The Horticultural Trade and Ornamental Plant Invasions in Britain

Abstract:  Ornamental horticulture has been recognized as the main pathway for plant invasions worldwide. We examined the link between propagule pressure created by the presence of ornamental plants in the market and their ability to escape from cultivation and establish in the wild. A random sample of 534 non-native ornamental species on sale in nineteenth century Britain showed that 27% of these species were recorded growing outside cultivation and 30% of those were established. Species that had escaped from cultivation were more frequently on sale both in the nineteenth century and today than nonescaping species. We used logit regression models to identify biological and socioeconomic variables that affect species' abilities to escape cultivation and become established. Frequencies in the market in the nineteenth century and today were good explanatory variables that distinguished escaping from nonescaping species, whereas for the transition from casual to established status these two socioeconomic variables were either absent or only of weak significance. Biological characteristics that increased the probability that a species would escape from cultivation were species height, a European native range, and being an annual. Climbing plants and species intolerant of low temperatures were less likely to escape. In contrast, the establishment probability was greater if the species belonged to a genus native to Britain and increased as the number of continents in a plant's native range increased. Annual plants had a reduced probability of establishment. Market presence, prices, and the date of introduction are among the socioeconomic factors that have had important effects on the observed course of invasions.     

The Control of Biological Invasions in the World's Oceans

Abstract: The introduction of alien, or nonindigenous, animals and plants has been identified by scientists and policy makers as a major threat to biodiversity in marine ecosystems. Although government agencies have struggled to control alien species on land and freshwater for decades with mixed success, the control of alien marine species is in its infancy. Prevention of introduction and establishment must be the first priority, but many populations of alien marine species are already well established worldwide. National and international policies leave loopholes for additional invasions to occur and provide only general guidance on how to control alien species once they are established. To address this issue, a multinational group of 25 scientists and attorneys convened in 1998 to examine options for controlling established populations of alien marine species. The discussions resulted in a framework for control of alien marine species to provide decision-making guidance to policymakers, managers, scientists, and other stakeholders. The framework consists of seven basic steps: (1) establish the nature and magnitude of the problem, (2) set objectives, (3) consider the full range of alternatives, (4) determine risk, (5) reduce risk, (6) assess benefits versus risks, and ( 7) monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation.     

Are Modern Biological Invasions an Unprecedented Form of Global Change?

Abstract:  The uniqueness of the current, global mass invasion by nonindigenous species has been challenged recently by researchers who argue that modern rates and consequences of nonindigenous species establishment are comparable to episodes in the geological past. Although there is a fossil record of species invasions occurring in waves after geographic barriers had been lifted, such episodic events differ markedly from human-assisted invasions in spatial and temporal scales and in the number and diversity of organisms involved in long-distance dispersal. Today, every region of the planet is simultaneously affected and modern rates of invasion are several orders of magnitude higher than prehistoric rates. In terms of its rate and geographical extent, its potential for synergistic disruption and the scope of its evolutionary consequences, the current mass invasion event is without precedent and should be regarded as a unique form of global change. Prehistoric examples of biotic interchanges are nonetheless instructive and can increase our understanding of species-area effects, evolutionary effects, biotic resistance to invasion, and the impacts of novel functional groups introduced to naïve biotas. Nevertheless, they provide only limited insight into the synergistic effects of invasions and other environmental stressors, the effect of frequent introductions of large numbers of propagules, and global homogenization, all of which characterize the current mass invasion event .     

Man's Role in Changing the Face of the Ocean: Biological Invasions and Implications for Conservation of Near-Shore Environments

La reorganización de una gran cantidad de organismos marinos en los Sultimos 5 siglos se debe a actividades humanus, especialmente a desplazamientos globales de organismos asociados con embarcaciones marinus y con productos pesqueros comerciales La mayoría de encuestas biológicas posfechan dichos eventos de transportación, y por consecuencia se intetpreta la distribución de muchas de estas especies, hoy cosmopolitas, como resultado de pcesos naturales, subestimando el rol humano en la alteración de la diversidad natural y en la distribución de organismos marinos en los márgenes costeros del mundo.
Se ilustran percepciones sobre el estado natural de algunos sistemas versus su reciente alteración ecológica en el "NATIONAL ESTUARINE RESERVE RESEARCH SYSTEM," dentro del cual muchos santuarios "naturales" han sido fuertemente alterados por especies exóticas Debido a la falta de comunicación entre los cientificos que trabajan con diferentes grupos de organismos, habitats y regiones, es drficil reconocer la escala y tasa de las invasiones recientes en los océanos, causados por actividades humanas. Evidencias disponibles sugíeren que las introducciones continúan en gran escala en todo el mundo.
A pesar que desde 1973 se han establecido numerosas convenciones internacionales con el motivo de controlar el desplazamiento de otganismos exóticos marinos, un control adecuado sólo ocurre en los niveles locales y regionales.     

Discrepancies in Reported Levels of International Wildlife Trade

Abstract:  The international wildlife trade is a principal cause of biodiversity loss, involving hundreds of millions of plants and animals each year, yet wildlife trade records are notoriously unreliable. We assessed the precision of wildlife trade reports for the United States, the world's largest consumer of endangered wildlife, by comparing data from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) with U.S. Customs data. For both U.S. imports and exports, CITES and Customs reported substantially different trade volumes for all taxa in all years. Discrepancies ranged from a CITES-reported volume 376% greater than that reported by Customs (live coral imports, 2000) to a Customs' report 5202% greater than CITES (conch exports, 2000). These widely divergent data suggest widespread inaccuracies that may distort the perceived risk of targeted wildlife exploitation, leading to misallocation of management resources and less effective conservation strategies. Conservation scientists and practitioners should reexamine assumptions regarding the significance of the international wildlife trade.     

Enhancing Sustainability of the International Trade in Seahorses with a Single Minimum Size Limit

Abstract:  Management tools are needed to help regulate the international trade in seahorses (  Hippocampus spp.) under the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora. Given the limited understanding of seahorse population dynamics and fishing mortality, a single minimum size limit for all seahorse species appears to be a useful initial step toward adaptive management, both biologically and socially. We collected data on maximum height and size at first maturity for 32 seahorse species and cross-validated the data with results from an analysis across marine teleosts. A minimum height restriction of 10 cm would permit, based on calculated data, reproduction in 15 species before they recruited to the fishery. Of the remaining 17 species, 16 were essentially not in international trade, were safeguarded under domestic legislation, or were partly protected by this size limit. Only one species, H. kelloggi , was not well served by the 10-cm minimum size limit. The CITES technical committee on animals has now decided to propose this single size limit to all 167 signatory nations as one option toward sustainable trade. Complementary management measures for seahorses are also required, particularly for populations primarily exploited in bycatch.     

Declines in Woodland Salamander Abundance Associated with Non-Native Earthworm and Plant Invasions

Abstract:  Factors that negatively affect the quality of wildlife habitat are a major concern for conservation. Non-native species invasions, in particular, are perceived as a global threat to the quality of wildlife habitat. Recent evidence indicates that some changes to understory plant communities in northern temperate forests of North America, including invasions by 3 non-native plant species, are facilitated by non-native earthworm invasion. Furthermore, non-native earthworm invasions cause a reduction in leaf litter on the forest floor, and the loss of forest leaf litter is commonly associated with declines in forest fauna, including amphibians. We conducted a mark-recapture study of woodland salamander abundance across plant invasion fronts at 10 sites to determine whether earthworm or plant invasions were associated with reduced salamander abundance. Salamander abundance declined exponentially with decreasing leaf litter volume. There was no significant relationship between invasive plant cover and salamander abundance, independent of the effects of leaf litter loss due to earthworm invasion. An analysis of selected salamander prey abundance (excluding earthworms) at 4 sites showed that prey abundance declined with declining leaf litter. The loss of leaf litter layers due to non-native earthworm invasions appears to be negatively affecting woodland salamander abundance, in part, because of declines in the abundance of small arthropods that are a stable resource for salamanders. Our results demonstrate that earthworm invasions pose a significant threat to woodland amphibian fauna in the northeastern United States, and that plant invasions are symptomatic of degraded amphibian habitat but are not necessarily drivers of habitat degradation.     

International Biological Programme: Co-ordinated studies on grey mullets

The International Biological Programme/Marine Productivity Section (IBP/PM) initiated cooperation in world-wide studies on the grey mullet; grey mulltests are of great economic importance in many places in the world, but mainly in the tropical and subtropical regions. The aim of IBP/PM is the intensification of studies and the use of lagoons and estuaries for fish production. The importance of the mullet lies also in the fact that it is a detritus feeder, a fast growing fish, and can be successfully bred under artificial conditions. To make cultivation of these fish economical and independent of natural supply (which is becoming ever more unreliable through pollution of laggons and coastal waters), the life cycle of these fish has to be completed and the problem of induced spawning solved. Such investigations are underway in several laboratories in the World. Dissemination of the knowledge acquired, accumulation of experience on this subject, and eventual use of the results as models for induced spawning and cultivation of other species of fish and invertebrates, is another aim of IBP/PM.     

International Trade Status and Crisis for Snake Species in China

Abstract:  In recent years, the purchase of snakes for leather, food, and traditional medicine has increased in China, which has greatly reduced certain snake populations. Trade records show that since the 1990s, with respect to some species of snakes, China is changing from a net export country to a net import country. We analyzed data on international trade in snake species, concentrating, in particular, on trade dynamics and species composition. The overall number of snakes exported appears to have decreased in the last 10 years. However, the number of snakes imported during this period has increased steadily. Many species of snakes that are traded in significant numbers are endangered or threatened species. To conserve snakes in China, we recommended that the Chinese government and the international conservation community take the following actions: enhance legislation and list several species in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) appendices; register all snake farms in China; carry out population and market surveys; monitor the dynamics of trade; encourage biological research; encourage change in food habits; and enhance cooperation between Hong Kong and mainland China.     

Environmental Policy and International Trade when Governments and Producers Act Strategically

Some environmentalists express concern that trade liberalization may damage the environment by giving governments incentives to relax environmental policies to give domestic producers a competitive advantage. Support for such concern may be given by models of imperfectly competitive trade where there may be “rent-shifting” incentives for governments to relax environmental policies. But there are also incentives for producers to act strategically, e.g., through their investment in R&D, and in this paper I extend the literature on strategic environmental policy by allowing for strategic behavior by producers as well as governments. I show that (i) allowing for producers to act strategically on balance reduces the incentive for governments to act strategically; (ii) allowing governments to act strategically increases the incentive for producers to act strategically; (iii) welfare is lower when both parties act strategically; and (iv) strategic behavior by producers and governments is greater when governments use emission taxes than when they use emission standards.