Relationships between individual movement,trophic position and growth of juvenile pike (Esox lucius)

Variation in movement between individuals can have important ecological effects on populations and ecosystems, yet the factors driving differences in movement and their consequences remain poorly understood. Here, individual variability in the movements of juvenile (age 0 +  and 1 +  year) pike Esox lucius was assessed using passive integrated transponder (PIT) telemetry in off‐channel nursery areas over a 26‐ month period. Differences in the movement patterns of individuals were tested against their body sizes, ages, growth rates and trophic positions using data collected through a combination of catch‐and‐release sampling and stable isotope analyses. Results revealed that variation in movement between individuals was affected by age, with 1 +  individuals moving more than individuals of age 0 + , but not length. Individuals whose TP was low on their initial capture event moved significantly less than those with a higher initial TP. Individuals that moved more grew faster and achieved a higher final TP. These results suggest that higher activity (i.e., increased movement) increases resource acquisition that enhances growth rates, which could ultimately maximise individual performances.     

土壤浸提液中硝酸盐氮氧同位素组成的反硝化细菌法测定

本研究优化了采用反硝化细菌法同时测定土壤浸提液中硝酸盐氮氧同位素组成的方法。在已有研究结果的基础上,通过采用5000~8000 r·min-1的转速离心、高纯氮气吹扫1 h、减少加样量及改造仪器自动进样器等措施对已发表方法进行了优化。对国际标准样品USGS34的分析表明,0.1~0.8μg NO-3-N样品量即可以得到较稳定、准确的测定值和校正值;同一时间内制备的硝酸盐δ15N的SD介于0.05‰~0.09‰之间,δ18O的SD介于0.28‰~0.48‰之间;在三个月之内δ15N和δ18O的测定值基本一致,表明该方法具有较好的准确度、精密度和稳定性。通过研究浸提剂、保存条件以及加热对测定土壤浸提液中硝酸盐氮氧同位素组成的影响,结果表明:常用的去离子水、KCl、Ca Cl2可能都含有微量的硝酸盐,随着加样量增大,浸提剂中含有的硝酸盐可能就会影响δ15N和δ18O的测定;对于土壤硝酸盐的浸提液,冷冻保存效果较好,保证了土壤硝酸盐氮氧同位素的准确性和稳定性;尽管加热对硝酸盐标准样品USGS34和IAEA-NO3的δ15N没有显著影响,但δ18O显著升高,说明加热易引起氧同位素分馏;而土壤硝酸盐浸提液样品加热前后的δ15N和δ18O的测定值没有显著变化,因此为避免产生氧同位素分馏和节省测试时间,建议同时测定土壤浸提液硝酸盐δ15N和δ18O时直接和反硝化细菌反应。应用本方法对不同肥料处理田间土壤浸提液硝酸盐的氮氧同位素组成进行了测定。     

Influence of stage of development in the efficiency of nitrogen fertilization on poplar

Poplar cuttings (Populus x euroamericana) were planted in pots and grown in a greenhouse for four months with drip irrigation. Two nitrogen (N) doses of 60 and 120 kg nitrate (N-NO₃^?) ha^?1 (labeling with ¹⁵N stable isotopes) were applied at one (time I), two (time II) and three months after of the plantation (time III). The aim of this study was to determine the N-fertilizer application method that resulted in optimal N-uptake by a short-rotation of poplar crop during first year of growth. Our data revealed that NUE (N use efficiency) was largest in the last part of the experiment. The larger development of those plants at this stage enabled the improved absorption and assimilation of N. Furthermore, ¹⁵N also revealed that supply of N at three months post-planting generated more biomass and increased the N reserves in the stem; a key factor for ensuring the optimum regrowth during the second year.     

内蒙农牧交错带地区土地利用方式和施肥对土壤碳库的影响

内蒙武川是我国典型的内蒙农牧交错带地区,土地利用方式转变和施肥是影响该地区农业生产和土壤碳储量的重要人类活动。选取内蒙武川地区,针对不同土地利用方式(耕地、退耕还林/还草)和施肥措施(化肥、有机肥)的长期定位试验土壤,分析土壤有机碳(SOC)、土壤无机碳(SIC)和全氮(TN)含量和储量,结合13C和15N稳定同位素方法,研究土地利用方式和施肥措施对于该地区土壤碳氮转化的影响规律。研究表明,退耕还灌/还草后,SOC储量较耕地均有显著提高(提高幅度0.60~0.98 Mg hm-2 a-1),SIC储量也增加或保持相同水平(柠条地除外)。相比不施肥处理,施用有机肥能显著增加SOC(1.08~1.19 Mg hm-2 a-1),施化肥处理则会降低SIC(0.06~0.16 Mg hm-2 a-1),且主要影响次生碳酸盐。施肥SIC中原生碳酸盐比例(0~23%)低于自然土壤(3%~29%)。施肥措施对于土壤碳氮的转化强度远大于土地利用方式的改变。对于内蒙等干旱半干旱地区土壤,土地利用和施肥措施对于土壤有机和无机碳的影响应该在区域固碳管理中给予全面考虑。     

不同水分条件下小麦碳同位素分辨率的遗传分析和QTL定位

为探讨小麦碳同位素分辨率(△)与抗旱性及产量性状的关系,以小麦品种宁春4号和宁春27号杂交构建的重组自交系（RILs）群体为材料,分析△在不灌水（W0）、灌1水（W1）、灌2水（W2）和灌3水（W3）四种水分条件下与其他不同性状间的遗传相关性,并定位控制小麦△的QTL位点。结果表明,△在RILs群体中呈双向超亲分离,分布频率表现为正态分布。随着干旱胁迫的增强,△值降低,RILs株系间的△变异程度增大,△双向超亲分离的比例增加。四种水分处理下叶片△与千粒重、穗粒重均呈负相关。穗粒重（Y）与△ (X₁)、叶绿素含量(X₂)、千粒重(X₃)的回归方程为:Y=0.056-0.110X₁+0.046X₂+0.037X₃,表明在适度干旱条件下低△影响了穗粒重。采用QTL IciMapping 4.0对△进行QTL检测,共检测到5个QTL,其中位于7B染色体上的有3个,位于5B和3D上的各1个。位于7B染色体上的3个QTL是在W0、W2和W3三种水分条件下分别检测到的,且W0和W3下检测到的2个QTL的标记区间相同（barc267~gwm46）,其中Q△-7B.3对△表型的贡献率达到40.3%。     

Discrimination of geographical origin of rice (Oryza sativa L.) by multielement analysis using inductively coupled plasma atomic emission spectroscopy and multivariate analysis

This study aims to determine the authenticity of the geographical origin of rice using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and chemometrics. The profiles of 25 elements in brown rice measured by ICP-AES were subjected to data-mining processes, including principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). PLS-DA clearly discriminated the geographical origin of rice samples grown in three countries. Eleven elements (Cu, Ag, Zn, Cr, Ca, Ba, Cd, Bi, K, Pb, and In) significantly contributed to the ability to discriminate the geographical origin of the rice. These results demonstrate the use of multielement profiling combined with chemometrics as a tool for discriminating food origins. This study extends our knowledge about the applications of both multielement profiling and chemometrics for the determination of food authenticity, and thus can be useful for controlling the geographical origin of rice by governmental administration and protecting consumers from improper domestic labeling.     

A preliminary study of water use strategy of desert plants in Dunhuang,China

Water is a restrictive factor for plant growth and ecosystem stability in arid and semiarid areas. The dynamics of water availability in soils and water use by plants are consequently critical to ecosystem functions, e.g. maintaining a high resistance to the changing climate. Plant water use strategies, including water-use efficiency(WUE) and the main water source that a plant species utilizes, play an important role in the evaluation of stability and sustainability of a plantation. The water use strategies of desert plants(Tamarix chinensis, Alhagi sparsifolia, Elaeagnus angustifolia, Sophora alopecuroides, Bassia dasyphylla and Nitraria sphaerocarpa) in three different habitats(saline land, sandy land and Gobi) in Dunhuang(located in the typical arid area of northwestern China) were studied. The stable isotope of oxygen was used to determine the main water source and leaf carbon isotope discrimination was used to estimate the long-term WUE of plant species in the summer of 2010. The results suggest that: 1) the studied desert plants took up soil water below the depth of 80 cm; 2) T. chinensis in the three habitats used deeper soil water and T. chinensis in the Gobi site had higher WUE than those in the saline land and the sandy land. The results indicated that desert plants in Dunhuang depended on stable water source and maintained high WUE to survive in water limited environments.     

Spatial distribution of δ~2H and δ~18O values in the hydrologic cycle of the Nile Basin

Existing δ2H and δ18O values for precipitation and surface water in the Nile Basin were used to analyze precipitation inputs and the influence of evaporation on the isotopic signal of the Nile River and its tributaries. The goal of the data analysis was to better understand basin processes that influence seasonal streamflow for the source waters of the Nile River, because climate and hydrologic models have continued to produce high uncertainty in the prediction of precipitation and streamflow in the Nile Basin. An evaluation of differences in precipitation δ2H and δ18O values through linear regression and distribution analysis indicate variation by region and season in the isotopic signal of precipitation across the Nile Basin. The White Nile Basin receives precipitation with a more depleted isotopic signal compared to the Blue Nile Basin. The hot temperatures of the Sahelian spring produce a greater evaporation signal in the precipitation isotope distribution compared to precipitation in the Sahara/Mediterranean region, which can be influenced by storms moving in from the Mediterranean Sea. The larger evaporative effect is reversed for the two regions in summer because of the cooling of the Sahel from inflow of Indian Ocean monsoon moisture that predominantly influences the climate of the Blue Nile Basin. The regional precipitation isotopic signals convey to each region's streamflow, which is further modified by additional evaporation according to the local climate. Isotope ratios for White Nile streamflow are significantly altered by evaporation in the Sudd, but this isotopic signal is minimized for streamflow in the Nile River during the winter, spring and summer seasons because of the flow dominance of the Blue Nile. During fall, the contribution from the White Nile may exceed that of the Blue Nile, and the heavier isotopic signal of the White Nile becomes apparent. The variation in climatic conditions of the Nile River Basin provides a means of identifying mechanistic processes through changes in isotope ratios of hydrogen and oxygen, which have utility for separating precipitation origin and the effect of evaporation during seasonal periods. The existing isotope record for precipitation and streamflow in the Nile Basin can be used to evaluate predicted streamflow in the Nile River from a changing climate that is expected to induce further changes in precipitation patterns across the Nile Basin.     

Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau,China

The hydrogen isotopic composition of plant leaf wax(δDwax) is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water(δDwater) and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content(SWC)(R2=0.9166), and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha(GCh) and Gahai(GH) transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC(R2=0.6835), which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau.