宁夏农牧业发展方向与草地农业结构调整问题的探讨

针对宁夏农牧业发展结构失衡的现状,指出长期推行重农轻牧的农区模式而不是发展草地农业是一种方向性失误。为此探讨了宁夏农牧业结构调整的生态学依据,分区调整方向与拓宽结构调整思路的问题。     

Pitch shifts and song structure indicate male quality in the dawn chorus of black-capped chickadees

The fee-bee song of male black-capped chickadees (Poecile atricapillus) is considered a single-type song that singers transpose up and down a continuous frequency range. While the ability to shift song pitch in this species provides a mechanism for song matching as an aversive signal in male-male territorial song contests, the functional significance of this behaviour during the solo performances of males during the dawn chorus is unclear. We analysed the dawn chorus songs and singing behaviour of males whose winter-flock dominance status we determined. We used correlation analysis to show that pitch shifts were accompanied by changes to other fine structural characteristics in song, including temporal and relative amplitude parameters. We also found that songs of socially dominant males and songs of their most subordinate flockmates could be distinguished using these methods by the way they performed a between-note frequency measure accompanying pitch shifts. That is, a ratio measure of the internote frequency interval remained constant for songs of high-ranking birds despite changes in absolute pitch, while low-ranking males sang a smaller ratio as they shifted to higher absolute pitches. These findings identify previously unrecognised variation in the songs of black-capped chickadees. More importantly, they indicate a mechanism by which pitch shifting during the dawn chorus of black-capped chickadees could provide a reliable indicator of relative male quality.Communicated by I. Hartley     

On the social structure of offspring rearing in the burrower bug,<Emphasis Type="Italic"> Sehirus cinctus</Emphasis> (Hemiptera: Cydnidae)

Maternal-offspring interactions are important in a variety of animals. Understanding the evolution of these interactions requires that we also study the broader social context in which they occur. To date, behavioral studies on burrower bugs, Sehirus cinctus, have focused exclusively on interactions between mothers and offspring. Here we ask whether these interactions occur in a social context that extends beyond the family unit of a mother and her own genetic offspring. Such social structure can arise from behaviors that occur before eggs are laid, or from actions of individuals that occur post-hatching. We present field data showing that lay sites of mothers are spatially aggregated on a scale that would lead to behavioral interactions among families. Microsatellite markers suggest neighboring mothers are unrelated. Laboratory experiments do not support the hypothesis that spatial aggregation results from a direct attraction of females to one another. Other laboratory studies reported here indicate that, after hatching, unrelated clutches sometimes join together to form multifamily groups. Experiments reveal that mothers are not necessary for these joining events to occur. In sum, these data suggest that both mothers and offspring play active, but different, roles in generating the social environment in which offspring rearing occurs.Communicated by N. Wedell     

芜湖市郊土壤污染对土壤动物群落结构的影响

研究表明，芜湖市郊农田土壤动物群落的组成与数量随污染程度的加重而减少，土壤动物密度也呈同样的变化趋势，特别是中小型土壤动物，优势类群数量发生较大消长，常见类群和稀有类群的组成逐渐减少．多样性指数H与重金属污染程度之间关系因受到季节的影响而变得复杂：冬季和初夏污染较重样地优势类群数量减少，群落均匀性指数E增加而优势度指数C减小，多样性指数H较高；而春季处于过渡阶段，某些类群(如螨类)数量爆发，C增高，H较小．土壤动物群落密度一类群指数DG随污染加重而减小．受到重金属污染的农田土壤动物的表聚性减弱，甚至出现逆分布现象．图1表4参15     

长江上游沿江产业带产业结构演进研究

长江上游沿江产业带是一个资源富集,开发潜力巨大的区域,既是长江产业带的重要组成部分,也是西南地区经济发展的重心地带。区域经济的快速发展有赖于区域产业结构的有序演进。本文在分析长江上游沿江产业带产业结构演进背景－产业基础,经济基础,资源基础和宏观环境的基础上,根据国外产业结构演进手一般经验,对本区产业结构演进的历史进程和目前所处阶段进行了分析和判定。     

韶山灌溉工程对区域社会经济的影响研究

韶山灌溉工程是湖南省最大的水利灌溉工程,到目前已安全运行了３０多年,该工程的兴建,使该地区摆脱了旱魔的长期威胁,促进了区内农业经济持续,稳定,快速发展,从而带动了区域经济的全面提高。从纵向与横向和定性与定量的计算,对比分析研究中,总结了该工程对区域社会经济的深远影响。     

Fish Community Structure as a Measure of Degradation and Rehabilitation of Riparian Systems in an Agricultural Drainage Basin

/ Assessing the health of ecological components of agroecosystems may be accomplished by examining changes in the drainage basin, which serves as an integrator of the agroecosystem landscape. In this study we examined fish communities in terms of an array of indicators of structure and related these to changes in riparian vegetation and agricultural practice. Evidence suggests management practices designed to foster healthier environments by, for example, reestablishing riparian vegetation were associated with positive impacts on the integrity of the fish community. At the same time, continued intensification of agricultural practices in parts of the drainage basin in recent years likely has had an off-setting influence in overall improvements in agroecosystem health. Assessments of changes in the structure of the fish associations provide the balance sheet by which the counteracting influences can be aggregated and assessed.KEY WORDS: Fish community structure; Riparian system; Agricultural drainage basin     

MB1870型球磨机噪声治理

球磨机运转时噪声很大,不仅生产操作时工人难以承受,而且对周围居民的生活环境造成严重污染.我们采用约束型粘弹阻尼结构减震,并结合吸声、隔声和消声技术进行综合治理,取得了良好的降噪效果.     

长江口湿地景观镶嵌结构演变的数量特征与分形分析

鉴于国内湿地研究对象大多为块状湿地。而对狭长形湿地鲜有研究，本文利用1990年和2003年遥感影像作为基本信息源。在GIS技术支持下。选取长江口狭长湿地，建立长江口湿地植被空间数据库。选取斑块大小、分维数、景观破碎度、景观多样性和优势度等指标，研究区域景观的数量特征动态变化；运用分形理论建立各种景观类型形态的分形结构模型，以分维数为依据分析各种景观形态的复杂性；探讨控制和影响区域景观格局的主要因素。结果显示，1990—2003年期间，在自然与人为双重因素作用下该地区的湿地景观发生了显著变化，景观趋于破碎化。植物群落的演替由于人为的原因加速，一些地区景观呈自然变化趋势。一些地区由于围垦的原因。人为扰动大。呈现衰退趋势。     

大型电站通风及空冷空调设备防腐蚀研究

大型电站的通风及空冷空调设备是电站设备的重要组成部分,它的使用寿命直接关系到电站的运行情况.通过对火电站、核电站所处环境的分析,证明了这些电站周边环境的恶劣状况.经过对电站现有设备腐蚀情况的研究,并结合实际的环境情况,得出了一套大型电站的通风及空冷空调设备防腐蚀的工艺方案.