武夷山不同类型森林土壤细菌、丝状真菌优势菌属的初步研究

本文对武夷山不同类型森林土壤优势细菌丝状真菌属的生态分布进行了初步研究。结果表明：不同类型森林土壤或同一种类型森林土壤剖面的不同层次,均有其特殊和优势的异养细菌丝状真菌。大致是“肥沃”的生境即适宜土壤异养微生物繁殖的环境,优势菌属种类多,密度也大。     

黄、东海底栖性甲壳动物种类组成的季节变化

根据2004年春、夏、秋和冬季在东、黄海底拖网渔业资源监测调查资料,分析了东、黄海甲壳动物种类组成的季节变化。四季共捕获虾类33种、蟹类12种和虾蛄3种。东、黄海的优势种有：大管鞭虾、假长缝拟对虾、鹰爪虾、长角赤虾、凹管鞭虾、脊腹褐虾、东海红虾、高脊管鞭虾、双斑蟳、三疣梭子蟹和口虾蛄,其中,大管鞭虾、假长缝拟对虾和鹰爪虾为调查海域的主要优势种。多样性指数中的丰富度指数（D）与多样度指数（H’）的四季变化趋势一致。在春季,由北到南呈下降趋势;夏、秋两季由北到南呈上升趋势;冬季则处于东海北部较高、黄海南部和东海中部较低的趋势。均匀度指数（J’）在3个区域各个季节之间相差不大。相似性指数结果表明,东海中部的群落相对稳定,而东海北部具有黄海南部和东海中部的群落特征。     

Weed emergence as affected by maize (Zea mays L.)-cover crop rotations in contrasting arable soils of Zimbabwe under conservation agriculture

Weed control in smallholder farming systems of sub-Saharan Africa is labour intensive or costly. Many researchers have therefore advocated for the use of cover crops in weed management as an affordable alternative for smallholders. Cover crops may be grown in rotations to suppress weeds and reduce the reliance on herbicides. The use of cover crops creates microenvironments that are either conducive or inhibitive to the emergence of certain weed species. A study, initiated in 2008 in contrasting soils at four different locations of Zimbabwe, investigated the effect of maize (Zea mays L.)-cover crop rotations on the emergence of weeds that showed dominance in those soils. Weed assessments were however, carried out from 2011 to 2014. The weed species Galinsoga parviflora Cav., Commelina benghalensis L., and Richardia scabra L. showed dominance in all four locations with weed densities as high as 500 plants m⁻² being recorded for R. scabra L. in a sandy soil. Maize-cover crop rotations resulted in higher densities of Bidens pilosa compared with maize monocropping (control treatment) due to its high nitrogen (N) requirement to produce more seeds. On the other hand, the integration of cover crops such as pigeon pea [Cajanus cajan (L.) Millsp.] that had poor shading qualities, due to large gaps or spaces and slower initial growth, had limited effects on competitive weeds such as Cyperus esculentus L. which tend to dominate exhausted soils. The density of C. esculentus was 38% greater in maize–pigeon pea rotations compared with the control treatment. Variability between seasons and sites affected emergence of all weeds in the present study, which masked long-term trends. The results suggest that there is need to identify the germination and emergence requirements of specific weeds and select cover crops best suitable for their control. The study provides useful information for farmers and advisors on the best cover crops for control of certain problematic weeds in different soil types of Zimbabwe.     

综合养鱼高产池塘的浮游植物

根据对综合养鱼不同养殖结构类型、不同产量水平的高产池塘浮游植物定性定量的连续观测：查明了浮游植物丰度及其季节变化；分析了浮游植物群落组成类型及其季节变化；讨论了各型鱼池浮游植物群落组成上的差异性、共同性及浮游植物水华类型与养鱼水质的生物等级。得出结论：综合养鱼高产池塘里主要是隐藻、膝口藻、蓝裸甲藻、角甲藻、裸藻、空球藻、衣藻、棕鞭藻等鞭毛藻类和硅藻、大型绿球藻等优势属种交替形成水华，它们是滤食性鱼类的充足的优质适口饵料，这１０种水华都是一等水质。     

黄土高原生态经济区功能定位研究

在以往黄土高原生态经济分区的基础上,定义了生态经济功能定位的概念,确定了黄土高原经济发展的主导性资源,并对其主导性和空间分布进行了系统论述;运用区位商分析法评价了黄土高原18个生态经济区的资源比较优势和产业比较优势,系统归纳总结了黄土高原生态功能极重要的区域及其分布格局;根据生态经济功能定位依据,运用系统分析和综合归纳法,对各生态经济区进行特征描述和功能定位,为区域可持续协调发展提供参考。     

Models for predicting tree and stand development on larch plantations in Hallormsstaður,Iceland

The aim was to model the growth of Siberian larch (Larix sibirica Ledeb.) and Russian larch (Larix sukaczewii Dyl., syn. L. sibirica var. sukaczewii) plantations in Hallormsstaeur, Iceland. The field inventory was carried out in eastern Iceland in June 2006. Models were constructed for predicting dominant height, total tree height and 5-year diameter increment. Several linear and non-linear forms of models were tested in preliminary analyses to find the equations that fitted the modelled characteristics best. Due to the spatially hierarchical correlation structure of the data (stands, plots and trees), the assumption of non-correlated error terms did not hold. Therefore, a random parameter modelling approach was adopted using mixed models when the estimates obtained for the random effects were statistically significant. The variance estimates for the random effects can be further used to calibrate the models. The models generated here performed well with independent test data and were consistent with the forest growth theory. They can be used to evaluate site quality and to estimate the growth and yield of larch stands in eastern Iceland in connection with forest planning.     

湛江地区蝶类资源调查初报

经过几年来对湛江地区的各种蝶类进行标本采集和分类鉴定,结果表明,湛江蝶类共60种,隶属7科,32属。其中蛱堞科、凤蝶科是湛江地区蝶类的优势类种群,同时记述了各种蝴蝶的寄主,     

佳木斯大学校园草坪杂草群落组成和多样性研究

采取"W"9点取样法对佳木斯大学校园草坪杂草进行调查分析.结果表明:校园常见的杂草主要包括15科24属27种,其中菊科种类最多.优势种杂草主要有紫花地丁、老鹳草、蒲公英和白三叶等.同时,根据草坪杂草的分布特点和危害状况,提出了草坪杂草的防除措施.     

吴江地区蔺草制品仓储昆虫群落结构初步研究

[目的]为有效防治仓储害虫奠定理论基础。[方法]对吴江地区15个蔺草制品加工点的原料和半成品仓库的仓储害虫种类和数量进行调查,进而研究该地区仓储害虫的群落结构。[结果]共发现14种昆虫,其中黑白雪灯蛾是鳞翅目害虫,黑头叉胸花蝽为半翅目昆虫的天敌。其余害虫均属于鞘翅目。黄粉虫和黑菌虫的发生频率最高。鞘翅目昆虫是蔺草制品储藏昆虫群落的主要类群,其数量比例为88%,种类比例为85.7%,危害最大。鳞翅目昆虫的数量比例为6.1%,危害较小。黄粉虫和黑菌虫的优势度最高,分别为0.12和0.11,赤拟谷盗和烟草甲次之,为0.09和0.07。黄粉虫、黑菌虫和赤拟谷盗的优势度在8月1日到9月15日最高,在5月15日到7月15日次之。[结论]蔺草加工点仓储害虫的优势种为黄粉虫,高发期为5月中旬到9月初。     

陕西省佛坪县山地灾害与形成机理研究——以2002年6月9日及2007年8月30日山地灾害为例

陕西省佛坪县地处秦岭南坡,是山地灾害频发的地区之一。其中以2002年6月9日及2007年8月30日2次山地灾害最为严重和典型,发生大量山体崩塌、河岸坍塌、滑坡及泥石流山地灾害事件,造成严重的人员、财产损失。通过野外实地考察研究,认为此次山地灾害的形成主要受地质因子、物质因子、地形地貌因子、人为活动因子等主导因素和暴雨诱发因素所影响。同时强调山地城市建设应尊重自然规律、科学规划、重视灾害环境评估、加强日常人为生产生活行为管理等是预防山地灾害发生、降低山地灾害损失的有效途径。