大通北川河源区自然保护区季节性冻土调查研究初探

本文就大通县北川河源区自然保护区季节性冻土分布与特点作了初步调查与研究,并将冻土与环境关系作了分析与阐述。     

330kV兰州-西宁-格尔木青海段输变电的生态影响

运用类比分析法、图形叠置法对330kV兰州-西宁-格尔木青海段输变电线路两侧的动植物进行调查研究,分析了植被及农业经济损失,以及输变电工程施工期和运营期对野生动物的影响,并提出相应的补偿与保护措施。     

百色坡地果园水土流失的生物覆盖治理研究

为研究生物覆盖治理对坡地果园水土流失的影响,在坡地芒果园边坡种植生物栅篱、在梯面种植绿肥和覆盖秸杆,试验结果表明:生物覆盖综合治理区与对照区相比,平均减少水流失389.85m3/hm2,减少63.72%;土壤侵蚀量年平均减少4.66t/hm2,减少83.65%,土壤含水量平均提高4个百分点,且耕层土壤水分波动较小。     

高速公路植被养护技术研究

通过对高速公路植被的养护技术进行研究，发现：修剪后的紫穗槐（Amorpha fruticosa）长势较小，且呈原球状，尤为美观。深根性的紫穗槐与草皮混栽，可破坏掉由单纯草皮形成的境界层，防止了边坡的滑坡及其它危害。在条件允许的情况下对枯黄草进行焚烧，是改良退化草皮的有效方法，但也会发生污染和火灾危险。移植的热性草坪生长速度快，在1年中已达到80％的郁闭度。使用乙烯利、2，4-D、烯效唑、青鲜素等均可对草坪生长产生抑制作用     

路径覆盖中控制流图的自动生成技术

在软件测试的静态测试技术中,路径覆盖能保证最大程度的代码覆盖率,路径测试用例设计和程序环路复杂度度量都需要用到控制流图。介绍了软件静态测试常用技术和路径覆盖的相关概念,提出了自动生成模块控制流图的思想,并给出了自动分析和生成程序的关键算法。     

Restoration and Rehabilitation of Arid and Semiarid Mediterranean Ecosystems in North Africa and West Asia: A Review

Mediterranean-type vegetation and ecosystems have undergone intense processes of degradation for decades, centuries, or millennia under heavy and prolonged pressure from human and livestock populations. An extensive literature on exclosures, afforestation, reafforestation, rehabilitation, and other regeneration operations over several million hectares in Mediterranean bioclimatic areas from the Atlantic Ocean to the Aral Sea, combined with 50 years of personal field experience, allowed us to draw a number of conclusions on the consequences of these efforts, constraints, and limitations: (1) Exclosure usually permits the restoration and biological recovery of vegetation structure, composition, biomass, and productivity in a time span of 3-5 years in steppic ecosystems and 25-30 years in coniferous or sclerophyllic vegeta tion areas. There are exceptions, however, when vegetation is so degraded to the level that it has reached a new metastable equilibrium, characterized, e.g., unpalatable range weeds, perennial dwarf ephemeroids, cryptogams, or soil surface sealing by raindrop splash or other physical or biological factors. (2) Controlled access and rationally managed utilization of the land may achieve similar and sometimes better results than full exclosure. (3) Afforestation and reafforestation are usually successful above the isohyet of 200 mm a-1 precipitation and, occasionally, at a lower annual precipitation, where the species introduced or reintroduced is appropriate and the causes for degradation have been discontinued or seriously mitigated. (4) Rehabilitation operations, including water and/or soil conservation, may quickly achieve spectacular results but at a higher cost and subjected to a number of constraints pertaining to the techniques utilized and adequate subsequent management. (5) The main constraint for success is the discontinuation of situations that have caused degradation. The most difficult to overcome usually are of a socioeconomic and/or sociocultural nature. The speed of biological recovery is commensurate (inter alia) with the rate to which this constraint is overcome. (6) The present land surface concerned with regeneration (restoration + rehabilitation) in this part of the world represents ca. 4 X 10 6 ha, representing some 6% of the actual ''forest and woodland'' in these areas. The National Regeneration Effort (NRE), a novel concept, is evaluated by using the ratio between the Annual Regeneration Expenditure (ARE) and both the Annual National Budget Expenditure (ANBE) and Gross National Product (GNP).     

考虑沼泽植被盖度差异对湿地腾发量计算的影响

以我国北方湿地为研究对象,在统计分析沼泽植被盖度的基础上,分析了盖度对湿地实际腾发与潜在腾发之间关系的影响.结果表明,盖度最高为95％,最低为5％～10％.植被盖度在70％以上的沼泽占总沼泽数的75％;植被盖度在50％以下的沼泽只占总数的12％.在考虑盖度影响的情况下,实际腾发量大于当地潜在腾发量的沼泽占总数的82％;实际腾发量为潜在腾发量2倍以上的沼泽占总数的58％.     

亚热带四种主要植被类型土壤细菌群落结构分析

应用PCR-DGGE方法分别对天目山和玲珑山的四种典型森林土壤细菌群落结构进行了研究分析。结果表明,阔叶林、杉木林、马尾松林和毛竹林在天目山土壤中的DGGE条带数分别为49、45、51和51条,在玲珑山土壤中的DGGE条带数分别为42、4i多是奥前啊2、44和48条。不同森林植被土壤DGGE带谱差异不明显,天目山和玲珑山4种森林土壤分别有31条和23条共性条带,分别占总数的61%和48%以上,然而每种林分也有各自的特征条带。相对而言,两个样地杉木林与其他三种林分的土壤细菌群落结构相似度较低,相似值分别为0.72和0.68,其土壤细菌多样性指数也明显低于其他3种林分,而毛竹林和马尾松林多样性指数则没有显著差异。同时分析两个采样区的土壤细菌DGGE发现,土壤性质对细菌群落结构的影响大于植被。     

青藏高原不同植被类型土壤微生物数量及影响因子

应用稀释平板法对青藏高原不同植被土壤0~25 cm土层的细菌、真菌和放线菌的数量特征进行对比研究。结果表明:植被类型、温度、土壤理化性质都影响微生物数量。不同植被类型下,微生物数量未达显著性差异,但是藏嵩草草甸和沼泽草甸的土壤微生物数量要大于其他植被类型。其中、灌丛草甸强烈的抑制细菌的生长,真菌对植被类型和温度最为敏感。不同植被下的土壤理化性质差异性显著,土壤理化性质与微生物数量显著相关,较适的土壤全氮(6.96～15.72 g kg-1)、磷和土壤有机质(302.41~367.79 g kg-1)促进土壤微生物的生长;高含量的磷不利于真菌、细菌和放线菌的生长。     

长白山自然保护区道路影响域土壤Zn和Pb分布及污染分析

分别在长白山自然保护区北坡的阔叶红松林、针叶林和岳桦林等3种森林中不同利用强度的6个路段,垂直于道路设置长50 m、宽10 m采样断面,在距路基4、12、20、28、40和48 m随机采集表层0~20 cm土壤,利用ICP-ES测定土壤样品中Zn和Pb的含量。研究不同森林类型、不同利用强度道路50 m路域范围土壤重金属含量、分布特征和污染状况。结果表明:随道路利用强度增强,在阔叶红松林和岳桦林带,路域50 m范围土壤Zn和Pb含量增加明显;在针叶林带,路域50 m范围土壤Pb含量增加明显;随道路利用强度增强,Pb在阔叶红松林带路域土壤中积累范围为12~28 m,在针叶林带路域中积累范围为20~40 m,在岳桦林带路域0~50 m范围积累都明显;与阔叶红松林带土壤相比,岳桦林带路域土壤Pb含量变化对道路产生的Pb污染更敏感;利用强度强的岳桦林带路域土壤Zn和Pb的污染分指数最大,分别为1.49和1.52,都为轻度污染。