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Questions: Field‐based ecosystem mapping is prone to observer bias, typically resulting in a mismatch between maps made by different mappers, that is, inconsistency. Experimental studies testing the influence of site, mapping scale, and differences in experience level on inconsistency in field‐based ecosystem mapping are lacking. Here, we study how inconsistencies in field‐based ecosystem maps depend on these factors. Location: Iškoras and Guollemuorsuolu, northeastern Norway, and Landsvik and Lygra, western Norway. Methods: In a balanced experiment, four sites were field‐mapped wall‐to‐wall to scales 1:5000 and 1:20,000 by 12 mappers, representing three experience levels. Thematic inconsistency was calculated by overlay analysis of map pairs from the same site, mapped to the same scale. We tested for significant differences between sites, scales, and experience‐level groups. Principal components analysis was used in an analysis of additional map inconsistencies and their relationships with site, scale and differences in experience level and time consumption were analysed with redundancy analysis. Results: On average, thematic inconsistency was 51%. The most important predictor for thematic inconsistency, and for all map inconsistencies, was site. Scale and its interaction with site predicted map inconsistencies, but only the latter were important for thematic inconsistency. The only experience‐level group that differed significantly from the mean thematic inconsistency was that of the most experienced mappers, with nine percentage points. Experience had no significant effect on map inconsistency as a whole. Conclusion: Thematic inconsistency was high for all but the dominant thematic units, with potentially adverse consequences for mapping ecosystems that are fragmented or have low coverage. Interactions between site and mapping system properties are considered the main reasons why no relationships between scale and thematic inconsistency were observed. More controlled experiments are needed to quantify the effect of other factors on inconsistency in field‐based mapping.Field‐based ecosystem maps often have high spatial uncertainty. We found that the area assigned to each ecosystem is considerably more reliable. Moreover, spatial uncertainty is highly influenced by site properties. In particular, mapping of ecosystems that are fragmented or have low coverage is associated with uncertainty. [ABSTRACT FROM AUTHOR]

The global distribution of vegetation is largely determined by climatic conditions and feeds back into the climate system. To predict future vegetation changes in response to climate change, it is crucial to identify and understand key patterns and processes that couple vegetation and climate. Dynamic global vegetation models (DGVMs) have been widely applied to describe the distribution of vegetation types and their future dynamics in response to climate change. As a process‐based approach, it partly relies on hard‐coded climate thresholds to constrain the distribution of vegetation. What thresholds to implement in DGVMs and how to replace them with more process‐based descriptions remain among the major challenges. In this study, we employ machine learning using decision trees to extract large‐scale relationships between the global distribution of vegetation and climatic characteristics from remotely sensed vegetation and climate data. We analyse how the dominant vegetation types are linked to climate extremes as compared to seasonally or annually averaged climatic conditions. The results show that climate extremes allow us to describe the distribution and eco‐climatological space of the vegetation types more accurately than the averaged climate variables, especially those types which occupy small territories in a relatively homogeneous ecological space. Future predicted vegetation changes using both climate extremes and averaged climate variables are less prominent than that predicted by averaged climate variables and are in better agreement with those of DGVMs, further indicating the importance of climate extremes in determining geographic distributions of different vegetation types. We found that the temperature thresholds for vegetation types (e.g. grass and open shrubland) in cold environments vary with moisture conditions. The coldest daily maximum temperature (extreme cold day) is particularly important for separating many different vegetation types. These findings highlight the need for a more explicit representation of the impacts of climate extremes on vegetation in DGVMs. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to investigate the role of traits in beetle community assembly and test for consistency in these effects among several bioclimatic regions. We asked (1) whether traits predicted species' responses to environmental gradients (i.e. their niches), (2) whether these same traits could predict co-occurrence patterns and (3) how consistent were niches and the role of traits among study regions. Location: Boreal forests in Norway and Finland, temperate forests in Germany. Taxon: Wood-living (saproxylic) beetles. Methods: We compiled capture records of 468 wood-living beetle species from the three regions, along with nine morphological and ecological species traits. Eight climatic and forest covariates were also collected. We used Bayesian hierarchical joint species distribution models to estimate the influence of traits and phylogeny on species' niches. We also tested for correlations between species associations and trait similarity. Finally, we compared species niches and the effects of traits among study regions. Results: Traits explained some of the variability in species' niches, but their effects differed among study regions. However, substantial phylogenetic signal in species niches implies that unmeasured but phylogenetically structured traits have a stronger effect. Degree of trait similarity was correlated with species associations but depended idiosyncratically on the trait and region. Species niches were much more consistent--widespread taxa often responded similarly to an environmental gradient in each region. Main conclusions: The inconsistent effects of traits among regions limit their current use in understanding beetle community assembly. Phylogenetic signal in niches, however, implies that better predictive traits can eventually be identified. Consistency of species niches among regions means niches may remain relatively stable under future climate and land use changes; this lends credibility to predictive distribution models based on future climate projections but may imply that species' scope for short-term adaptation is limited. [ABSTRACT FROM AUTHOR]

Background: Although a standard taxonomy of organisms has existed for nearly 300 years, no consensus has yet been reached on principles for systematization of ecological diversity (i.e., the co‐ordinated variation of abiotic and biotic components of natural diversity). In a rapidly changing world, where nature is under constant pressure, standardized terms and methods for characterization of ecological diversity are urgently needed (e.g., to enhance precision and credibility of global change assessments). Aim: The aim is to present the EcoSyst framework, a set of general principles and methods for systematization of natural diversity that simultaneously addresses biotic and abiotic variation, and to discuss perspectives opened by this framework. Innovation: EcoSyst provides a framework for systematizing natural variation in a consistent manner across different levels of organization. At each ecodiversity level, EcoSyst principles can be used to establish: (a) an extensive attribute system with descriptive variables that cover all relevant sources of variation; (b) a hierarchical‐type system; and (c) a set of guidelines for land‐cover mapping that is consistent across spatial scales. EcoSyst type systems can be conceptualized as multidimensional models, by which a key characteristic (the response) is related to variation in one or more key sources of variation (predictors). EcoSyst type hierarchies are developed by a gradient‐based iterative procedure, by which the "ecodiversity distance" (i.e., the extent to which the key characteristic differs between adjacent candidate types) is standardized and the ecological processes behind observed patterns are explicitly taken into account. Application: We present "Nature in Norway" (NiN), an implementation of the EcoSyst framework for Norway for the ecosystem and landscape levels of ecodiversity. Examples of applications to research and management are given. Conclusion: The EcoSyst framework provides a theoretical platform, principles and methods that can complement and enhance initiatives towards a global‐scale systematics of ecodiversity. [ABSTRACT FROM AUTHOR]

Veteran hollow oaks (Quercus spp.) are keystone structures hosting high insect diversity but are declining in numbers due to intensification of land use and the abandonment of traditional management. The loss of this vital habitat is resulting in a reduction of biodiversity, and this likely has consequences for ecosystem functioning, especially if functional diversity is reduced. A considerable amount of research has been done on predictors of beetle taxonomic diversity in veteran oaks, but predictors of functional diversity have remained largely unexplored. The aim of this study was to establish whether the features and surroundings of veteran oaks are related to functional diversity within three functional groups of beetles (decomposers, predators, and flower visitors) and determine whether species richness and functional diversity within the groups are dependent on the same predictors. Sampling was carried out intermittently between 2004 and 2011 on 61 veteran oaks in Southern Norway. Of the 876 beetle species that were collected, 359 were determined to be decomposers, 284 were predators, and 85 were flower visitors. Species richness and functional diversity in all groups were consistently higher in traps mounted on veteran oaks in forests than in open landscapes. However, additional predictors differed between groups, and for species richness and functional diversity. Decomposer species richness responded to tree vitality, while functional diversity responded to habitat connectivity, predator species richness responded to regrowth of shrubs while functional diversity responded to tree circumference, and flower visitor richness and functional diversity did not respond to any additional predictors. Previous studies have found that the features and surroundings of veteran oaks are important for conservation of taxonomic diversity, and the results from this study indicate that they are also important for functional diversity within multiple functional groups. [ABSTRACT FROM AUTHOR]

Abstract: In climate change ecology, simplistic research approaches may yield unrealistically simplistic answers to often more complicated problems. In particular, the complexity of vegetation responses to global climate change begs a better understanding of the impacts of concomitant changes in several climatic drivers, how these impacts vary across different climatic contexts, and of the demographic processes underlying population changes. Using a replicated, factorial, whole‐community transplant experiment, we investigated regional variation in demographic responses of plant populations to increased temperature and/or precipitation. Across four perennial forb species and 12 sites, we found strong responses to both temperature and precipitation change. Changes in population growth rates were mainly due to changes in survival and clonality. In three of the four study species, the combined increase in temperature and precipitation reflected nonadditive, antagonistic interactions of the single climatic changes for population growth rate and survival, while the interactions were additive and synergistic for clonality. This disparity affects the persistence of genotypes, but also suggests that the mechanisms behind the responses of the vital rates differ. In addition, survival effects varied systematically with climatic context, with wetter and warmer + wetter transplants showing less positive or more negative responses at warmer sites. The detailed demographic approach yields important mechanistic insights into how concomitant changes in temperature and precipitation affect plants, which makes our results generalizable beyond the four study species. Our comprehensive study design illustrates the power of replicated field experiments in disentangling the complex relationships and patterns that govern climate change impacts across real‐world species and landscapes. [ABSTRACT FROM AUTHOR]

Over the past centuries, humans have transformed large parts of the biosphere, and there is a growing need to understand and predict the distribution of biodiversity hotspots influenced by the presence of humans. Our basic hypothesis is that human influence in the Anthropocene is ubiquitous, and we predict that biodiversity hot spot modeling can be improved by addressing three challenges raised by the increasing ecological influence of humans: (i) anthropogenically modified responses to individual ecological factors, (ii) fundamentally different processes and predictors in landscape types shaped by different land use histories and (iii) a multitude and complexity of natural and anthropogenic processes that may require many predictors and even multiple models in different landscape types. We modeled the occurrence of veteran oaks in Norway, and found, in accordance with our basic hypothesis and predictions, that humans influence the distribution of veteran oaks throughout its range, but in different ways in forests and open landscapes. In forests, geographical and topographic variables related to the oak niche are still important, but the occurrence of veteran oaks is shifted toward steeper slopes, where logging is difficult. In open landscapes, land cover variables are more important, and veteran oaks are more common toward the north than expected from the fundamental oak niche. In both landscape types, multiple predictor variables representing ecological and human-influenced processes were needed to build a good model, and several models performed almost equally well. Models accounting for the different anthropogenic influences on landscape structure and processes consistently performed better than models based exclusively on natural biogeographical and ecological predictors. Thus, our results for veteran oaks clearly illustrate the challenges to distribution modeling raised by the ubiquitous influence of humans, even in a moderately populated region, but also show that predictions can be improved by explicitly addressing these anthropogenic complexities. [ABSTRACT FROM AUTHOR]

Biotic interactions are often ignored in assessments of climate change impacts. However, climate-related changes in species interactions, often mediated through increased dominance of certain species or functional groups, may have important implications for how species respond to climate warming and altered precipitation patterns. We examined how a dominant plant functional group affected the population dynamics of four co-occurring forb species by experimentally removing graminoids in seminatural grasslands. Specifically, we explored how the interaction between dominants and subordinates varied with climate by replicating the removal experiment across a climate grid consisting of 12 field sites spanning broad-scale temperature and precipitation gradients in southern Norway. Biotic interactions affected population growth rates of all study species, and the net outcome of interactions between dominants and subordinates switched from facilitation to competition with increasing temperature along the temperature gradient. The impacts of competitive interactions on subordinates in the warmer sites could primarily be attributed to reduced plant survival. Whereas the response to dominant removal varied with temperature, there was no overall effect of precipitation on the balance between competition and facilitation. Our findings suggest that global warming may increase the relative importance of competitive interactions in seminatural grasslands across a wide range of precipitation levels, thereby favouring highly competitive dominant species over subordinate species. As a result, seminatural grasslands may become increasingly dependent on disturbance (i.e. traditional management such as grazing and mowing) to maintain viable populations of subordinate species and thereby biodiversity under future climates. Our study highlights the importance of population-level studies replicated under different climatic conditions for understanding the underlying mechanisms of climate change impacts on plants. [ABSTRACT FROM AUTHOR]

The journey of wind-dispersed seeds does not necessarily end when they land. Secondary dispersal and/or predation can positively or negatively affect the spread of invasive plants. Here we studied post-dispersal seed removal of nodding and plumeless thistle ( Carduus nutans and C. acanthoides) in part of their invaded range in Pennsylvania, USA. The relative impact of small mammals and insects was determined using exclusion treatments in the field. In cages that allowed insect access, 88 % of the seeds were removed after 1 day, and 99.9 % were removed after the 6-day trial. When insects were excluded, the removal rate was significantly lower (18 % after 1 day, 40 % after 6 days). The seed removal rates provide an upper limit to the seed predation rate, with the understanding that it is also possible for seed removal to be an important secondary dispersal mechanism. We discuss a combined empirical-theoretical approach to evaluate the impact of these alternative seed fates on the spread and management of these thistles. [ABSTRACT FROM AUTHOR]

Questions Effects of climate on flowering performance are often investigated independently of plant size. We ask how temperature and precipitation impact flowering probability and flower production: via direct effects, size-dependent indirect effects, changes in minimum size for flowering and/or changes in reproductive investment. Location Twelve calcareous grasslands in western Norway (4°50′-8°45′ E, 60°20′-61°50′ N). Methods The investigations were carried out at the rear temperature edge of alpine plants and at the leading temperature edge of lowland plants to capture the variety of climate responses occurring in different parts of species climate niches within our study landscape. The study was conducted within a natural 'climatic grid' consisting of temperature gradients replicated along a precipitation gradient. In each study site, we sampled populations of two alpine ( Viola biflora, Veronica alpina) and two lowland ( Viola palustris, Veronica officinalis) species. The relative importance of each effect was assessed under a 2 °C increase in mean summer temperature and a 10% increase in annual precipitation. Results Flowering was climate- and size-dependent in all species except Viola palustris. Both direct climate effects and climate-driven variation in reproductive investment were detected for the three other species. Indirect climate effects were detected for Veronica officinalis, and climate-driven variation in minimum size for flowering in Viola biflora. Climatic responses were not consistent within or between distributional types (alpine vs lowland) or genera. A temperature increase of 2 °C was predicted to increase flower production by 22% for Veronica alpina and by 74% for Veronica officinalis. A precipitation increase of 10% had a limited impact on Viola biflora flowering probability (0.08% increase) and increased Veronica officinalis flower production by 1.7%. Conclusions Our study shows that climate affects flowering performance both directly and through size dependence. Understanding such size-dependent responses to climate is important for our understanding of how climate change will affect flowering performance and recruitment in plant populations. [ABSTRACT FROM AUTHOR]

In recent decades we have seen rapid and co-occurring changes in landscape structure, species distributions and even climate as consequences of human activity. Such changes affect the dynamics of the interaction between major forest pest species, such as bark beetles (Coleoptera: Curculionidae, Scolytinae), and their host trees. Normally breeding mostly in broken or severely stressed spruce; at high population densities some bark beetle species can colonise and kill healthy trees on scales ranging from single trees in a stand to multi-annual landscape-wide outbreaks. In Eurasia, the largest outbreaks are caused by the spruce bark beetle, Ips typographus (Linnaeus), which is common and shares a wide distribution with its main host, Norway spruce ( Picea abies Karst.). A large literature is now available, from which this review aims to synthesize research relevant for the population dynamics of I. typographus and co-occurring species under changing conditions. We find that spruce bark beetle population dynamics tend to be metastable, but that mixed-species and age-heterogeneous forests with good site-matching tend to be less susceptible to large-scale outbreaks. While large accumulations of logs should be removed and/or debarked before the next swarming period, intensive removal of all coarse dead wood may be counterproductive, as it reduces the diversity of predators that in some areas may play a role in keeping I. typographus populations below the outbreak threshold, and sanitary logging frequently causes edge effects and root damage, reducing the resistance of remaining trees. It is very hard to predict the outcome of interspecific interactions due to invading beetle species or I. typographus establishing outside its current range, as they can be of varying sign and strength and may fluctuate depending on environmental factors and population phase. Most research indicates that beetle outbreaks will increase in frequency and magnitude as temperature, wind speed and precipitation variability increases, and that mitigating forestry practices should be adopted as soon as possible considering the time lags involved. [ABSTRACT FROM AUTHOR]

The most comprehensive data on many species come from scientific collections. Thus, we developed a method of population viability analysis (PVA) in which this type of occurrence data can be used. In contrast to classical PVA, our approach accounts for the inherent observation error in occurrence data and allows the estimation of the population parameters needed for viability analysis. We tested the sensitivity of the approach to spatial resolution of the data, length of the time series, sampling effort, and detection probability with simulated data and conducted PVAs for common, rare, and threatened species. We compared the results of these PVAs with results of standard method PVAs in which observation error is ignored. Our method provided realistic estimates of population growth terms and quasi-extinction risk in cases in which the standard method without observation error could not. For low values of any of the sampling variables we tested, precision decreased, and in some cases biased estimates resulted. The results of our PVAs with the example species were consistent with information in the literature on these species. Our approach may facilitate PVA for a wide range of species of conservation concern for which demographic data are lacking but occurrence data are readily available. [ABSTRACT FROM AUTHOR]

1. Red-listed species are species of great conservation concern, but they are inherently difficult to observe. Therefore, prediction models for hotspots of such species would be very useful for biodiversity monitoring and management. 2. Red-listed species are ecologically heterogeneous, and they may be associated with many different environmental variables that may be more or less correlated. To overcome these challenges, we introduce a new technique to species richness modelling: Partial Least Squares Regression (PLSR), a multivariate regression technique developed specifically for similar statistical problems in econometrics. 3. Partial Least Squares Regression models were developed for hotspots of red-listed beetles associated with oaks. In this system, environmental variables and the richness of red-listed species were often correlated. 4. Without exceptions, the PLSR performed better as prediction models than generalised linear models (GLM) and principal components regression (PCR). 5. Different combinations of variables associated with individual trees were important in continuous forest with a closed canopy and a natural understory vs. man-made wooded park landscapes. 6. Our results suggest that important variables related to hotspots for red-listed species in forests in forests are trees with cavities of intermediate size, as well as dead wood and broadleaved tree species other than oak in the surrounding forest. In parks, large trees with wood mould, but also other oak trees in the surroundings, seem to be important. 7. In conclusion, the PLSR models may be used to improve the prediction of species richness in the presence of many correlated predictors and thus improve biodiversity monitoring and management. [ABSTRACT FROM AUTHOR]

Plant survival, growth, and flowering are size dependent in many plant populations but also vary among individuals of the same size. This individual variation, along with variation in dispersal caused by differences in, e.g., seed release height, seed characteristics, and wind speed, is a key determinant of the spread rate of species through homogeneous landscapes. Here we develop spatial integral projection models (SIPMs) that include both demography and dispersal with continuous state variables. The advantage of this novel approach over discrete-stage spread models is that the effect of variation in plant size and size-dependent vital rates can be studied at much higher resolution. Comparing Neubert- Caswell matrix models to SIPMs allowed us to assess the importance of including individual variation in the models. As a test case we parameterized a SIPM with previously published data on the invasive monocarpic thistle Carduus nutans in New Zealand. Spread rate (c*) estimates were 34% lower than for standard spatial matrix models and stabilized with as few as seven evenly distributed size classes. The SIPM allowed us to calculate spread rate elasticities. over the range of plant sizes, showing the size range of seedlings that contributed most to c* through their survival, growth and reproduction. The annual transitions of these seedlings were also the most important ones for local population growth (λ). However, seedlings that reproduced within a year contributed relatively more to λ than to c*. In contrast, plants that grow over several years to reach a large size and produce many more seeds, contributed relatively more to λ than to c*. We show that matrix models pick up some of these details, while other details disappear within wide size classes. Our results show that SIPMs integrate various sources of variation much better than discrete-stage matrix models. Simpler, heuristic models, however, remain very valuable in studies where the main goal is to investigate the general impact of a life history stage on population dynamics. We conclude with a discussion of future extensions of SIPMs, including incorporation of continuous time and environmental drivers. [ABSTRACT FROM AUTHOR]

The pinewood nematode (PWN) is one of the worst tree-killing exotic pests in East-Asian countries. The first European record of establishment in Portugal in 1999 triggered extensive surveys and contingency plans for eradication in European countries, including immediate removal of large areas of conifer host trees. Using Norway as an example, we applied a simulation model to evaluate the chance of successful eradication of a hypothetical introduction by the current contingency plan in a northern area where wilting symptoms are not expected to occur. Despite a highly variable spread of nematode infestations in space and time, the probability of successful eradication in 20 years was consistently low (mean 0.035, SE 0.02). The low success did not change significantly by varying the biological parameters in sensitivity analyses (SA), probably due to the late detection of infestations by the survey (mean 14.3 years). SA revealed a strong influence of management parameters. However, a high probability of eradication required unrealistic measures: achieving an eradication probability of 0.99 in 20 years required 10,000 survey samples per year and a host tree removal radius of 8,000 m around each detection point. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of coupled demographic-dispersal models to address the relative importance of different approaches for controlling the local abundance and population growth of thistle Carduus nutans in France, Australia and New Zealand. The study analyzed the demographics of the insect population among the three regions and found that growth and spread are affected by same life cycle transitions. Moreover, it cites the advantages of the vital-rate-based modeling approach.

The dynamics of species interactions are of central importance for the understanding of ecological coexistence, community structure and the effects of biological invasions. Using bark beetles that colonize the same habitat as an example, we explore species interactions in a resource-based model system with positive feedback between insect abundance and resource availability. The net interspecies interaction was found to be highly dynamic and may alternate in time between competition and mutualism. When both bark beetle species were able to kill trees (“aggressive”), our simulations showed strong facilitations between beetle species. This may lead to escape from control by competition, and increase the frequency of outbreaks of tree-killing. The frequency of net positive interactions varied with interaction strengths and the relative aggressiveness of the species and was highest when both species were strongly aggressive; which predicts disastrous outbreaks if, e.g., the European spruce bark beetle Ips typographus and the North American spruce beetle Dendroctonus rufipennis should become interacting species due to introductions. In imbalanced pairs, the relatively less aggressive species was facilitated more often than the aggressive species. Net positive interactions did not occur for strongly inferior species, but their survival was an increasing function of interaction strength with aggressive species and availability of resources. The benefits for the inferior species in the model are consistent with the structure of one aggressive and several less aggressive or non-aggressive species, which is common in bark beetle communities in many parts of the world. [ABSTRACT FROM AUTHOR]

1. Many invasive species are introduced by trade, and there is a need for studies of pre-emptive measures to lower the risk of introductions, as post-establishment management is often extremely costly or nearly impossible. 2. In this study, we present a generic model for the first step of the invasion process for trade-imported pests, and further develop this model for potentially harmful bark beetles to assess the risk of introductions and alternative management options. 3. Our results suggest that introductions of bark beetles are likely, given present timber import practices, and that immigration may often go undetected by pheromone traps. 4. The most effective measures for reducing introduction risk were those aimed at isolating the storage from forest (storage enclosure, location) followed by those reducing the available resources for forest pests (debarking, timber irrigation, rapid processing), whereas delayed import was least effective. 5. Synthesis and applications: The generic model framework of species introductions presented here may easily be adapted to other import systems. The submodels of population dynamics and dispersal are also quite general, and we expect our qualitative results to hold in many cases, although the models were parameterized for bark beetles in this study. Our results suggest that detection of dispersal from storage to forests will be difficult, which implies that management actions should not be deferred until after detection in nature, as the pest species may then already be established and eradication may be too late. However, pre-emptive measures reducing propagule pressure at one or several stages of the introduction process, in particular isolation measures, may strongly reduce introduction risk. [ABSTRACT FROM AUTHOR]

1. Invasive species usually exhibit different spatial population dynamics in their native and invaded range. This is often attributed to demographic differences, but may be due to differences in dispersal as well. 2. Regardless of how these dispersal and demographic differences from the native range arose, studying how they contributed to increases in population spread rates will increase our understanding of what has made these species invasive. Here we investigate which vital rates and dispersal parameters of the invasive thistle Carduus nutans drive the increases in spread rate in different invaded ranges compared to that in the native range in Eurasia. 3. We construct and analyse spatial integrodifference models that combine structured, local population models with mechanistic (WALD) models of seed dispersal by wind across a homogeneous landscape. Published and new demographic and dispersal data for single populations from the native (France) and invaded (Australia, New Zealand, Kansas and Pennsylvania) ranges were used for the parameterization. 4. We developed a variance decomposition method ( c*-LTRE) to analyse the contributions of the changes in the vital rates and dispersal parameters to the increases in the invasion wave speed ( c*) estimates for the different invaded ranges compared to that for the native range. 5. The c*-LTRE analysis showed that the net contribution of the dispersal parameters to c* increases varied among the populations from 51% (Australia), to 79% (Kansas), to 80% (New Zealand) and to 85% (Pennsylvanian experiment). Escape from natural enemies that reduce seed set by floral herbivory was important in all invaded ranges. Large positive contributions were also made by increases in rapid growth of seedlings and small rosettes, increases in flowering probabilities and potential seed production, as well as by increased plant height and lower falling velocities of the plumed seeds. 6. Synthesis. By incorporating a mechanistic dispersal model with a structured population model, and by linking this joint model to field data from several continents, we demonstrate the relative importance of dispersal and demography to invasion success. This approach can be used to analyse which aspects of an invader's life history have changed most importantly from the native range. [ABSTRACT FROM AUTHOR]

1. Emergence traps were set overnight on the sediment surface to sample the littoral microcrustaceans of 22 Canadian Shield lakes that ranged in pH from 4.56 to 6.92. Traps were randomly allocated in quintuplicate in both wave-washed sandy habitats where pipewort ( Eriocaulon septangulare) was the dominant macrophyte (termed pipewort habitats), and more protected habitats dominated by floating-leaved macrophytes (termed floating-leaved habitats). 2. In total, 50 cladoceran and 22 copepod species were found, with 16–45 species in each lake. Lakes that had never acidified exhibited a more diverse fauna than lakes that had acidified. 3. There were only minor differences between the numbers of species found in floating-leaved versus pipewort habitats except for one lake. Non-chydorid cladoceran, chydorids and copepods constituted 45%, 26% and 29% of the total number of individuals, respectively. 4. Based on presence/absence, dominance scores and frequency of occurrences of species, the microcrustacean faunal composition was similar in the two habitats. A detrended correspondence analysis confirmed that there was no separation between the two main types of habitat, and that pH was the parameter most strongly correlated with the dominant microcrustacean compositional gradient among lakes. [ABSTRACT FROM AUTHOR]

1. The distribution of dispersal distances (the dispersal kernel) is a major determinant of spatial population dynamics, yet little is known about the shape of the dispersal kernel for most species. This is partly because of the relative difficulty of measuring dispersal, exacerbated by a lack of standardized protocols. We suggest that this problem can be addressed by using modelling approaches to aid the design of studies to quantify dispersal. 2. In this study we present such an approach by optimizing seed trap sampling design using stochastic simulations. A number of alternative sampling designs (random placements, grid arrays, transects, sectors and annuli arrangements) for a point source were tested against a common kernel to assess the best methods for estimating the dispersal kernel. 3. For a given source strength and total trap area, transects and sectors of traps usually provided better data for kernel estimation than random placement, grid arrays and annuli. Kernel estimation was improved by increasing the source strength (the number of dispersing propagules) and the trap area, as expected. 4. When the ‘true’ kernel was unknown, transects were slightly better for identifying the thin-tailed exponential distribution, whereas sectors were better for detecting the fat-tailed half-Cauchy. 5. In the case of anisotropic dispersal (here, dispersal biased in one direction), annuli and grid arrays performed better than transects and sectors when the anisotropy was unknown. However, when the anisotropy was anticipated, and the trap arrangements were adjusted accordingly, transects and sectors were better. This was true regardless of source strength and total trap area. 6. Synthesis and applications. This study presents a simulation approach to the design of dispersal experiments. While the general results of our simulations can be used by those designing field studies for plant point sources, the simulation approach itself can be modified for a wide range of organisms, dispersal mechanisms and dispersal measurement approaches. Thus, the approach presented here facilitates improvements of dispersal study designs, which in turn will increase the precision of dispersal kernel estimates and predictions of spatial population dynamics, including modelling of rates of spread or metapopulations. This is invaluable in a range of ecological applications, such as the management of rare or invasive species, predicting species’ response to climate change, or planning species reintroductions. Journal of Applied Ecology (2005) 42, 731–739 doi: 10.1111/j.1365-2664.2005.01056.x [ABSTRACT FROM AUTHOR]

1 We measured and modelled the dispersal of a wind-dispersed herb, the leafless hawk's beard (Crepis praemorsa, Asteraceae), using a combination of measurement techniques, selected empirical models and mechanistic models originally developed for trees.2 Dispersal was measured by releasing individual seeds and by placing seed traps around an experimentally created point source of seeding plants. Dispersal distances varied considerably between the experiments. In the seed releases, dispersal distances were positively related to horizontal wind speed (linear regression,P < 0.001) and, under favourable conditions, many seeds dispersed over several metres, with a few at> 30 m.3 Four empirical models (the inverse power (IP), the negative exponential (NE), Bullock&Clarke's mixed model (MIX) and Clarket al.'s 2Dt model) were fitted to the data. IP and NE models often failed to accommodate the shape of the empirical distribution of dispersal distances, and the MIX model, although extremely flexible, tended to overfit the data. The 2Dt model was, however, flexible and realistic in each experiment. Nevertheless, the parameter values for all of the empirical models varied dramatically between experiments; no set of parameter values predicted the observed dispersal distances under all conditions.4 Two mechanistic models (Greene&Johnson's analytical model (GJ) and Nathanet al.'s individual-based simulation model (NSN)), originally developed for trees, were parameterized using independent data and parameter values from the literature. Although the NSN model provided a poor fit for the seed trap experiment, it performed almost as well as the best empirical models in the seed release experiments. Its predictions were further improved by including convection, and predicted dispersal> 30 m corresponded closely with our observations. The prediction of low (< 1%) dispersal> 200 m requires further... [ABSTRACT FROM AUTHOR]

This paper reports an experimental study of water dispersal potential and germination of the shingle beach plant Mertensia maritima in which we consider the effects of physical factors (cold treatment, mechanical wear of the pericarp and salt-water exposure) on the diaspores. Our approach also includes testing effects of different orders of the treatments, in contrast to most earlier studies of diaspore ecology. A cold period was necessary to break seed dormancy, and prolonged cold treatment (stratification at 2°C) enhanced germination. Mechanical wear of the pericarp before cold treatment did not affect germination, whereas mechanical wear after cold treatment increased germination significantly. Seeds exposed to 6 weeks of cold treatment before floating in salt water for 6 weeks did not germinate. In contrast, for seeds given the same cold treatment after floating, the germination was more than 50%. Most undamaged and slightly damaged nutlets stayed afloat throughout the dispersal experiment (9 weeks) in 3% salt water, whereas seeds that fell out of damaged nutlets sunk immediately. Thus, the results suggest that the potential for long-distance dispersal is high unless the diaspores (nutlets) are severely damaged, but the order of cold treatment and water dispersal seems to be of great importance for germination: seeds dispersed in autumn (before cold periods) have a much higher probability of germinating than seeds dispersed in winter or early spring (after a cold period). Similar effects of the relative timing of physical processes have hitherto only been reported for two other water-dispersed beach plants. Future studies in diaspore ecology should consider such timing effects as they may be important determinants of the distribution and abundance of plants. [ABSTRACT FROM AUTHOR]