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McDougall K.L.,Climate Change and Water | Alexander J.M.,ETH Zurich | Haider S.,TU Munich | Pauchard A.,University of Concepcion | And 4 more authors.
Diversity and Distributions | Year: 2011

Aim We use data from 13 mountain regions and surrounding lowland areas to identify (1) the origins, traits and cultural uses of alien plant species that establish in mountains, (2) the alien species that are most likely to be a threat and (3) how managers might use this information to prevent further invasions.Location Australia, Canada, Chile, India, New Zealand, South Africa, Spain, Switzerland, USA. Methods Lists of alien species were compiled for mountains and their surrounding or nearby lowlands. Principal co-ordinates analysis was performed on a matrix of similarities created using presence/absence data for alien species. The significance of differences between means for (1) similarity metrics of lowland and mountain groups and (2) species traits of lowland and mountain alien floras was determined using t-tests. In seven of the 13 mountain regions, lists of alien species undergoing management were compiled. The significance of differences between proportions of traits for species requiring and not requiring management input was determined with chi-square tests.Results We found that the proximal lowland alien flora is the main determinant of a mountain region's alien species composition. The highest similarities between mountain floras were in the Americas/Pacific Region. The majority of alien species commonly found in mountains have agricultural origins and are of little concern to land managers. Woody species and those used for ornamental purposes will often pose the greatest threat. Main conclusions Given the documented potential threat of alien species invading mountains, we advise natural resource managers to take preventive measures against the risk of alien plant invasion in mountains. A strategy for prevention should extend to the surrounding lowland areas and in particular regulate the introduction of species that are already of management concern in other mountains as well as climatically pre-adapted alien mountain plants. These may well become more problematic than the majority of alien plants currently in mountains. © 2010 Blackwell Publishing Ltd. Source

Bustamante-Sanchez M.A.,University of Santiago de Chile | Armesto J.J.,University of Santiago de Chile | Armesto J.J.,Institute of Ecology and Biodiversity IEB | Halpern C.B.,University of Washington
Journal of Ecology | Year: 2011

Most studies of tree regeneration are limited to particular environments and may not capture variation in the biotic or abiotic factors that regulate recruitment at larger spatial scales. Critical processes such as competition and facilitation can vary spatially, along gradients in resource availability and environmental stress, and temporally, with plant development. We examined patterns of natural tree recruitment and experimentally followed germination and seedling survival of five tree species (pioneer to late seral) in three early successional communities of contrasting bio-physical environments in a rural landscape on Chiloé Island, Chile. We quantified natural recruitment of juveniles and saplings and assessed relationships between tree density and local environment. We used a removal experiment to test the influence of early successional vegetation on seed germination and early survival of tree species. In each community, seeds and seedlings were placed in paired experimental plots from which vegetation was removed or left intact (control). To identify potential correlates of germination and seedling survival, we measured light transmittance and soil properties in each plot. In all communities, established vegetation had either a positive or neutral effect on germination and/or survival although responses varied among life stages and species. Germination and survival were correlated with the lower levels of light in controls, consistent with negative correlations between natural tree densities and light. Vegetation cover was not dense enough to facilitate survival of late successional species, but not too dense to inhibit survival of shade-intolerant or mid-tolerant species. Among communities, natural densities of juveniles were greatest under conditions where experimental germination rates were highest. Seedling height growth was lowest in the community characterized by waterlogged soils, consistent with the naturally low transition rate from juveniles to saplings and a negative correlation between density of shade-intolerant trees and soil moisture. Synthesis. Our experiments indicate strong, mostly positive controls (facilitation) on tree recruitment in early seral shrublands with differing bio-physical environments. Benefits of shading are manifested at different stages in the life history. However, community context is critical: variation in seasonal patterns of soil moisture may explain spatial variation in the density and size structure of natural tree recruitment. © 2010 The Authors. Journal of Ecology © 2010 British Ecological Society. Source

Carcamo P.F.,Catolica del Norte University | Carcamo P.F.,Institute Fomento Pesquero | Garay-Fluhmann R.,University of La Serena | Gaymer C.F.,Catolica del Norte University | Gaymer C.F.,Institute of Ecology and Biodiversity IEB
Ocean and Coastal Management | Year: 2013

The implementation of ecosystem-based management usually develops from existing institutional and governance arrangements in a given area. Therefore, it is necessary to analyze the institutional framework of a region or country to assess whether this framework is compatible and whether it will promote or potentially hinder the implementation of new management strategies. This paper explores the possibilities and constraints of institutional frameworks (represented by legislation) concerning the possible implementation of ecosystem-based management of the Chilean coast. We evaluated the functional fit between a conceptual ecosystem defined by stakeholders (and based on ecosystem services, threats and uses/activities) and Chilean legislation related to coastal and marine resource planning and management. First, we measured the functional fit between the defined ecosystem and legislation through a quantitative analysis based on text revision and network analysis. Second, we evaluated different management, conservation and planning instruments existing in Chilean legislation, with respect to their suitability for the implementation of ecosystem-based management. We found that Chilean legislation rarely accounts for relationships defined between the different components of the ecosystem model. We observed low functional fit potential and many gaps in legislation. However, we found that certain existing instruments in the current legislation can be used as a foundation for implementing management based on the principles and criteria of ecosystem-based management (e.g., Multiple-Use Coastal Marine Protected Areas). © 2013 Elsevier Ltd. Source

Bustamante-Sanchez M.A.,University of Concepcion | Armesto J.J.,University of Santiago de Chile | Armesto J.J.,Institute of Ecology and Biodiversity IEB
Journal of Applied Ecology | Year: 2012

Re-establishment of native forest species in rural landscapes may be conditioned by the proximity of seed sources, the post-disturbance composition of successional patches and the seed dispersal patterns of frugivores. Knowledge of seed dispersal rates into early seral communities, and how these are influenced by the structural and compositional characteristics of these communities is still quite poor. We used an observational approach to quantify the seed rain and seed limitation (SL) (proportion of sites to which seeds were not dispersed) of woody species during two growing seasons in three early successional shrublands with contrasting species composition and attractiveness to frugivores on Chiloé Island, Chile. We compared species immigration based on dispersal types (bird- vs. wind dispersed) and life-form (shrubs vs. trees). Concomitantly, we used an experimental approach to test whether artificial perches would relieve SL and enhance seed dispersal and seedling establishment of fleshy-fruited species. Most seeds collected were of pioneer shrubs already present in the early successional sites. Few (5%) were from trees appearing only in the surrounding second-growth forest. Density of seeds from fleshy-fruited trees and shrubs was seven times higher in the seral community most attractive to frugivores, whereas density of seeds from wind-dispersed trees was similar among communities. Artificial perches significantly increased the density and species richness of seeds from fleshy-fruited trees in all communities, but the magnitude of the facilitation effect depended on the ecological context of each seral community. Seed rain enhancement was higher in the community less attractive to frugivores. Seedling recruitment, however, remained low even under perches, indicating that additional constraints act during seed germination and/or seedling survival and growth. Synthesis and applications. Forest succession in this rural landscape may be delayed or arrested by extremely low seed rain, despite the proximity (<100 m) of seed sources in older forest patches. Although artificial perches significantly enhance inputs of bird-dispersed tree seeds into shrublands, especially where fleshy-fruited pioneer species are absent from the seral community, they do not overcome other site-related barriers to establishment, as the lack of shaded places and limited soil drainage. Thus, in some ecological contexts, multiple approaches, such as direct seeding or planting, and the use of nurse plants, may be required to enhance seed rain and seedling establishment of fleshy-fruited species. © 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society. Source

McCluney K.E.,Arizona State University | Belnap J.,U.S. Geological Survey | Collins S.L.,University of New Mexico | Gonzalez A.L.,University of Santiago de Chile | And 7 more authors.
Biological Reviews | Year: 2012

Species interactions play key roles in linking the responses of populations, communities, and ecosystems to environmental change. For instance, species interactions are an important determinant of the complexity of changes in trophic biomass with variation in resources. Water resources are a major driver of terrestrial ecology and climate change is expected to greatly alter the distribution of this critical resource. While previous studies have documented strong effects of global environmental change on species interactions in general, responses can vary from region to region. Dryland ecosystems occupy more than one-third of the Earth's land mass, are greatly affected by changes in water availability, and are predicted to be hotspots of climate change. Thus, it is imperative to understand the effects of environmental change on these globally significant ecosystems. Here, we review studies of the responses of population-level plant-plant, plant-herbivore, and predator-prey interactions to changes in water availability in dryland environments in order to develop new hypotheses and predictions to guide future research. To help explain patterns of interaction outcomes, we developed a conceptual model that views interaction outcomes as shifting between (1) competition and facilitation (plant-plant), (2) herbivory, neutralism, or mutualism (plant-herbivore), or (3) neutralism and predation (predator-prey), as water availability crosses physiological, behavioural, or population-density thresholds. We link our conceptual model to hypothetical scenarios of current and future water availability to make testable predictions about the influence of changes in water availability on species interactions. We also examine potential implications of our conceptual model for the relative importance of top-down effects and the linearity of patterns of change in trophic biomass with changes in water availability. Finally, we highlight key research needs and some possible broader impacts of our findings. Overall, we hope to stimulate and guide future research that links changes in water availability to patterns of species interactions and the dynamics of populations and communities in dryland ecosystems. © 2011 The Authors. Biological Reviews © 2011 Cambridge Philosophical Society. Source

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