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| 1 | Variations in silicate concentration affecting photosynthetic carbon fixation by spring phytoplankton assemblages in surface water of the Strait of Malacca显示文摘The Strait of Malacca (SoM), the world's busiest sea-route, is increasingly polluted as the rapid development of world trades, affecting phytoplankton primary productivity therein. The variations of surface phytoplankton biomass, size-structure and carbon fixation were investigated across the SoM during the spring period (May 4 to 9, 2011). Chlorophyll a concentration increased from 0.12 μg/L at the northwest entrance of the SoM to a maximal 0.63 μg/L at narrowest section, and decreased to 0.10 μg/L at the southeast entrance. Photosynthetic carbon fixation by phytoplankton coincided well with Chl a biomass, and increased from 10.8 to 22.3 μg C/(L d), then decreased to 9.21 μg C/(L d); while the carbon fixation rate showed an inverse pattern to the changes of Chl a, and decreased from 87.1 to 35.5 μg C/(μg Chl a d) and increased thereafter to 95.3 μg C/(μg Chla·d). Picophytoplankton cells (<3 μm) contributed to more than 60% and 50% of the total Chl a and carbon fixation at both the entry waters; while the contributions of pico-cells decreased sharply to the minimum of 18.3% and 27.5% at the narrowest part of the SoM. In particular, our results showed that the silicate concentration positively regulated Chl a biomass and carbon fixation, reflecting that the higher silicate favoured the growth of phytoplankton and thus led to higher primary production in this strait. | LI Gang LIN Qiang SHEN Pingping NI Guangyan SONG Xingyu WANG Shengfu FAN Yanzhi HUANG Liangmin TAN Yehui | 2013 | Acta Oceanologica Sinica2013，32，4： | 4 |
| 2 | Longitudinal patterns of spring-intermonsoon phytoplankton biomass,species compositions and size structure in the Bay of Bengal显示文摘Vertical distributions of phytoplankton biomass,compositions and size structure were investigated during the spring-intermonsoon (April 22 to 30) of 2010 along transact 10 N of the Bay of Bengal,northern Indian Ocean.Surface phytoplankton biomass (Chl a) was (0.065 ± 0.009) μg/L,being greater than 80% of which was contributed by pico-phytoplankton (<3 μm).The Chl a concentration vertically increased to the maximal values at deep chlorophyll maximum (DCM) layer that shoaled eastwards from 75 to 40 m.The Chl a biomass at DCM layer generally varied between 0.2 and 0.4 μg/L,reaching the maximum of 0.56 μg/L with micro-phytoplankton cells (>20 μm) accounting for 58% and nano-(3-20 μm) or pico-cells for 15% and 27%,respectively.In particular,the cells concentration coupling well with phosphate level was observed at middle layer (75-100 m) of 87 to 89 E,dominated by micro-cells diatoms (e.g.,Chaetoceros atlanticus v.neapolitana,Chaetoceros femur and Pseudonitzschia sp.) and cyanobacteria (i.e.,Trichodesmium hildebrandtii),with the cells concentration reached as high as 4.0 × 10 4 and 4.3 × 10 4 cells/L.At the rest of the transact however,dinoflagellates (e.g.,Amphisdinium carterae and Prorocentrum sp.) were the dominant species,with the cells concentration varying from 0.3 × 10 3 to 6.8 × 10 3 cells/L.Our results also indicate that the regulation of large cells (micro-,nano-) on phytoplankton biomass merely occurred at DCM layer of the Bay. | LI Gang KE Zhixin LIN Qiang NI Guangyan SHEN Pingping LIU Huaxue YIN Jianqiang LI Kaizhi HUANG Liangmin TAN Yehui | 2012 | Acta Oceanologica Sinica2012，31，2： | 2 |
| 3 | Hydrologic balance, net primary productivity and water use efficiency of the introduced exotic Eucalyptus grandis × Eucalyptus urophylla plantation in south-western China显示文摘Aims Land cover changes can disrupt water balance and alter the partitioning of precipitation into surface runoff,evapotranspiration and groundwater recharge.The widely planted Eucalyptus trees in south-western China have the potential to bring about hydrologic impacts.Our research aims to elucidate the hydrologic balance characteristics of the introduced exotic Eucalyptus grandis×Eucalyptus urophylla plantation and to assess whether its high productivity results from high water use efficiency(WUE)or large water consumption.Methods A 400-m^(2) experimental plot was established in an E.grandis×E.urophylla plantation in south-western China.Water balance components,including stand transpiration(T_(r)),evapotranspiration(E_(t))and runoff(R)were obtained as follows:T_(r) was estimated based on sap flow measurements,E_(t) was estimated as the average of surface transpiration and evaporation weighted by the fractional green vegetation cover using a modeling approach,and R was collected using the installed metal frame.Net primary productivity(NPP)was obtained from allometric equation and annual diameter at breast height(DBH)increment determination.Important Findings Annual E_(t) and T_(r) were 430±31 and 239±17 mm,respectively.Annual T_(r) accounts for 56±8%of total evapotranspiration on average.WUE(NPP/T_(r))of the E.grandis×E.urophylla was estimated to be 3.3–3.9 mmol·mol^(−1).Based on the comparative analysis of T_(r) and WUE,E.grandis×E.urophylla had a high productivity due to its high WUE without exhibiting prodigal water use.Meteorological factors including vapor pressure deficit and global solar radiation(R_(s))were key factors regulating E_(t) and T_(r) in our research site.Annual surface runoff,E_(t) and canopy interception occupied 7%,27–30%and 16%of total precipitation,while the remaining 46–50%of precipitation was used for sustaining groundwater recharge and altering soil water storage.The higher runoff coefficient(7.1%)indicated the weaker capability of E.grandis×E.urophylla to reserve water resource than natural forests and less disturbed plantations.The planting and protection of understory vegetation may decrease the surface runoff and exert beneficial effects on water conservation capacity of Eucalyptus plantation. | Yanting Hu Ping Zhao Yuqing Huang Liwei Zhu Guangyan Ni Xiuhua Zhao Zhihong Huang | 2019 | Journal of Plant Ecology2019，12，6： | 2 |
| 4 | Water transport of native and exotic tree species in relation to xylem anatomical characteristics in low subtropical China显示文摘Aims Exotic fast-growing tree species have been commonly planted as pioneer species to facilitate ecological restoration in South China.Their growth and resource utilization behavior related to intrinsic physiology and structural properties have profound influences on forest ecosystem.However,the contrastive research focusing on water utilization features along with xylem anatomical properties between native and exotic species is scarce in South China.The objective of this study is to investigate the sapwood anatomical characteristics and water utilization conditions of native and exotic fast-growing species,and to elucidate the relationship between sap-flux density and conduit features.Methods We measured sap-flux density,conduit length,diameter and density of four native species(Schima superba,Michelia mac-clurei,Castanopsis hystrix and Castanopsis fissa)and four exotic species(Eucalyptus citriodora,Eucalyptus urophylla×grandis,Acacia auriculaeformis and Acacia mangium).Sap flux density was measured based on the Granier’s thermal dissipation probe method.The whole-tree water transport was quantified by mul-tiplying sap-flux density by sapwood area.The measurements of conduit characteristics were conducted by using segregation and slice method.Important Findings Sapwood area increased with the growing diameter at breast height(DBH)as a power function.Native species had a larger water-conducting tissue area than exotic species at the same DBH value when trees grew to a size with a certain value of DBH.The con-duit diameter of exotic species was significantly larger than that of native species.Conversely,native species,such as S.superba and M.macclurei,had longer conduit length and higher conduit den-sity than other tree species.Based on a physiological interpretation of the measured conduit characteristics,native tree species devel-oped a safe water transport system while exotic fast-growing tree species come into being an efficient system instead.Water trans-port increased with the growing DBH as a power function,and the exponent for native species(1.60)was higher than that for exotic species(1.22).Under the combined impact of sap-flux density and sapwood area,native species presented a larger water transport at a larger DBH value,indicating that growth advantage of exotic fast-growing species might weaken as DBH increased. | Yanting Hu Jianguo Gao Ping Zhao Weijun Shen Peiqiang Zhao Liwei Zhu Guangyan Ni Junfeng Niu Lei Ouyang | 2018 | Journal of Plant Ecology2018，11，3： | 0 |
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