mildly, moderately and severely affected areas were 1939.4, 367.2 and 34.9 hm², which accounted for 25.35%, 4.08% and 0.46% of the county’s total tea area, respectively. The estimation was consistent with the field investigation.

Feasibility and technical design for enhancing habitat connectivity across two separated components in Shennongjia World Natural Heritage Site, China.

ZHOU You-bing, XU Wen-ting, ZHAO Chang-ming, SHEN Guo-zhen, XIONG Gao-ming, FAN Da-yong, XIE Zong-qiang*

2017, 36(10):  2988-2996. 

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A key topic in biodiversity and ecosystem conservation is how to enhance the connectivity of isolated and fragmented habitats, enabling the effective exchange of wildlife to maintain ecosystem functionality. Shennongjia is a World Natural Heritage Site with an exceptionally rich biodiversity supporting unique ecological and biological processes, which provides an outstanding example of pristine subtropical highelevation ecosystem. Unfortunately, the Site is split into two parts. The distance separating the two parts ranges from 3.0 to 13.4 km, and a fenced National Road 209 runs through the jointed area between two parts. This study compiled previous literature and conducted additional field surveys to assess the feasibility of enhancing connectivity between the two components comprising Shennongjia Heritage Site, and proposed specific schemes for implementation. Vegetation covers over 97% of the jointed area, facilitating the development of wildlife corridors or stepping stones across this buffer zone. To achieve sufficient connectivity between the two parts to ensure consistent ecosystem functionality and resilience, we propose that two strip corridors, four stepping stones, four wildlife overpass crossings and 45% roadfence dismantlement will be required. With completion of this strategic scoping study, it is now crucial to establish a detailed timeframe to implement this initiative as soon as possible. Furthermore, we advocate that construction methods and materials should be responsible to the environment and be subject to continuous monitoring and regulation by the administrating authorities.