Growth and Physiological Response of Organs of Phragmites australis to Different Water Compensation in Degraded Wetlands     

LIXiaoyu  LIUXingtu  LIXiujun  LINJixiang  WENBolong 《湿地科学》2012,10(1):23-31

To study the effect of different water compensation on growth and physiology of reed in degraded wetlands,three water treatments in the field were conducted to test the height and photosynthesis of reed,the ions and soluble sugar contents of different organs.In the controls(without extra water compensation for 10 years),the height of reed was only 50 cm,the net photosynthetic rate,stomatal conductance,the intercellular CO2 concentration and transpiration rate were very low.The contents of Na + and Clin rhizome were higher than those in other organs.Discontinuous water compensation(continuous for 8 years,then stopped for 2 years)increased the height(2.1-fold),the net photosynthetic rate(41.8%),stomatal conductance(1.8-fold),transpiration rate(1.3-fold)of reed(Phragmites australis),and decreased the content of Na + (62.3%)and Cl- (71.1%)of rhizome significantly.Continuous water compensation(continuous for 10 years)increased the height(3.2-fold),the net photosynthetic rate(104%),stomatal conductance(2.4-fold),transpiration rate(1.5-fold)of reed,and decreased Na + (82.5%)and Cl - (64.7%)contents in rhizome, then accumulated the K+ ,H2PO4-,SO42- and soluble sugar contents significantly in rhizome.Interrupting water compensation led to the decrease of height(25.3%),the net photosynthetic rate(30.7%),stomatal conductance(17.3%) and increase of Na + (1.16-fold)in rhizome when comparing to the continuous water compensation.These results showed that recovering the degraded reed wetlands needed continuous water compensation yearly to promote reed growth.The organs of reed had corresponding physiological response characteristic to the different water compensation condition.Under long-time dry and waterlogging condition,the rhizomes both helped reed to adapt located environment,by enriching the ions such as Na+ ,Cl- ,and K+ ,H2PO4-,SO42- ,respectively.  相似文献   

一种时频信号相位补偿方法     

钟巍  龚大亮  龚航 《时间频率学报》2011,34(1)

为消除信号产生器内温度变化对信号相位的影响,提出了一种恒温控制和实时相位调整相结合的方法。在这种方法中,除恒温控制外,基于对信号产生器内部温度、相位测量值变化率、设备调相分辨率和相位波动指标等的分析研究,合理计算实时相位调整关键参数,进行实时相位调整,有效地减小信号产生器内部温度变化引起的相位波动,提高了输出端信号相位的一致性和稳定性。  相似文献   

生态补偿机制中的企业责任研究     

张平  胡明杰  张雪华  赵金锋 《河南气象》2009,(3):51-54

研究了企业在市场经济体制中的主体地位和企业承担的环境责任,通过对生态补偿的涵义和政策范围进行分析,明确了生态补偿与排污费、资源费之间的区别和联系,提出了完善企业履行生态补偿责任的政策框架、搭建企业履行生态补偿责任的职能体系及创新企业履行生态补偿责任执行形式的建议。  相似文献   

有限区域风速场求解流函数和速度势场的有效方案   总被引：3，自引：1，他引：2       下载免费PDF全文

朱宗申  朱国富 《应用气象学报》2008,19(1):10-18

流函数和速度势是表示风场的一种变量, 在数值天气预报模式和分析、同化方案中经常使用, 通常可以用风速分量场求解Poisson方程得到。对于有限区域系统, 往往采用差分方法, 但由于存在边界问题, 用计算所得到的流函数和速度势场重建风速场, 在边界附近经常出现明显的偏差。基于差分方法、利用有限区域风速场求解流函数和速度势场的基本方法和特点的分析, 在Arakawa A网格分布的有限区域, 设计了一种用差分方法求解流函数和速度势场的有效方案。在该有效方案中, 通过将有限区域向外扩展二圈, 风速场线性外推, 改进计算边界风速值和边界定解条件的效果; 尽可能使用协调、一致的差分格式, 提高求解精度; 最后利用一种增量订正迭代方法, 迭代2~3次就可以获得令人满意的结果。实例试验的对比、检验显示, 用该方案计算求得的流函数和速度势场重建风速场, 具有非常高的精度。  相似文献   

稳定有效的反Q滤波方法     

王珊  于承业  王云专  刘颖超 《物探与化探》2009,33(6)

反Q滤波是补偿大地吸收衰减有效方法之一,其稳定性和有效性是反Q滤波的前提条件.笔者研究了一种稳定的反Q滤波方法,并通过理论模型和实际数据与传统的增益限制反Q滤波方法进行了对比.结果表明:稳定反Q滤波更好地恢复了衰减的地震信号,并自动限制了对噪声的过渡放大.同时,还分析了噪声和增益限制因子G_(lim)对稳定反Q滤波的影响.  相似文献   

月球激光测距的现状及可能的改进方法     

熊耀恒  冯和生 《天文研究与技术》2002,(3):117-122

月球激光测距 (LLR)代表了单光子探测技术的高峰 ,是国际激光测距界奋斗的目标。本文回顾了月球激光测距的现状以及它所特有的技术难度 ,同时介绍了我们为增加月球激光测距回波光子数所提出的一些可能的改进方法。特别介绍了在月球激光测距中利用月面反射器近旁的月面扩展源探测与计算大气倾斜量 ,进而对测月的激光束实施大气倾斜量实时改正这样一个全新的概念。最后介绍了云南天文台的激光测距系统以及它的近期工作目标。  相似文献   

Numerical studies of hyperplasticity with single,multiple and a continuous field of yield surfaces     

Itai Einav  Alexander M. Puzrin  Guy T. Houlsby 《国际地质力学数值与分析法杂志》2003,27(10):837-858

The development of a new constitutive model would normally require a new procedure to be established for derivation of the incremental response. However, for models generated within the framework of hyperplasticity (using single, multiple or continuous yield surfaces), this derivation can be carried out using standard procedures. In this paper we present first the unified incremental response for a model using a single internal variable for general loading conditions. Next, we develop and explore three different numerical techniques for implementation of this procedure. One of the approaches, which seems superior, is extended to the multi‐surface hyperplastic formulation. Finally, to allow integration of continuous hyperplastic models within the same multi‐surface hyperplastic setting, the issue of discretization of the continuous field of yield surfaces is addressed. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

吉林省南部元古宙宇宙尘的某些特征及其意义   总被引：2，自引：0，他引：2  

徐光荣  梁宜林  张林  林文蔚  陈克樵  梁细荣  王安平 《矿物岩石地球化学通报》1997,(4)

吉林省南部元古宙宇宙尘的某些特征及其意义徐光荣梁宜林张林（长春工业高等专科学校，长春１３００２１）林文蔚陈克樵梁细荣王安平（中国地质科学院矿床地质研究所，北京１０００３７）（长春科技大学，长春１３００２６）关键词宇宙尘高铬特征共轭性吉林作者在吉林省南...  相似文献   

Compensatory responses of an arid land crucifer, Chorispora tenella (Brassicaceae), to experimental flower removal     

Jos M. Gmez  Marcelino Fuentes 《Journal of Arid Environments》2001,49(4):855

We studied experimentally the compensatory ability of an annual arid land crucifer, Chorispora tenella, with respect to density of conspecifics. Chorispora tenella was able to compensate for flower losses by modulating the rates of abortion of flowers, fruits and ovules. In addition, plants growing at lower density compensated more intensely against losses than plants growing at high density. Nevertheless, as a consequence of compensation, plants in all treatments produced the same quantity of seeds (equal compensation). These results suggest that, from flower production to fruit and ovule maturation, C. tenella maintained a number of ovules that exceeded those that it could eventually mature. This could help to colonize arid environments successfully, in which resources are typically scarce and spatio-temporally unpredictable.  相似文献   

Characteristics of turnover of carbonyl sulfide in four different soils     

Susanne Lehmann  Ralf Conrad 《Journal of Atmospheric Chemistry》1996,23(2):193-207

Release and uptake of carbonyl sulfide (OCS) were measured at 25°C in samples of three forest soils (BL, BW, PBE) and one soil from a rape field (RA). The soil samples were flushed with a constant flow of either air (oxic conditions) or nitrogen (anoxic conditions) containing defined concentrations of OCS. A cryogenic trapping technique with liquid argon (-186 °C) was used to collect gas samples for analysis in a gas chromatograph equipped with a flame-photometric detector. The dependence of net OCS fluxes between soil and atmosphere could be described by a simple model of simultaneous OCS production and OCS uptake. By using this model, production rates (P), uptake rate constants (k) and compensation concentrations (m _c ) of OCS could be determined as function of the soil type and the incubation conditions. Under oxic conditions, OCS production (P) and uptake were observed in all soils tested. However, the compensation concentrations (<166 ng l^-1; 1 ng OCS l^-1=0.41 ppbv) that were calculated from the model were high relative to the ambient OCS concentration (ca. 0.5 ppbv). The production rates (0.16–1.9 ng h^-1 g^-1 dw) that were actually measured when flushing the soil samples with air containing zero OCS were smaller than those (17–114 ng h^-1 g^-1 dw) calculated from the model. This observation was explained by two different concepts: one assuming the existence of a threshold concentration (m _t ) below which OCS was no longer consumed in the soil; the other assuming the existence of two different OCS consumption processes, of which only the process active at elevated OCS concentrations was covered by the experiments. The latter concept allowed the estimation of OCS compensation concentrations that were partially low enough to allow the uptake of atmospheric OCS by soil. Both OCS production and uptake in PBE soil were dependent on soil temperature (optimum 20 °C) indicating a microbial process. However, both production and consumption of OCS were not consistently inhibited by sterilization of the soil, suggesting that they were not exclusively due to microbiological processes. Under anoxic conditions, OCS was also produced, but was not consumed except in one soil (RA). Production of OCS in the soils was stimulated after addition of thiocyanate, but not thiourea, thiosulfate, thioglycolate, tetrathionate, sulfate, elemental sulfur, cysteine and methionine.  相似文献