Description:    Understanding the factors which affect the distribution of alien plants in arid islands is complicated by the complex and stochastic nature of the invasion process per se , the harsh environmental conditions, and the low number of researchers and sampling effort. We present the results of the most comprehensive inventory to date of alien vascular plant species occurring in Socotra Island, a global biodiversity hotspot just beginning to be developed. A floristic survey was conducted between 2006 and 2008 in 36 grid cells of 10 × 10 km. We integrated this data from this survey with those from scientific literature. We recorded 88 alien plant species. Tree and herbaceous species were the most common growth forms. Species from Asia and edible species were prevalent. We identified 80 species considered weeds worldwide with 〉50 % adapted to arid conditions. We used a two-part model to analyze the spatial distribution of naturalized and alien plant species in relation to environmental and anthropogenic factors. Altitude and human-related factors play a significant role in the distribution of both naturalized and invasive species. Notably, the latter can potentially spread mainly in the alluvial basal areas. This study underpins the knowledge about alien species and their spatial distribution in Socotra Island. It provides a baseline for plant invasion management and contributes data for the analyses of invasion processes on islands worldwide. Content Type Journal Article Pages 1-12 DOI 10.1007/s11258-012-0098-1 Authors Ali S. Senan, Department of Environmental Science, Bangalore University, Bangalore, India Federico Tomasetto, Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand Alessio Farcomeni, Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy Rayasamuda K. Somashekar, Department of Environmental Science, Bangalore University, Bangalore, India Fabio Attorre, Department of Environmental Biology, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome, Italy Journal Plant Ecology Online ISSN 1573-5052 Print ISSN 1385-0237

Description: The biodiversity of aquatic inland habitats currently faces unprecedented threats from human activities. At the same time, although much is known about the functioning of freshwater ecosystems the successful transfer of such knowledge to practical conservation has not been universal. Global awareness of aquatic conservation issues is also hampered by the fact that conditions under the water surface are largely hidden from the direct experience of most members of society. Connectivity, or lack of it, is another challenge to the conservation of freshwater habitats, while urban areas can play a perhaps unexpectedly important positive role. Freshwater habitats frequently enjoy benefits accruing from a sense of ownership or stewardship by local inhabitants, which has led to the development of conservation movements which commonly started life centred on the aquatic inland habitat itself but of which many have now matured into wider catchment-based conservation programmes. A demonstrable need for evidence-based conservation management in turn requires scientific assessments to be increasingly robust and standardised, while at the same time remaining open to the adoption of technological advances and welcoming the rapidly developing citizen science movement. There is evidence of real progress in this context and conservation scientists are now communicating their findings to environmental managers in a way and on a scale that was rarely seen a couple of decades ago. It is only in this way that scientific knowledge can be efficiently transferred to conservation planning, prioritisation and ultimately management in an increasingly scaled-up, joined-up and resource-limited world. The principle of ‘prevention is better than cure’ is particularly appropriate to most biological conservation issues in aquatic inland habitats and is inextricably linked to educating and/or nudging appropriate human behaviours. When prevention fails, some form of emergency rescue such as captive breeding or translocations may be justified for particularly important animal or plant populations. However, long-haul missions of habitat rehabilitation or restoration are generally to be preferred even if they usually take many years if not decades to reach fruition. Conservation researchers, managers and practitioners must be realistic in their objectives and timescales for such programmes and take positive steps to communicate such information to stakeholders. Now more than ever, people are interested in conservation and sustainability. There are substantial challenges ahead, but these are better days for the biological conservation of aquatic inland habitats.