库布齐沙漠几种常见灌木光合生理特征与土壤含水量的关系

2006年7—9月,采用Licor-6400便携式光合作用测定系统在模拟光照条件下,对库布齐沙漠不同水分处理的3年生柽柳、小叶锦鸡儿、杨柴苗木进行观测。观测指标包括:光饱和点（LSP）、光补偿点（LCP）、表观量子效率（AQY）、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、羧化效率（CE）等。运用SPSS数据处理软件进行分析,确定这3种灌木光合生理特征与土壤含水量之间的定量关系。结果表明:①3种灌木光合生理特征对土壤含水量变化具有明显的阈值响应。②不同土壤含水量（SWC）下,柽柳、小叶锦鸡儿、杨柴苗木Pn最大值（Pnmax）的增加幅度分别为521、648、14.31 μmol/(m2·s)。③LSP随土壤含水量（SWC）的变化并不是特别明显,值在1 000～1 400 μmol/(m2·s)之间波动。④LCP随SWC的增加呈下降趋势,变化范围为217～741 μmol/(m2·s)。⑤AQY随SWC的增加呈上升趋势,变化范围为0.01～0.04。⑥柽柳、小叶锦鸡儿和杨柴维持Pnmax的SWC分别为13.8%、13.3%和15.2%;维持最高叶片水分利用效率（WUE）的SWC分别为10.0%、11.0%和8.5%;土壤水合补偿点分别为1.1%、0.8%和0.9%。⑦柽柳、小叶锦鸡儿和杨柴最适宜的SWC范围分别为10.0%～13.8%、11.0%～13.3%和8.5%～15.2%。      

沙漠铁路周边生态环境恢复演化研究

十一五期间,国家将重点加强中西部铁路建设,到2010年,西部铁路网总规模即达35000km。选择位于腾格里沙漠东南缘的包兰铁路中卫至干螗段为研究对象,通过对该段铁路周边生态环境的回访调查与监测,研究分析沙漠铁路对周边生态环境的影响以及恢复演变过程。认为铁路工程建设在施工期对地表植被、沙结皮等原有覆盖层会造成不同程度的破坏,从而加剧风沙活动,但通过采取卵石覆盖、土工网垫、草方格沙障、植树造林等治理措施,能够得到有效控制。人工干预措施中,灌溉造林对沙漠铁路生态环境起到了良好的改善作用,但投资较大;旱生造林也有改善作用,但作用缓慢;沙化严重地区植被自然恢复能力较差,较人工干预条件下的恢复要慢得多。通过治理。铁路周边生态环境已由铁路修建前沙漠化严重的生态背景逐步演化为绿色防护体系格局。这为修建铁路过程中沙漠地区生态环境保护,尤其是沙漠化严重地区的生态恢复与重建提供了参考依据,并对西部大开发战略实施具有重要的实践意义。     

The formation age and evolution of Kumtagh Desert

The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past.Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau.The first integrated scientific investigation to the desert was carried out during the period of 2004-2006.Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed.The integrated field investigation and studies on sedimentary,chronology and palynology of typical profiles named Suosuo gully,Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP.During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP,the desert largely expanded and formed its modern distribution pattern.The desert was originally developed in the southwest,subsequently,expanded to the north and northeast.The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary.The neotectonic movements played an important role in the formation,development and geomorphology of the desert.On one hand,the movements caused the formation of intermontane fault basin,which was further developed towards the closed drought basin,and caused the formation of natural environment.On the other hand,under the control of surrounding faults,the unique broom-shaped desert landscape was formed,and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45'-39°55'N.The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP.The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China,and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.     

Impact factors of soil wind erosion in the center of Taklimakan Desert

The development and progress of soil wind erosion are influenced by the factors of climate,terrain,soil and vegetation,etc. This paper,taking Tazhong region,a town in the centre of the Taklimakan Desert,as an example and using comparative and quantitative methods,discussed the effects of climate,surface roughness(including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3,while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region,the surface roughness height is relatively small with a mean of 6.32 × 10-5 m,which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types,soil particle size,lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate,vegetation and surface soil properties.     

鄱阳湖沙地生态经济产业初探——以都昌县为例

阐述了都昌鄱阳湖区沙地生态现状,尝试提出了沙地生态经济产业发展组合模式,为鄱阳湖生态经济发展提供有益的参考思路。     

荒漠刺叶墙藓DNA的提取及PCR扩增反应条件

采用改进CTAB法、NaOH法和直接PCR法(direct PCR amplification)提取藓类生物结皮中刺叶墙藓(Tortula desertorumBroth.)基因组DNA,比较其分离效果以及ISSR扩增效果。结果表明:改进CTAB法提取的基因组DNA质量好、纯度高,ISSR扩增反应效果好。直接PCR法一旦体系建立,则是最简易快速、经济高效的模板制备方法,适于植株矮小、生物量很小的荒漠藓类植物个体模板DNA的制备。利用改进CTAB法获得的基因组DNA作为模板,对ISSR反应组分浓度及反应程序中的一些重要参数进行摸索和优化实验,建立了刺叶墙藓最优ISSR反应体系。反应总体积为20μL,各反应组分终浓度为:2μL10×Buffer,2 mM Mg2 ,0.1 mM dNTPs,0.2μM引物,10~40 ng模板DNA,1U Taq酶。扩增程序为:94℃4 min,1个循环;94℃45 s,退火温度(Tm)45 s,72℃1 min,35个循环;72℃7 min,1个循环;4℃保存。刺叶墙藓是组成古尔班通古特沙漠藓类生物结皮的优势种,研究结果为进一步开展刺叶墙藓遗传多样性的研究奠定了基础。     

不同沙丘部位和不同结皮类型对土壤种子库的影响

采用萌发法对古尔班通古特沙漠沙垄不同部位生物结皮类型的种子库进行研究,发现不同沙丘部位和结皮类型种子分布特征有一定的规律性:藻类结皮的种子数量、丰富度和多样性均显著高于地衣和苔藓结皮。生物结皮从藻类到地衣和苔藓的演替,有降低种子数量和种子多样性的现象。在不同沙丘部位,沙丘顶部流沙的种子数量和多样性较低,与丘顶流沙相比沙丘底部的藻类结皮显示出较高的丰富度和多样性,但沙丘底部的地衣和苔藓结皮与丘顶流沙相比未表现出明显的差异。背风坡中部的藻类结皮种子多样性较高,显著高于迎风坡中部的藻类结皮。     

古尔班通古特沙漠生物结皮中藓类植物形态解剖特征

对组成古尔班通古特沙漠生物土壤结皮的4种1变种藓类植物刺叶墙藓(Tortula desertorum Broth.)、真藓(Bryum argenteum Hedw.)、绿色流苏藓〔Crossidium squamiferum(Viv.)Jur.〕、泛生墙藓(Tortula muralis Hedw.)、泛生墙藓无芒变种(Tortula muralis var. aestiva Brid. ex Hedw.)的茎、叶形态解剖结构进行了观察。结果表明:除刺叶墙藓叶片上部为2层细胞组成外,其他4种叶片均由1层细胞组成。所有藓类植物叶片都具有明显或粗壮的中肋,起到了支持叶片和导水的作用。茎皮部外层细胞壁不同程度加厚。生物结皮中的藓类植物表现出叶片背卷或内卷、具疣状突起、透明毛尖(泛生墙藓无芒变种除外)以及边缘细胞壁加厚等特征,这些特征是对干旱荒漠环境长期适应的结果。研究结果为进一步揭示荒漠藓类植物形态特征与环境之间的关系提供理论依据。     

策勒绿洲外围2种植物幼苗对NaCl的生理响应

2006年8～10月,在塔克拉玛干沙漠南缘策勒绿洲外围,研究了不同浓度NaCl处理对疏叶骆驼刺(Alhagi sparsifoliaShap.)、多枝柽柳(Tamarix ramosissimaLedeb.)一年生幼苗生理状况的影响.结果表明: ① 2种植物幼苗的水势(ψ)和净光合速率(Pn)均随NaCl浓度的增加呈明显下降趋势,但下降幅度不尽一致;然而,气孔导度(Gs)和蒸腾速率(Tr)表现出相同的变化规律;②在较高NaCl浓度下,随着处理时间的增加,2种植物幼苗的ψ都呈下降趋势,而柽柳幼苗的Pn无明显变化,骆驼刺幼苗的Pn则出现进一步下降的特征;③柽柳较骆驼刺具有更强的耐盐性.     

平茬时期与留茬高度对宁夏荒漠草原柠条营养成分和再生的影响

以宁夏荒漠草原的人工柠条林带为对象,研究不同月份平茬和留茬高度为0、5、10和15cm对柠条营养成分及再生性能的影响。结果表明,各个生育期内,柠条蛋白质、粗脂肪、酸性洗涤纤维、中性洗涤纤维和粗灰分质量分数呈现波动变化,其中粗蛋白质量分数变幅为11.19%~15.38%,6月最高。留茬高度对柠条当年再生速度、分枝数、地上生物量无显著影响;留茬0cm植株地径的日增量和冠幅最高,留茬15cm最低;返青率随着留茬高度的增加而降低。5、6月平茬柠条的再生速度、冠幅增量、地径增量和萌枝长增量显著好于其他月份平茬,返青率以5-7月平茬柠条较高。研究认为,从饲用营养成分和柠条再生考虑,宁夏荒漠草原柠条最佳平茬时期为6月,高度为齐地平茬。