Biological control of waterhyacinth in Sinaloa Mexico with the weevils Neochetina eichhorniae and N. bruchi

Water hyacinth (Eichhornia crassipes (Mart.) Solms.)creates severe problems in the irrigationdistricts of Mexico, particularly in westernSinaloa. Therefore water hyacinth weevils(Neochetina eichhorniae Warner and N. bruchi Hustache), imported from the USA in1993, were used to initiate a biologicalcontrol program. Precautionary screeningrevealed that some were infected with amicrosporidian so disease-free colonies wereproduced by eliminating infected breedinglines. To demonstrate effectiveness prior toopen field releases, weevils were firstreleased in cages at field sites. Weevilintensity increased to 6.3 weevils/plant after320 days when the plants were all dead ordying. More than 8,600 N. bruchi and14,500 N. eichhorniae were then releasedat various sites during January 1995 to August1996. Waterhyacinth coverage declined atBatamote reservoir (134 ha) from 95% to <3%by 1997; at the 12-ha Hilda reservoir from100% in May 1995 to 1% by March 1998; at the42.3-ha Arroyo Prieto reservoir from 100% to1% during the same interval; and at theMariquita reservoir (492 ha), the largestreservoir in the Humaya system, from 394 ha(80%)to 98.4 ha (20%).     

Geographical patterns and determinants of species richness in Mexico across selected families of vascular plants: implications for conservation

Mexico is considered a megadiverse country containing more than 10% of the world's biodiversity. The distribution of this species richness and endemism is different among the different Mexican states. We examined the species richness patterns of 13 families of vascular plants (including ferns, gymnosperms and angiosperms) in Mexico using political divisions (states) as units of analysis. We analysed the species richness values (absolute richness, endemic richness and restrictive richness) of these plant families using stepwise multiple regression analysis, assessing their relationship with a set of 10 environmental variables (expressed as heterogeneity coefficients). A combined cluster analysis with multidimensional scaling analysis (MDS) and an analysis of similarities were also undertaken to define the spatial–geographical patterns. Additionally, we proposed a methodological strategy to determine which states of Mexico have priorities for conservation. Our results suggested that the three species richness values used were significantly predicted by environmental factors, especially by climatic heterogeneity. Notwithstanding that a linear pattern was recognized, the Mexican states were gathered in four groups, which were confirmed by the MDS and the cluster analysis: (1) the Yucatan Peninsula, (2) arid Mexico, (3) the Mexican Transition Zone and (4) the megadiverse states. We proposed that 12 Mexican states include all the environmental conditions and are candidates for developing conservation programmes: (1) Quintana Roo, Tabasco and Yucatán, (2) Baja California, Chihuahua and Sinaloa, (3) Guerrero, Jalisco and Nuevo León and (4) Chiapas, Oaxaca and Veracruz.     

广州外来入侵植物

根据野外调查及相关文献资料,初步探讨了广州市外来入侵植物的种类组成、分布生境、生长特性、危害以及来源.结果表明:广州市现有外来人侵植物73种,隶属于27科59属,其中菊科(19种)、禾本科(8种)、豆科(7种)和苋科(7种)植物占了入侵植物总种数的56.2%.生活型分析发现,在广州有分布的外来入侵植物中,陆生草本植物最多(58种),其次为灌木(10种)、水生草本(3种),乔木种类最少(2种),它们主要生长在人类干扰比较频繁的低海拔地区.另外,基于对外来入侵植物目前在野外的生长和分布状况等生态学特性进行分析,可大致将它们对本地生物多样性危害程度分为3级,其中危害严重的有11种,危害中等的有25种,危害较轻的有37种.从原产地分析来看,61种来自于热带美洲地区,占广州外来入侵植物总种数的83.6%.与国内其他地区外来入侵植物进行比较发现,广州和广西共有种数最多,有62种,然而,对已经造成严重危害的外来植物种类,在数量上广州与香港、深圳和广西相同种类较多,分别有8种、7种和6种.对广州市目前外来植物的入侵风险(潜在威胁)的评估结果表明,对一些在其它地区已经造成严重危害的外来植物,应当加强监控,防止入侵扩散并造成重大生态灾难.还对广州市外来植物入侵的主要途径及防治策略做了简要分析和说明.     

Phytogeographical analysis of seed plant genera in China

BACKGROUND AND AIMS: A central goal of biogeography and ecology is to uncover and understand distributional patterns of organisms. China has long been a focus of attention because of its rich biota, especially with respect to plants. Using 290 floras from across China, this paper quantitatively characterizes the composition of floristic elements at multiple scales (i.e. national, provincial and local), and explores the extent to which climatic and geographical factors associated with each flora can jointly and independently explain the variation in floristic elements in local floras. METHODS: A study was made of 261 local floras, 28 province-level floras and one national-level flora across China. Genera of seed plants in each flora were assigned to 14 floristic elements according to their worldwide geographical distributions. The composition of floristic elements was related to climatic and geographical factors. KEY RESULTS AND CONCLUSIONS: Variations in percentages of cosmopolitan, tropical and temperate genera among local floras tend to be greater at higher latitudes than at lower latitudes. Latitude is strongly correlated with the proportions of 13 of the 14 floristic elements. Correlations of the proportions of floristic elements with longitude are much weaker than those with latitude. Climate represented by the first principal component of a principal component analysis was strongly correlated with the proportions of floristic elements in local floras (|r| = 0.75 +/- 0.18). Geographical coordinates independently explained about four times as much variation in floristic elements as did climate. Further research is necessary to examine the roles of water-energy dynamics, geology, soils, biotic interactions, and historical factors such as land connections between continents in the past and at present in creating observed floristic patterns.     

中国外来入侵植物的学名考证 (3)

基于中国外来入侵植物的相关报道与文献,发现一些入侵植物的学名使用比较混乱：不同时期、不同地区、不同作者在报道同一外来物种时使用不同的学名,或因中文名相近,而将其他植物作为外来入侵植物报道。依据最新资料,对国内报道的16种外来入侵植物学名进行了考证,包括中文名、英文名、异名、原产地及其在国内外的分布情况。     

Invading plants at high altitudes on Tenerife especially in the Teide National Park

Invading plants at high altitudes on Tenerife, especially in the Teide National Park. Eighty-three flowering plants are discussed as successful, failed or potential invaders of the Teide National Park, Tenerife, a caldera at 2000 m altitude and above with a largely endemic native flora. Two important methods of invasion are considered. Firstly, there was dispersal by pastoralism, goat-herding, an ancient practice which stopped over 30 years ago. Secondly, the development of mass tourism in the last 25 years has brought a fresh influx of alien plantS. Many of the 83 invaders discussed have had only transient occurrences, but 30 are well-established, 15 being grasses among which Bromus tectorum and Vulpia myuros are the most abundant. Chenopodium vulvaria and Poa pratensis are new to Tenerife and Dactylis glomerata subsp. hispanica is new to the Canary IslandS. Control measures are outlined. Attempts have already been made to contain Avena barbata, hactuca serriola and Chenopodium species.     

Species concepts and floras: what are species for?

In 1992, in a special paper in the American Journal of Botany, Ernst Mayr attempted to ‘prove’ the biological species concept (BSC) worked as well in plants as it did in animals by analyzing the flora of the Concord region of northern Massachusetts. He concluded that there were minimal difficulties when applying the BSC for the plants of this particular area, and concluded that botanists were misguided in not accepting the BSC. He suggested that what he called ‘typological’ thinking was prevalent in the taxonomic community, and that this was a factor in botanical resistance to the BSC. Typology, as defined by Mayr in his 1992 foray into botany, is to a certain extent a straw‐man and, by the late 20th Century, no longer a way of thinking in widespread use in the taxonomic community in any organismal group. Here, I examine his analysis in the light of current interest in plant diversity. Species can be characterized as hypotheses about the distribution of variation in nature, subject to test with new data of many kinds. Species concepts like the BSC, although of interest philosophically and to researchers looking at mechanisms of speciation, may actually get in the way of achieving a baseline understanding of the diversity of life on Earth. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 17–25.     

The alien flora of Kashmir Himalaya

Compilation of alien flora from phytogeographically distinct regions is of immediate relevance not only for better understanding the patterns of plant invasion but also for explicating the processes promoting invasion at local, regional or global scales. Despite being at higher risk of invasion by plants because of its European colonial past, south Asia has received very little attention in respect of characterization of its alien flora. This paucity of baseline data necessitated compilation of the first catalogue of alien flora from the Kashmir Himalaya—a phytogeographically distinct south Asian region nestled in the northwestern folds of Himalayan biodiversity hotspot. Total alien flora of the region is represented by 571 plant species, belonging to 352 genera and 104 families. It constitutes a relatively higher (29%) proportion of the total flora of the region. Families with largest number of alien representatives are Poaceae (60 species), Asteraceae (54 species), and Brassicaceae (30 species). However, families such as Amaranthaceae (83%) and Chenopodiacae (71%) show higher percentage of aliens relative to their total number of plant species in the region. Most of the alien plant species (38%) trace their origin to Europe, followed by Asia (27%) and Africa (15%). Present study also reports, for the first time, occurrence of seven plant species in this region. Each alien plant species is provided with information on the origin, habit, mode/purpose of introduction, current invasion status, altitudinal range and the primary published source.     

上海外来植物及其入侵等级划分

汇总分析了上海外来植物75科232属357种(和种下类群)基础资料,并对其入侵危害进行等级划分;其中入侵植物64种,一般或偶见外来植物293种;报道了9种上海新纪录逸生植物。上海外来植物总体呈现种类繁多、国产种类较多、分布密度大、严重危害种类较多且分布广、入侵途径集中等特征。同时对上海外来入侵植物的管理与防治提出具体措施。     

浙江省外来入侵植物研究

基于国内外文献资料、标本信息和野外调查,初步整理了浙江省外来入侵植物的种类组成、生活型、原产地、危害程度和入侵途径。结果表明,浙江省现有外来人侵植物46科106属166种,种数最多的是菊科、豆科和禾本科。根据原产地分析,来源于南美洲的物种最多,约占总数的32．16％,其次为北美洲,约占总数的25．63％,欧洲排第三位,约占总数的19．59％;已产生严重危害的有23种,中等危害的60种,危害较轻的83种。还有一些物种虽然没有在表里列出,但它们具有潜在的危害,必须密切关注。同时,与之前的研究相比,我们去除了一些已报道为人侵的物种,又增加了一些新的入侵种。在此基础上,对浙江省外来入侵植物的生活型、来源及危害进行了分析,并与以往的研究进行了比较,提出了针对性的管理建议。     

浙江省外来入侵植物研究

基于国内外文献资料、标本信息和野外调查,初步整理了浙江省外来入侵植物的种类组成、生活型、原产地、危害程度和入侵途径。结果表明,浙江省现有外来入侵植物46科106属166种,种数最多的是菊科、豆科和禾本科。根据原产地分析,来源于南美洲的物种最多,约占总数的3216%,其次为北美洲,约占总数的2563%,欧洲排第三位,约占总数的1959%;已产生严重危害的有23种,中等危害的60种,危害较轻的83种。还有一些物种虽然没有在表里列出,但它们具有潜在的危害,必须密切关注。同时,与之前的研究相比,我们去除了一些已报道为入侵的物种,又增加了一些新的入侵种。在此基础上,对浙江省外来入侵植物的生活型、来源及危害进行了分析,并与以往的研究进行了比较,提出了针对性的管理建议。     

Role of non-established plants in determining biotic homogenization patterns in Pacific Oceanic Islands

Numerous organisms have been relocated by human agency among remote regions of the world. One of the consequences of alien invasions (and associated native extinctions) is that the taxonomic similarity between areas trends to increase, a process called biotic homogenization. This process is studied in plants using naturalized species, while the role of non-established (but nevertheless present) plants is not investigated. Here we evaluate if adding the non-established component to the pool of alien plants modifies similarity patterns recorded in a preceding study of biotic homogenization in six Oceanic Islands of the South-eastern Pacific. Although our analyses confirm previous findings of floristic homogenization for these Islands, the effect of adding the non-established component results in several changes. By consideration of only naturalized plants we detected two cases of increased similarity (i.e. floristic homogenization), while the other 13 comparisons yielded non-significant changes. By adding non-established plants, four pairs of Islands show increased similarity, while in one case there is decreased similarity (i.e. floristic differentiation). These results support the hypothesis that non-established species can modify qualitative and quantitative trends of floristic change, revealing the complexity of biotic change. Although discrimination between only native and naturalized species appears reasonable for some groups, among plants it becomes a critical decision because of the importance of non-established species as ecological players and as purveyors of early information on future biotic change.     

Agricultural development and maize diversity in Mexico

Mexico is within the center of origin of Zea mays and has among the highest levels of maize genetic diversity in the world. This diversity is traced to factors at the regional and farm levels. Loss of crop genetic diversity has been related to economic and agricultural development, although opposed views of this exist for the Mexican case. Agricultural development appears to be affecting virtually all types of farms in Mexico. A case study in Chiapas suggests that the adoption of some improved varieties has enhanced genetic diversity in maize, but one improved type competes with landraces in the most favorable land. The adoption of this improved type is associated with greater access to capital and with lower risk.The research for this project was carried out with the support of the UC/MEXUS program of the University of California and CONACYT. We wish to acknowledge the advice and assistance provided by Esteban Betanzos of the Chiapas office of the Instituto Nacional de Investigaciones Forestales y Agropecuarios, Efraim Hernandez of the Colegio de Postgraduados at Chapingo, Robert Tripp of the Centro Internacional de Mejoramiento de Maiz y Trigo, and to Manuel Parra of the Centro de Investigaciones Ecologicas del Sureste in San Cristobal de las Casas. The authors wish to thank J. Edward Taylor, Andraes Buerkert, Aaron Zazueta, and Daniel Mountjoy for their useful comments on an earlier draft.