Chinese Journal of Applied Ecology

Spatio-temporal characteristics of the expansion of poplar plantation in West Dongting Lake wetland, China.

JING Lei, LYU Cai, ZHOU Yan, ZUO Ao-jie, LEI Guang-chun

2016, 27(7): 2039-2047. doi:10.13287/j.1001-9332.201607.025

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The rapid expansion of poplar plantation and its impacts on the wetland ecosystem have become a critical issue in West Dongting Lake ecosystem management. In the study, we explored the spatio-temporal characteristics of poplar plantation distribution in West Dongting Lake from 2000-2014 using Landsat imagery, topographic and hydrological data. Results showed that the area of the poplar plantation increased from 3233.5 hm² to 10915.6 hm² during the period of 2000 to 2011 (i.e. mean growth rate was 698.4 hm²·a^-1), and the highest growth rate happened during the period of 2004 to 2007 (1000.6 hm²·a^-1). Then, from 2011 to 2014, the expansion rate recorded a net loss, with the total poplar plantation area decreasing to 10153.1 hm² in 2014. Reed marsh, open water and mudflat, and wet meadows contributed to the expansion of poplar plantation, which accounted for 41.8%, 37.0% and 21.2%, respectively. Failure policy incentives, as well as the market need for economic interests were the key drivers of the popular plantation expansion, and meanwhile, operation of the Three Gorges Dam that lowered down the flooding water level, as well as the sediment deposition within the lake bed offered favorable environment for popular tree growth. The project of “returning forest to wetland” after 2013 was the main reason for the decreased poplar plantation area in 2014.

Sapflow characteristics of Kandelia obovata and their controlling factors in Zhangjiang estuary, China.

YAN Guang-yu, FENG Jian-xiang, YANG Sheng-chang, LIN Guang-hui

2016, 27(7): 2048-2058. doi:10.13287/j.1001-9332.201607.024

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In this study, the Grainer’s thermal dissipation probe method was applied to monitor sap flux density (SFD) of a mangrove species Kandelia obovata over a period of one year (2010-10—2011-10) in Zhangjiangkou Mangrove National Nature Reserve, Fujian, China. The results showed that both season and diameter class exerted significant effects on the SFD of K. obovata trees. In summer, when the diameter at breast height (DBH) reached 8-10 cm, the highest SFD was found at a depth of 2 cm with a value of 38.21 g·m^-2·s^-1, which was comparable with those for other mangrove tree species and forested wetland tree species. The mean whole tree transpiration (i.e. daily water use) of all stem size classes demonstrated large changes from winter to summer, increased from 0.14 to 0.19 kg·d^-1 in small trees (S, DBH=2-4 cm), from 0.94 to 1.45 kg·d^-1 in medium trees (M, DBH=4-8 cm) and from 1.96 to 3.43 kg·d^-1 in large ones (L, DBH=8-10 cm). The daily transpiration of K. obovata stand was calculated by summing all size classes, which was then summed up for entire year to estimate annual transpiration of entire K. obovata forest, which was about 100.38 mm, less than 6% of local annual precipitation. Key environmental factors all had significant effects (all P<0.001) on the stand transpiration rate (E_s) of K. obovata forest, and photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) were the main driving factors, which explained 60%-92% seasonal variation of E_s. The PAR and VPD had larger effects on the E_s in summer than that in winter. In addition, we observed an obvious time lag phenomenon in the relationship between E_s and PAR or VPD, which should be taken into account when explaining seasonal variation of E_s in K. obovata forest.

Vegetation carbon stocks and net primary productivity of the mangrove forests in Shenzhen, China.

PENG Cong-jiao, QIAN Jia-wei, GUO Xu-dong, ZHAO He-wei, HU Na-xu, YANG Qiong, CHEN Chang-ping, CHEN Lu-zhen

2016, 27(7): 2059-2065. doi:10.13287/j.1001-9332.201607.029

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Mangroves are the most important coastal blue carbon sinks. The accurate estimation on the carbon sequestration capacity of plant communities would guide the mangrove conservation, afforestation and management. This study investigated the vegetation carbon stocks of dominant mangrove communities, which were Avicennia marina, Kandelia obovata, Sonneratia caseolaris, and Sonneratia apetala in Futian Nature Mangrove Reserve in Shenzhen, Guangdong Province of China. Vegetation carbon stock consisted of living trees (aboveground and belowground biomass), understory, pneumatophore, standing dead trees, fallen dead trees and litter in these communities. The net primary productivity (NPP) was calculated from the litterfall and incremental growth in the same year of each community. Our results showed that the vegetation carbon stocks for A. marina, K. obovata, S. caseolaris, and S. apetala communities were 28.7, 127.6, 100.1, and 73.6 t C·hm^-2, and the NPP were 8.75, 7.67, 9.60, and 11.8 t C·hm^-2·a^-1, respectively. Therefore, acting as urban forests, Futian mangroves in Shenzhen assimilated about 4000 t CO₂·a^-1. These results provided guidance for mangrove blue carbon assessment, and theoretical basis for the construction of coastal carbon sequestration forests in China.

Diversity of culturable endophytic fungi of common reed (Phragmites australis) in coastal wetland.

LI Hai-lin, MA Bin, ZHANG Xiao-li, ZHANG Qian-qian, GUO Xiao-hong, FAN De-peng, GONG Jun

2016, 27(7): 2066-2074. doi:10.13287/j.1001-9332.201607.014

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Endophytic fungi play an important ecological role in promoting growth and alleviating environmental stress of host plants. In this study, we investigated the diversity and community composition of endophytic fungi isolated from the common reed in wetlands of the Yellow River Delta. A total of 318 endophytic fungal isolates were obtained from 1350 tissue (leaf, stem, and root) fragments and from three tidal zones with different soil salinity levels. rDNA ITS regions of these isolates were PCR amplified, sequenced, and phylogenetically analyzed. All the sequences were divided into 12 operational taxonomic units (OTUs) at the 98% similarity threshold. Ascomycota was found to be the most abundant flora at the level of the phylum and distributed in all tissues and sites. There were generally richer OTUs in roots than in leaves and stems, and leaves and stems shared the same OTU numbers. All the OTUs retrieved from leaves appeared in roots. The supra tide (low salinity zone) had the most OTUs among the three sampling sites, followed by high tide. Furthermore, the roots had the highest richness and diversity, whereas the leaves had the lowest; supra tide held the highest richness, and the middle tide had the highest diversity. Although unique OTUs could be found in different tissues and tidal zones of different salinity, the communities of culturable endophytic fungi were not substantially different among tissues or tidal zones (ANOSIM, P>0.05). Alternaria sp. was the shared dominant taxa among all samples.

Temporal and spatial distribution of soil organic carbon and its storage in the coastal wetlands of Jiaozhou Bay, China.

ZI Yuan-yuan, XI Min, KONG Fan-long, LI Yue, YANG Ling

2016, 27(7): 2075-2083. doi:10.13287/j.1001-9332.201607.004

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This study selected four typical types of wetlands around Jiaozhou Bay including Spartina anglica wetland, the barren wetland, Suaeda glauca wetland and Phragmites australis wetland, to analyze and compare the contents of soil organic carbon (SOC) and their stock with seasonal and vertical variations. The results showed that the SOC contents of S. anglica wetland, S. glauca wetland and P. australis wetland all decreased with the increasing soil depth except that the concentration of SOC in the barren wetland showed a decreasing trend first, and then increased slightly along the soil profile. S. anglica wetland ranked first in SOC content, followed by the barren wetland, S. glauca wetland and P. australis wetland. Seasonally, the SOC contents in Jiaozhou Bay coastal wetlands were in an order of spring>summer>autumn>winter. Correlation analysis demonstrated that SOC content was positively correlated with soil salinity, moisture content, TN and C/N. Negative relationships were observed between SOC content and pH, and between SOC content and soil bulk density. The carbon densities of soil profile were in a decreasing order of the barren wetland, P. australis wetland and S. glauca wetland. There were some differences in the distributions of SOC and carbon density among the various types of wetlands. The barren wetland had a significant higher value for carbon stock per unit area than P. australis wetland and S. glauca wetland due to the differences in carbon density and thickness of carbon storage layer, playing a significant role in the carbon sink process of coastal wetlands.

Water purification of four aquatic plant species with the presence of iron-carbon interior electrolytic substrates.

ZONG Xiao-xiang, MIN Meng-yue, SUN Guang-fang, LI Ning, AN Shu-qing, LENG Xin

2016, 27(7): 2084-2090. doi:10.13287/j.1001-9332.201607.037

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To compare water purification of common aquatic plants in wetland ecosystem, four common aquatic plant species (Eichhornia crassipes, Nymphaea tetragona, Acorus calamus and Phragmites australis) were used as study species. The effect of aquatic plants on the change of sewage ammonium nitrogen, COD, TP content during different experimental time (1-5 d) with the presence of iron-carbon interior electrolytic substrates were analyzed in small scale experimental apparatus. The results showed that single and combined aquatic plants could effectively remove ammonium nitrogen, COD, TP from the sewage compared with the no-plant control group, but the efficiencies were significantly different among the different species. Ammonium nitrogen removal up to 100% was achieved with E. crassipes in two days, and A. calamus in three days. Each plant combination performed well on ammonium nitrogen removal. Concentration of the sewage COD approached zero with E. crassipes in three days, A. calamus performed secondly. The concentration of COD in combination of E. crassipes and A. calamus water decreased by 85.1% to a minimum of 4.33 mg·L^-1. The concentration of TP was the lowest with E. crassipes in four days, and second with P. australis. The lowest concentration of TP was found with the combination of E. crassipes and A. calamusin two days. The combination effect of interior electrolyte and plant was better than that of pure interior electrolyte on the purification of sewage. Plant configuration should be optimized according to the level of pollutants.

Effect of environmental and biotic factors on net ecosystem CO₂ exchange over a coastal wetland in the Yellow River Delta.

CHU Xiao-jing, HAN Guang-xuan, ZHU Shu-yu, LYU Juan-zhang, YU Jun-bao

2016, 27(7): 2091-2100. doi:10.13287/j.1001-9332.201607.010

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Using the eddy covariance technique, we measured the net ecosystem CO₂ exchange (NEE) and its environmental and biotic factors over a coastal wetland in the Yellow River Delta to investigate the diurnal and seasonal variation in NEE and quantify the effect of environmental and biotic factors on NEE. The results showed that the diurnal change of NEE showed a distinct U-shaped curve during the growing season, but not with substantial variation in its amplitude during the non-growing season. During the growing season, the wetland acted as a significant net sink for CO₂, while it became carbon source during the non-growing season. On the scale of a whole year, the wetland functioned as a strong carbon sink of -247 g C·m^-2. Daytime NEE was mainly dominated by photosynthetically active radiation (PAR). Apparent quantum yield (α) and daytime respiration of ecosystem (R_eco,d) reached maximum in August, while maximum photosynthesis rate (A_max) reached its maximum in July. Nighttime NEE had an exponential relationship with air temperature (T_a). The mean value of temperature sensibility coefficient (Q₁₀) was 2.5, and it was positively related to soil water content (SWC). During the non-growing season, NEE was negatively correlated with net radiation (R_n), but not with other environmental factors significantly. However, during the growing season NEE was significantly correlated with R_n, T_a, soil temperature at 10 cm depth (T_{s 10}) and leaf area index (LAI), but not with aboveground biomass (AGB). Stepwise multiple regression analysis indicated that R_n and LAI explained 52% of the variation in NEE during the growing season.

Construction and analysis of the EWE model of the wetland ecosystem in lake buffering zone of Zhushan Bay, China.

XIAN Yi, YE Chun, LI Chun-hua, WANG Yan-hua

2016, 27(7): 2101-2110. doi:10.13287/j.1001-9332.201607.011

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Lake buffering zones play a special role in spatial arrangement of the lake watershed, and the wetland in buffering zones also is of great significance in basin ecological health and lake water environmental quality. Taking Zhushanhu wetland ecosystem in the area of lake buffering zone of Zhushan Bay, Lake Taihu as the research object, the biotic components were divided into 16 functional groups to construct the Ecopath with Ecosim (EWE) model, and the characteristics and state of the ecosystem and the interrelation between the functional groups were analyzed. The results showed that the range of effective trophic level in Zhushanhu wetland ecosystem was 1-3.72, tro-phic flows were mainly concentrated in the first 4 trophic levels, and most of the food chains started from submerged plants and detritus. The total energy conversion efficiency of the wetland ecosystem was 5.1%, being lower than the "1/10 law", indicating that the current energy conversion efficiency was low. The average transmission efficiency of material throughput in the ecosystem was 4.3%. The sum of all production in the ecosystem was 2496.66 t·km^-2·a^-1, and the total system throughput was 10145.2 t·km^-2·a^-1. The characteristic parameters of ecosystem showed that the current ecosystem was at the immature stage.

Community characteristics in Qingyihe River basin of Xuchang section and their relationships with environmental factors.

MIN Meng-yue, ZONG Xiao-xiang, DUAN Yi-fan, LI Ning, LENG Xin

2016, 27(7): 2111-2118. doi:10.13287/j.1001-9332.201607.031

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We took Xuchang section of Qingyihe River Basin as study object to explore biodiversity in Qingyihe River. On the basis of field survey and in-laboratory analysis, community characteristics of aquatic macrophytes, riparian zone plants and macrobenthos, with environmental characteristics of water and surface sediment were investigated. Results showed that a total of 12 species of aquatic macrophytes, 66 species of riparian zone plants, and 10 species of macrobenthos were found. The communities varied sharply with the changes in the environmental factors, such as NH₄⁺-N, TN, TP in the water and oxidation-reduction potential (ORP), TP, Cd, Hg, Zn in the surface sediment. The CCA ordination results indicated that COD, temperature, pH, DO, TP in the water were key factors influencing aquatic macrophytes, while ORP, pH in the water and Ni, Hg, TOC, Pb, Cd in the surface sediment were key factors for riparian zone plants. pH, temperature, ORP, As, Pb, Ni in the surface sediment and temperature in the water were the key factors influencing community characteristic of macrobenthos. In Qingyihe River basin of Xuchang section, the water had been polluted and the biodiversity of communities was low, so it is urgent to treat wastewater along the river as well as protect and recover communities.

Scale effect of Nanjing urban green infrastructure network pattern and connectivity analysis.

YU Ya-ping, YIN Hai-wei, KONG Fan-hua, WANG Jing-jing, XU Wen-bin

2016, 27(7): 2119-2127. doi:10.13287/j.1001-9332.201607.006

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Based on ArcGIS, Erdas, GuidosToolbox, Conefor and other software platforms, using morphological spatial pattern analysis (MSPA) and landscape connectivity analysis methods, this paper quantitatively analysed the scale effect, edge effect and distance effect of the Nanjing urban green infrastructure network pattern in 2013 by setting different pixel sizes (P) and edge widths in MSPA analysis, and setting different dispersal distance thresholds in landscape connectivity analysis. The results showed that the type of landscape acquired based on the MSPA had a clear scale effect and edge effect, and scale effects only slightly affected landscape types, whereas edge effects were more obvious. Different dispersal distances had a great impact on the landscape connectivity, 2 km or 2.5 km dispersal distance was a critical threshold for Nanjing. When selecting the pixel size 30 m of the input data and the edge wide 30 m used in the morphological model, we could get more detailed landscape information of Nanjing UGI network. Based on MSPA and landscape connectivity, analysis of the scale effect, edge effect, and distance effect on the landscape types of the urban green infrastructure (UGI) network was helpful for selecting the appropriate size, edge width, and dispersal distance when developing these networks, and for better understanding the spatial pattern of UGI networks and the effects of scale and distance on the ecology of a UGI network. This would facilitate a more scientifically valid set of design parameters for UGI network spatiotemporal pattern analysis. The results of this study provided an important reference for Nanjing UGI networks and a basis for the analysis of the spatial and temporal patterns of medium-scale UGI landscape networks in other regions.

Relationship between land surface temperature and land cover types based on GWR model: A case of Beijing-Tianjin-Tangshan urban agglomeration, China.

WANG Jia, QIAN Yu-guo, HAN Li-jian, ZHOU Wei-qi

2016, 27(7): 2128-2136. doi:10.13287/j.1001-9332.201607.008

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We used land cover data derived from Landsat thematic mapper (TM) and land surface temperature (LST) data from moderate-resolution imaging spectro-radiometer (MODIS) satellite images to study the variations in LST in July of different land cover types in Beijing-Tianjin-Tangshan urban agglomeration. Ordinary linear regressions (OLS) models and geographically weighted regressions (GWR) models were used to investigate the relationships between the proportions of land cover types and LST. The results showed that great variations in LST occurred among different land cover types. The average LST ranged from high to low in the order of developed land (40.92±3.49 ℃), cultivated land (39.74±3.74 ℃), wetland (35.42±4.33 ℃), and forested land (34.43±4.16 ℃). The proportions of land cover types were significantly related to LST, but with spatial non-stationarity. This might be due to inherent difference in land cover across locations, and the surrounding environments. GWR models had higher R² values, compared to OLS, indicating better model performance. In addition, GWR models could reveal the spatial non-stationarity of the relations between LST and the proportions of different land cover types.

Impacts of population spatio-temporal dynamics on ecosystem quality during fast urbanization in Beijing, China.

WANG Kun, ZHOU Wei-qi, LI Wei-feng

2016, 27(7): 2137-2144. doi:10.13287/j.1001-9332.201607.009

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The spatio-temporal dynamics of population and its impact on the regional ecosystem quality in Beijing were analyzed at city-county-township hierarchical levels during 2000 to 2010, based on the 5^th and 6^th population census data and MODIS-NDVI thematic data. We found that the resident population of Beijing increased by 43.9% during the study period, and the trend of population gathering to the urban fringe resulted in an obviously circular distribution. The annual maximum NDVI of Beijing had the trend of increase, however, decreased significantly between the 5^th Ring and the 6^th Ring. The change trends of NDVI in urban and exurban areas showed significantly negative relationships with the change ratios of population density, respectively. The increment of urban population caused by urbanization did not show negative influence on the regional ecosystem quality of Beijing. On the contrary, the ecosystem quality in urban core and exurban areas was improved, due to the adjustment of city functions and the population transfer from rural to urban area. Therefore, the functional orientation and development mechanism were the main contribution to the evolution of population pattern and its ecological impacts.

Multi-scale effects of landscape heterogeneity on pollinators’ diversity in the middle and lower reaches of the Yellow River: A case study in Gongyi, Henan, China.

WANG Run, DING Sheng-yan, LU Xun-ling, SONG Bo

2016, 27(7): 2145-2153. doi:10.13287/j.1001-9332.201607.020

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Eco-services provided by non-agricultural organisms are the basis of ecosystem to keep its stability in agricultural landscapes. With the strengthening of agricultural intensification, the ongoing loss of biodiversity is one of the most extrusive issues in the development of modern agriculture. In this paper, the study area was set up in Gongyi County, a typical agricultural region in the middle and lower reaches of the Yellow River. According to its typical topography (mountain-hilly-plain) type, we explored the effects of landscape heterogeneity on the diversity of pollinators at three different scales, which were geomorphic categories, landscape and habitat. Pan traps were used to obtain pollinators in this study. The effects of agricultural landscape heterogeneity at multi-scales on the diversity of pollinators were analyzed by using multivariable ANOVA. The results showed that a total of 67012 pollinator individuals that belonged to 86 classes and 7 subjects were classified. The dominant groups inclu-ded Syrphidae and Anthomyiidae. The common groups included Drosophilidae, Calliphoridae, Bombyliidae, Pipunculidae, Cantharidae, Cynipidae, Vespidae, Chalalcididae, Megachilidae and Apidae. Geomorphic categories showed the most significant impact on pollinators (P<0.001), suggesting that hilly and mountainous areas were the pollinators’ ground of nectar. It was followed by habitat scale (P<0.05), with non-significant effect on the scales of landscape and the interaction between scales. The effect of landscape heterogeneity on the diversity of pollinators in hilly and mountainous areas provided a theoretical support for landscape planning and biodiversity conservation on the local area with different geomorphic categories.

Effects of landscape heterogeneity on the availability of amphibians’ habitats in agricultural region on the lower reaches of the Yellow River, China.

ZHANG Li, LIANG Guo-fu, GUO Hao-jie, LI Cheng-xi, SUN Bo-lin, LU Xun-ling, DING Sheng-yan

2016, 27(7): 2154-2160. doi:10.13287/j.1001-9332.201607.018

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SelectingFengqiu County in Henan Province, a typical region of the lower Yellow River, as the study area, adopting the analysis method of graph theory, with the support of geographic information systems (GIS) and R software, we analyzed the effects of landscape composition and landscape configuration, the mean pond size (MS), the number of ponds (NP), and distance to the nearest roads (DR), on habitat availability of amphibian species under different levels of dispersal ability (250, 500, 1000 and 2000 m), by referring the probability index of connectivity (PC) and the important value of patches (percentage of the variation in PC, dPC_k) to the degree of availability of ponds for amphibians’ breeding. The results indicated that the ponds availability for amphibians’ breeding was closely related to MS, NP, and DR. Therein, MS and NP were the key factors determining the availability of ponds under the dispersal ability of 250 m, and then MS and DR were the most significant influencing factors on pond availability under the dispersal ability of 500 m. However, under the high dispersal ability (1000 and 2000 m), MS and NP were the most important factors determining the availability of ponds. Therefore, with regard to the protection of amphibian species and their habitats in plain agricultural landscape, the number, mean size, and distances to the nearest roads of ponds should be taken into full consideration.

Research progress of ecosystem service flow.

LIU Hui-min, FAN Yu-long, DING Sheng-yan

2016, 27(7): 2161-2171. doi:10.13287/j.1001-9332.201607.005

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With the development of social economy, human disturbance has resulted in a variety of ecosystem service degradation or disappearance. Ecosystem services flow plays an important role in delivery, transformation and maintenance of ecosystem services, and becomes one of the new research directions. In this paper, based on the classification of ecosystem services flow, we analyzed ecosystem service delivery carrier, and investigated the mechanism of ecosystem service flow, including the information, property, scale features, quantification and cartography. Moreover, a tentative analysis on cost-effective of ecosystem services flow (such as transportation costs, conversion costs, usage costs and cost of relativity) was made to analyze the consumption cost in ecosystem services flow process. It aimed to analyze dissipation cost in ecosystem services flow process. To a certain extent, the study of ecosystem service flow solved the problem of “double counting” in ecosystem services valuation, which could make a contribution for the sake of recognizing hot supply and consumption spots of ecosystem services. In addition, it would be conducive to maximizing the ecosystem service benefits in the transmission process and putting forward scientific and reasonable ecological compensation.

Branch quantity distribution simulation for Pinus koraiensis plantation in Heilongjiang Pro-vince, China.

ZHENG Yang, DONG Li-hu, LI Feng-ri

2016, 27(7): 2172-2180. doi:10.13287/j.1001-9332.201607.021

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Based on the measurement of 955 branch samples of 65 Korean pine (Pinus koraiensis) trees in 12 plots from Mengjiagang forest farm, Heilongjiang Province, and by using Poisson model and negative binomial model, the second-order branch count models for Korean pine were developed in this paper. AIC, Pseudo-R², RMSE and Vuong test were selected to compare the goodness-of-fit statistics of the models. The results indicated that the first-order branch count in a whorl was 3 to 5, with mean value of 4, and the first-order branch count in a whorl for Korean pine plantation associated with its own characteristics. The second-order branch count of the first-order standard branch had a large discrete degree. All subset regression techniques were used to develop the second-order branch count model. The negative binomial regression model E(Y)=exp(β₀+β₁lnRDINC+β₂RDINC²+β₃HT/DBH+β₄CL+β₅DBH) was selected as the optimal second-order branch count model (β represented the parameter, RDINC represented the relative depth into crown from tree apex, HT represented the total tree height, DBH represented the tree diameter at breast height, CL represented the crown length). Pseudo-R² of the optimal model was 0.79, the mean error was close to 0 and the mean absolute error was less than 7. For the developed model, the parameter values of lnRDINC, CL and DBH were negative, and the parameter values of RDINC² and HT/DBH were positive. With the increase of RDINC, the number of second-order branch had a peak value in the tree crown. On the whole, the precision of the second-order branch count model for Korean pine plantation was 96.4%, which would be suitable for predicting the second-order branch count for the study area and provide a theoretic basis for branch photosynthesis and biomass research.

Effects of conversion of evergreen broad-leaved forest to Chinese chestnut plantation on soil organic carbon pools.

YUE Tian, LI Yong-fu, XIAO Yong-heng, LI Yong-chun, HE Jie, JIANG Pei-kun, ZHOU Guo-mo, LIU Juan

2016, 27(7): 2181-2188. doi:10.13287/j.1001-9332.201607.035

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Converting natural forests to plantations significantly affects the characteristics of soil organic carbon (C) pools, due to the changes of vegetation cover and management practices. In this paper, to investigate the effects of conversion from evergreen broad-leaved forest (EBF) to Chinese chestnut plantation (CP) on soil organic C pool, the soils from surface (0-20 cm) and subsurface (20-40 cm) layers were sampled from the above two forests (the CP was converted from the EBF and had been intensively managed for 10 years) in Lin’an City, Zhejiang Province. The soil orga-nic C storage, labile organic C pools, and other basic soil properties were determined. The chemical composition of soil organic C was determined by nuclear magnetic resonance (NMR) technique. Results showed that the soil organic C storage, water soluble organic C (WSOC), hot water soluble organic C (HWSOC), microbial biomass C (MBC) and readily oxidizable C (ROC) concentrations in the surface layer decreased by 19.7%, 34.4%, 25.8%, 30.4% and 25.2%, respectively, after the conversion from EBF to CP. Such values for the subsurface layers decreased by 13.5%, 38.4%, 19.8%, 34.1% and 22.2%, respectively. The O-alkyl C content, aromatic C content and aromaticity of soil organic C in the surface layer decreased signi-ficantly by the land-use conversion, while alkyl C content, carbonyl C content and alkyl C to O-alkyl C (A/O-A) ratio increased signi-ficantly. The O-alkyl C content of soil organic C in the subsurface layer decreased significantly by the land-use conversion, alkyl C content and A/O-A ratio increased significantly, and aromatic C content, carbonyl C content and aromaticity of soil organic C were not changed. In conclusion, conve-rting EBF to CP and subsequent intensive management significantly decreased the soil organic C sto-rage and labile C pool contents and altered the chemical composition of soil organic C.

Effects of nitrogen addition on microbial respiration and root respiration in a sandy grassland.

LIN Li-tao, SUN Xue-kai, YU Zhan-yuan, WANG Ke-lin, ZENG De-hui

2016, 27(7): 2189-2196. doi:10.13287/j.1001-9332.201607.012

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Soil respiration includes root respiration and microbial respiration. Effects of nitrogen addition on root respiration and microbial respiration may be quite different. We examined the effects of N-addition on the releasing of soil CO₂ and the responses of root respiration and microbial respiration in a Keerqin sandy grassland, Northeast China. Results showed that both soil respiration and microbial respiration firstly rose then declined during the growing season (May to October). Microbial respiration was the main contributor of soil respiration, accounting for 82.6%. Contribution rate of root respiration altered with months, peaking in May (49.4%) and August (41.9%), with an average contribution rate of 17.4% during the growing season. Root respiration (with a decrease of 17.7%) was more sensitive to N-addition compared with microbial respiration (with a decrease of 3.9%) at 10 ℃. N-addition increased Q₁₀ values of soil respiration and microbial respiration, and enhanced their sensitivity to soil water content variation.

Spatial distribution and scale effect of species diversity of secondary forests in montane region of eastern Liaoning Province, China.

DEND Li-ping, BAI Xue-jiao, QIN Sheng-jin, WEI Ya-wei, ZHOU Yong-bin, LI Lu-lu, NIU Sha-sha, HAN Mei-na

2016, 27(7): 2197-2204. doi:10.13287/j.1001-9332.201607.022

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With secondary forest in the montane region of eastern Liaoning Province as research object, this paper analyzed the spatial distribution and scale effect of Gleason richness index, Simpson dominance index, Shannon diversity index and Pielou evenness index in a 4 hm² plot. The results showed that spatial distributions of the four diversity indices showed higher spatial heterogeneity. Variance of the four diversity indices varied with increasing scale. Coefficients of variation of the four diversity indices decreased with increasing scale. The four diversity indices of the tree layer were higher than those of the shrub layer, and the variation tendency varied with increasing scale. The results indicated that sampling scale should be taken into account when studying species diversity in the montane region of eastern Liaoning Province.

Analysis of reproductive ecological factors of endangered Rhodiola gannanica.

WANG Ke-peng, DONG Bo, WANG Yan-wu, LIU Ya-nan

2016, 27(7): 2205-2211. doi:10.13287/j.1001-9332.201607.040

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To find effective ways for protecting and recovering an endangered species Rhodiola gannanica in Gannan, an important distribution region of this species in the eastern Tibetan Plateau of China, the breeding system, reproductive process, flowering phenological characteristics and other reproductive controlling factors were investigated. The results showed that there was a unique breeding system in R. gannanica, which was dioecious, and male flowers were also bisexual plants in the early stage of flower bud differentiation. While the sac of pistil was aborted in a certain stage with the development of flowers, the bisexual plants only played the role of males’ functions. The outcrossing reproduction was observed, the pollination mode was mainly by wind, and the population flowering occurred in the season with abundant precipitation and high temperature. The bud satge appeared in early June, the florescence was in mid-June, and the flourishing florescence was in early July. The flo-wering duration of R. fastigiata was about 36 d, and the fruit ripening began in late August. The flo-wering time and the flowering duration of the bisexual plants were earlier than female plants. Due to the low pollination rate of the female plants, the buds and ovules were damaged and the 1-3 years young plants barely got flowering and fruiting, the rate of flowering and fruiting of the community only reached 11.0% and the rate of seed natural propagation was low (about 2.0%). 20.0%-25.1% buds of female plants were damaged from bud to flowering stages. 51.1%-65.0% flowers were aborted from flowering to fruiting stages. Only 10.1%-21.0% of ovules developed into seeds. The seed production of per female plant was 158.1, seed germination rate was 81.5% under artificial conditions, and seedling survival rate reached 36.0% in the first year. Our results revealed that seed quality was not the key ecological factor, while it was the pollen limitation, low seed production and the survival rate of seedling that resulted in the reproductive success and species endangered situation.

Dynamics and prediction models of ground surface dead fuel moisture content for typical stands in Great Xing’an Mountains, Northeast China.

HU Hai-qing, LU Xin, SUN Long, GUAN Dao

2016, 27(7): 2212-2224. doi:10.13287/j.1001-9332.201607.007

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The fuel moisture content dynamics of mixed forest of Populus davidiana-Betula platyphylla, Larix gmelinii, Pinus sylvestris var. mongolica, mixed forest of L. gmelinii-B. platyphylla, B. platyphylla at different slope positions in spring and autumn were investigated in Xilinji Forestry Bureau ofthe Great Xing’an Mountains region. The moisture content prediction models of different stands in different seasons were established and the predicted errors were analyzed.The results showed that the fuel moisture content in the same stand varied with slope position. The mean absolute error of Nelson model (0.13) was lower than that of Simard model (0.14), and was significantly lower than that of meteorological element regression model (0.25). The prediction accuracy of the autumn model was higher than the spring model and spring-autumn mixed model.

Variations in leaf C, N, P stoichiometry of Quercus acutissima provenance forests.

ZHANG Hui, GUO Wei-hong, YANG Xiu-qing, HAN You-zhi, YU Mu-kui, WU Tong-gui

2016, 27(7): 2225-2230. doi:10.13287/j.1001-9332.201607.001

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In order to explore the variations in leaf stoichiometry based on the method of forest tree breeding, we determined the leaf carbon (C), nitrogen (N), phosphorus (P) stoichiometry among 29 Quercus acutissima provenances grown at 3 sites. The results indicated that the site (environment) effect was statistically significant on leaf stoichiometry, with 13.2%-66.7% of the total variations accounted for leaf C, N, P, C/N, C/P and N/P, while the provenance effect was insignificant and only accounted for 2.9%-11.0% of total variations for leaf stoichiometry. The leaf N and C/N, N and N/P, P and C/P, P and N/P were significantly correlated, and the common standardized major axis slope was also observed among three sites and two provenance groups. It could be concluded that the leaf stoichiometry of Q. acutissima, was mainly determined by its growing environment, due to the similar C, N and P biochemical pathways at species level. The stable correlation coefficients among sites and provenances implied the coupling ratios of leaf stoichiometry were independent of environment and provenance, which supported the leaf stoichiometric homeostasis.

Response of plant leaf traits to grazing intensity in Stipa krylovii steppe.

Daorina, SONG Yan-tao, Wuyunna, HUO Guang-wei, WANG Xiao-meng, XU Zhi-chao

2016, 27(7): 2231-2238. doi:10.13287/j.1001-9332.201607.034

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Grazing disturbance is one of the ways to influence plant traits, and plant leaf traits actually reflect the adaptability of plants to the environment. In this study, taking Stipa krylovii steppe under different grazing intensities in Hulunbuir as research area, the relationships of leaf traits and the variation of plant traits among plant life-form functional groups was investigated. Results showed that plant traits with different life-forms had no significant difference in S. krylovii steppe. However, the relationships between plant traits were strongly correlated. The leaf phosphorus content (LPC) and the ratio of nitrogen and phosphorus (N/P) in the heavy grazing treatment had significant difference from those in the moderate grazing and the light grazing treatments. For different life-form functional groups, grazing disturbance had significant effect on LPC and N/P in the perennial forbs, indicating the perennial forbs were sensitive to grazing, and the plant nutrient utilization strategy was changed by heavy grazing. It was suggested that reasonable grazing could improve the nutrient traits of plants and restrain the degradation in S. krylovii steppe.

Ecological stoichiometry of surface soil nutrient and its influencing factors in the wild fruit forest in Yili region, Xinjiang, China.

TAO Ye, ZHANG Yuan-ming, ZHOU Xiao-bing

2016, 27(7): 2239-2248. doi:10.13287/j.1001-9332.201607.002

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Soil samples and environmental factors in 60 plots of 20 communities in the wild fruit forest in Yili valley were investigated, and then the stoichiometric characteristics of soil organic carbon (C), total nitrogen (N), total phosphorus (P) and total potassium (K) in 0-10 cm and 10-20 cm layers and their influencing factors were studied. The results showed that soil C, N, P and K contents in 0-10 cm layer were 73.15, 7.00, 1.14 and 14.74 g·kg^-1, respectively. Soil C:N, C:P, C:K, N:P, N:K and P:K were 10.37, 62.73, 5.05, 6.05, 0.48 and 0.08, respectively. Except for K and C:N, the stoichiometric values in 0-10 cm layer were significantly higher than that in 10-20 cm layer. Soil P, K, C:N and P:K presented high stability (CV=8%-24%), while others showed moderate variability (CV=28%-46%). Soil nutrient contents and their stoichiometric ratios differed markedly in different sampling sites, communities and slope aspects. Except the power relationship between C and N, all the soil nutrient contents and their stoichiometric ratios represented quadratic relationships, indicating nonlinear coupling among soil stoichiometric traits. Slope aspect, precipitation and temperature were the main factors influencing soil stoichiometry in the wild fruit forest in Yili region.

Influence of Chaetomium globosmn ND35 fungus fertilizer on physiological characteristics of poplar in replanted soil.

XIA Xuan-xuan, ZHANG Shu-yong, ZHANG Guang-can, XING Wei, FANG Xiao-chen, LIU Jing-wen, YANG Rui

2016, 27(7): 2249-2256. doi:10.13287/j.1001-9332.201607.030

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In the Forestry Experimental Station of Shandong Agricultural University, we determined the photosynthetic physiological and biochemical indexes including photosynthetic parameters, chlorophyll fluorescence, and chlorophyll content of one-year-old poplar seedlings under different doses (0.17, 0.33, 0.67, 1.00, 1.33 and 1.67 g·kg^-1) of Chaetomium globosmn ND35 fungus fertilizer treatment to study the effects of fungus fertilizer on photosynthesis of poplar in replanted soil. The results showed that with the increase of fungus fertilizer dose, the chlorophyll content of poplar lea-ves (Chl) showed an increasing trend, while the physiological indexes such as electron transport rate (ETR), net photosynthetic rate (P_n), quantum efficiency (Φ), nitrate reductase (NR) activity and root vigor showed an increasing first and then decreasing trend. Meanwhile, the heat dissipation that depended on xanthophyll cycle decreased and non-photochemical quenching (NPQ) increased first and then decreased. When the dose of C. globosmn ND35 fungus fertilizer was 0.67 g·kg^-1 or 1.00 g·kg^-1, excess light energy of photosynthetic apparatus was reduced, and photosynthetic apparatus distributed more light energy to the direction of photochemical reactions, which improved the energy use efficiency. Applying an appropriate amount (0.67-1.00 g·kg^-1) of C. globosmn ND35 fungus fertilizer could improve root physiological activity and light use ability of poplar leaves, which was conducive to the improvement of operating states of photosynthetic apparatus, and then increased the photosynthetic efficiency of the poplar leaves.

Response of vegetative growth and biomass allocation of Lappula semiglabra seedlings to dew gradient.

GONG Xue-wei, LYU Guang-hui, RAN Qi-yang, YANG Xiao-dong

2016, 27(7): 2257-2263. doi:10.13287/j.1001-9332.201607.003

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Three dew amount gradients,i.e., few amount of dew (W₀), natural amount of dew (W₁) and the doubled amount of natural dew (W₂) were set to study the response strategies of the morphology, physiology and the dry matter allocation of Lappula semiglabra seedlings on dew amount in Ebinur Lake Wetland National Nature Reserve in Xinjiang, China. The results showed that plant traits in connection with absorbing water by plant leaves, involving in relative content of chlorophyll, leaf water potential, plant height, crown breadth, stem mass and leaf mass ratio increased significantly with the amount of dew. On the contrary, the main stem diameter, root length and root diameter which associated with water absorption and transportation by root had no significant change with the amount of dew. Plant height and the relative content of chlorophyll were the most obvious traits in response to dew amount among all leaf absorption water traits. The proportion of stem biomass had no significant difference along the dew amount gradient. However, the root mass ratio declined gradually along the growth of seedlings, and seedlings in W₀ had the smallest decline rather than W₁ and W₂. In conclusion, L. semiglabra seedlings changed aboveground traits in response to the change of dew amount. Specifically, it increased its photosynthetic capacity and ratio of leaf dry matter to adapt to the variation on dew amount.

Photosynthetic gas exchange and water utilization of flag leaf of spring wheat with bunch sowing and field plastic mulching below soil on semi-arid rain-fed area.

YANG Wen-xiong, LIU Na, LIU Xiao-hua, ZHANG Xue-ting, WANG Shi-hong, YUAN Jun-xiu, ZHANG Xu-cheng

2016, 27(7): 2264-2272. doi:10.13287/j.1001-9332.201607.033

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Based on the field experiment which was conducted in Dingxi County of Gansu Province, and involved in the three treatments: (1) plastic mulching on entire land with soil coverage and bunching (PMS), (2) plastic mulching on entire land and bunching (PM), and (3) direct bunching without mulching (CK). The parameters of SPAD values, chlorophyll fluorescence parameters, photosynthetic gas exchange parameters, as well as leaf area index (LAI), yield, evapotranspiration, and water use efficiency in flag leaves of spring wheat were recorded and analyzed from 2012 to 2013 continuously. The results showed that SPAD values of wheat flag leaves increased in PMS by 10.0%-21.5% and 3.2%-21.6% compared to PM and CK in post-flowering stage, respectively. The maximum photochemical efficiency (F_v/F_m) , actual photochemical efficiency (Φ_PS_Ⅱ) of photosystem Ⅱ (PSⅡ), and photochemical quenching coefficient (q_P) of PMS were higher than those of PM and CK, the maximum increment values were 6.1%, 9.6% and 30.9% as compared with PM, and significant differences were observed in filling stage (P＜0.05). The values of q_N in PMS were lowest among the three treatments, and it decreased significantly by 23.8% and 15.4% in heading stage in 2012 and 2013 respectively, as compared with PM. The stoma conductance (g_s) of wheat flag leaves in PMS was higher than that of PM and CK, with significant difference being observed in filling stage, and it increased by 17.1% and 21.1% in 2012 and 2013 respectively, as compared with PM. The transpiration rate (T_r), net photosynthetic rate (P_n), and leaf instantaneous water use efficiency (WUE_i) except heading stage in 2013 of PMS increased by 5.4%-16.7%, 11.2%-23.7%, and 5.6%-7.2%, respectively, as compared with PM, and significant difference of WUE_i was observed in flowering stage in 2012. The leaf area index (LAI) of PMS was higher than that of PM and CK, especially, it differed significantly in seasonal drought of 2013. Consequently, the PMS increased the SPAD values in flag leaves of spring wheat, and the capacity of flag leaves for photo energy assimilation and photosynthetic gas exchange were enhanced, caused more photosynthetic energy flowing into photochemical process, as well as decreased the heat dissipation, resulted in the increment of P_n and WUE_i. Based on the higher P_n and LAI, the yield and WUE of PMS increased.

Trade-offs among light, water and nitrogen use efficiencies of wheat cultivars under different water and nitrogen application levels.

ZHANG Kai, CHEN Nian-lai, GU Qun-ying

2016, 27(7): 2273-2282. doi:10.13287/j.1001-9332.201607.027

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To study the responses of light use efficiency (LUE), water use efficiency (NUE) and nitrogen use efficiency (NUE) in wheat to water and nitrogen application levels and their interrelationship, a field experiment designed in split-split-plots was conducted with three spring wheat cultivars (Heshangtou, Xihan No.2, Ningchun No.4), under two irrigation levels (full irrigation 4500 m³·hm^-2 and limited irrigation 3000 m³·hm^-2) and five nitrogen application levels (0, 75, 150, 225, 300 kg N·hm^-2). The results showed that LUE, WUE and NUE of three wheat cultivars differed significantly. The LUE increased as irrigation and nitrogen quantity increased in a certain range, but decreased under excessive nitrogen application. The WUE of strong and moderate drought resistant cultivars (Hsahangtou and Xihan No.2) were less affected by irrigation than non-drought resistant cultivar (Ningchun No.4). Nitrogen application could regulate WUE of wheat, and the highest WUE at medium nitrogen levels (strong and moderate drought resistant cultivars in 150 kg·hm^-2, non-drought resistant cultivar in 225 kg·hm^-2). As the nitrogen application level increased, nitrogen accumulation in plants increased first and then decreased, nitrogen dry matter production efficiency (NUE_b), nitrogen harvest index (NHI), nitrogen agronomic use efficiency (NAE), and nitrogen partial factor productivity (PFP) were all decreased significantly. Irrigation had no significant effect on NHI. As the irrigation level increased, nitrogen accumulation of wheat increased significantly, the NUE_b and NAE of strong and moderate drought resistant cultivars decreased significantly, the NUE_b and PFP of the non-drought resistant cultivars increased significantly, while it had no significant effects on other indicators. Extremely significantly negative correlation between nitrogen acquisition ability and nitrogen use efficiency was found in all three wheat cultivars, and NUE_b was significantly negatively correlated with LUE and WUE, LUE was significantly positively correlated with WUE, demonstrating clear trade-offs among nitrogen use efficiency to light use efficiency and water use efficiency of spring wheat. Higher resource utilization efficiencies were achieved under irrigation of 3000 m³·hm^-2, and application of 150 kg N·hm^-2 for strong and moderate drought resistant cultivars and 225 kg N·hm^-2 for non-resistant cultivar.

Effects of different crop rotations on growth of continuous cropping sorghum and its rhizosphere soil micro-environment.

WANG Jin-song, FAN Fang-fang, GUO Jun, WU Ai-lian, DONG Er-wei, BAI Wen-bin, JIAO Xiao-yan

2016, 27(7): 2283-2291. doi:10.13287/j.1001-9332.201607.036

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The effects of crop rotation on sorghum [Sorghum biocolor (L) Moench] growth, rhizosphere microbial community and the activity of soil enzymes for successive crops of sorghum were evaluated. Five years of continuous monoculture sorghum as the control (CK) was compared to alfalfa and scallion planted in the fourth year. The results showed that incorporation of alfalfa and scallion into the rotation significantly improved sorghum shoot growth. Specifically, sorghum grain yield increased by 16.5% in the alfalfa rotation plots compared to the CK. The rotations also increased sorghum root system growth, with alfalfa or scallion rotation increasing sorghum total root length by 0.3 and 0.4 times, total root surface area by 0.6 and 0.5 times, root volume by 1.2 and 0.6 times, and root biomass by 1.0 and 0.3 times, respectively. Alfalfa rotation also expanded sorghum root distribution below the 10 cm soil depth. A Biolog analysis on biome functions in the sorghum flowering period indicated significantly higher microbial activity in the rotation plots. The alfalfa and scallion rotation increased the Shannon index by 0.2 and 0.1 times compared to the CK, and improved the sucrose activity in the rhizosphere soil. It was concluded that including alfalfa in rotation with sorghum improved sorghum rhizosphere soil environment, enhanced soil microbial enzyme activity, alleviated the obstacle of continuous cropping and thus increased the sorghum yield.

Maize biomass simulation based on dynamic photosynthate allocation.

MA Xue-yan, ZHOU Guang-sheng

2016, 27(7): 2292-2300. doi:10.13287/j.1001-9332.201607.026

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Photosynthate allocation is critical to crop growth and biomass formation, and it is also a key part of crop simulation. A photosynthate allocation model of maize was established based on photosynthate allocation mechanisms as well as the photosynthate allocation characteristics of maize at different stages. This model was then coupled with the CO₂ assimilation module of WOFOST crop model to simulate the biomass dynamics of different organs of maize on daily scale. It was validated by 5 years’ field experiment data of spring maize from Jinzhou Agricultural Ecosystem Research Station. The results showed that, the model could explain about 95.4% of maize’s total biomass change, while 87.0%, 85.3%, 67.9%, 76.5% and 87.5% of vegetative, leaf, root, stem, and ear biomass variations, respectively. This model could fulfill accurate simulation of different organ biomass dynamics of maize.

Effects of combined drought and salinity stress on germination and physiological characteristics of maize (Zea mays).

YAO Hai-mei, LI Yong-sheng, ZHANG Tong-zhen, ZHAO Juan, WANG Chan, WANG Han-ning, FANG Yong-feng

2016, 27(7): 2301-2307. doi:10.13287/j.1001-9332.201607.023

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In this study, 15% PEG, 100 mmol·L^-1 NaCl and PEG-NaCl mixed solution were employed to respectively simulate the drought (D), salinity (S) and the combined stress (D+S), and effects of these three stresses on the seed germination and the physiological characteristics of seedlings were investigated. The results showed that seed germination, seedling growth and biomass accumulation were significantly inhibited by these three stresses, and the impact of stress ranked as D>D+S>S. The content of reactive oxygen species like H₂O₂ and O^-·₂, as well as malondialdehyde (MDA) and membrane permeability were increased under these stresses, meanwhile, proline (Pro), soluble sugar and soluble proteins contents were significantly improved, which were higher in seedlings than in roots with a rank of D>D+S>S. The activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxide (POD), catalase (CAT) and ascorbate peroxide (APX) were also obviously increased. In addition, SOD and APX induced by PEG-NaCl mixed solution were ranked in the middle compared to those induced by their single stress, but POD and CAT were more induced by PEG-NaCl mixed solution than their single stress. It was demonstrated that effect of drought-salinity combined adverse condition on maize seed germination and seedlings physiological characteristics were not simply additive of their single stress, compared with their single stress, drought-salinity combined adverse condition could reduce the effects of drought stress on maize seeding to a certain extent.

Influence of over expression of CsRCA on photosynthesis of cucumber seedlings under high temperature stress.

BI Huan-gai, DONG Xu-bing, LIU Pei-pei, LI Qing-ming, AI Xi-zhen

2016, 27(7): 2308-2314. doi:10.13287/j.1001-9332.201607.028

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In the present work, transgenic cucumber seedlings over expressing CsRCA and wild-type cucumber seedlings ‘08-1’at three-leaf stage exposed to high temperature (40 ℃, PFD 600 μmol· m^-2 · s^-1) were used to study the regulatory mechanism of photosynthesis by CsRCA. The results showed that the mRNA abundance of rbcL and rbcS as well as the activities of ribulose bisphosphate carboxylic enzyme (Rubisco) and Rubisco activase (RCA) were significantly higher in CsRCA over-expressing cucumber seedlings than in wild type (WT). Following 2-h exposure to high temperature, a notable decrease was observed in photosynthetic rate (P_n), photochemical perfor-mance index based on the absorption of light energy (PI_ABS), activities of Rubisco and RCA as well as the relative expression of rbcL, rbcS and CsRCA in both wild-type cucumber seedlings and transgenic cucumber seedlings. It was found that high temperature stress led to higher W_k, a parameter of chlorophyll (Chl) a fluorescence OJIP curve. Furthermore, high temperature greatly reduced the efficiency of electron transfer along the electron transport chain beyond Q_A(ψ₀) and the quantum yield for electron transport (φ_E0), indicating that PSII oxygen complexes (OEC) and electron transport chain downstream Q_A were inhibited by high temperature. However, the inhibition could be alleviated by over expressing CsRCA in cucumber seedlings. Taken together, our data suggested that over expressing CsRCA improves photosynthesis in cucumber seedlings under high temperature stress by enhancing activities of the Rubisco and RCA, and maintaining the number of active reaction centers.

Effects of rice-duck mutualistic organic farming on rice quality in the Yellow River Delta, China.

WANG Jian-lin, LI Jie, CAO Yuan-yuan

2016, 27(7): 2315-2320. doi:10.13287/j.1001-9332.201607.038

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Three cultivation models including rice-duck mutualistic, manual weeding and conventional rice farming were designed in the Yellow River Delta area to study the effects on rice milling quality, appearance quality, cooking and eating quality, and sanitation quality. The results showed that compared to conventional rice farming, the rice-duckmutualistic treatment increased grain width and brown rice rate, milled rice rate, head rice rate and reduced the chalkiness. This was mainly due to the increase of panicle numbers and grain mass and the decrease of the inferior grains. Due to the application of organic manure, the gel consistency increased, amylose and protein contents decreased, and the rice taste improved under rice-duck mutualistic and manual weeding cultivation treatments. As no chemical fertilizers and pesticides were applied under rice-duck mutualistic and manual weeding treatments, pesticide residues were greatly reduced or even not detected. Rice duck farming could improve the quality of rice and protect the environment, which would be a good ecological technology for high quality rice production.

Response of Olsen-P to P balance in yellow soil upland of southwestern China under long-term fertilization.

LI Yu, LIU Yan-ling, ZHANG Ya-rong, SHEN Yan, ZHANG Wen-an, JIANG Tai-ming

2016, 27(7): 2321-2328. doi:10.13287/j.1001-9332.201607.032

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Based on a long-term fertilization experiment in Guizhou Province, we explored the relationships between the soil available phosphorus (Olsen-P), soil apparent P balance and P application rate in order to quantify the best application rate of P fertilizer in yellow upland soil of southwestern China. Moreover, the response curve of crop yield to soil Olsen-P was fitted by Mitscherlich equation to determine the critical content of Olsen-P for crop yield. The results showed that the long-term application of P fertilizer could significantly increase the content of soil Olsen-P, and the increasing rates of Olsen-P across different treatments could be mainly explained by the application rate of P fertilizer. Under no-P treatment, the soil P content was in a deficient state for each year, while it displayed a surplus state in the treatments with P fertilizer, and the crop P uptake and P accumulation were found the highest under MNPK treatment. In contrast to single application of chemical fertilizer treatment (NPK), the combined application of organic fertilizer and chemical fertilizer (1/4 M+3/4 NPK, 1/2 M+1/2 NPK) could enhance crop P uptake and improve accumulative P use efficiency. The soil apparent P balance was significantly (P<0.05) correlated with soil Olsen-P. With average P accumulation of 100 kg·hm^-2, the soil Olsen-P increased by 16.4, 13.0 , 21.4 , and 5.6 mg·kg^-1 in the treatments of MNPK, 1/4 M+3/4 NPK, 1/2 M+1/2 NPK, and NPK, respectively. The result showed that combined application of organic fertilizer and chemical fertilizer could effectively increase the soil Olsen-P content, and the critical value of soil Olsen-P was 22.4 mg·kg^-1 in yellow upland soil of southwestern China. The soil P balance and Olsen-P content were significantly (P<0.01) correlated with the annual P application rate. When the amount of average P application was 33.3 kg P·hm^-2·a^-1, the budgets of soil P balance remained stable, and the application rate of P fertilizer corresponding to the critical value of soil Olsen-P for crop yield was 45.9 kg P·hm^-2·a^-1. The content of soil Oslen P was mainly affected by the P fertilizer input amount. When the average P application rate was 45.9 kg P·hm^-2·a^-1, higher crop yield and P fertilizer efficiency would be achieved. When the average P application rate was greater than 45.9 kg P·hm^-2·a^-1, crop yield showed no response to P fertilizer input, but resulted in a large amount of P surplus in soil, thereby increasing the environmental risk of soil P loss. The long-term application of manure resulted in a higher increase of Olsen-P than the single chemical P ferti-lizer.

Farmer’s perception and adaptation intention for climate change in high-cold eco-fragile region: A case of Gannan Plateau, China.

ZHAO Xue-yan, XUE Bing

2016, 27(7): 2329-2339. doi:10.13287/j.1001-9332.201607.039

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In order to provide reference for formulating the effective policies of climate change, we selected Ganan Plateau located in the eastern margin of Qinghai-Tibet Plateau as the study area, and used the farmer’s investigation data to analyze the impact of the farmers’ perception of climate change on their adaptation indention. The results showed that the farmer’s severity perception of climate change declined from the pure agriculture household to the household with combined occupation, and to the non-agriculture household, but the farmer’s adaptation efficacy perception was vice versa. Moreover, all of the perceived probability, self-efficacy and adaptation cost of the household with combined occupation were highest, those of the non-agriculture household were the second place and those of the pure agriculture household were the lowest. The farmer’s positive adaptation indention of climate change increased from the pure agriculture household to the household with combined occupation, and to the non-agriculture household. Increasing the perceived risk and adaptation efficacy would promote the farmer’s positive adaptation intention, but increasing the perceived adaptation cost would promote the farmers’ passive adaptation intention. Meanwhile, the more the farmer’s agricultural acreage, livestock, income and optimistic degree were, the stronger the farmer’s positive adaptation intention was; But the more the farmers’ fixed capital, unpaid cash assistance opportunities, relative number and the number of people offering help were, the weaker the farmers’ positive adaptation intention was. Finally, we pointed out the measures of promoting the positive adaptation intention and the problems on which we should focus in the future research.

Genetic characterization of different populations of Rhopilema esculentum based on the mitochondrial COI sequence.

LI Yu-long, DONG Jing, WANG Bin, LI Yi-ping, YU Xu-guang, FU Jie, WANG Wen-bo

2016, 27(7): 2340-2347. doi:10.13287/j.1001-9332.201607.019

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To investigate the genetic characterization and population genetic structure of Rhopilema esculentum, we sequenced the mtDNA COI gene (624 bp) in 56 individuals collected from Liaodong Bay and the Ganghwado Island in the estuarine waters of the Han River. In addition, the homologous sequences of other 15 individuals which were sampled from the Bohai and Yellow seas and Sea of Japan were analyzed. A total of 28 polymorphic nucleotide sites were detected among the 71 individuals, which defined 32 haplotypes. Haplotype diversity levels were high (0.91±0.06-0.94±0.01) in R. esculentum populations, whereas those of nucleotide diversity were moderate to low [(0.60±0.34)%-(0.68±0.40)%]. Compared with several other giant jellyfish species, the variation level of R. esculentum was high. Phylogeographic analysis of the COI region revealed two lineages. The pairwise F_ST comparison and hierarchical molecular variance analysis (AMOVA) showed that significant population structure existed throughout the range of R. esculentum. The results of this study indicated that the life-cycle characteristics, together with possible anthropogenic introduction such as stock enhancement and the prevailing ocean currents in this region, were proposed as the main factors that determined the genetic patterns of R. esculentum.

Multiple time-scale analysis of nitrogen retention characteristics and influencing factors in Shanmei Reservoir, Fujian, China.

LIU Mei-bing, CHEN Xing-wei, CHEN Ying

2016, 27(7): 2348-2356. doi:10.13287/j.1001-9332.201607.016

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The retention effect of reservoir on nitrogen is an important influence factor on the eutrophication prevention and control. In order to reveal the differences of nitrogen retention characteristics and the influence factors at multiple timescales, an ecological dynamic model was developed in Shanmei Reservoir watershed. Based on the retention flux and retention rate calculation, the nitrogen retention effect was analyzed at three time scales of yearly, monthly and daily, respectively. Furthermore, multiple linear correlation analysis was conducted to analyze the influence of inflow runoff, ratio of inflow to outflow, residence time, velocity and temperature on the retention of nitrogen in the reservoir. The results showed that the process of nitrogen retention always displayed fluctuant characteristic at different time scales. On a yearly scale, the reservoir mainly played a role of nitrogen sink; on a monthly scale, seasonal variation of nitrogen retention and release effect made the reservoir as nitrogen sink in wet period and as nitrogen source in dry period; on a daily scale, the nitrogen retention process fluctuated intensely, with the retention rate ranging from -300% to 100% in dry year. At different time scales, ratio of inflow to outflow and velocity were always the important factors to affect nitrogen retention in the reservoir, with significant correlation coefficients consistently. With the time scale changing from yearly to monthly, daily, the influence degree of inflow runoff and temperature on nitrogen retention was gradually strengthened. The correlations between the residence time and retention rate could be positive or negative at different time scales.

Oxygen consumption rate of Sepia pharaonis embryos.

WANG Peng-shuai, JIANG Xia-min, RUAN Peng, PENG Rui-bing, JIANG Mao-wang, HAN Qing-xi

2016, 27(7): 2357-2362. doi:10.13287/j.1001-9332.201607.013

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This research was conducted to unravel the variation of oxygen consumption rate during different developmental stages and the effects of different ecological factors on embryonic oxygen consumption rate of Sepia pharaonis. The oxygen consumption rates were measured at twelve deve-lopmental stages by the sealed volumetric flasks, and four embryonic developmental periods (oosperm, gastrula, the formation of organization, endoskeleton) were selected under various ecological conditions, such as salinity (21, 24, 27, 30, 33), water temperature (18, 21, 24, 27, 30 ℃) and pH (7.0, 7.5, 8.0, 8.5, 9.0). The results showed that the oxygen consumption rate rose along with the developmental progress, and distinctly differed from each other. The oxygen consumption rate was 0.082 mg·(100 eggs)^-1·h^-1 during oosperm period, and rose to 0.279 mg·(100 eggs)^-1·h^-1 during gastrula period, which was significantly higher than that of blastula period. Finally, the oxygen consumption rate rose to 1.367 mg·(100 eggs)^-1·h^-1 during hatching period. The salinity showed a significant effect on oxygen consumption rate during the formation of organization and endoskeleton formation stage (P<0.05), but no significant effect during oosperm and gastrula periods (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of salinity, and reached the highest values [0.082, 0.200, 0.768 and 1.301 mg·(100 eggs)^-1·h^-1, respectively] at salinity 30. The water temperature had a significant effect on the embryo oxygen consumption rates of gastrula, and the formation of organization and endoskeleton formation stage (P<0.05), with the exception of oosperm (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of temperature, and reached the highest values at 27 ℃ [0.082, 0.286, 0.806 and 1.338 mg·(100 eggs)^-1·h^-1, respectively]. The pH had no significant effect on the oxygen consumption rates of four embryonic stages (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of pH. The oxygen consumption rates of gastrula, the formation of organization, endoskeleton reached the according highest values [0.281, 0.799 and 1.130 mg·(100 eggs)^-1·h^-1] at pH 8.5, but that during oosperm period occurred at pH 8.0 [0.116 mg·(100 eggs)^-1·h^-1].

Soil meso- and micro-fauna community structures in different urban forest types in Shanghai, China.

JIN Shi-ke, WANG Juan-juan, ZHU Sha, ZHANG Qi, LI Xiang, ZHENG Wen-jing, YOU Wen-hui

2016, 27(7): 2363-2371. doi:10.13287/j.1001-9332.201607.015

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Soil meso- and micro-fauna of four urban forest types in Shanghai were investigated in four months which include April 2014, July 2014, October 2014 and January 2015. A total of 2190 soil fauna individuals which belong to 6 phyla, 15 classes and 22 groups were collected. The dominant groups were Nematoda and Arcari, accounting for 56.0% and 21.8% of the total in terms of individual numbers respectively. The common groups were Enchytraeidae, Rotatoria, Collembola and Hymenoptera and they accounted for 18.7% of the total in terms of individual numbers. There was a significant difference (P<0.05) among soil meso- and micro-fauna density in the four urban forest types and the largest density was found in Metasequoia glyptostroboides forest, the smallest in Cinnamomum camphora forest. The largest groupe number was found in near-nature forest, the smallest was found in M. glyptostroboides forest. There was obvious seasonal dynamics in each urban forest type and green space which had larger density in autumn and larger groupe number in summer and autumn. In soil profiles, the degree of surface accumulation of soil meso- and micro-fauna in C. camphora forest was higher than in other forests and the vertical distribution of soil meso- and micro-fauna in near-nature forest was relatively homogeneous in four layers. Density-group index was ranked as: near-nature forest (6.953)> C. camphora forest (6.351)> Platanus forest (6.313)>M. glyptostroboides forest (5.910). The community diversity of soil fauna in each vegetation type could be displayed preferably by this index. It could be inferred through redundancy analysis (RDA) that the soil bulk density, organic matter and total nitrogen were the main environmental factors influencing soil meso- and micro-fauna community structure in urban forest. The positive correlations occurred between the individual number of Arcari, Enchytraeidae and soil organic matter and total nitrogen, as well as between the individual number of Diptera larvae, Rotatoria and soil water content.

Protocol optimization of eDNA analysis workflow for detecting Hucho bleekeri.

JIANG Wei, WANG Qi-jun, DENG Jie, ZHAO Hu, KONG Fei, ZHANG Hong-xing

2016, 27(7): 2372-2378. doi:10.13287/j.1001-9332.201607.017

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Environmental DNA (eDNA) analysis in water, consisting of water sample collection, DNA extraction and analysis, is increasingly important in detecting rare aquatic species and determining their distribution. Optimization of protocols used in an eDNA molecular workflow is critical to reduce its uncertainty in detecting target species, especially rare species. In this study, 250 mL, 500 mL, 1 L and 2 L water samples were collected by filtering method from a pond for Sichuan taimen (Hucho bleekeri) culture, followed by extraction and purification of eDNA using DNeasy Tissue and Blood DNA extraction kit or MoBio Power Water DNA extraction kit. A PCR procedure was then applied using specific primers from the D-loop region of mtDNA in Sichuan taimen. To explore an appropriate eDNA analysis protocol, the effect of filtering method, sample size and extraction protocols on the detection rate of target gene in water eDNA was studied. The results showed that the target gene was 100% detected from the water sample by using DNeasy Tissue and Blood DNA extraction kit, which was much better that the MoBio Power Water DNA extraction kit with a detection rate of 0%. Larger volume of water samples yielded better PCR products, with 2 L being the most appropriate volume. Sequence alignment results showed that target sequence from the D-loop region of mtDNA in Sichuan taimen was successfully amplified. The results indicated that DNA extracting method and water sample volume could strongly affect the detection rate. The protocol combining filtration, 2 L water sample, DNeasy Tissue and Blood DNA extraction kit was appropriate for eDNA analysis, and mtDNA D-loop region was recommended for detecting DNA of Sichuan taimen from water samples.

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