Analysis of the seed dispersal patterns of wild soybean as a reference for vegetation management around genetically modified soybean fields

There are concerns that genetically modified soybean might threaten the genetic diversity of the wild soybean populations that are distributed in East Asia because genetically modified soybean has no crossing barrier with wild soybean. A simple and effective method to prevent hybridization via pollen flow is spatial separation between the two species because their hybridization occurs only when they grow in close proximity. Therefore, the invasiveness of wild soybean needs to be known in order to secure the appropriate distances. As wild soybean seeds are dispersed mechanically by pod dehiscence, an experiment was conducted in which white sheets were placed on the ground, concentric circles were drawn around the parent plants, and the number of dispersed seeds within each 0.5 m‐wide zone were counted. About 40% of the produced seeds were dispersed and the number of dispersed seeds gradually declined as the distance from the parent plants increased. The model that explained the relationship between the number and distance of the dispersed seeds was produced by using a generalized linear model procedure. More than 95, 99, and 99.9% of the produced seeds stayed within 3.5, 5.0, and 6.5 m after natural pod dehiscence. Knowing these values is useful for evaluating the level of invasive risk by mechanical seed dispersal. The goal of the work is to efficiently and deliberately prevent hybridization by isolating genetically modified soybean fields and wild soybean populations by vegetation management, including weeding and setting up specific‐width buffer zones.     

Genetic diversity of Pueraria lobata (kudzu) and closely related taxa as revealed by inter-simple sequence repeat analysis

Kudzu (Pueraria lobata) is a noxious weed infesting some areas of the USA. Knowledge of its genetic variation in both native and invasive areas can lead to effective biological control measures. Inter-simple sequence repeat (ISSR) variations were studied in P. lobata and its four closely related congeneric species (P. edulis, P. montana, P. phaseoloides and P. thomsoni). ISSR results allowed a clear separation of these five species. For P. lobata, 108 plants from China and USA were analysed. The samples from the US were genetically closer to Chinese P. lobata populations than to other congeneric populations. High genetic differentiation was found for P. lobata, P. montana and P. thomsoni in Chinese samples. High genetic diversity and low population differentiation was found in P. lobata samples of the US. This supports the hypothesis of multiple introductions into the USA from different sources in Japan or China, followed by subsequent gene exchange and recombination.     

Prospects for management strategies of invasive crayfish populations with an emphasis on biological control

• 1. The white‐clawed crayfish, Austropotamobius pallipes (Lereboullet), is the only freshwater crayfish indigenous to Great Britain and Ireland. It has a widespread, though declining distribution in England and parts of Wales but does not occur naturally in Scotland.
• 2. The North American signal crayfish, Pacifastacus leniusculus (Dana), is not native to Europe and was introduced to Britain in the 1970s. The signal crayfish out‐competes the native white‐clawed crayfish as it is larger and more aggressive. It is also responsible for the introduction and spread of crayfish plague, which has devastated white‐clawed crayfish populations in Europe.
• 3. Signal crayfish populations are causing significant changes to the equilibrium of native flora and fauna through increased grazing and predation pressures; they also contribute to habitat degradation through burrowing.
• 4. Manual removal of crayfish using traps and pond trials with biocides have met with moderate success in reducing crayfish numbers and containing populations. However, with new populations of signal crayfish being reported each year within the UK, there is now an urgent need to develop a strategy with which to eradicate or contain their spread.
• 5. Signal crayfish have populated many habitat types in the UK, each of which may require a different control strategy; hence no single strategy or universal solution is likely to be attainable.
• 6. Signal crayfish are susceptible to various biocides and microbial pathogens but significant scientific research will be required to develop safe biological control methods and integrated pest management (IPM) strategies to control these invasive organisms. Copyright © 2009 John Wiley & Sons, Ltd.

     

Pattern and Composition of Secondary Succession Beneath Caribbean Pine Plantations of Southwest Sri Lanka

This study examined the vegetation growing beneath Caribbean pine (Pinus caribaea) plantations established within previously abandoned tea lands adjacent to intact rain forest in southwest Sri Lanka. To examine the pattern and composition of secondary succession and factors affecting it, vegetation was sampled in different relative locations (interior and edge conditions) within plantations. Results demonstrated that more vegetation was found near the plantation edges than in the interior, and this pattern was prominent for both wind- and bird- dispersed species. The vegetation represented a mixture of species belonging to a range of successional guilds representing early (17 species, 42.4% in stem count) and late-successional species (52 species, 40.6%), although native long-lived canopy tree species were mostly absent. Bird-dispersed species dominated the flora (80 species, 86.7% in stem count). Abundance of an exotic shrub Clidemia hirta (Melastomataceae) showed a negative correlation with that of other species, indicating its impact on native flora. Underplanting of native canopy species may be effective in assisting secondary succession and control C. hirta in the plantations.     

常用杀虫剂对新入侵害虫螺旋粉虱的田间药效试验

螺旋粉虱是新入侵中国海南的危性害虫，为迅速压低虫口密度，进而将其逐步扑灭，开展了螺旋粉虱的药剂防治研究；选用2.5%敌杀死乳油、20%吡虫啉可溶性液剂、480g/L乐斯本乳油、1.8%阿维菌素乳油、2.5%功夫水乳剂、20%啶虫脒可溶性液剂等常用杀虫剂，进行了田间药效试验；结果表明：药后1~10d，2.5%敌杀死乳油的防效在94.09%~100%之间，2.5%功夫水乳剂的防效在91.72%~100%之间，20%吡虫啉可溶性液剂的防效在32.24%~70.96%之间，1.8%阿维菌素乳油的防效在-11.54%~21.54%之间；因此，2.5%敌杀死乳油和2.5%功夫水乳剂是防治时可供选用的良好药剂，20%吡虫啉可溶性液剂和1.8%阿维菌素乳油对螺旋粉虱的速效性和持效性均较差，不适用于螺旋粉虱的防治。     

滇西北高山牧场入侵物种土大黄生态学调查

2003年8月,对滇西北贡山县迪麻洛村色娃龙巴夏季高山牧场进行了植被和土大黄空间分布调查.结果表明:45%的样点中出现土大黄,9%的样点中覆盖率>25%;土大黄的出现与‘草地’景观、放牧强度、牧民住所的近远呈正相关,与海拔高度和坡度呈负相关;土大黄的分布和扩张与传统的轮牧体系息息相关.     

外来植物豚草入侵对土壤碳氮转化的影响

选取撂荒田地为试验样地,以入侵植物豚草（Ambrosia artemisiifolia L.）为对象,以土著优势物种窃衣（Torilis scabra Thunb.）为参照,通过对入侵植物和土著植物根际土壤的采样分析,研究了入侵植物对入侵地土壤特性及土壤碳氮转化的影响。结果表明,与土著物种窃衣相比,豚草入侵使土壤有机质含量增加89.13%,全氮含量增加42.15%,铵态氮含量增加43.69%,硝态氮含量增加35.36%,微生物量碳增加52.08%,微生物量氮增加61.26%,氮净矿化速率增加1.41倍,氮净氨化速率增加206倍,但硝化速率和反硝化速率变化不明显。由此可见,豚草显著改变了入侵地土壤的理化特性,加速了土壤碳氮转化过程。     

武安国家森林公园外来入侵植物调查

经调查及整理分析文献资料,初步认定武安国家森林公园外来入侵植物的种类有14种,分属于9科13属,禾本科种类最多,有4种,其中欧洲入侵植物占主要份额。并对入侵植物的原产地、入侵途径、危害及防治对策进行了讨论。     

海南省蝶形花科3种新记录外来入侵植物

报道了海南省3种新记录外来入侵植物.它们是紫花大翼豆Macroptilum atropurpureum(DC.)Urban、大翼豆M.lathroides(L.)Urban和南美山蚂蝗Desmodium tortuosum(Sw.)DC..标本存放于华南农业大学林学院植物标本室(CANT).