宁波市城市绿地系统建设

生态城市建设对生态环境有着更加严格的要求，能否拥有一个良好的城市绿地系统，将成为生态城市建设的一个重要内容。在对彩红外航空遥感绿化调查结果进行分析、研究的基础上，对宁波市城市绿地系统景观的现状与存在的问题进行了讨论，提出了构建宁波市城市绿地系统的基本思路和绿地系统建设的主要内容。     

秸秆还田对土壤有机碳结构的影响

秸秆还田既可以缓解土壤污染问题又可以增加土壤养分及改善土壤结构从而提高土壤质量。研究秸秆还田后土壤有机碳结构的变化对了解碳周转规律、促进农业管理和生产以及环境可持续发展具有重要意义。选取3种性质差异较大的土壤,分别为红壤、褐土及黑土。实验分为对照处理和添加质量分数为5%的水稻秸秆的秸秆处理。土壤在温室条件下培养24个月,每4个月取样一次,测定土壤中总有机碳含量及采用碳1s X射线吸收光谱测定土壤有机碳分子结构及各类型有机碳含量。实验结果显示,(1)黑土中总有机碳含量最高,达29.5-32.5 g·kg^-1,是红壤的4.7-6.4倍,褐土的3.9-4.9倍。加入秸秆后,红壤、褐土及黑土中有机碳含量较对照分别显著增加124%-196%、60%-110%和21%-28%。(2)3种土壤的对照中,有机碳主要以脂肪碳、羧基碳和烷氧碳存在。这3部分有机碳占总有机碳的百分比在红壤、褐土和黑土中分别为69.1%-86.6、79.6%-88.5%和87.3%-90.3%。加入秸秆后,3种土壤中有机碳类型依旧是上述3种有机碳占主导。(3)秸秆处理使红壤和黑土中有机碳疏水性增强,提高土壤团聚体稳定性,对改善土壤结构起促进作用。(4)秸秆加入后,红壤和褐土中发生正激发效应,这两种土壤中有机碳结构简单、稳定性减弱;黑土中发生负激发效应,其中有机碳结构趋于复杂,稳定性增强。     

山西高原天然油松群体过氧化物酶和多酚氧化酶分析

利用聚丙烯酰胺凝胶电泳技术,对山西高原5个油松(Pinus tabulaeformis)天然种群的过氧化物酶和多酚氧化酶进行了分析。从140份供试材料的带型计算出油松种群多态位点百分数为95%,等位基因平均数为1.95,期望杂合度为0.357,遗传分化系数为0.036。表明山西高原天然油松种群间产生一定程度的分化,在同工酶水平上呈现出遗传多态性,且大部分遗传变异存在于种群内。     

不同来源的苏云金芽孢杆菌aiiA基因表达及其抗病性分析

苏云金芽孢杆菌(Bacillus thuringiensis,Bt)aiiA基因所编码的AiiA蛋白是一种内酯酶,可以降解N-乙酰高丝氨酸内酯(N-acyl-homoserine lactones,AHLs),从而减弱致病菌产生的危害.本研究克隆了6株不同来源的苏云金芽孢杆菌aiiA基因,并对来自于苔藓(LLB15)和土壤(LLS9)的BtaiiA基因进行了生物信息学分析.结果表明,AiiA-B15分子量为27.97×103,等电点为4.59;AiiA-S9分子量为28.14×103,等电点为4.32,两者都是亲水性蛋白.AiiA蛋白具有很高的保守性,AiiA-B15和AiiA-S9同源性为90%.进化树结果表明,AiiA-B15与Bacillus thuringiensis subsp.kyushuensis进化距离最近,AiiA-S9与Bacillus cereus进化距离最近.将aiiA-B15基因克隆到pGEX-4T-3表达载体中,构建重组质粒pGEXaiiA-B15,IPTG诱导后可大量表达融合蛋白.对表达的条件进行优化.结果表明,0.6mmol/LIPTG,30℃下诱导3h为最佳诱导条件.致病性检测表明,该融合蛋白对胡萝卜欧文氏软腐病菌具有较强的抗病作用.图13表4参23     

三江平原典型小叶章种群地上生物量的空间结构分形特征

2005年5月至10月,应用分形几何学的原理和方法对三江平原典型小叶章种群地上生物量与株高的空间结构分形关系进行了研究。结果表明,典型草甸小叶章和沼泽化草甸小叶章的地上生物量与株高存在良好的静态分形关系,其分形维数(D)是对地上生物量在各器官中积累规律的表征;二者地上生物量与株高的对数值线性相关,相关系数分别介于0.579～0.919和0.655～0.914之间(P<0.01,D值介于1.778～3.414和2.238～3.924之间,各时期地上生物量均以株高的幂函数形式积累;二者地上生物量与株高静态分形关系D值的季节动态基本一致,其变化均符合抛物线模型(P<0.05),而局部波动又与地上生物量的变化有关;生长季内,二者地上生物量与株高动态分形关系的D值分别为2.749和2.738,说明地上生物量的积累具有自相似性,符合幂函数增长的分形生长过程。研究还表明,仅用D值来刻画不同植物地上生物量的空间积累与展布存在一定的局限性,它只能用于测度和描述一种植物体生物量的空间积累及其对空间的占据,而一般不能用于植物间相应指标的类比;导致不同植物D值差异的原因可能与植物生长所处生境、外在因素以及模型参数(C)有关。     

森林生态系统的水文调节功能及生态学机制研究进展

森林水文调节功能是森林所实现的重要服务功能之一,可是由于森林资源被无节制的开采利用,导致人们不断遭受森林破环所带来的洪旱灾害。因此关于森林生态水文功能研究已成为生态学和水文学的研究重点之一。近年来,国内外对森林水文调节过程及其生态学机制进行了广泛深入的研究,所以文章从森林的水文过程出发,对林冠截留、树干流、凋落物层截留、林地水分涵养和蒸发蒸腾及其影响因子的国内外研究现状进行了归纳分析,研究认为林地各冠层均能够截留降雨,降低雨水动能,从而减少地表径流的产生和对地表的冲击;凋落物层能蓄留水分、抑制蒸散、减缓地表径流;而树干流改变降雨水平空间格局,影响水分入渗以及土壤水源涵养。森林结构复杂,明显改变了降雨分配过程,而森林水文过程及调节功能又受到森林结构的制约,因此定量定性探讨森林生态系统的结构、过程与水文调节功能之间关系,是未来森林生态水文功能研究的重点。     

Seasonal polydomy and unicoloniality in a polygynous population of the red wood ant Formica truncorum

Ant colonies may have a single or several reproductive queens (monogyny and polygyny, respectively). In polygynous colonies, colony reproduction may occur by budding, forming multinest, polydomous colonies. In most cases, budding leads to strong genetic structuring within populations, and positive relatedness among nestmates. However, in a few cases, polydomous populations may be unicolonial, with no structuring and intra-nest relatedness approaching zero. We investigated the spatial organisation and genetic structure of a polygynous, polydomous population of Formica truncorum in Finland. F. truncorum shifts nest sites between hibernation and the reproductive season, which raises the following question: are colonies maintained as genetic entities throughout the seasons, or is the population unicolonial throughout the season? Using nest-specific marking and five microsatellite loci, we found a high degree of mixing between individuals of the population, and no evidence for a biologically significant genetic structuring. The nestmate relatedness was also indistinguishable from zero. Taken together, the results show that the population is unicolonial. In addition, we found that the population has undergone a recent bottleneck, suggesting that the entire population may have been founded by a very limited number of females. The precise causes for unicoloniality in this species remain open, but we discuss the potential influence of intra-specific competition, disintegration of recognition cues and the particular hibernation habits of this species.     

Patterns of Genetic Diversity and Its Loss in Mammalian Populations

Abstract:  Policy aimed at conserving biodiversity has focused on species diversity. Loss of genetic diversity, however, can affect population persistence, evolutionary potential, and individual fitness. Although mammals are a well-studied taxonomic group, a comprehensive assessment of mammalian genetic diversity based on modern molecular markers is lacking. We examined published microsatellite data from populations of 108 mammalian species to evaluate background patterns of genetic variability across taxa and body masses. We tested for loss of genetic diversity at the population level by asking whether populations that experienced demographic threats exhibited lower levels of genetic diversity. We also evaluated the effect of ascertainment bias (a reduction in variability when microsatellite primers are transferred across species) on our assessment of genetic diversity. Heterozygosity did not vary with body mass across species ranging in size from shrews to whales. Differences across taxonomic groupings were noted at the highest level, between populations of marsupial and placental mammals. We documented consistently lower heterozygosity, however, in populations that had experienced demographic threats across a wide range of mammalian species. We also documented a significant ( p = 0.01) reduction in heterozygosity as a result of ascertainment bias. Our results suggest that populations of both rare and common mammals are currently losing genetic diversity and that conservation efforts focused above the population level may fail to protect the breadth of persisting genetic diversity. Conservation policy makers may need to focus their efforts below the species level to stem further losses of genetic resources.     

AGA法及其在非线性数学模型参数估计中的应用

介绍了在基因算法基础上改进的加速基因算法（ＡＧＡ），并通过环境非线性数学模型参数估计实例对该法与传统参数估计方法进行了比较。初步结果表明，ＡＧＡ法直观、简便、拟合精度高、通用性强，易为广大环境工程技术人员理解和使用。     

广州白云山次生常绿阔叶林的群落结构动态

根据对广州白云山次生常绿阔叶林群落相隔６ａ的两次植被调查，分析了广州白云山次生常绿阔叶林在保护条件下，自然演变过程中的群落结构动态．群落的垂直结构变化主要以大量幼树进入第一层成树为特点；水平结构则以密度和盖度的增长为特点．在种类组成方面，６ａ前群落中居多的阳性树种现已逐渐为耐阴性较强的种类所代替．在组织结构水平上，乔木层的物种多样性指数、群落均匀度指标趋于增加，而生态优势度指标趋于降低，反映了群落向着组成结构复杂、物种多样性增高的方面演变，且前期变化速度较快，后期较慢并趋于稳定．