Table of Content

10 July 2017, Volume 36 Issue 7

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Influences of elevated CO₂ concentration on hydraulic architecture of seedlings of 4 tree species.

LIU Juan-juan1, ZHANG Jian-guo1, LI Ji-yue2*, ZHA Wei-wei1

2017, 36(7):  1769-1776. 

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Hydraulic architecture parameters with relative ramification rate and in different area stem segments under ambient and elevated CO₂ concentrations were measured by improved flushing method. The aims were to study the change of hydraulic architecture, hydraulic safety and efficiency under elevated CO₂ concentration. Saplings of four tree species (Pinus tabuliformis, Platycladus orientalis, Acer truncatum and Robinia pseudoacacia) had been exposed to ambient and elevated CO₂ concentration for 13 months. The results showed that xylem specific conductivity (K_s) and leaf specific conductivity (LSC) increased in all the ramifications under elevated CO₂ concentration. However, the percent loss of hydraulic conductivity (PLC) decreased in P. orientalis and R. pseudoacacia in all the ramifications, and PLC only decreased in branch 2 of P. tabuliformis and in branch 0 and 1 of A. truncatum. K_s increased and PLC decreased in branch 2 of P. tabuliformis and R. pseudoacacia. In P. orientalis, P. tabuliformis and R. pseudoacacia, K_s increased by 12.8%, 19.6% and 51.24% in branch 2 whereas PLC decreased by 11.80%, 9.6% and 51.01% under elevated CO₂ concentration, respectively. The hydraulic conductivity (K_h) of P. tabuliformis and P. orientalis in the non-restricted area were respectively larger than that in the restricted area, whereas K_h of A. truncatum and R. pseudoacacia were respectively smaller than that in the restricted area. However, the PLC was not significantly affected by elevated CO₂ concentration. K_s and LSC of P. orientalis and A. truncatum in the nonrestricted area were respectively larger than those in the restricted area, whereas K_s and LSC of P. tabuliformis and R. pseudoacacia were respectively smaller than those in the restricted area. Under elevated CO₂ concentration, four tree species with relative ramification showed different strategies to adapt to the changed environment. The strategies included: increasing hydraulic safety and hydraulic efficiency, and decreasing hydraulic security to tradeoff the hydraulic efficiency. However, four tree species in different area stem segments showed different strategies, keeping higher hydraulic efficiency to adapt to the elevated CO₂ concentration.

 

Geographical distribution and habitat characteristics of critically endangered species, Thuja sutchuenensis.

MA Fan-qiang1, QIN Ai-li1, GUO Quan-shui1*, JIAN Zun-ji1, PEI Shun-xiang2, WANG Xiang-fu3, ZHANG Shi-qiang4, XING Ji-chou5

2017, 36(7):  1777-1784. 

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Through overall survey, sampling survey and laboratory analysis, the geographical coordinates, elevation, climate, soil and vegetation of the distribution area of Thuja sutchuenensis were analyzed to reveal its habitat characteristics and their relationships. The objective was to provide basic data and theoretical basis for the effective protection of T. sutchuenensis. The results showed that: (1) The main distribution zone of T. sutchuenensis located in Southern and Southeast of China’s Daba Mountain, including Chengkou County and Kaizhou District of Chongqing City, Xuanhan County of Sichuan Province. The geographical distribution range of T. sutchuenensis was 31°25′ N—31°44′ N and 108°23′ E—108°54′ E, and its vertical distribution range was from the elevation of 700 to 2200 m. (2) The distribution area was warm and humid with the annual mean temperature of 9.98 ℃. The highest temperature and the lowest temperature were 29.1 and -7.2 ℃, respectively. Annual precipitation was 1315.2 mm, and the snow cover of the highest distribution altitude had a period of 3 months. The soil types were mountainyellowbrown soil and mountainbrown forests soil, the soil was neutral or alkalescent, and soil density and porosity were generally suitable for plant growth. (3) The zonal vegetation in the distribution zone was deciduous broad-leaved forest with evergreen broad-leaved synusia. T. sutchuenensis was mainly distributed in the warm, low mountain, deciduous and broad-leaved mixed forest area and humid, middle mountain, coniferous forest area. The main companion trees were Cyclobalanopsis jenseniana, Carpinus fargesiana, Cyclobalanpsis gracillis, Carpinus cordata var. chinensis and Quercus semecapifolia. The age structure of T. sutchuenensis population was not integrated. Seedlings and young trees with basal diameter less than 4 cm were only 25-800 plants per hectare, indicating an obvious population decline. (4) The geographical isolation of Qinling Mountain and Daba Mountain played an important role for its preservation. The strong tolerance toward drought and barrenness was an important reason for its survival and growth on the cliff edge and steep slope of the limestone area. Decentralized distribution and small population of T. sutchuenensis were closely related to its poor natural regeneration capacity and excessive disturbance of human activities.

The resources of the cliff plants and their application prospect for afforestation at unsuitable sites in Shanxi Province.

LIU Xu-shi*

2017, 36(7):  1785-1790. 

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Based on the field survey and data citation, species composition, flora, growth form, living habits and resource types of cliff plant species in Shanxi Province were analyzed. The results showed that there were 241 species of cliff plants in Shanxi Province, belonging to 53 families and 133 genera. Among them, 7 families, containing more than 10 species, included 55 genera and 105 species; Rosaceae had the most species. At the level of species, 188 species were endemic to China and characteristic of temperate distribution, belonging to 80 genera. Growth form was mainly composed of herbaceous perennials, followed by deciduous shrubs. Our investigation found that cliff plants had the characteristics of wide ecological adaptability and strong tolerance. Domestication and cultivation of cliff plants can provide valuable germplasm resources for afforestation at unsuitable sites.

Impacts of mycorrhizal fungi inoculum on growth characteristics of four kinds of afforestation seedlings in Horqin sandy land, China.

ZHANG Ke-ke1,2, JIANG De-ming1*, YU Hai-bin1, ZHOU Quan-lai1, WEI Yun3

2017, 36(7):  1791-1800. 

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Mycorrhizal fungi play key roles in vegetation restoration and vegetation reconstruction of degraded ecosystems in arid and semiarid lands. In the present study, a mycorrhizal afforestation experiment in Horqin sandy land was carried out to understand the influence of two mycorrhizal fungi inoculums (arbuscular mycorrhiza inoculum and ectomycorrhizal inoculum) on growth of four kinds of afforestation seedlings. We analyzed mycorrhizal colonization rate and morphological indicators, accumulation and allocation of biomass, and rhizosphere soil nutrients of seedlings of two native species Acer mono and Ulmus pumila, and two introduced species Fraxinus chinensis and Pinus sylvestris var. mongolica in Horqin sandy land, China across one growth season. The results showed that: (1) Both mycorrhiza inoculums could well colonize the roots of the four kinds of seedlings. Inoculation of the mycorrhiza inoculums significantly increased the plant height, basal radium, crown stem length and biomass of all tree species. (2) Inoculation with the mycorrhiza inoculums on roots of seedlings significantly affected the allocation of biomass (P<0.05); the rootshoot ratio significantly decreased in Fraxinus chinensis seedlings, and significantly increased in Pinus sylvestris var. mongolica seedlings. (3) The mycorrhizal colonization rate was significantly positively correlated with the plant height and crown stem length of Fraxinus chinensis seedlings, and significantly positively correlated with the coarse root dry mass, shoot biomass and total biomass of Pinus sylvestris var. mongolica seedlings. (4) Inoculation of the mycorrhiza inoculums also increased the contents of organic matter and total nitrogen of rhizosphere soil, which can improve the soil matrix of seedling growth, but the difference was insignificant (P>0.05). Mycorrhizal effect of the four kinds of afforestation seedlings was significant, which indicated that it was very valuable to apply mycorrhizal fungi inoculum to afforestation in arid and barren regions.

Ecological characteristics of Alhagi sparsifolia in relation to environmental factors in saline habitat.

LUO Han-lin1,2,3,4, ZENG Fan-jiang1,2,3*, ZHANG Ling1,2,3,4, LI Mei-mei1,2,3,4, LI Shi-min1,2,3,4, WANG Bo1,2,3,4

2017, 36(7):  1801-1807. 

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Age structure and dynamics of Pinus tabuliformis population in the Liaoheyuan Nature Reserve of Hebei Province.

SHI Jia-yu, HAN Hai-rong*, CHENG Xiao-qin, DONG Ling-ling, TIAN Hui-xia, CAI Meng-ke, KANG Feng-feng

2017, 36(7):  1808-1814. 

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Based on the population life table and the theory of survival analysis, the static life table of Pinus tabuliformis population in Liaoheyuan Nature Reserve was complied by using the “spacefortime” substitution approach and the stagesmoothing technique. The graphs of mortality rate curve, killing power curve, survival rate curve, and survival function curve were also sketched. The results showed that P. tabuliformis population presented a fluctuating trend of development and would experience three death peaks. The age structure of P. tabuliformis population showed an inverted Jtype pattern and the number of seedlings was large. However, due to the high intensity selection through environmental sieve in the stage from seedling to sapling (from age class 1 to 2), the P. tabuliformis population would experience the first death peak. The second and the third death peak occurred during the transition period from the subforest layer to the main forest layer (from age class 7 to 8) and the later stage of growth (from age class 11 to 12), which were caused by the competitioninduced selfthinning and the physiological death, respectively. The survival curve of P. tabuliformis population was similar to the DeevyII type, thus the population was classified as a stable one. The four survival functions indicated that the population dynamics of P. tabuliformis was characterized by decreasing in the early stage, being stable in the medium stage and depressing in the later stage.

Comparison of net ecosystem exchange light-response curve fitted parameters at four types of forest ecosystems.

ZHOU Li-guo1,5, SONG Qing-hai1, ZHANG Yi-ping1,3,*, FEI Xue-hai1,5, DENG Yun1，2, WU Chuan-sheng1,3,5, ZHOU Rui-wu1,5, LIN You-xing1,5, DENG Xiao-bao1,2, CHEN Ai-guo4, LI Pei-guang1,4

2017, 36(7):  1815-1824. 

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In this study, carbon dioxide (CO₂) fluxes were continuously measured using the openpath eddy co-variance systems at four forest ecosystems sites (including Xishuangbanna tropical rain forest, Xishuangbanna rubber plantation, Ailaoshan subtropical evergreen broadleaved forest and Yuanjiang savanna ecosystem). Photosynthetically active radiation (PAR) was calculated using the routine meteorological measurement system, and the net ecosystem exchange (NEE) lightresponse curve fitted parameters were calculated using the MichaelisMenten equation. The highest maximum photosynthesis rate (P_max) and ecosystem daytime respiration (R_d) were observed at Xishuangbanna rubber plantation, indicating a strong photosynthetic potential and respiration rate in manmade monoculture system. Ailaoshan subtropical evergreen broadleaved forest exhibited the highest apparent quantum yield (α), which indicated the greatest efficiency of ecosystem light use under low light conditions. Yuanjiang savanna ecosystem showed the lowest NEE lightresponse curve fitted parameters and their seasonal variations displayed a definite unimodal curve. NEE lightresponse curve fitted parameters of Xishuangbanna tropical rain forest were lower than those of Xishuangbanna rubber plantation and higher than those of the Yuanjiang savanna ecosystem. All NEE lightresponse curve fitted parameters of the four forest ecosystems had similar seasonal dynamics with higher value during rainy season than that during dry season in relation to the temperature and moisture conditions. There were consistent relationships between NEE lightresponse curve fitted parameters and carbon absorbing efficiency in the four forest ecosystems. NEE lightresponse curve fitted parameters had an indicative function of carbon sequestration capacity in this study. The results of this study provide a basis for further study on carbon sink capacity of different forest ecosystems.

 

ISSR analysis of genetic diversity of rare and endangered species Alcimandra cathcartii in the Gaoligong Mountains National Nature Reserve.

CHAI Yong1,2, WU Tao1, SHAO Jin-ping1, HE Li-ping1, FANG Bo1, LI Gui-xiang1,2*

2017, 36(7):  1825-1831. 

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Alcimandra cathcartii is a rare and endangered plant species, with important value in taxonomy and ornamental horticulture, and it is also a firstclass nationally protected species in China. Analysis of ISSR markers was conducted on three natural populations (NK, ZD and DHP) of A. cathcartii from Gaoligong Mountains National Nature Reserve with the objective of investigating the genetic diversity within and among the populations. Leaf samples of 62 individuals from the three populations were collected for DNA extraction. The results were as follows: (1) Fifteen ISSR primers were used to generate highly reproducible and stable DNA fragments (the sizes of ISSRPCR products ranged from 250 to 2200 bp). One hundred and eighty seven discernible DNA fragments were produced, among which 171 fragments were polymorphic loci (mean 12.5 bands and 11.3 polymorphic bands per primer). The percentage of polymorphic bands (PPB) was 91.44% at the species level, and PPB within population ranged from 21.93% (DHP population) to 66.30% (ZD population). (2) The genetic differentiation among populations was detected in A. cathcartii \[0.2294, 0.27 and 27% for Nei’s genetic coefficient of differentiation (G_st), Shannon’s diversity index and AMOVA\], which indicated that genetic differentiation mainly occurred within populations. The cluster analysis showed that the largest category included most individuals of the three populations. (3) The correlation coefficient (r=-0.519, P=0.323) obtained by Mantel test did not show any significant relationship between the matrices of geographical distances and pairwise genetic distances based on ISSR. On the basis of the genetic and ecological information, it is recommended that strengthening the nature reserve management and promoting the insitu conservation is a promising strategy for the protection of this species.

Response of Larix chinensis to temperature change and its response mechanism in Qinling Mountains.

HUANG Xiao-yue, BAI Hong-ying*, SU Kai, ZHANG Yang, LIU Rong-juan

2017, 36(7):  1832-1840. 

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Alpine timberline of Qinling Mountains is sensitive to climate change, providing an-ideal place for studying climate change. Based on the MODIS NDVI (normalized difference vegetation index) and air temperature data over the span of 2000 to 2015, the characteristics of response of Larix chinensis to air temperature variation were investigated and the mechanism of response was explored in this paper. The results showed that: (1) The average annual NDVI of L. chinensis was positively correlated with the annual average temperature, and 96.30% of the correlations were positive with 31.42% being significant. It meant that the annual temperature was conductive to the growth of L. chinensis. (2) On the monthly scale, the monthly mean NDVI response of L. chinensis distribution region to monthly mean air temperature was mostly positive, with the characteristics of synchronism and hysteretic nature, and the lag time was around 1-3 months. The NDVI in August was negatively correlated with the temperature of previous period, the current temperature and accumulated temperature, and most of the correlations were significantly negative. (3) The annual maximum NDVI of L. chinensis was negatively correlated with the air temperature in different periods, which indicated that the rise of temperature was not conducive to the maximum NDVI growth of L. chinensis to a certain extent. (4) The analysis of correlation between annual maximum NDVI and the mean air temperature from August of previous year to current July showed that the number of negative pixels was much more than that of positive pixels. Furthermore, when the annual mean temperature from previous August to current July was within the range of -0.4-0.8 ℃, the response of maximum NDVI to air temperature reached the peak. On the other hand, if the temperature was lower than -0.4 ℃ or higher than 0.8 ℃, the percentage of negative pixel number increased and the growth of L. chinensis would be inhibited somewhat.

Variation characteristics and the impact factors of flowering phenology of Lagerstroemia indica in urban gardens in south Sichuan.

CHEN Fa-jun1,2, YANG Yin-hua3, LIU Ji-rao3, XU Shu-pei3, ZHANG Jing1, CHEN Hai-xia1, YANG Ping1

2017, 36(7):  1841-1846. 

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To clarify the variation characteristics of flowering phenology of Lagerstroemia indica in urban gardens, to explore factors impacting its flowering phases and to provide guidance to disposition in planting, cultivated individuals of the species in southern Sichuan were observed every week in 2011-2014. The difference of phenological events was analyzed at individual level and population level, and the effects of plant size and weather factors on flowering phenology were also discussed. The results showed that the period of flowering at individual level began in early June to middle September and ended in October, lasting for 8-137 d, and most individuals had a 60-90 d flowering duration. The proportion of blooming plants and the phonological characteristics varied in different years. The shortest duration of flowering was 106 d in 2014, while the longest duration was 130 d in 2012. Similar temporal pattern of flowering plant number was recorded in different years, and the first flowering phase was significantly correlated to flowering duration. Basal diameter had a significant effect on flowering phenology. The individuals with big size bloomed earlier and lasted for longer time. Peak flowering phase of L. indica often occurred from July to September. The number of flowering individuals was positively correlated to the average air temperature in previous month, but had no significant correlation to current air temperature and rainfall. Being affected by weather and other factors, flowering phenology differed obviously among various years, showing some regular patterns as well. Diversified flowering phenology at individual level was beneficial to maintaining high ornamental value at population level, and selection of big size plants in gardens could obtain stable flowering effects.

Influences of cadmium and nitrogen on the accumulation and distribution of dry matter and N, P, K, Cd in Alnus formosana.

TAN Chang-qiang1,2,3, HUANG Zhi-ling1,2,3, PENG Yu-hua1,2,3, SHEN Wen-hui1,2,3*, HAO Hai-kun1,2,3, CAO Yan-yun1,2,3, LIU Xiu1,2,3

2017, 36(7):  1847-1854. 

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A controlled potexperiment with different treatments of Cd and N concentrations was conducted to investigate the biomass production and accumulation and the distribution of N, P, K and Cd in Alnus formosana. The results indicated that the dry matter accumulation, N, P, K absorption and accumulation in roots, stems and leaves in A. formosana were significantly inhibited under Cd stress without adding N; the N and K contents in roots and leaves were reduced, but there was no significant effect on P content. Under Cd stress, the A. formosana adapted to the Cd stress conditions by increasing proportions of N, P, K and dry matter in roots, reducing their proportions in leaves, and improving N and K use efficiency. The root was the main part of Cd enrichment, whose transfer coefficient ranged between 0.06 and 0.22. Cd stress decreased both transfer coefficient and enrichment coefficient of Cd in A. formosana. N addition increased the contents and accumulations of dry matter and N, K in roots, stems, and leaves of A. formosana under 30 mg·kg^-1 Cd stress, alleviated N, K absorption restrictions caused by Cd stress, but had no significant effect on P content and its accumulation. Also, N addition increased the proportion of dry matter in roots and root/shoot ratio, especially under 0.4 g·kg^-1 N application. Furthermore, the accumulation and proportion of Cd were increased in stems and leaves and decreased in roots. The Cd transfer factor (TF) and stem/leaf biological enrichment coefficients (BCF) increased, but the root BCF was observably reduced. Overall, N application improved A. formosana’s ability to adapt to the environment under Cd stress.

Effects of arbuscular mycorrhizal fungi on growth and root traits of dicotyledons plants: A metaanalysis.

GUO Han-ling, LIU Shi-jun, XU Jing, SONG Shu-rui, TANG Jian-jun, CHEN Xin*

2017, 36(7):  1855-1864. 

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Arbuscular mycorrhizal fungi (AMF) can help host plants acquire nutrients and water from soil and therefore can enhance plant growth. Although AMF can change root traits of host plants, whether the effects of AMF on growth correlate with the effects on root traits is not well known. Here we performed a meta-analysis to quantify the effects of AMF on growth and root traits of dicotyledonous plants, and the correlation between these two effects under different soil phosphorus (Olsen-P) levels. AMF significantly increased total biomass, shoot and root biomass, length and area of roots, but decreased the specific root length. These AMF effects were influenced by soil P levels. Effects of AMF on plant growth were higher under low and intermediate soil P than under high soil P level. For root traits, however, the AMF effects were higher under intermediate soil P than under low and high soil P level. Regression correlation analysis showed a high association between the effect of AMF on plant growth and the effect on length and volume of roots. The correlation between effect of AMF on root length and mycorrhizal growth response was higher under low soil P level than under low and intermediate soil P level. The results suggest that the AMF effects on plant growth could be through altering the root traits, further affecting carbon allocation and water and nutrient acquisition.

 

Microbial community diversity of Fu brick tea produced in different regions by Illumina MiSeq technology.

ZHAO Ren-liang1，2，3, XU Wei1，2, WU Dan1，2, JIANG Yi-he1，2, ZHU Qi1，2*

2017, 36(7):  1865-1876. 

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Illumina Miseq technology was used to study the microbial community structure and diversity of Fu brick tea made in different regions. The results showed that the bacterial species of Fu brick tea were various, which consisted of 9 phyla, 16 classes, 29 orders, 50 families, 66 genera, and Lactococcus was dominant fungi. The prokaryotic microbial abundance and diversity of Fu brick tea made in Hunan were highest. Fungi analysis results showed that there were 2 phyla, 6 classes, 6 orders, 7 families and 7 genera, and the Aspergillus was the absolutely dominant strain, with the abundance of over 92% in each sample. In addition, the abundance of yeasts was less than 1%, and the yeasts included Candida, Pichia, Galactomyces, with different abundances for the samples produced in different regions. The eukaryotic microbial abundance of Fu brick tea made in Shaanxi was the highest. The cluster analysis showed that the samples of Fu brick tea produced in the same area were closer, suggesting that the regional environment and processing technology were the main factors affecting microbial community structure of Fu brick tea.

Diel vertical distribution patterns of phytoplankton community in Shidu Reservoir, Beijing.

LAN Xin, Lü Jing, MA Jing-yu, LIANG Hang-hai, WANG Hai-su, YANG Juan*

2017, 36(7):  1877-1884. 

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The diurnal migration rhythm and vertical pattern of phytoplankton are one of the important factors that influence the primary productivity of freshwater ecosystems, which is affected by the physiological characteristics of specific phytoplankton and the fluctuating aquatic environment. In order to understand the diurnal vertical migration characteristics of the phytoplankton and its potential constraints, an investigation on the vertical variation of phytoplankton communities was carried out for four times in one day at two sites (deep water and shallow water) of Shidu Reservoir, Beijing, in late April 2015. Physical and chemical features of water samples from the water columns were measured. Meanwhile, phytoplankton species from each layer of the water column were identified. The results showed that the vertical pattern and diurnal migration rhythm of specific algae were different between the two sites. Generally, the phytoplankton community as a whole was under high density and prone to be concentrated in the upper water layer during the daytime. In deep water, the vertical distribution and migration of phytoplankton was mainly affected by temperature, light, dissolved oxygen and nutrients. The dominant genus Microcystis migrated to the surface water at night due to the illumination. Peridinium aggregated in the deep layer, with its vertical migration mainly influenced by temperature and illumination. In contrast, Navicula dominantly concentrated in the surface layer of deep water. In shallow water, the dominant genera of algae fluctuated in a wider range than those in deep water. The relative abundance of Fragilaria was positively correlated with total dissolved solids (TDS). The distribution of Scenedesmus was mainly impacted by the dissolved oxygen and water temperature.

Influence of Pb²⁺, Zn²⁺ stress on the chlorophyll content and photosynthetic fluorescence characteristics of epiphytic moss Homaliodendron montagneanum (C. Muell.) Fleisch.

LIU Tao1,2, LIU Wen-yao1*, LIU Shuai1,2, SONG Liang1, HU Tao1,2, HUANG Jun-biao1,2

2017, 36(7):  1885-1893. 

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In this study, we used the method of submerged culture to detect the health status, chlorophyll contents and photosynthetic fluorescence parameters of epiphytic moss Homaliodendron montagneanum (C. Muell.) Fleisch under the pollution stress of Pb²⁺, Zn²⁺ and their combination. The results showed that chlorophyll contents decreased significantly when the moss were cultured under Pb²⁺, Zn²⁺ and combination of both, respectively, and the effect of Pb²⁺ stress was greater than that of Zn²⁺ stress. Pb²⁺, Zn²⁺ stress and Pb²⁺Zn²⁺ combination stress caused obvious decreases in maximal photochemical efficiency of PSII (F_v/F_m), effective photochemical efficiency of PSII (F_v′/F_m′), effective quantum yield of PSII (Ф_PSⅡ), coefficient of photochemical quenching (q_P) and acyclic electron transfer rate (ETR). However, coefficients of nonphotochemical quenching (NPQ) increased initially and then decreased under low concentration stress while NPQ was continuously decreased under high concentration stress. Furthermore, the chlorophyll contents and the photosynthetic fluorescence parameters of H. montagneanum responded differently under the treatments of Pb²⁺, Zn²⁺ and their combination. The variations of chlorophyll contents and photosynthetic fluorescence parameters indicated that the influence of Pb²⁺ stress on H. montagneanum was greater than that of Zn²⁺ or Pd²⁺Zn²⁺ combination under the same concentrations.

Fish community structure in Yangpu waters of Beibu Gulf.

ZHANG Wen-chao, YE Zhen-jiang*, TIAN Yong-jun, LI Zeng-guang, ZHUANG Long-chuan

2017, 36(7):  1894-1904. 

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Yangpu is located in the west of Zhanzhou City in Hainan Province. Yangpu water area is a good inshore spawning ground of Beibu Gulf. Based on the bottom trawl surveys in Yangpu waters in June and December 2014, the community structure of fishery resources and the diversity were analyzed. The results indicated that 68 fishes were collected in the two surveys, which belonged to 10 orders, 37 families and 49 genera, and they were warm water and warmtemperate species. The Perciformes was the most abundant (39 species), followed by the Pleuronectiformes (9 species) and Scorpaeniformes (6 species). The main catch resources were both demersal fishes and nearbenthic fishes, which accounted for 93.7% in total species. The fish community was characterized by miniaturization and showed a remarkable seasonal change between the two surveys. There were 11 common fish species in June and December, with a similarity index of 21.8%. The dominant species were Siganus fuscescens, Cynoglossus arel and Apogon quadrifasciatus in June, and Harpadon nehereus, Cynoglossus oligolepis, Setipinna taty and Apogon quadrifasciatus in December. The average biomass was 137.66 kg·km^-2 in June and 84.67 kg·km^-2 in December, and the average abundance was 11.38×10³ ind·km^-2 in June and 3.21×10³ ind·km^-2 in December. Cluster analysis, analysis of similarity (ANOSIM) and similarity of percentage (SIMPER) showed that there existed spatiotemporal heterogeneity to some extent for the community structure of fish. Biota and environment matching showed that sea bottom temperature and sea bottom salinity were the major environmental factors dominating the fish community pattern, and depth factor had different influences in different months.

A comparative study on the metabolic level and escape ability of guppy (Poecilia reticulata) before and after parturition.

XIA Ji-gang*, LU Yan, FU Shi-jian, PENG Jiang-lan

2017, 36(7):  1905-1909. 

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In order to investigate the effects of reproductive status on the survival fitness of ovoviviparous fish, the resting metabolic rate (RMR) and faststart escape performance of guppy (Poecilia reticulata) before and after parturition were examined. In addition, the relationships between the preparturition RMR and fecundity, and the parameters of preparturition faststart escape performance and fecundity were also determined. The preparturition RMR was found to be significantly higher than the postparturition RMR (P<0.05), whereas no difference was detected in faststart escape performance before and after parturition (P>0.05). The fecundity was positively related to the preparturition RMR (P<0.05), but had no correlation with the parameters of preparturition faststart  escape performance (P>0.05). The results indicated that the reproduction of guppy increased energy burden. However, as the survival fitnessrelevant parameter, the faststart escape performance was not affected by the reproductive status. These characteristics were hypothesized to be related to the evolutionary strategy of this species.

The spring waterbird community and home range of the whooper swan Cygnus cygnus at the upper and middle reaches of Yellow River in Inner Mongolia, China.

LI Shu-hong1, MENG Wei-yue1, CHEN Li-xia1, LI Yun-feng2, GAO Ru-yi2, RU Wen-dong2, SUN Meng-he3, DAI Qiang4, ZHANG Guo-gang1*, LU Jun1

2017, 36(7):  1910-1916. 

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To establish baseline information about the spring migration of waterbirds, we conducted surveys on the current status and habitats of whooper swans (Cygnus cygnus) and other waterbirds along the upper and middle reaches of the Yellow River in Inner Mongolia, ranging from Dengkou County to Tumed Right Banner based on distributions of vegetation types and the river stream in March 2015 and April 2016. Day and night home ranges for tracking whooper swans were determined using kernel density estimation (KDE) at levels of 90% and 50%. Enhanced vegetation index (EVI) of these two levels were calculated and compared. A total of 25671 waterbirds were recorded, belonging to 37 species, of which swans and ducks accounted for 89.6%. The whooper and tundra swan (C. columbianus) were predominant. According to GPStracking data, the upper and middle reaches of Yellow River were important stopover sites for spring migratory whooper swans, where the most swans stayed for long periods ((24.74±9.38) d). Their diurnal and night movements were roughly similar. The EVI at the upper and middle reaches of Yellow River were very low. Compared with that of the 90% level of KDE, the home range size of the 50% level and corresponding EVI were much lower from Dengkou County to Tumed Right Banner. During our field surveys, we discovered that these stopover sites were located on farmland around the Yellow River, providing abundant food and better shelter habitats for whooper swans and other waterbirds.

Breeding ecology and behavioral rhythm of brown-cheeked laughing thrushes (Garrulax henrici) in Linzhi, Tibet, China.

GAO Hong-mei1,2, WANG Zhong-bin2, YU Jing-jing2, YANG Xiao-lin2, ZONG Cheng1，2*

2017, 36(7):  1917-1922. 

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The browncheeked laughing thrush (Garrulax henrici) is endemic to China, and little work on its breeding biology has been done. From April to July of 2016, we investigated the breeding ecology of Garrulax henrici on the campus of Tibet Agriculture and Animal Husbandry College in Linzhi, Tibet. The behaviors during courtship period were observed by instantaneous scanning method, and behavioral rhythms of incubation and brooding period were monitored by infrared cameras. The results showed that 75.0% of the Garrulax henrici nests were built in conifers, 12.5% in deciduous trees, 8.3% in shrubs, and 4.2% in Poaceae plant. The clutch size was 2-3, egg length 29.6±0.4 cm, width 20.3±0.17 mm, weight 6.66±0.12 g. Nesting success rate was 86.7%, hatching success rate 60%, reproductive success rate 43.3%, and the factors impacting reproductive success were human disturbance and predation. In courtship period the foraging behavior percentage of G. henrici was 32.03% and moving was 29.27%. G. henrici had peak time for foraging, moving and singing in morning, and spent more time on resting in afternoon. The main behavior during incubation period was sitting in nest and incubation, accounting for 85.31% of total time and eggturning accounting for 5.02%. The behaviors in brooding period were mainly clearing up nest (39.74%) and sitting in nest (35.92%), and the mean feeding frequency was 2.95 times per hour. Feeding of G. henrici was mainly done by single female or male rather than by parents simultaneously.

Oxidative response of earthworm Eisenia fetida to Cd²⁺ stress based on factor analysis.

LIU Li-yan1, NING Yu-cui2, WU Xin-hui2, WANG Guang-dong2, LI Jing2, RONG Guo-hua2, ZHOU Dong-xing2*

2017, 36(7):  1923-1932. 

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When earthworms are exposed to pollutants, their antioxidant system will have responses immediately. Consequently earthworms are widely used to monitor various pollutants as sensitive bioindicator organisms. However, there are a large number of indices associated with the oxidative stress response. Finding out the key monitoring indices in the stress process becomes a practical demand of pollution monitoring and warning process. Factor analysis approach is a statistical method that uses a few factors to replace many original factors. This paper is aimed at analyzing and sorting factors related to Cd²⁺ on the earthworm Eisenia fetida under oxidative stress. Our experiment was divided into two groups: shortterm test and longterm test. The former one was for ten days, taking out an earthworm every day for analysis; The latter test lasted for 30 days, taking out an earthworm every ten days. The Cd²⁺ concentration was set at 0, 50, 100, 125, 250 and 500 mg·kg^-1. Postclitellum segments of earthworms were chosen to determine SOD, POD, GPX, GST, CAT, VE, MDA and AChE. The results showed that in the shortterm group, the main bioindicator associated with oxidative stress reaction was CAT at the exposure time of 1-3 days, MDA at 4-5 days, POD at 6-7 days, and GST and GPX at 8th day, CAT at days 9-10. With the longterm test, GPX was the main bioindicator associated with oxidative stress reaction.

 

Effects of soil biological disinfestation on tomato bacterial wilt control, soil physicochemical properties and soil microorganism community.

WU Chao-rong1,2, HUANG Fei1,2, GAO Yang1,2, MAO Yi-hang1,2, CAI Kun-zheng1,2*

2017, 36(7):  1933-1940. 

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Rice bran application and anaerobic treatment with irrigation were conducted to explore the effective ways of prevention and control of bacterial wilt. The results showed that the effects of rice bran (B), rice bran + irrigation (DB) and rice bran + anaerobic disinfestation (ADB) on bacterial wilt suppression were 82.5%, 90% and 100%, respectively. ADB treatment significantly increased plant height, stem diameter and fresh weight of tomato by 176%, 111% and 755%, respectively. In comparison with the control, DB and ADB treatments significantly increased soil temperature, pH and conductivity (EC), but reduced redox potential (Eh); ADB treatment significantly increased the contents of succinic acid, fumaric acid and citric acid in soil. In addition, DB and ADB treatments reduced the amounts of soil bacteria, actinomycetes and fungi, but increased the ratios of bacteria/fungi and bacteria/actinomycetes, and significantly reduced the amount of Ralstonia solanacearum in soil and plant stems. This study indicated that both DB and ADB treatments could significantly improve soil physicochemical properties and regulate soil microbial community structure, thus inhibiting R. solanacearum development and reducing the occurrence of tomato bacterial wilt.

Effects of passivators and urea on soil Cd availability.

YU Chun-xiao1,2, ZHANG Li-li1*, YANG Li-jie1,2, LI Dong-po1, WU Kai-kuo1,2, CUI Ya-lan1,2, XUE Yan1,2, WU Zhi-jie1

2017, 36(7):  1941-1948. 

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In the current research, an incubation experiment was conducted to test the passivation effect of biochar (B), sepiolite (S) and phosphorite (P) in combination of urea application on cadmium (Cd) availability in order to explore the effective materials for the development of Cdpassivation fertilizers. The results showed that surface area, specific surface area and functional group of passivators B, S and P were all increased after acid modification. Compared to the treatments without application of passivators, all the treatments with application of passivators alone or in combination decreased available Cd content, among which, S+P exhibited the best passivation effect, and available Cd content decreased by 23%. Compared to the application of urea alone, the application of urea combined with passivators decreased available Cd content and S+P treatment showed the best effect. Passivator addition can alleviate soil acidification caused by the ureaN transformation, increase the soil pH, and reduce the availability of Cd to a certain extent. The results suggest that acid modified P and S can be used in the development of new type toxic metalpassivation fertilizers.

Effects of land use patterns on soil enzyme activity in Chongming Island.

NING Mu-lei1, GAO Huan-huan1, HUANG Tian-ying1, YU Wen-juan2, KANG Hong-zhang1,3*

2017, 36(7):  1949-1956. 

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In order to explore the change of soil enzyme activities under different landuse patterns, Metasequoia glyptostroboides (MG) forests (16-, 25-, 35-year-old), 20-year-old Cinnamomum camphora (CC) forest and deforested land (formerly a 25-year-old Cryptomeria fortunei forest) were investigated at Dongping National Forest Park in Chongming Island. With rice paddy field as a control, we assessed the effects of different landuse patterns on the activities of soil urease (URE), invertase (INV), catalase (CAT) and alkaline phosphatase (ALP) in 0-10, 10-20 and 20-30 cm soil layers. The results showed that: (1) The difference in the activities of the four enzymes under different landuse patterns was significant (P<0.05). Returning farmland to forests increased soil enzyme activities and improved soil properties, but deforestation had opposite effects. (2) Afforestation tree species and afforestation duration were also important factors affecting soil enzyme activities. There was a significant linear correlation between stand age and soil enzyme activities. CC had higher soil enzyme activities than MG, and improved soil microbiological properties better. (3) Soil enzyme activities decreased with the increase of soil depth. (4) There were significant or very significant correlations between INV, ALP and URE activities in the same landuse type (P<0.05 or P<0.01), while CAT activity showed relatively weak correlations with other enzymes.

Contents of soil organic carbon and nitrogen forms in rhizosphere soil of Cunninghamia lanceolata and the rhizopshere effect.

LIU Shun1,2, SHENG Ke-yin2, LIU Xi-shuai2, WU Zhen-hua2, GUO Xiao-min2,3, XIAO Fu-ming4, ZHANG Wen-yuan2,3*

2017, 36(7):  1957-1964. 

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Chenshan red fir (Cunninghamia lanceolata) is an endemic tree species in Jiangxi Province granted with national geographical protection status, but the relationship between plants and soils were not well understood. In the current study, different tree ages (5, 10, 20 and 40 years) of C. lanceolata were selected to examine the contents of soil organic carbon (SOC) and different nitrogen forms in the rhizosphere and nonrhizosphere soils and their relationships. The results showed that the pH value of rhizosphere soil was slightly lower than that of nonrhizosphere soil, while SOC and nitrogen contents were higher. SOC and nitrogen contents of rhizosphere and nonrhizosphere soil decreased initially with the increasing plantation age, but increased thereafter. The rhizosphere effects of SOC, total N and organic N increased initially with plantation age and then decreased, but that of nitrate and ammonium firstly increased and then kept relatively stable. The rhizosphere effects on pH and alkaline hydrolysis N experienced little change. The rhizosphere effects of different N forms on soil pH and SOC were in order of total N>inorganic N>alkaline hydrolysis N. In terms of the rhizosphere effect, the influences of alkaline hydrolysis N and total N on pH and SOC were the greatest. The proportion of nitrate increased with the plantation age compared with that of ammonium. More attentions should be paid to the N loss caused by soil denitrification and subsequent soil nutrient decline. At age about 10 years, forest soil organic matter and N pools should be replenished so as to prevent the soil fertility decline.

Cadmium pollution in soil and rice plants in Zhangyizhan Town of Zhangshi irrigation area of Shenyang.

FU Yu-hao1,2,3, LI Feng-mei1,3*, GUO Shu-hai1,3, WU Bo1,3, ZHANG Ling-yan1,3

2017, 36(7):  1965-1972. 

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Samples of paddy soil and rice plants were collected in the Zhangyizhan Town, which was located in downstream area of Zhangshi, Shenyang, China. Total Cd and different fractionations of Cd in soil and rice plants were determined. The pollution status of soil and brown rice was analyzed by single factor pollution index method. The factors that affected Cd uptake of plants were investigated according to the analysis of Cd migration coefficient and Cd enrichment factor in plants, contribution rate of different Cd fractionations to plants, and the relationship between Cd fractionations and soil physicochemical properties. Results showed that Cd concentrations in soil ranged from 0.47 mg·kg^-1 to 2.49 mg·kg^-1, which exceeded the second class soil standard in China’s Soil Environment Quality Standard (GB 15618-1995). Compared to the soil background value, the concentrations of Cd were 1.47-12.11 times more than the local background value in Shenyang. The proportions of different Cd species in studied soils were: Residual fraction>weakacid soluble fraction >reducible fraction >oxidizable fraction. The amount of Cd accumulated in different parts of rice followed the order of root>stem>leaf>grain. In addition, the Cd concentration of 41.6% brown rice samples exceeded the pollution limit for food and classified as slight pollution. The accumulation of Cd in rice, the migration ability of Cd in rice plants and the distribution of Cd in soil were important factors affecting the uptake of Cd in rice. The largest contribution to the uptake of plants came from weakacid soluble fraction and reducible fraction. There were significant negative correlations between weakacid soluble and reducible fractions and soil characters such as pH and CEC.

 

Comprehensive evaluation of ecological health functions of green space in Beijing Purple Bamboo Park.

DUAN Min-jie1, WANG Yue-rong1*, LIU jing2

2017, 36(7):  1973-1983. 

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In order to make a comprehensive evaluation of ecological health functions of urban park green space to guide the construction of urban green space and green travel, the study selected four structure types of green spaces and 13 different plant configuration modes in Beijing Purple Bamboo Park as the research objects. A quantitative assessment of ecological health functions of four ecological health factors: negative air ions concentration, human comfort degree (referring to temperature, humidity and wind speed), PM_2.5 concentration and noise level were carried out both in single and comprehensive ways. The results showed that in spring and summer, all the green spaces could improve the negative air ions concentration, and the diurnal variation of negative air ions concentration showed a singlepeak trend (lower in the morning and evening, higher at noon), the daily variation ranges were 75-750 ions·cm^-3 and 123-1074 ions·cm^-3 respectively. In autumn and winter, the daily variation ranges of negative air ions concentration of green space were small, being 324-527 ions·cm^-3 and 277-523 ions·cm^-3 respectively. The seasonal rankings of negative air ions concentration were summer > spring > autumn > winter. In spring and summer, all the types of green spaces could make the PM_2.5 concentration reduced, while the PM_2.5 concentrations in a few green spaces in autumn and winter were higher than in control. The diurnal variation of PM_2.5 concentrations of green spaces showed a trend of high in the morning and evening, and low at noon. The seasonal variations of PM_2.5 reduction capability were spring > winter > summer > autumn, with a range of reduction of -2.35%-12.02%. The human comfort degree of green spaces was improved in spring and summer, especially in summer, but reduced in autumn and winter. The seasonal rankings of human comfort degree were spring > summer > autumn > winter. All the green spaces could reduce the noise in summer, and the range of net attenuation rate was 0-5.57% and each had its best noise reduction width. Comprehensive analysis indicated that the ecological health function of the arborshrubgrass structure type was the best in Beijing Purple Bamboo Park in summer, followed by arborgrass and shrubgrass, the lawn structure type was the worst. The optimal landscape plant configuration mode was Sabina chinensis + Acer truncatum-Lonicera maackii+ Buxus sinica var. parvifolia + Viburnum sargentii + Amygdalus triloba+ Buxus sempervirens -Carex tristachya.

Cool island effect of urban parks and its influencing factors within the Fifth Ring in Beijing.

QIU Kuan-biao1,2,3,4, JIA Bao-quan2,3,4*, CHENG Jun-feng5

2017, 36(7):  1984-1992. 

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Parks play a vital part in mitigating the urban heat island. However, the cooling effect of parks and its relationship with the landscape composition have not been well studied so far. In this work, we retrieved the surface temperature in the parks and conducted the analysis of the relationship between the surface temperature and the landscape composition both inside and outside the parks, via buffer zone analysis method and regression method, using the land use data and Landsat 8 image data in 2013. Results showed that the surface temperature in the parks was 28.91 ℃, while the surface temperature within the Fifth Ring was 30.67 ℃. The parks in the northwestern and eastern parts had much lower surface temperature than those in the southern and southwestern parts. A negative relationship was found between the surface temperature and the percentage of water bodies in the parks, while a power relationship was found between the surface temperature and the percentage of impervious surface,  in the parks. Among the landscape characteristics outside the parks, the percentage of the impervious surface, the patch density of both water bodies and impervious surface exerted great influences on the surface temperature inside parks. The percentage of the impervious surface had an influencing scope of 300 m, while the patch density of water bodies approximately 800 m, the significant (P<0.05) and extremely significant (P<0.01) scope were 500 m and 200 m. The results of stepwise regression showed that the landscape characteristics in the outer scope with a width of 200-400 m controlled the surface temperature in the parks, and the landscape composition within a width of 300 m exerted greater influences on the surface temperature in the parks. These findings can be applied into the park design and urban planning.

Indications and causes of “evaporation paradox” in Jilin Province.

YUE Yuan1,2, SHEN Shuang-he1,2*, JIN Yu1,3, WANG Qi4

2017, 36(7):  1993-2002. 

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Based on the data collected from 45 meteorological stations of Jilin Province from 1970 to 2014, the paper reviews the change trend of pan evaporation and lays emphasis on the analysis over the distribution patterns and the causes of the “evaporation paradox” in Jilin Province. The results show that in the past 45 years, the temperature in Jilin Province has increased significantly and there is a noticeable decrease trend of pan evaporation, indicating the occurrence of “evaporation paradox”. In the four seasons, the evaporation in spring decreased significantly, while the evaporation in the other three seasons increased slightly, but the difference is not obvious. Averagely the “evaporation paradox” occurred at 30 meteorological stations in total and the places of occurrence varied from west to east in an increasing manner. The “evaporation paradox” occurred more in spring than in the other seasons; in the other seasons the occurrence of “evaporation paradox” was only found at a very few stations in western and eastern regions of Jilin Province. The degree of influence of relevant meteorological factors on evaporation is: wind speed > vapor pressure difference > temperature > sunshine hours. The main factor affecting the change of evaporation in spring is wind speed, while the main factor affecting the change of evaporation in the other three seasons of summer, autumn and winter is the vapor pressure difference. The main factors affecting the annual evaporation of the western and central regions of Jilin Province are wind speed and sunshine hours, while in the south, it is the vapor pressure difference.

Effect of land use change on landscape ecological security in Erhai Basin.

WANG Tao, ZHANG Chao*, YU Xiao-tong, CAO Xiao-wang

2017, 36(7):  2003-2009. 

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To study the landscape spatial change of smallscale natural watersheds integrated by plateau lakes and its impacts on landscape ecological risk, Landsat remote sensing image interpretation data in Erhai Lake Basin in 1995, 2005 and 2015 were used, and GIS spatial analysis technique and Fragstats 3.4 were used to calculate the landscape pattern index. Accordingly, the landscape ecological risk model was constructed, and the temporal and spatial characteristics of ecological risk and its evolution mechanism in Erhai Lake Basin were analyzed. The results showed that: (1) The area of landscape types changed obviously from 1995 to 2015 in Erhai Basin. Woodland, grassland and water landscape decreased gradually, the cultivated land and wetland decreased first and then increased, while the construction land increased significantly. (2) The quantitative analysis of landscape index in Erhai Basin showed that the landscape spatial heterogeneity decreased, and the landscape type distribution changed from centralized to scattered, and as a result, the control effect of woodland was weakened. (3) During the past 20 years, the ecological security of the watershed tended to deteriorate, the average ecological risk index changed from 0.4998 in 1995 to 0.5896 in 2015, the proportion of high ecological risk area changed from 34.0% in 1995 to 47.8% in 2015, and the distribution of high ecological risk region changed from the arc pattern along the periphery of the basin to the multicore pattern centered on the Erhai Lake. The spatial and temporal changes of the ecological risk of the basin were closely related to the evolution of land use types and human activities. Largescale tourism development and the differences in urbanrural development mechanism were important factors leading to the increase and transfer of high ecological risk area in this region.

Effects of climate warming on flowering plants, pollinators and their interactions.

WANG Ying-jie1, LU Ning-na2, YANG Jie-yu1, DING Tian-feng1, ZHAO Zhi-gang1*

2017, 36(7):  2010-2018. 

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The interactions between flowering plants and their pollinators constitute complex pollination networks. Over the past twenty years, the effects of global warming, as the main feature of climate change, on flowering plants, pollinators and their interactions have become a hot topic of research. These studies will help us to better predict the effect of climate warming on pollination networks and even the ecosystem functions. This paper reviews the influences of climate warming on reproduction of flowering plants, including flowering phenology, characteristics of floral attraction and reward, pollinator activities and plantpollinator interactions, as well as plantpollinator networks at the community level. Flowering plants can respond to climate warming by adjusting floral resource availability (the amount of nectar, the quantity and quality of pollen) and reproduction output of pollinating insects. Climate warming can affect pollinatormediated patterns of pollen flow and thus pollination success. Under the background of climate warming, therefore, changes in plants, pollinators and their interactions will alter the structure of pollination networks. However, the pollination networks can alleviate the mismatch between plants and pollinators caused by inconsistent changes by the buffering mechanisms, and thus maintain the stability. Overall, the studies on pollination networks under the background of global warming are still lacking, and future researches should highlight the following aspects: (1) to shed light on the causes and mechanisms of effects of global warming on phenology matching degree between plants and pollinators; (2) further to explore interactions between plants and pollinators in different ecosystems globally; (3) to conduct longterm studies of interaction networks between plants and pollinators at the levels of community and ecosystem.

Effects of dissolved oxygen on nitrogen transformation in paddy soil and nitrogen metabolism of rice: A review.

HU Ji-jie, ZHU Lian-feng, ZHONG Chu, ZHANG Jun-hua, CAO Xiao-chuang, YU Sheng-miao, Allen Bohr James, JIN Qian-yu*

2017, 36(7):  2019-2028. 

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Dissolved oxygen (DO) plays an important role in nitrogen cycling in paddy fields and in the growth and development of rice. To deepen the understanding of the effects of DO on nitrogen transformation in paddy fields and nitrogen metabolism in rice plants is of great significance for reducing nitrogen loss in paddy fields and improving nitrogen utilization efficiency of rice. In recent years, studies have elucidated the effects of DO on soil biochemical processes such as nitrogen fixation, ammonification, nitrification and denitrification, as well as the diversity of microbial populations. In addition, a large number of studies have also proved the importance of DO for nitrogen uptake and utilization in rice. In this paper, we systematically introduced the effects of DO on microbial community structure and activity, as well as its relationship with transformation of different forms of nitrogen in paddy fields. We then reviewed the latest research progresses about the response mechanisms of rice root growth characteristics, nitrogen uptake and assimilation, and relevant amino acid metabolisms to DO. Finally, the problems and prospects of rice production were put forward according to the research status of oxygen nutrition in rice fields at the present stage.

The research progress in environmental factors and control techniques of filamentous green algae growth.

ZHANG Lu1,2, LIU Bi-yun2*, GE Fang-jie2, LIU Qi1,2, YI Ke-lang2, WU Zhen-bin2

2017, 36(7):  2029-2035. 

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Filamentous green algae (FGA) are one group of the important primary producers in aquatic ecosystems. Because of high niche overlapping, there are complex interactions among FGA, submerged macrophytes and planktonic microalgae. In recent years, a large number of FGA have appeared in the clear lakes that have successfully recovered submerged plants, and excessive growth of FGA could affect the growth and propagation of submerged macrophytes and dynamic changes of planktonic communities. Thus, how to control the excessive proliferation of FGA becomes one of the hot topics in the aquatic ecosystem research. This paper reviews the progresses in the study of ecological functions of FGA, the effects of environmental factors on the growth, control methods of overgrowth and the competitive advantages between FGA and submerged plants and phytoplankton. The control strategy of FGA is forecasted from the aspects of life history and competition mechanism of FGA in order to provide important insights into the ecological restoration and management of eutrophic shallow lakes.

Research advances in microbial volatiles and their biocontrol potential.

ZHANG Qing-hua1,2, HUNG Li-li1, LIAN Xin-kun1, ZHAN Zhen-liang1, FENG Li-zhen1,2*

2017, 36(7):  2036-2044. 

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In recent years, increasing attention has been paid on the study of microbial volatile organic compounds (MVOCs) not only because of the species diversity of MVOCsemitted microbes, but also the complexity and versatility of MVOCs. This review summarized the methods for MVOCs collection and analysis, diversity of MVOCsemitted fungal and bacterial species, diversity of antimicrobial MVOCs substances and its application in the biological control of plant diseases. Microbial volatiles represent a new frontier in bioprospecting. The discovery of new MVOCsemitted microbial species and the specific biological activity, function, action mechanism and application of MVOCs should be considered as important research areas.

Effects of reclamation on wetland waterbird populations, behaviors and habitats.

YAN Feng, LI Ning, YANG Wen, QIAO Ya-jun, AN Shu-qing*

2017, 36(7):  2045-2051. 

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Waterbirds are important components of wetland ecosystems, which are regarded as indicators used to monitor the quality of wetland environment owing to their sensibility to environmental change. Reclamation has seriously damaged the ecological environment of wetland and caused significant impacts on waterbird populations, behaviors and habitats. This paper analyzed the effects of reclamation on the population and diversity of birds in the aspects of population ecology, summarized the effects of reclamation on feeding, reproduction, migration and mixedspecies flocks, and discussed the effects of reclamation on habitat use and selection. Reclamation usually reduces the population of specialist rather than the generalist. The intensity of reclamation determines the diversity of waterbirds. Moderate reclamation makes habitat diversified, which is conducive to increase the diversity of waterbirds, and excessive reclamation makes habitat fragmented, which decreases diversity of waterbirds. The situation of habitat after reclamation affects waterbird feeding, reproduction, migration, mixedspecies flocks and habitat selection. More-over, the reduced tidalflat area and changed plant community are not conducive to the foraging and inhabitation of grallatores, while the artificial wetland provides abundant food sources and good habitat for natatores. We should expand the spatial and temporal scales of the research to analyze the mechanism of reclamation effect and analyze a variety of waterbirds together to find the mechanism of response to the reclamation in the future research.

Application of R software on tree ring width measurement.

SHI Jing-ning, YU Jian, ZHOU Hua, MENG Sheng-wang, LIU Qi-jing*

2017, 36(7):  2052-2059. 

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Tree rings record the growth histories of trees. The means by which researchers extract precise characteristics of tree rings are fundamental to the related fields. The objective of this study was to measure treering widths with statistical analysis software R. This method provides custom R functions to automatically or manually mark treering boundaries on digital images based on edge detection algorithm, and calculates treering widths using coordinates of successive boundary points. Width of inclined treering is corrected with R based on trigonometric functions. Custom R functions offer the ability to compare with multiple sample images to mark rings, handle broken samples and quickly reconstruct previous results. The results showed that this method allowed accurate measurement of treering widths. Tree ring widths calculated by this method was in good agreement with results measured with WinDENDRO. This method is simple and reliable. Digital images stored in the hard disk are convenient to maintain for long periods; R is open source software, and much cheaper than commercial tools like LinTab and WinDENDRO. In addition, R provides a wide variety of statistical and graphical functions, and can be easily extended with R packages. Thus, data analyses of treering widths could run in the same software without outputting.

Comparison of light response modeling of photosynthesis in Castanopsis sclerophylla leaves under different CO₂ concentrations.

TANG Xing-lin1,2, CAO Yong-hui1,2, ZHOU Ben-zhi1,2*, ZHOU Yan3, GU Liang-hong4

2017, 36(7):  2060-2067. 

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The light response curves of Castanopsis sclerophylla leaves, a constructive species in subtropical forest, were measured under four different CO₂ concentrations, and were fitted with five models to explore the optimal models for different CO₂ concentrations and investigate the adaptability of parameters of C. sclerophylla to CO₂ concentrations. The results showed that the fitting effects of the five models were in descending order of modified rectangular hyperbola model > modified exponential model > exponential model > non-rectangular hyperbola model > rectangular hyperbola model. The light saturation point (LSP) and the maximum net photosynthetic rate (P_max) were best fitted by modified rectangular hyperbola model, and the dark respiration rate (R_d) was best fitted by non-rectangular hyperbola model. The adaptability of the five models to different CO₂ concentration varied. Rectangular hyperbola model, exponential model, and modified rectangular hyperbola model were fitted well to the curves under low CO₂ concentration, non-rectangular hyperbola model to high CO₂ concentration. The light compensation point (LCP) and R_d of C. sclerophylla decreased with the increased CO₂ concentration and P_max increased with the increased CO₂ concentration. In conclusion, increased CO₂ concentration can improve the photosynthesis and facilitate its use to low light for C. sclerophylla leaves, and suppressed its respiration.

Wetland information extraction based on climate division and remote sensing technology in Daxing’an Mountains.

LIU Huan-jun1, SHENG Lei1, YU Sheng-nan1, ZHAO Hui-ying2, GAO Yong-gang2, QIN Le-le1, WANG Xiang1, ZHANG Xin-le1*

2017, 36(7):  2068-2076. 

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As to the complexity of wetland remote sensing on high mountain wetlands, an objectoriented hierarchical segmentation based on climate division was proposed in this study to extract information of high mountain wetlands. Time series of MODIS normalized difference vegetation index (NDVI) and the data of Digital Elevation Model (DEM) were deployed to extract wetlands on the basis of climate division, and the temporalspatial changes and causes of wetlands in Daxing’an Mountains during 2001-2013 were quantitatively analyzed. The objectoriented method with characteristics of MODIS images showed better accuracy than maximum likelihood method and Logistic model with pixels in wetland extraction. The cartographic accuracy of Daxing’an Mountains reached 82% by the objectoriented method, and the Kappa coefficient was 0.74. The Daxing’an Mountains wetland area was 414.89 hm² in 2001 and then decreased to 340.39 hm² in 2013. The area of wetlands increased and decreased differently in various regions. Increased wetland area mainly distributed in Tahe and Huma counties due to higher annual rainfall in 2013, while decreased wetland area mainly concentrated in Gannan and Longjiang counties due to conversion of wetlands into cultivated lands. This study provides technical support for information extraction of spatial and temporal dynamics of mountain wetlands.

Macroinvertebrate community structure and IBI based health assessment of Liuxi River.

LIN Luo-min1, GUAN Zhao-ying2, ZHENG Xun-hao1, LIN Shu-zhong3, WANG Zhi-jun4, CHEN Gang4, WEI Gui-feng1*

2017, 36(7):  2077-2084. 

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Macroinvertebrates were sampled at 21 sites in Liuxi River, Guangdong Province in February, June, September and December of 2015. In total, 114 species from 95 genera and 54 families of macroinvertebrate were identified. There were 81 species in Insecta, accounting for 71.05% of the total species; 23 species in Mollusca (Gastropoda, Lamellibranchia), accounting for 20.18%; and 10 species of Hirudinea, Oligochaeta and Crustacea, accounting for 8.77%. The spatial distribution range, discrimination, and paired Pearson correlation of 21 candidate metrics were explored over the sampling sites, including 6 reference sites and 15 impaired sites. Six biological metrics were finally selected for the B-IBI index, including Shannon’s diversity index, EPT number of taxa, percentage of Chironomidae taxa, percentage of Tubificidae taxa, the number of sensitive taxa and percentage of tolerance taxa. These six biological metrics were calculated in their relative values based on the disturbance, and B-IBI was the summation of all the six metrics. According to these established ranking criteria, our assessment showed that among 21 sites of Liuxi River, 5 sites were healthy, 3 sites subhealthy, 10 sites fair, and 3 sites unhealthy. Overall, the Liuxi River was fair in health status; the upstream and the branches (including Guifeng River, Shiba River, and Lvtian River) were healthy, the midstream and the downstream, Niulan stream, most of the branches were fair or poor. Our results suggested that the B-IBI was suitable for evaluating the water quality of Liuxi River, and human activities had great impacts on the community structure of macroinvertebrates.