巴布亚新几内亚、菲律宾和斐济林业发展比较与分析

热带森林生态系统具有重要的生态系统服务功能和价值，然而人类社会发展正影响着其完整性和稳定性。以巴布亚新几内亚、菲律宾和斐济为代表的太平洋岛国拥有丰富的热带森林资源，但森林资源的过度采伐和土地资源的不合理利用正在导致热带森林面积急剧减少。文中介绍了巴布亚新几内亚、菲律宾和斐济这3个太平洋岛国的森林资源现状，着重分析和比较了这些国家的森林资源现状、林业管理体制、政策与机构，以及林业生产与贸易状况，以期为在“一带一路”倡议下我国开拓太平洋岛国地区国际市场提供重要信息支撑。     

Antispasmodic effects of Persea cordata bark fractions on guinea pig ileum

The present study describes the antispasmodic activity of some fractions from the bark of Persea cordata, against guinea pig ileum contracted by acetylcholine and histamine. Hexane and dichloromethane fractions demonstrated the most promising biological effects, having similar potency to that of papaverine, a well-known antispasmodic agent.     

Of Harold and Chimbu revisited

Abstract: This paper discusses my collaboration with Harold Brookfield in the study of Chimbu land and society. We began in 1958 at the Australian National University and worked together until 1965 in joint fieldwork and writing, and then collaborated occasionally after that. It began both of our professional contributions that continued throughout our professional careers. The work could never have been done by one person, either geographer or anthropologist. Our joint paper of 1990 may be the only multigenerational land study in anthropology/geography. Our long‐term study of the Mintima area is a constant reminder of the hazards of short‐sighted development projections. Brookfield always knew what he wanted to find out, and always constructed original methods of research and analysis. The Chimbu–Mintima maps were redrawn many times with many different measuring methods, new air photography and increasing precision. He always connected any specific study and report of work to general theory and would compare a wide range of related findings in other places. His work is a model of scientific method and its place in geographical theory.     

Rice genetic diversity at farm and village levels and genetic structure of local varieties reveal need for in situ conservation

Rice genetic diversity partitioning between farms, varieties and, within-variety diversity, were analysed in two villages of Maritime Guinea with contrasted agroecological conditions. One thousand and two hundred individual plants belonging to 45 accessions collected in eight farms were genotyped using 10 SSR markers. The molecular variance was evenly shared between and within accessions, while the farm effect was almost nil. Local varieties had a multi-line genetic structure. The number of multilocus genotypes was proportional to the utilisation rate of the variety in the village. The F _ST values between different accessions of each variety were significant which indicated low genetic consistency in the variety names. This varietal structure could mainly be explained by the migration phenomenon and the high varietal turnover. Compared to allelic diversity, multilocus genotypic diversity seemed to be the most suitable indicator of the quantitative distribution of diversity at different management scales (accession, farm and village). The within- and between-farm F _ST values were in the same order of magnitude. The within-farm diversity was not farm-specific but quantitatively high, i.e. up to 50% of the total genotypic diversity of a given village. Given the relative importance of the within-variety diversity, the in situ approach stands out as the most effective solution. As farms do not host specific diversity the in situ approach could be implemented by working with a small number of farms.     

PCR Marker-based Analysis of Wild and Cultivated Yams (<Emphasis Type="Italic">Dioscorea</Emphasis> spp.) in Nigeria: Genetic Relationships and Implications for <Emphasis Type="Italic">ex situ</Emphasis> Conservation

Reliable characterization of the variation among wild and cultivated yams in Nigeria is essential for improved management and efficient utilization of yam genetic resources. RAPD and double stringency PCR (DS-PCR) analyses were used to investigate genetic relationships and the extent of redundancy among 30 accessions of two cultivated, and 35 accessions of four wild yam species collected from Nigeria. Twenty-five selected random decamer and two microsatellite primers were used individually and in combination to generate DNA profiles for each accession of the six Dioscorea species. The number of amplified fragments varied from 7 to 18 fragments per primer/primer combination. Different levels of intraspecific genetic diversity were found, with Dioscorea rotundata Poir. being the most variable. Based on identical profiles for the RAPD and DS-PCR primers, 12 duplication groups consisting of a total number of 37 accessions were observed in the present study. An UPGMA analysis grouped the majority of plants according to the species. Cultivated yams belonging to the D. cayenensis–rotundata species complex, which were classified into seven morphotypes/varietal groups, could be clearly separated into two major groups corresponding to D. rotundata Poir. and D. cayenensis Lam. D. cayenensis cultivars exhibited a low level of intraspecific variation and were genetically close to the wild species Dioscorea burkilliana J. Miège. D. rotundata cultivars classified into six varietal groups showed a high degree of DNA polymorphism and were separated into two major groups that appeared most closely related to Dioscorea praehensilis Benth. and Dioscorea liebrechtsiana de Wild. We propose, based on these results, that cultivars classified into D. cayenensis should be considered as a taxon separate from D. rotundata. The implications of intraspecific variability for the ex situ conservation of wild and cultivated yam germplasm in Nigeria are discussed.     

Isozyme Banding Pattern and Estimation of Genetic Diversity among Guinea Grass Germplasm

Isozyme banding pattern was studied in Guinea grass (Panicum maximum Jacq.), a widely cultivated grass having good fodder value. Similarity among 63 accessions collected from diverse sources was worked out using five enzyme systems (SOD, GOT, ACP, Esterase and Peroxidase) following horizontal starch gel electrophoresis. Biochemical markers such as isozymes are useful supplements in identifying the genetic variation present in any crop. A total of 35 clear and unambiguous bands were used for analysis of which 8 bands were monomorphic. Polymorphism exhibited by 27 bands from all five enzyme systems indicate presence of considerable diversity in this species. The dendrogram generated after UPGMA and SAHN cluster analysis using Jaccard genetic distance showed that 63 accessions from diverse geographical locations could be grouped in three main clusters, of which two could further be divided into sub-clusters. Although the clusters comprised members from different locations, most of the accessions from similar geographical locations tended to cluster in same group.     

Efficacy of an oral live vaccine for veterinary use against pseudotuberculosis

Pseudotuberculosis, an infection caused by the ubiquitous enteropathogenic bacterium Yersinia pseudotuberculosis, is a recurrent veterinary problem in livestock and zoo animals. The only vaccine currently available in zoos is Pseudovac (a mixture of killed strains of various serotypes), but its efficacy is not well established. We show here that Pseudovac does not protect guinea pigs against a severe Y. pseudotuberculosis infection. We thus evaluated the possibility of using a live attenuated Y. pseudotuberculosis strain (IP32680) as an oral vaccine against animal pseudotuberculosis. We report that IP32680 is avirulent for guinea pigs and induces a strong IgG response against various serotypes of Y. pseudotuberculosis. One and two oral inoculations of IP32680 provided 50% and 83% protection, respectively against a severe infection with a highly pathogenic strain. The avirulent Y. pseudotuberculosis IP32680 is therefore much more protective than Pseudovac and may represent a valuable oral vaccine against pseudotuberculosis in zoo animals.     

Longitudinal variation in fish species composition in the Angabanga river, Papua New Guinea with observations on the trophic status of certain fish species

Abstract– Longitudinal variation in fish species composition at various sites on the Angabanga river showed an increase in diversity from source to mouth and that only a few fish species occur at all sites. The fish assemblage of floodplain pool areas contained fewer species than the main channel and was dominated by two exotic species Oreochrornis mossambicus (Peters 1852) and Trichoguster pectoralis (Regan 1910). Most native fish species utilize invertebrates as a food source. The absence of indigenous detritus/substrate feeders in the Angabanga community may account in part for the success of the two introduced species on the floodplain.     

An evaluation of Colwell‐P as a measure of plant‐available phosphorus in soils of volcanic and non‐volcanic origins in the highlands of Papua New Guinea

Various soil test methods including Olsen, Colwell, Bray and Truog have been used to assess the levels of plant‐available P (PAP) in soils situated in the highlands of Papua New Guinea (PNG). Up until now, though, there has been no guarantee that these tests provide valid assessments of PAP in these somewhat atypical organic matter‐rich tropical soils. Furthermore, the critical soil‐P concentrations associated with the tests have been based on studies conducted elsewhere in sub‐tropical and temperate latitudes and as such may or may not be valid for soils or cropping situations in PNG. Soil (Colwell)‐P and leaf‐P data collected during a recent survey of sweet potato gardens in the highlands of PNG were therefore used to determine if useful relationships existed between these variables for different groups of soils, and if they do, to use these relationships to evaluate critical soil Colwell‐P concentrations corresponding to a known critical concentration of P in sweet potato index leaf tissue. Separate, highly significant linear relationships were obtained between leaf‐P and Colwell‐P for soils of volcanic and non‐volcanic origins. Based on these relationships, the critical Colwell‐P concentration for volcanic soils was found to be four times greater than that for non‐volcanic soils, presumably because much of the P extracted from the former soils with alkaline sodium bicarbonate had been chemically ‘fixed’ via sorption and precipitation reactions with sesquioxides and rendered unavailable to plants at ambient soil pH. These critical Colwell‐P concentrations if adopted as benchmark values for the soil groups in question should ensure that the results of future soil fertility surveys involving Colwell‐P assessments are correctly interpreted.