塔里木河下游生态输水过程中荒漠河岸林活力恢复监测

根据近5年来对塔里木河下游荒漠河岸林植被的监测数据,分析了生态输水后植物活力的恢复状况.结果显示:应急生态输水增加了塔里木河下游的生物多样性,使原本面临死亡的荒漠河岸植被重新复活,而且不同程度上促进了胡杨群落的自然更新;在近河道50 m的范围内均出现了少量的胡杨、柽柳实生苗,并且在离河道150 m的范围内已经有相当数量的胡杨次生苗,在离河道400 m范围内大约有25%的胡杨均有不同程度的基部新枝萌蘖.通过生态输水后地下水位的逐步抬升,河道两岸的低阶地发育着一定面积的草甸植被,形成了由胡杨、柽柳和草本植物所组成的干旱区非地带性河岸稀疏植被群落,说明应急生态输水对于胡杨为建群种的荒漠河岸林植被的恢复和自然更新产生了积极的影响.     

毛白杨杂种无性系稳定碳同位素值的特征及其水分利用效率

2008年在北京林业大学对9个毛白杨(Populus tomentosa)杂种无性系苗木生长不同时期的叶片、小枝、根的碳同位素δ~(13)C和瞬时水分利用效率WUEi的差异进行研究,分析不同无性系间δ~(13)C与瞬时水分利用效率WUEi的相互关系,目的在于探求δ~(13)C在筛选高水分利用效率毛白杨杂种无性系中的应用价值.结果表明:不同生长时期叶片δ~(13)C值表现为7月<8月<10月<9月,小枝δ~(13)C值表现为8月<9月<10月,叶片δ~(13)C值、小枝δ~(13)C值在不同时期和不同无性系间的差异均达显著水平,无性系间的差异是引起δ~(13)C值变化的主要因素.不同部位碳同位素比值表现为叶片<小枝<根,毛白杨杂种无性系δ~(13)C值在不同部位和无性系间差异均达显著水平,部位间的差异是引起δ~(13)C值变化的主要因素.δ~(13)C值较高的无性系30、83、BL5的WUEi也较高,δ~(13)C值较低的无性系42、26、BT17的WUEi也较低,且不同时期δ~(13)C和WUEi呈较强的正相关,相关系数分别为0.766、0.872、0.675,高δ~(13)C可以作为筛选高WUEi毛白杨的有效指标,且在苗木生长旺盛时期选育能得到更为可靠的结果.     

Benefits of Conservation of Plant Genetic Diversity to Arthropod Diversity

Abstract:  We argue that the genetic diversity of a dominant plant is important to the associated dependent community because dependent species such as herbivores are restricted to a subset of genotypes in the host-plant population. For plants that function as habitat, we predicted that greater genetic diversity in the plant population would be associated with greater diversity in the dependent arthropod community. Using naturally hybridizing cottonwoods (  Populus spp.) in western North America as a model system, we tested the general hypothesis that arthropod alpha (within cross-type richness) and beta (among cross-type composition) diversities are correlated with cottonwood cross types from local to regional scales. In common garden experiments and field surveys, leaf-modifying arthropod richness was significantly greater on either the F₁ (1.54 times) or backcross (1.46 times) hybrid cross types than on the pure broadleaf cross type (  P. deltoides Marshall or P. fremontii Watson). Composition was significantly different among three cross types of cottonwoods at all scales. Within a river system, cottonwood hybrid zones had 1.49 times greater richness than the broadleaf zone, and community composition was significantly different between each parental zone and the hybrid zone, demonstrating a hierarchical concentration of diversity. Overall, the habitats with the highest cottonwood cross-type diversity also had the highest arthropod diversity. These data show that the genetics of habitat is an important conservation concept and should be a component of conservation theory.     

塔克拉玛干绿洲外围胡杨林的水分特征研究

塔克拉玛干沙漠南缘地区年均降水量不足50mm,胡杨在这一地区绿洲外围自然植被中占有重要地位.对塔克拉玛干沙漠绿洲外围胡杨林水分特征的研究表明,在生境地下水含量较稳定的条件下,胡杨林受到的水分胁迫程度不大,干旱胁迫未对胡杨林的持续存在构成主要威胁.胡杨的水分生理特点显示植物更加依靠稳定的水分供应来应对极端干旱的环境条件,并且在蒸腾作用中形成了细胞水平上的生理适应策略.因此,保持地下水的稳定是维持绿洲前沿天然胡杨林持续存在的关键因素.     

土壤温度和湿度对鲁东南杨树人工林土壤呼吸的协同影响

利用GXH．3051红外C02气体分析仪结合自制密闭箱对鲁东南中龄杨树人工林（MAP）和成熟杨树人工林（MP）土壤呼吸、自养呼吸和异氧呼吸进行了为期2a的定位研究,分析土壤温度和湿度与土壤呼吸的关系及动态变化,探讨土壤温度和湿度对土壤呼吸的协同影响。结果表明,（1）MAP和MP土壤呼吸具明显的季节特征,均呈单峰变化,7月达到高峰,分别为4．43和3．55μm01·m-2．s-1,1月处于低谷,分别为0．72和0．54tmaol·m-2．S-1。（2）土壤温度与土壤呼吸的关系可用指数模型R=ae加’进行拟合,土壤湿度与土壤呼吸的关系可用线性模型R=aW＋b进行拟合。（3）土壤温度和湿度与土壤呼吸的综合关系可用非线性模型R=aebrWc较好地拟合,共同解释了MAP和MP不同年份土壤呼吸、自养呼吸和异氧呼吸的83．3％－85．1％、71％－79．2％、58．6％－76．5％和82．4％－88．3％、68．9％－78．2％、50．2％－78．2％,双因素模型明显优于仅考虑土壤温度或土壤湿度的单因素模型,表明鲁东南杨树人工林土壤呼吸主要受土壤温度和土壤湿度的协同影响。     

胡杨生理指标对塔里木河下游生态输水的响应

根据塔里木河下游受生态输水影响的断面和未受输水影响断面的胡杨生理指标脯氨酸、脱落酸和叶片含水量的变化,就胡杨生理指标对生态输水的响应进行了初步分析.结果显示:①在受到生态输水影响的断面,胡杨叶相对含水量增加,脯氨酸、脱落酸因水分条件的好转而分解降低;在未受到生态输水影响的断面,因为干旱胁迫程度的加重,胡杨叶相对含水量减少,脯氨酸、脱落酸因积累而增加.②在生态输水前,胡杨生理指标总体上与地下水位变化相一致,即:随着地下水位的降低,胡杨脯氨酸和脱落酸水平增加;随地下水位的升高,脯氨酸和脱落酸水平有降低的趋势.③从个别数据的异常看,在塔里木河下游,当地下水位较低时,地下水位的升降仅是影响胡杨干旱胁迫的一个因子.因此,在塔里木河下游开展的生态输水工程,对该区胡杨生长的影响非常显著,它在一定程度上缓解了胡杨水分的亏缺,减轻了干旱胁迫程度.      

V系列转基因银中杨(Salix alba var Tristis)与非转基因组长势差异的初步分析

经对鄂尔多斯市达拉特旗树林召镇的转基因试验林中的v系列转基因银中杨与非转基因对照组的生长性状的对比研究证明:该转基因系列具有较强的环境适应性,生长状况明显优于非转基因杨树。     

Studies in the Biodegradation of 5 PAHs (Phenanthrene,Pyrene, Fluoranthene,Chrysene und Benzo(a)pyrene) in the Presence of Rooted Poplar Cuttings

Cuttings of Populus nigra L. cv. Loenen were cultivated in sand treated with one of the following PAHs: phenanthrene (Phen), fluoranthene (Flt), pyrene (Pyr), chrysene (Chr) and benzo[a]pyrene (BaP). The PAHs were applied at varying levels of concentration to each test series. After 6 weeks the concentration and the distribution of the PAHs in the substrate of the various sets of tests were compared with the concentration in the substrate of the control. Additionally the substrate and the plant roots were tested for evidence of degradation products of PAHs. The results revealed that the levels of concentration of Phen and Pyr detected in the substrate surrounding the roots was in some cases significantly lower than in the corresponding section of substrate in the unplanted set (= control). This phenomenon did not occur for Flt and BaP and in the case of Chr only in those substrates, which had been treated with the highest levels of concentration. As the presence of lesser amounts of Phen and Pyr in the plant pots cannot only be attributed to their accumulation and metabolism in the roots, it is fair to assume that the chemical transformation of these three PAHs took place outside the roots. The set of tests treated with Phen revealed the presence of 2- or 3-hydroxy-Phen (main components), a hydroxy-methoxy-Phen, 9,10-Phenanthrenequinone and one unidentified compound in metabolite form. Altogether eleven metabolites of Pyr were identified in the root extracts, which can be divided into three groups: 1-Hydroxy-Pyr and derivatives, dihydroxy-Pyr and derivatives and ring fission products (4-Hydroxy-Pyr and a derivative of the 4-Phen-carbonic acid). However, the metabolite mass detected for Phen and Pyr represents only an insignificant percentage in comparison with the lesser amounts of PAHs observed in the planted set of tests. This indicates that the three PAHs were reduced to lower molecular compounds, which are methodically impossible to record, and subsequently translocated to other parts of the plant and integrated into the biomass. Although no lesser amount for Flt and BaP was found in the plant pots, 1-Hydroxy-Flt, an unidentified compound of Flt and 1-Methoxy-BaP were detected. These are presumably end products which were enhanced in the roots. It was not possible to identify any transformation products of Chr. It can be assumed that the majority of metabolites were not synthesised in the roots but are a result of microbial degradation in the rhizosphere. The test plants improved the conditions for the biotransformation of Phen and Pyr significantly and accumulated Flt, Pyr, Chr and BaP in their roots. It can therefore be concluded that the use of plants in the bioremediation of contaminated soils is a promising option.     

干旱区荒漠植被的特点及恢复问题的研究--以塔里木河流域胡杨林生态系统为例

干旱区除存在唯一的真正森林-胡杨(Populuseuphratica)林外,植被普遍极其稀疏,以降水稀少,蒸发显著为特点的干旱区,荒漠植被的存在对于生态环境的保护和良性发展起到极大的作用,干旱区的荒漠植被表现出特有的生理特征,本文研究塔里木河流域胡杨林的特征及对生态环境的适应规律,进一步提出了扩展荒漠植被的可能性及其措施。     

Biodegradation of anthracene in the roots and growth substrate of poplar cuttings

Following their exposure to anthracene, the roots of Populus nigra L. Loenen showed traces of 9 substances classed as products of biodegradation. The main substances detected were phthalic acid and 9,10-anthraquinone, followed by hydroxyanthracene and methoxyanthracene and five other compounds which could not be identified. Due to the relatively low concentration of degradation products found in the roots, further degradation to lower molecular compounds are discussed. The presence of 9,10-anthraquinone as the main product of the degradation of anthracene was also evident in the control tests with unplanted sandy substrate, although the content was higher in the planted series of tests. As a non-sterile approach was chosen, it may be assumed that a microbial degradation for 9,10-anthraquinone took place in the control series. However, it is difficult to differentiate clearly between a microbial degradation of anthracene in the substrate and metabolization in the roots due in part to the absence of specific degradation products in the various reaction areas.