Bird assemblages as bio-indicators of water regime management and hunting disturbance in natural wet grasslands

Responses of the waterbird community to the management regime of a wet grassland system (primarily small changes in the water regime but also hunting disturbance) in a large floodplain lake, Grand-Lieu, were studied during three consecutive years (winter and spring in 1998-2000). These temporarily flooding grasslands (1100 ha) constituted a very important feeding area by supporting large flocks of waterbird species (52 regular spp., totalling up to 14?250-22?850 birds). A global similar seasonal pattern in the presence of waterbird species was recorded whatever the year. The March-May period was a key phase with the maximum species richness (42-48 spp.) and the maximum abundance (30-40% of the total according to year, essentially Anseriformes). Late in spring Ciconiiformes and to a lesser extent some waders exploit this feeding area. Nevertheless some changes in bird assemblages were exhibited according to the management regime (a decreasing spring water level from 1998 to 2000, and an exceptional hunting ban in January 2000, instead of an usual stop in late February). The hunting disturbance clearly limited diurnal accessibility of ducks to wet grasslands in January and February 1998 and 1999. Also, the duck population in flooding grasslands increased by 55-65% in January 2000 when hunting was prohibited and in the same time the richness species grew from 14-19 spp. up to 23 spp. in 2000. The overall impact of a high spring water level on waterbirds as in 1998 and to a lesser extent in 1999 (with respectively 54 and 35 cm of mean water level against 25 cm in 2000) was an increase in diving fish-eating birds and larger flocks of resting gulls. Conversely these conditions, notably a reduced period with a spring water level under 25 cm in spring (20 days in 1998-1999 instead of 40 days in 2000) were adverse to numerous ground-feeding waterbirds (Ciconiiformes and waders) that require shallow waters. This study showed that limitation of human disturbance and moderate flooding of wet grasslands can increase their attractiveness for numerous species of high conservation status.     

Morphological Diversity of Bambara Groundnut [Vigna subterranea (L.) Verdc.] Landraces in Tanzania

A field experiment was conducted in Tanzania for two seasons to assess the genetic diversity of bambara groundnut landraces based on morphological characters. One hundred accessions collected from a wide range of agricultural zones in the country were evaluated in a 10 × 10 triple lattice block design at Maruku station in Bukoba, Tanzania. For the qualitative characters evaluated, considerable morphological variations were observed for growth habit, pod shape and pod colour. Quantitative morphological characters such as peduncle length, number of leaves per plant, terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant length, pod width, seed length, seed width, number of pods per plant, shelling percentage and days to 50% flowering showed significant variation among accessions for the two test seasons. Multivariate analysis for 15 quantitative morphological traits that showed significant variation indicated that the first four PCs with eigenvalues ≥1 accounted for 63.0 and 65.0% of the total variance among the accessions during the two test seasons, respectively. The most important loadings for PC1 and PC2 for the two seasons were terminal leaflet width, terminal leaflet length, petiole length, plant spread, plant height and pod length, pod width, seed length, seed width, numbers of pods per plant. Cluster analysis grouped bambara groundnut accessions into three major groups with respect to their geographic origins. Based on this present study, bambara groundnut landraces from Tanzania displayed a considerable diversity for morphological and agronomic traits useful for germplasm management and utilization into crop improvement.     

Electrophoretic variation as a measure of speciesdifferentiation between four species of the genus Lolium

Isozyme electrophoresis was carried out on 423 accessionsbelonging to four species of the genus Lolium toassess the genetic variation within and between the species. Fourenzyme systems (acid phosphatase, glutamate oxaloacetatetransaminase, phospho-gluco isomerase and superoxidedismutase) were used to array allelic diversity at fivepolymorphic loci. Nei's genetic distance analysis andmultivariate analyses were computed and the taxonomic position ofeach species is discussed as a result of these computations.Electrophoresis is shown to clearly differentiate the inbreedingspecies, L. temulentum fromthe outcrossing species, L.perenne, L.multiflorum and L.rigidum, and to separate the species within theout-breeding group. The taxonomic results are discussed inrelation to an earlier paper on morphological variation, concludingthat electrophoresis is a valid taxonomic tool showing distinctseparations between the species, but that current plant breeding andagricultural practises may be increasing the amount of hybridisationbetween the species than occurred in the past.     

Characterization of Portuguese populations of <Emphasis Type="Italic">Vitis vinifera</Emphasis> L. ssp. <Emphasis Type="Italic">sylvestris</Emphasis> (Gmelin) Hegi

Wild populations of Vitis vinifera L.␣have been located in Portugal. Morphological characterization was carried out in three populations located in Alcácer do Sal, Castelo Branco, and Montemor-o-Novo, and then compared using multivariate discriminant analysis. These populations were from three different hydrological basins, therefore cross-pollination was not possible. It was verified that in each population all plants were different. The data suggest that the frequency of female and male plants is rather variable in wild populations. The morphology of the adult leaf, from the Alcácer do Sal population, had particular features when compared with Castelo Branco and Montemor-o-Novo populations, which were more homogeneous. The length of teeth compared with width at the end of the base, and the density of prostrate hairs between and on main veins (lower side) were the variables which allowed the best discrimination among populations.     

Genetic diversity in African cucumber (Cucumis sativus L.) provides potential for germplasm enhancement

Genetic diversity among 26 cucumber (Cucumis sativus L. var. sativus) accessions from five African countries [Algeria (1), Egypt (21), Ethiopia (2), Kenya (1), and Libya (1)] present in the U.S. National Plant Germplasm System (NPGS) were examined by assessing variation at 71 polymorphic random amplified polymorphic DNA (RAPD) loci. Genetic distances (GD; simple matching coefficient) were estimated among these African accessions and a reference array (RA) of 21 accessions representative of the genetic variation in cucumber. GD among African accessions ranged between 0.41 and 0.97. GD among accessions in the reference array ranged between 0.36 and 0.88. Multivariate analysis identified three distinct groupings (1–3) of African accessions; Group 1 contained 21 accessions (Egypt, Ethiopia and Libya), Group 2 consisted of two accessions (Kenya, Algeria), and Group 3 possessed three accessions (Egypt). These groupings were distinct from each other (P > 0.001). Accessions in Group 1 differed genetically from all other accessions examined (P > 0.01), and accessions in Groups 2 and 3 were uniquely associated with several RA accessions. While GD among accessions in Group 1 ranged between 0.52 and 0.90, distances among Group 2 accessions varied between 0.93 and 0.97. The GD between the two accessions in Group 3 was 0.65. An accession from Syria (PI 181874) and from one Turkey (PI 199383) were genetically more similar to accessions in Group 1 than to other accessions in the RA. Likewise, accessions in Group 2 were genetically similar to two RA accessions from China and a European glasshouse cucumber line, and Group 3 accessions showed genetic affinities with the U.S. market class cultivar Dasher II. Data suggest that some Egyptian accessions (Group 1) possess unique genetic variation, that this germplasm has potential for broadening the genetic base of commerical cucumber, and that further collection of African germplasm is likely to enhance genetic diversity of cucumber in NPGS.     

生长绵羊毛——体营养分配解析以及动态营养需要探讨

本文以不同遗传基础的毛用、毛肉兼用和肉毛兼用型生长绵羊为对象,解析毛纤维与体组织之间(毛一体)营养分配机制,测定毛纤维与体组织沉积对机体摄入养分(主要对代谢能)的利用效率,建立营养需要估测方程,在此基础上提出绵羊生长期动态营养需要体系的初步思路。     

Multivariate analysis of management and biosecurity practices in smallholder pig farms in Madagascar

A cross-sectional study was carried out in 2005 and 2006 in three geographical areas of Madagascar to investigate and differentiate swine farm management and biosecurity practices in smallholder farming communities. Questionnaire data from a total of 709 pig farms were analysed using multiple factor analysis (MFA) and hierarchical cluster analysis (HCA). Variables describing management and biosecurity practices were organised into five groups: structure of the farm, animal-contacts, person- and vehicle-contacts, feeding, and sanitary aspects. In general, few biosecurity measures were implemented in the pig farms included in the study. Regional differences in management and biosecurity practices emerged from the MFA and were mainly due to, in order of decreasing importance: structure of the farm, sanitary aspects, feeding and animal-contacts and, to a lesser extent, person- and vehicle-contacts. HCA resulted in the differentiation of four distinct types of farms in each of two study areas, Arivonimamo and Marovoay, while no grouping could be identified amongst farms in Ambatondrazaka area. The characterisation of the different types of smallholder pig farms will allow adapting recommendations on husbandry practices and control measures in pig farms of these regions of Madagascar. The development of tailored recommendations is essential for Malagasy smallholders who have limited resources and need to make evidence-based management changes to reduce the risk of contagious diseases in their herds.     

短颈剑线虫和喜马拉雅剑线虫的形态与rDNA分子特征

描述了日本进境罗汉松根际截获的2种美洲剑线虫:短颈剑线虫Xiphinema brevicollum Lordello et Da Costa,1961和喜马拉雅剑线虫Xiphinema himalayense Ahmad,Lamberti,Rawat,Agostinelli et Srivastava,1998,并对这2种线虫rDNA-ITS和D2D3序列进行了扩增、克隆、测序及系统进化分析.短颈剑线虫和喜马拉雅剑线虫在国家质量监督检验检疫局内首次截获,喜马拉雅剑线虫在日本首次报道,在中国没有分布记载.     

基于多元统计和地统计的肇源县表层土壤重金属来源辨析

土壤圈是地圈系统中对人类健康影响最显著的圈层之一。土壤重金属的自然和人为来源辨析对土壤修复和保障人体健康有重要意义。本研究以黑龙江省肇源县为研究区域,通过空间插值分析、主成分分析和聚类分析等方法,对区域土壤表层和深层土壤重金属As、Hg、Cd、Cr、Cu、Ni、Zn的含量和空间分异特征进行分析,进而对区域表层土壤重金属来源进行辨析。结果表明:成土母质作为表层土壤的重要物质来源对表层土壤重金属含量及空间分布有显著影响;肇源县表层土壤中Hg元素表现出全局范围较明显的富集现象,局部区域Cd元素表现出一定的富集现象,富集原因是人为污染造成的;嫩江上游汇水区土壤重金属元素的迁入,是表层土壤重金属As、Cd、Cr、Cu、Ni、Zn等元素在研究区范围内轻度富集的主要原因。