Integrating invasive species policies across ornamental horticulture supply-chains to prevent plant invasions

1.Ornamental horticulture is the primary pathway for invasive alien plant introductions. We critically appraise published evidence on the effectiveness of four policy instruments that tackle invasions along the horticulture supply chain: pre-border import restrictions, post-border bans, industry codes of conduct and consumer education. 2.Effective pre-border interventions rely on rigorous risk assessment and high industry compliance. Post-border sales bans become progressively less effective when alien species become widespread in a region. 3.A lack of independent performance evaluation and of public disclosure, limits the uptake and effectiveness of voluntary codes of conduct and discourages shifts in consumer preference away from invasive alien species. 4.Policy implications. Closing the plant invasion pathway associated with ornamental horticulture requires government-industry agreements to fund effective pre- and post-border weed risk assessments that can be subsequently supported by widely adopted, as well as verifiable, industry codes of conduct. This will ensure producers and consumers make informed choices in the face of better targeted public education addressing plant invasions

Does public awareness increase support for invasive species management?:Promising evidence across taxa and landscape types

Management of invasive species often raises substantial conflicts of interest. Since such conflicts can hamper proposed management actions, managers, decision makers and researchers increasingly recognize the need to consider the social dimensions of invasive species management. In this exploratory study, we aimed (1) to explore whether species’ taxonomic position (i.e. animals vs. plants) and type of invaded landscape (i.e. urban vs. nonurban) might influence public perception about the management of invasive species, and (2) to assess the potential of public awareness to increase public support for invasive species management. We reviewed the scientific literature on the conflicts of interest around the management of alien species and administered two-phased questionnaires (before and after providing information on the target species and its management) to members of the public in South Africa and the UK (n = 240). Our review suggests that lack of public support for the management of invasive animals in both urban and non-urban areas derives mainly from moralistic value disagreements, while the management of invasive plants in non-urban areas mostly causes conflicts based on utilitarian value disagreements. Despite these general trends, conflicts are context dependent and can originate from a wide variety of different views. Notably, informing the public about the invasive status and negative impacts of the species targeted for management appeared to increase public support for the management actions. Therefore, our results align with the view that increased public awareness might increase the public support for the management of invasive species, independent of taxonomic position and type of landscape

Island Invasion by a Threatened Tree Species: Evidence for Natural Enemy Release of Mahogany (Swietenia macrophylla) on Dominica, Lesser Antilles

Despite its appeal to explain plant invasions, the enemy release hypothesis (ERH) remains largely unexplored for tropical forest trees. Even scarcer are ERH studies conducted on the same host species at both the community and biogeographical scale, irrespective of the system or plant life form. In Cabrits National Park, Dominica, we observed patterns consistent with enemy release of two introduced, congeneric mahogany species, Swietenia macrophylla and S. mahagoni, planted almost 50 years ago. Swietenia populations at Cabrits have reproduced, with S. macrophylla juveniles established in and out of plantation areas at densities much higher than observed in its native range. Swietenia macrophylla juveniles also experienced significantly lower leaf-level herbivory (∼3.0%) than nine co-occurring species native to Dominica (8.4–21.8%), and far lower than conspecific herbivory observed in its native range (11%–43%, on average). These complimentary findings at multiple scales support ERH, and confirm that Swietenia has naturalized at Cabrits. However, Swietenia abundance was positively correlated with native plant diversity at the seedling stage, and only marginally negatively correlated with native plant abundance for stems ≥1-cm dbh. Taken together, these descriptive patterns point to relaxed enemy pressure from specialized enemies, specifically the defoliator Steniscadia poliophaea and the shoot-borer Hypsipyla grandella, as a leading explanation for the enhanced recruitment of Swietenia trees documented at Cabrits

Global Island Monitoring Scheme (GIMS) : a proposal for the long-term coordinated survey and monitoring of native island forest biota

Islands harbour evolutionary and ecologically unique biota, which are currently disproportionately threatened by a multitude of anthropogenic factors, including habitat loss, invasive species and climate change. Native forests on oceanic islands are important refugia for endemic species, many of which are rare and highly threatened. Long-term monitoring schemes for those biota and ecosystems are urgently needed: (i) to provide quantitative baselines for detecting changes within island ecosystems, (ii) to evaluate the effectiveness of conservation and management actions, and (iii) to identify general ecological patterns and processes using multiple island systems as repeated 'natural experiments'. In this contribution, we call for a Global Island Monitoring Scheme (GIMS) for monitoring the remaining native island forests, using bryophytes, vascular plants, selected groups of arthropods and vertebrates as model taxa. As a basis for the GIMS, we also present new, optimized monitoring protocols for bryophytes and arthropods that were developed based on former standardized inventory protocols. Effective inventorying and monitoring of native island forests will require: (i) permanent plots covering diverse ecological gradients (e.g. elevation, age of terrain, anthropogenic disturbance); (ii) a multiple-taxa approach that is based on standardized and replicable protocols; (iii) a common set of indicator taxa and community properties that are indicative of native island forests' welfare, building on, and harmonized with existing sampling and monitoring efforts; (iv) capacity building and training of local researchers, collaboration and continuous dialogue with local stakeholders; and (v) long-term commitment by funding agencies to maintain a global network of native island forest monitoring plots.Peer reviewe

Think globally, measure locally: The MIREN standardized protocol for monitoring plant species distributions along elevation gradients

Climate change and other global change drivers threaten plant diversity in mountains worldwide. A widely documented response to such environmental modifications is for plant species to change their elevational ranges. Range shifts are often idiosyncratic and difficult to generalize, partly due to variation in sampling methods. There is thus a need for a standardized monitoring strategy that can be applied across mountain regions to assess distribution changes and community turnover of native and non-native plant species over space and time. Here, we present a conceptually intuitive and standardized protocol developed by the Mountain Invasion Research Network (MIREN) to systematically quantify global patterns of native and non-native species distributions along elevation gradients and shifts arising from interactive effects of climate change and human disturbance. Usually repeated every five years, surveys consist of 20 sample sites located at equal elevation increments along three replicate roads per sampling region. At each site, three plots extend from the side of a mountain road into surrounding natural vegetation. The protocol has been successfully used in 18 regions worldwide from 2007 to present. Analyses of one point in time already generated some salient results, and revealed region-specific elevational patterns of native plant species richness, but a globally consistent elevational decline in non-native species richness. Non-native plants were also more abundant directly adjacent to road edges, suggesting that disturbed roadsides serve as a vector for invasions into mountains. From the upcoming analyses of time series, even more exciting results can be expected, especially about range shifts. Implementing the protocol in more mountain regions globally would help to generate a more complete picture of how global change alters species distributions. This would inform conservation policy in mountain ecosystems, where some conservation policies remain poorly implemented

The biogeography of South African terrestrial plant invasions

Thousands of plant species have been introduced, intentionally and accidentally, to South Africa from many parts of the world. Alien plants are now conspicuous features of many South African landscapes and hundreds of species have naturalised (i.e. reproduce regularly without human intervention), many of which are also invasive (i.e. have spread over long distances). There is no comprehensive inventory of alien, naturalised, and invasive plants for South Africa, but 327 plant taxa, most of which are invasive, are listed in national legislation. We collated records of 759 plant taxa in 126 families and 418 genera that have naturalised in natural and semi-natural ecosystems. Over half of these naturalised taxa are trees or shrubs, just under a tenth are in the families Fabaceae (73 taxa) and Asteraceae (64); genera with the most species are Eucalyptus,Acacia, and Opuntia. The southern African Plant Invaders Atlas (SAPIA) provides the best data for assessing the extent of invasions at the national scale. SAPIA data show that naturalised plants occur in 83% of quarter-degree grid cells in the country. While SAPIA data highlight general distribution patterns (high alien plant species richness in areas with high native plant species richness and around the main human settlements), an accurate, repeatable method for estimating the area invaded by plants is lacking. Introductions and dissemination of alien plants over more than three centuries, and invasions over at least 120 years (and especially in the last 50 years) have shaped the distribution of alien plants in South Africa. Distribution patterns of naturalised and invasive plants define four ecologically-meaningful clusters or “alien plant species assemblage zones”, each with signature alien plant taxa for which trait-environment interactions can be postulated as strong determinants of success. Some widespread invasive taxa occur in high frequencies across multiple zones; these taxa occur mainly in riparian zones and other azonal habitats,or depend on human-mediated disturbance, which weakens or overcomes the factors that determine specificity to any biogeographical region

Interdisciplinary and transdisciplinary research: Finding the common ground of multi-faceted concepts

Inter- and transdisciplinarity are increasingly relevant concepts and practices within academia. While various definitions exist, a clear distinction between inter- and transdisciplinarity remains difficult. Although there is a wide consensus about the need to define and apply these approaches, there is no agreement over definitions. Building on data collected during the first year of the COST Action TD1408 “Interdisciplinarity in research programming and funding cycles” (INTREPID), this paper describes both tensions and common ground about the characteristics and building blocks of interand trans-disciplinarity. Drawing on empirical data from participatory workshops involving INTREPID network members coming from 27 different countries, the paper shows that diverse definitions of inter and trans-disciplinarity coexist within scientific literature and in the mind of researchers and practitioners. The understanding about the involvement of actors outside of academia also differs widely across scientific communities irrespective of disciplinary training or the research subjects. The focus should be on the knowledge that is required to deal with a specific problem, rather than discussing “if” and “how” to integrate actors outside the academia, and collaboration should start with joint problem framing. This diversity is, however, not an absolute obstacle to practice, since the latter is made possible through building blocks such as knowledge domains, problem- and solution- oriented approaches, common goals, as well as target knowledge. In order to move towards more effective inter- and transdisciplinary research, we identify the need for trained interdisciplinarity facilitators and ‘accompanying research’ (derived from the Danish term ‘følgeforskning’). These two roles can be essential to inter- and transdisciplinarity practices including the promotion of reflexivity

Managing the whole landscape: historical, hybrid, and novel ecosystems

The reality confronting ecosystem managers today is one of heterogeneous, rapidly transforming landscapes, particularly in the areas more affected by urban and agricultural development. A landscape management framework that incorporates all systems, across the spectrum of degrees of alteration, provides a fuller set of options for how and when to intervene, uses limited resources more effectively, and increases the chances of achieving management goals. That many ecosystems have departed so substantially from their historical trajectory that they defy conventional restoration is not in dispute. Acknowledging novel ecosystems need not constitute a threat to existing policy and management approaches. Rather, the development of an integrated approach to management interventions can provide options that are in tune with the current reality of rapid ecosystem change

Leaf litter traits of invasive alien species slow down decomposition compared to Spanish natives: a broad phylogenetic comparison.

Leaf traits related to the performance of invasive alien species can influence nutrient cycling through litter decomposition. However, there is no consensus yet about whether there are consistent differences in functional leaf traits between invasive and native species that also manifest themselves through their "after life" effects on litter decomposition. When addressing this question it is important to avoid confounding effects of other plant traits related to early phylogenetic divergences and to understand the mechanism underlying the observed results to predict which invasive species will exert larger effects on nutrient cycling. We compared initial leaf litter traits, and their effect on decomposability as tested in standardized incubations, in 19 invasive-native pairs of co-familial species from Spain. They included 12 woody and seven herbaceous alien species representative of the Spanish invasive flora. The predictive power of leaf litter decomposition rates followed the order: growth form > family > status (invasive vs. native) > leaf type. Within species pairs litter decomposition tended to be slower and more dependent on N and P in invaders than in natives. This difference was likely driven by the higher lignin content of invader leaves. Although our study has the limitation of not representing the natural conditions from each invaded community, it suggests a potential slowing down of the nutrient cycle at ecosystem scale upon invasion. © Springer-Verlag 2009