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AimTo assess if and how species’ range size relates to range structure, if the observed geographic range properties can be retrieved from predicted maps based on species distribution modeling, and whether range properties are predictable from biogeophysical factors.LocationEuropeTime periodCurrentMajor taxa studied813 vascular plant species endemic to EuropeMethodsWe quantified the size and spatial structure of species’ geographic ranges and compared ranges currently occupied with those predicted by species distribution models (SDMs). SDMs were constructed using complete occurrence data from the Atlas Florae Europaeae and climatic, soil and topographic predictors. We used landscape metrics to characterize range size, range division and patch shape structure, and analysed the phylogenetic, geographic and ecological drivers of species’ range size and structure using phylogenetic generalized least squares (pGLS).ResultsRange structure metrics were mostly decoupled from species’ range size. We found large differences in range metrics between observed and predicted ranges, in particular for species with intermediate observed range size and occupied area, and species with low and high observed patch size distribution, geographic range filling, patch shape complexity and geographic range fractality. Elevation heterogeneity, proximity to continental coasts, Southerly or Easterly geographic range positions and narrow ecological niche breadth constrained species’ observed range size and range structure to different extents. The strength and direction of the relationships differed between observed and predicted ranges.Main conclusionsSeveral range structure metrics, in addition to range size, are needed to adequately describe and understand species’ ranges. Species’ range structure can be well explained by geophysical factors and species niche width, albeit not consistently for observed and predicted ranges. As range structure can have important ecological and evolutionary consequences, we highlight the need to develop better predictive models of range structure than provided by current SDMs, and we identify the kinds of species for which this is most necessary.

Periphyton is increasingly used to assess the biological condition of lakes. The predominance of relatively shallow exposed waterbodies in Ireland implies that epilithic diatoms should have a prominent role as bioindicators for the WFD; but epilithic diatom ecology in these Irish systems is poorly described. We characterised spring and summer diatom populations in diverse periphyton communities in 91 Irish lake waterbodies. Six assemblage clusters of diatom species were identified, and variation in their assemblages was predominately associated with environmental gradients of acidity-alkalinity, total phosphorus, and true colour. Diatom composition differed amongst high status lakes in three a priori defined lake alkalinity groups commonly used as a diatom typology for lake classification. However, when waterbodies were evaluated with a lake trophic diatom index (LTDI) their distribution of ‘expected-values’ was equivalent. The LTDI was highly correlated with total phosphorus but also had similar responses in the three lake alkalinity types. These findings indicated that lake typology had a limited role for diatom classification with the LTDI in Ireland. Matched spring and summer sampling across wide environmental gradients allowed the role of seasonality to be investigated. Relatively few benthic diatoms had a significant seasonal indicator value suggesting that unbiased monitoring of the epilithon is possible during any month of the growing season in comparable temperate waterbodies. However, temporal variability was lower at low values of the LTDI and increased unpredictably on a lake by lake basis thereafter. Given that lake diatom classification has been validated we suggest that the approach could be developed and used for more targeted assessment objectives.

The increasing extent and intensity of agricultural land use has led to an increase in the volume of agrochemicals applied to the landscape, including those used to improve the nutritional quality of soils (fertilizers) as well as those used to control undesirable species in the agroecosystem (pesticides). Chemicals can disperse in the air and surface and ground water, leading to exposure of non-target organisms. Ruderal, disturbance-tolerant plants on which many flower-visiting insects rely are commonly exposed to these chemicals in agroecosystems. Our research questions were: 1) how does non-target exposure to agrochemicals affect plant growth? 2) what are the indirect effects of non-target exposure to agrochemicals on flower-visitation by insects? We designed a two year field experiment imitating field-realistic fertilizer run-off and non-target herbicide exposure scenarios to explore the impact of low concentrations of fertilizer and herbicide alone, and in combination, on communities of seven plant species, including six native perennials and one non-native annual commonly found in agricultural systems in Ireland (Cirsium vulgare, Epilobium hirsutum, Plantago lanceolata, Origanum vulgare, Filipendula ulmaria, Hypochaeris radicata, Phacelia tanacetifolia). We created field-realistic exposure scenarios by applying concentrations of mineral fertilizer similar to those detected in ground water, and glyphosate levels equivalent to 7.6 % of a standard field application, to the foliage and soil of the plots. We found low concentrations of fertilizer and herbicide affected plant growth: fertilised plants were taller when flowering, while plants exposed to herbicide flowered at shorter heights and produced shorter leaves. The size of the floral display had the largest effect on insect visitation, with larger floral displays significantly more likely to receive a visitor in a given sampling event. The size of the floral display also interacted significantly with the fertilizer treatment for both the abundance and species richness of floral visitors. Overall, our results suggest that there are direct and indirect effects of agrochemical exposure on plants in field margins, and that these effects change the interactions between ruderal plants and flower-visiting insects.

1. Introduced plants may initially experience enemy release, but some of those interactions may be reinstated through biological control. These cases provide opportunities to explore the dynamics of broken and remade consumer-resource interactions.

The Encyonopsis microcephala-complex occurs in oligo-mesotrophic freshwaters and is often abundant in the periphyton of low nutrient lakes of high conservation value. It is globally distributed and increasing in apparent diversity with the discovery of additional species. To better differentiate this taxonomic aggregate, we re-examined the original type material of E. alpina, E. angusta and E. tavirana with light (LM) and scanning electron (SEM) microscopy. We investigated the morphology, ultrastructure and ecology of Encyonopsis populations from Ireland, which included previously unreported taxa and morphodemes of E. krammeri, E. neerlandica and E. subminuta. The apparently cosmopolitan E. microcephala was not found in collections from Ireland but two new species were described and compared to others in the complex. Encyonopsis carraensis sp. nov. was associated with a marl-precipitating community in low nutrient lakes, while Encyonopsis hibernica sp. nov. occurred in more productive waterbodies. Several Encyonopsis species had environmental optima near the oligo-mesotrophic boundary characteristic of the microcephala-complex. However, the niches of others were distributed along a wider gradient of water quality. Therefore, when Encyonopsis populations are prevalent in epilithic communities, the use of a more refined taxonomy is recommended for lake ecological assessment.

Globally, modification of landscapes for agriculture has had a strong influence on the distribution and abundance of biota. In particular, woodland-dependent birds are under threat across agricultural landscapes in Britain, North America and Australia, with their decline and extirpation attributed to the loss and fragmentation of habitat. Other native species have become over-abundant in response to anthropogenic landscape change and have strong interactive effects on avian assemblage structure. In eastern Australia, the hyper-aggressive noisy miner (Manorina melanocephala) often dominates woodlands in agricultural landscapes through interspecific competition, resulting in declines of species richness of woodland-dependent birds. We aimed to determine the relative influence and importance of interspecific competition, in situ habitat structure and landscape structure for woodland-dependent bird species at the landscape level. We recorded species-specific landscape incidence of woodland-dependent birds in 24 agricultural-woodland mosaics (25 km2) in southern Queensland, Australia. We selected extensively cleared landscapes (10–23 % woodland cover) where fragmentation effects are expected to be greatest. We applied generalised linear models and hierarchical partitioning to quantify the relative importance of the landscape-level incidence of the noisy miner, mistletoe abundance, shrub cover, woodland extent, woodland subdivision and land-use intensity for the incidence of 46 species of woodland birds at the landscape-scale. The landscape-level incidence of the noisy miner was the most important explanatory variable across the assemblage. Both in situ habitat structure and landscape structure were of secondary importance to interspecific aggression, although previous research suggests that the increasing incidence of the noisy miner in fragmented agricultural landscapes is itself a consequence of anthropogenic changes to landscape structure. Species’ responses to fragmentation varied from positive to negative, but complex habitat structure had a consistently positive effect, suggesting in situ restoration of degraded habitats could be a conservation priority. Landscape wide conservation of woodland-dependent bird populations in agricultural landscapes may be more effective if direct management of noisy miner populations is employed, given the strong negative influence of this species on the incidence of woodland-dependent birds among landscapes.

Many passerine bird populations, particularly those that have open-cup nests, are in decline in agricultural landscapes. Current theory suggests that an increase in habitat generalist predators in response to landscape change is partially responsible for these declines. However, empirical tests have failed to reach a consensus on how and through what mechanisms landscape change affects nest predation. We tested one hypothesis, the Additive Predation Model, with an artificial nest experiment in fragmented landscapes in southern Queensland, Australia. We employed structural equation modelling of the influence of the relative density of woodland and habitat generalist predators and landscape features at the nest, site, patch and landscape scales on the probability of nest predation. We found little support for the Additive Predation Model, with no significant influence of the density of woodland predators on the probability of nest predation, although landscape features at different spatial scales were important. Within woodlands fragmented by agriculture in eastern Australia, the presence of noisy miner colonies appears to influence ecological processes important for nest predation such that the Additive Predation Model does not hold. In the absence of colonies of the aggressive native bird, the noisy miner, the influence of woodland predators on the risk of artificial nest predation was low compared with that of habitat generalist predators. Outside noisy miner colonies, we found significant edge effects with greater predation rates for artificial nests within woodland patches located closer to the agricultural matrix. Furthermore, the density of habitat generalist predators increased with the extent of irrigated land-use, suggesting that in the absence of noisy miner colonies, nest predation increases with land-use intensity at the landscape scale.

Management of damaging invasive plants is often undertaken by multiple decision makers, each managing only a small part of the invader's population. As weeds can move between properties and re‐infest eradicated sites from unmanaged sources, the dynamics of multiple decision makers plays a significant role in weed prevalence and invasion risk at the landscape scale. We used a spatially explicit agent‐based simulation to determine how individual agent behavior, in concert with weed population ecology, determined weed prevalence. We compared two invasive grass species that differ in ecology, control methods, and costs: Nassella trichotoma (serrated tussock) and Eragrostis curvula (African love grass). The way decision makers reacted to the benefit of management had a large effect on the extent of a weed. If benefits of weed control outweighed the costs, and either net benefit was very large or all agents were very sensitive to net benefits, then agents tended to act synchronously, reducing the pool of infested agents available to spread the weed. As N. trichotoma was more damaging than E. curvula and had more effective control methods, agents chose to manage it more often, which resulted in lower prevalence of N. trichotoma. A relatively low number of agents who were intrinsically less motivated to control weeds led to increased prevalence of both species. This was particularly apparent when long‐distance dispersal meant each infested agent increased the invasion risk for a large portion of the landscape. In this case, a small proportion of land mangers reluctant to control, regardless of costs and benefits, could lead to the whole landscape being infested, even when local control stopped new infestations. Social pressure was important, but only if it was independent of weed prevalence, suggesting that early access to information, and incentives to act on that information, may be crucial in stopping a weed from infesting large areas. The response of our model to both behavioral and ecological parameters was highly nonlinear. This implies that the outcomes of weed management programs that deal with multiple land mangers could be highly variable in both space and through time.

In plants where reproduction is fatal, seed-feeding insects may have a major impact on the evolutionarily stable reproductive strategy by altering fecundity schedules in a size-dependent manner. We explored this in Carduus nutans, a facultative biennial native to Europe, using two years of data from the South of France. An integral projection model based on detailed statistical models of the demography of Carduus nutans and characteristics of herbivore attack showed that seed predators select for smaller flowering size. An elasticity analysis showed that changes in the slope relating seed herbivore attack rates to plant total receptacle area had a large effect on lifetime reproductive success relative to most other plant demographic rates. Together, these two results indicate that in the absence of seed predators, as is the case in the exotic range of this invasive species, flowering size could evolve to be larger. Further analysis also showed that subsequent introduction of different species of seed-feeders as biocontrol agents could lead to different evolutionary outcomes dependent on the ecological characteristics of the seed-feeders, allowing the direction and magnitude of evolutionary change in flowering size to be predicted based on what seed predators have been introduced where and when. Such data would allow us to distinguish between the effect of seed predators and other hypotheses for size increase in the invasive habitat. © Springer Science+Business Media B.V. 2008.

Understanding the impact of herbivory on plant populations is a fundamental goal of ecology. Damage to individual plants can be visually striking and affect the fates of individuals, but these impacts do not necessarily translate into population‐level differences in vital rates (survival, growth, or fecundity) or population growth rates. In biological control of weeds, quantitative assessments of population‐level impacts of released agents on both target invasive plants and native, nontarget plants are needed to inform evaluations of the benefits and risks of releasing agents into new regions. Here we present a 3‐yr experimental demographic field study using the European root‐feeding biocontrol weevil, Mogulones crucifer, first released in Canada in 1997 to control the invasive weed Cynoglossum officinale (Boraginaceae). Mogulones crucifer is an effective “search and destroy” agent in Canada, but sporadically feeds, oviposits, and develops on native nontarget Boraginaceae. We investigated the population‐level impacts of this biocontrol insect on its target weed and a native nontarget plant, Hackelia micrantha (Boraginaceae), by releasing large numbers of weevils into naturally occurring patches of H. micrantha growing isolated from or interspersed with C. officinale. We followed the fates of individual plants on release and nonrelease (control) sites for two transition years, developed matrix models to project population growth rates (λ) for each plant species, and examined the contributions from differences in vital rates to changes in λ using life table response experiments (LTRE). In contrast to studies of the insect–plant interaction in its native range, as a biocontrol agent, M. crucifer increased mortality of C. officinale rosettes in the year immediately following release, depressing the weed's λ to below the population replacement level. However, λ for H. micrantha was never depressed below the replacement level, and any differences between release and nonrelease sites in the nontarget could not be explained by significant contributions from vital rates in the LTRE. This study is the first to simultaneously and experimentally examine target and nontarget population‐level impacts of a weed biocontrol insect in the field, and supports the theoretical prediction that plant life history characteristics and uneven herbivore host preferences can interact to produce differences in population‐level impacts between target and nontarget plant species.

Increased or fluctuating resources may facilitate opportunities for invasive exotic plants to dominate. This hypothesis does not, however, explain how invasive species succeed in regions characterized by low resource conditions or how these species persist in the lulls between high resource periods. We compare the growth of three co-occurring C4 perennial bunchgrasses under low resource conditions: an exotic grass, Eragrostis curvula (African lovegrass) and two native grasses, Themeda triandra and Eragrostis sororia. We grew each species over 12 weeks under low nutrients and three low water regimes differentiated by timing: continuous, pulsed, and mixed treatments (switched from continuous to pulsed and back to continuous). Over time, we measured germination rates, time to germination (first and second generations), height, root biomass, vegetative biomass, and reproductive biomass. Contrary to our expectations that the pulsed watering regime would favor the invader, water-supply treatments had little significant effect on plant growth. We did find inherent advantages in a suite of early colonization traits that likely favor African lovegrass over the natives including faster germination speed, earlier flowering times, faster growth rates and from 2 weeks onward it was taller. African lovegrass also showed similar growth allocation strategies to the native grasses in terms of biomass levels belowground, but produced more vegetative biomass than kangaroo grass. Overall our results suggest that even under low resource conditions invasive plant species like African lovegrass can grow similarly to native grasses, and for some key colonization traits, like germination rate, perform better than natives.

Understanding the mechanisms behind the successful colonization and establishment of introduced species is important for both preventing the invasion of unwanted species and improving release programs for biological control agents. However, it is often not possible to determine important introduction details, such as date, number of organisms, and introduction location when examining factors affecting invasion success. Here we use biological control introduction data to assess the role of propagule pressure, disturbance, and residence time on invasion success of four herbivorous insect species introduced for the control of the invasive wetland plant, Lythrum salicaria, in the Columbia River Estuary. Two sets of field surveys determined persistence at prior release sites, colonization of new sites, and abundance within colonized sites. We quantified propagule pressure in four ways to examine the effect of different measurements. These included three measurements of introduction size (proximity to introduction site, introduction size at a local scale, and introduction size at a regional scale) and one measure of introduction number (number of introduction events in a region). Disturbance was examined along a tidal inundation gradient (distance from river mouth) and as habitat (island or mainland). Statistical models and model averaging were used to determine which factors were driving invasion success. In this study we found: (1) sparse evidence for the positive influence of propagule pressure on invasion success; (2) disturbance can negatively affect the invasion success of herbivorous insects; (3) the effects of disturbance and propagule pressure are species specific and vary among invasion stages, and (4) not all measures of propagule pressure show the same results, therefore single measures and proxies should be used cautiously.

Questions: The following hypotheses of neighbourhood effects on drought-induced mortality are evaluated: (A) drought-induced stem death is randomly distributed in space, (B) stems are predisposed to drought-induced death through negative density-dependent effects and (C) stems are predisposed to drought-induced death due to local deficits in plant available resources. Location: Central Queensland, Australia. Methods: Recent mass mortality of woody stems was surveyed and mapped in three 1.21-ha quadrats within Eucalyptus melanophloia-dominated savanna. A multi-faceted analytical approach was adopted including spatial pattern analyses, two logistic regressions of neighbourhood density effects on survival and spatial autocorrelation analyses of model residuals. Results: Mortality was concentrated in stems ≤15-cm diameter at breast height (DBH). Survival was aggregated or random in quadrats 1 and 3 and random o regular in quadrat 2. Small neighbour density had a negative effect on survival in all quadrats. In addition, the second model identified a positive relationship between survival and living neighbour density in quadrat 3 (indicating a resource patch effect), but a negative relationship in quadrat 2 (density effect). Analysis of model residuals showed that neighbour density explained mortality equally well across quadrat 2, but not across quadrats 1 and 3. Conclusions: There was evidence in support of hypotheses B (neighbour density) and C (resource heterogeneity). We found strong support for an interaction between microsite quality and neighbourhood stem densities, and suggest that this interaction is driven by plant available water.

P>1. Restoration thinning involves the selective removal of stems in woody ecosystems to restore historical or ecologically desirable ecosystem structure and processes. Thinning may also accelerate carbon sequestration in dense regenerating forests. This study considers restoration thinning effects on both structural development and carbon sequestration in a regenerating forest ecosystem.

Summary 1. A seed-feeding biocontrol agent Bruchidius villosus was released in New Zealand (NZ) to control the invasive European shrub, broom Cytisus scoparius, in 1988 but it was subsequently considered unable to destroy sufficient seed to suppress broom populations. We hypothesized that an invasive mite Varroa destructor, which has caused honeybee decline in NZ, may cause pollinator limitation, so that the additional impact of B. villosus might now reach thresholds for population suppression. 2. We performed manipulative pollination treatments and broad-scale surveys of pollination, seed rain and seed destruction by B. villosus to investigate how pollinator limitation and biocontrol interact throughout the NZ range of broom. 3. The effect of reduced pollination in combination with seed-destruction was explored using a population model parameterized for NZ populations. 4. Broom seed rain ranged from 59 to 21 416 seeds m )2 from 2004 to 2008, and was closely correlated with visitation frequency of honeybees and bumblebees. Infestation of broom seeds by B. villosus is expected to eventually reach 73% (the average rate observed at the localities adjacent to early release sites). 5. The model demonstrated that 73% seed destruction, combined with an absence of honeybee pollination, could cause broom extinction at many sites and, where broom persists, reduce the intensity of treatment required to control broom by conventional means. 6. Nevertheless, seed rain was predicted to be sufficient to maintain broom invasions over many sites in NZ, even in the presence of the varroa mite and B. villosus, largely due to the continued presence of commercial beehives that are treated for varroa mite infestation. 7. Synthesis and applications. Reduced pollination through absence of honeybees can reduce broom seed set to levels at which biocontrol can be more effective. To capitalize on the impact of the varroa mite on feral honeybees, improved management of commercial beehives (for example, withdrawal of licences for beekeepers to locate hives on Department of Conservation land) could be used as part of a successful integrated broom management programme at many sites in NZ.

Identifying species boundaries within morphologically indistinguishable cryptic species complexes is often contentious. For the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodoidea: Aleyrodidae), the lack of a clear understanding about the genetic limits of the numerous genetic groups and biotypes so far identified has resulted in a lack of consistency in the application of the terms, the approaches used to apply them and in our understanding of what genetic structure within B. tabaci means. Our response has been to use mitochondrial gene cytochrome oxidase one to consider how to clearly and consistently define genetic separation. Using Bayesian phylogenetic analysis and analysis of sequence pairwise divergence we found a considerably higher number of genetic groups than had been previously determined with two breaks in the distribution, one at 11% and another at 3.5%. At >11% divergence, 11 distinct groups were resolved, whereas at >3.5% divergence 24 groups were identified. Consensus sequences for each of these groups were determined and were shown to be useful in the correct assignment of sequences of unknown origin. The 3.5% divergence bound is consistent with species level separations in other insect taxa and suggests that B. tabaci is a cryptic species composed of at least 24 distinct species. We further show that the placement of Bemesia atriplex (Froggatt) within the B. tabaci in group adds further weight to the argument for species level separation within B. tabaci. This new analysis, which constructs consensus sequences and uses these as a standard against which unknown sequences can be compared, provides for the first time a consistent means of identifying the genetic bounds of each species with a high degree of certainty.

Climate has an important influence on the distribution and abundance of invasive species. Habitat suitability for invasive plants could shift with a changing climate and management practices may need to shift in response. Anecdotal evidence suggests that groundsel bush (Baccharis halimifolia) has declined in abundance over the past 50 years in Australia, co-incident with the introduction of a suite of biological control agents. While biological control may be responsible for this decline, here we investigate an alternative hypothesis—that long-term change in the favourability of the climate may have changed growth conditions for groundsel bush throughout its Australian range. We also predict what may happen to the future distribution of this species, using a bioclimatic modelling technique (CLIMEX). We found a significant reduction in the favourability for growth of B. halimifolia over the past 50 years at 29 sites in Australia. Under a likely IPCC future climate scenario prediction (decrease in rainfall and increase in temperature), the favourability for growth of B. halimifolia will continue to decrease in Queensland and its distribution may move further south into New South Wales and Victoria. We conclude that climate alone may have had a significant effect on the distribution and abundance of B. halimifolia and future priorities for management of B. halimifolia should focus on its southern distribution. Determining the success of the biological control programme in isolation from the observed climate effects will be difficult. Given the likelihood of future climate change worldwide evaluation of biological control programmes in general will need to also account for climate effects.

P>Seed longevity has a major influence on the success of weed management and eradication programmes. A correlation between responses to a controlled aging test performed at 45 degrees C, 60% relative humidity (RH) and seed persistence in the field has recently been suggested. Here we investigated whether collections of differing quality of two closely related invasive weeds, Chrysanthemoides monilifera ssp. monilifera and ssp. rotundata (boneseed and bitou bush, respectively), had different seed longevity using the controlled aging test. Chrysanthemoides monilifera ssp. monilifera fruits were collected from across five Australian states, and C. monilifera ssp. rotundata from one state, covering their invasive ranges. Seed quality was assessed visually and using tetrazolium staining, and a series of germination tests established appropriate germination conditions. The controlled aging test was run for a subset of collections. Chrysanthemoides monilifera ssp. rotundata seeds died more quickly (time to lose 50% viability, P(50) = 16 days) than the C. monilifera ssp. monilifera collections (P(50) = 47 days) when aged at 45 degrees C and 60% RH. This difference was significant even considering the large differences in longevity between C. monilifera ssp. monilifera populations (P(50) = 35-61 days; probably due to differences in maturity at collection). Based on a published correlation, we predict that mature C. monilifera ssp. monilifera may have a long-lived (> 3 years) seed bank and C. monilifera ssp. rotundata may have a transient (< 1 year) seed bank. This suggests the two sub-species should be considered separately when designing effective control measures.

Woody regrowth is extensive on abandoned agricultural lands and developed pastures worldwide. Regrowth is actively controlled in working pastures, but it could be managed to offset greenhouse gas emissions from agriculture and other emitting industries with supplementary benefits for biodiversity conservation. This paper explores the case of Brigalow regrowth in the extensive pastoral landscape of north-eastern Australia. By synthesising current ecological knowledge with relevant socio-economic and policy considerations, it examines the potential of the Brigalow regrowth ecosystem to provide dual carbon/biodiversity benefits. Brigalow regrowth sequesters large amounts of carbon, especially when compared to other ecosystems from similar sub-humid climates. In addition, restoring regrowth is likely to have benefits for a wide range of native flora and fauna, including the endangered bridled nailtail wallaby. However, there are knowledge gaps relating to the landscape ecology of Brigalow regrowth and the impacts of management and climate change on carbon/restoration potential. Also, a conflict exists between short-term carbon sequestration and long-term restoration goals and we suggest a role for restoration thinning to resolve this. Regional demand for high biomass regrowth as a carbon offset is likely to be high but ambiguities in carbon policy threaten to diminish the use of natural regrowth for reforestation projects.

The intensity and type of damage exerted by a biological control agent on an invasive plant is often influenced by plant architecture or size, density, distribution and phenology as well as microhabitat. Here, herbivore and pathogen damage thought to be caused by seven biological control agents introduced up to 40 years ago for control of groundsel bush (Baccharis halimifolia) is examined. Sampling was conducted throughout the known introduced range of groundsel bush in Australia to determine how damage type and intensity were influenced by rainfall, temperature, elevation, population density, average plant size and variability in plant size. Sori abundance score (characteristic of the introduced rust fungus) was higher on large plants at high rainfall. Leaf skeletonization was negatively correlated with elevation and leaf miner damage was lower in high density plant populations. Leaf hole damage increased with rainfall particularly on large plants in homogeneous sized populations. Stem-borer damage increased with plant size, but this relationship was influenced by rainfall and plant population density. There was less stem-boring in large populations but the strength of the relationship was influenced by temperature and variation in plant size. Overall considerable variation in intensity of herbivore and pathogen damage was found throughout the range of groundsel bush. If herbivore and pathogen damage impact on plant vital rates and demography it would be expected that biological control success for this species would be patchy and depend on plant size, population density and site location.

The study was undertaken at Bulli State Forest, in the eastern Darling Downs, Queensland, Australia. The State Forest includes a minor area (65 ha) of sedentary cracking clay in the western portion with limited gilgai development. This area supports remnant (undisturbed) open forest of Brigalow and Belah (Casuarina cristata Miq.) (Regional Ecosystem 11.9.5, Young et al. 1999) and adjacent regrowth Brigalow communities of two ages (39 and 27 years old). Clearing permits indicate that the 39-year old regrowth (herein referred to as ‘old regrowth’) was originally cleared by ringbarking in 1968 and has been allowed to regenerate without subsequent clearing or thinning. The 27-year-old regrowth (herein referred to as ‘young regrowth’) was first cleared in 1968 by pulling and was later re-pulled in the early 1980s. Mean annual rainfall is 578 mm, with December, the wettest month, receiving 76.5 mm on average.

The role of mutualisms in contributing to species invasions is rarely considered, inhibiting effective risk analysis and management options. Potential ecological consequences of invasion of non-native pollinators include increased pollination and seed set of invasive plants, with subsequent impacts on population growth rates and rates of spread. We outline a quantitative approach for evaluating the impact of a proposed introduction of an invasive pollinator on existing weed population dynamics and demonstrate the use of this approach on a relatively data-rich case study: the impacts on Cytisus scoparius (Scotch broom) from proposed introduction of Bombus terrestris. Three models have been used to assess population growth (matrix model), spread speed (integrodifference equation), and equilibrium occupancy (lattice model) for C. scoparius. We use available demographic data for an Australian population to parameterize two of these models. Increased seed set due to more efficient pollination resulted in a higher population growth rate in the density-independent matrix model, whereas simulations of enhanced pollination scenarios had a negligible effect on equilibrium weed occupancy in the lattice model. This is attributed to strong microsite limitation of recruitment in invasive C. scoparius populations observed in Australia and incorporated in the lattice model. A lack of information regarding secondary ant dispersal of C. scoparius prevents us from parameterizing the integrodifference equation model for Australia, but studies of invasive populations in California suggest that spread speed will also increase with higher seed set. For microsite-limited C. scoparius populations, increased seed set has minimal effects on equilibrium site occupancy. However, for density-independent rapidly invading populations, increased seed set is likely to lead to higher growth rates and spread speeds. The impacts of introduced pollinators on native flora and fauna and the potential for promoting range expansion in pollinator-limited 'sleeper weeds' also remain substantial risks.

1. Coupled plant-herbivore models, allowing feedback from plant to herbivore populations and vice versa, enable us to predict the impact of biocontrol agents on their target weed populations; however, they are rarely used in biocontrol studies. We describe the population biology of the invasive plant Echium plantagineum and the weevil Mogulones larvatus, a biocontrol agent, in Australia. In order to understand the dynamics of this plant-herbivore system, a series of coupled models of increasing complexity was developed. 2. A simple model was extended to include a seed bank, density-dependent plant fecundity, competition between weevil larvae and plant tolerance of herbivory, where below a threshold plants could compensate for larval feeding. Parameters and functional forms were estimated from experimental and field data. 3. The plant model, in the absence of the weevil, exhibited stable dynamics and provided a good quantitative description of field densities before the weevil was introduced. 4. In the coupled plant-herbivore model, density dependence in both plant fecundity and weevil larval competition stabilized the dynamics. Without larval competition the model was unstable, and plant tolerance of herbivory exacerbated this instability. This was a result of a time delay in plant response to herbivore densities. 5. Synthesis and applications. The coupled plant-herbivore model allowed us to predict whether stable coexistence of target plant and biocontrol agents was achievable at an acceptable level. We found this to be the case for the Echium-Mogulones system and believe that similar models would be of use when assessing new agents in this and other invasive plant biocontrol systems. Density dependence in new biocontrol agents should be assessed in order to determine whether it is likely to result in the aims of classical biocontrol: low, stable and sustainable populations of plant and herbivore. Further work should be done to characterize the strength of density dependence according to the niche occupied by the biocontrol agent, for example the strength and functional form of density dependence in stem borers may be quite different to that of defoliators.

1. Most invasive plant species are not well controlled and where biocontrol programs are in place only one third are fully successful. Integrated weed management (IWM) emphasises the use of several complementary control measures. Choosing which combinations will yield control and how biocontrol fits within the strategy requires detailed knowledge of the dynamics of the target and its ecosystem. 2. We used models of increasing complexity to determine which parameters affect site occupancy of an invasive shrub, Mimosa pigra L. in tropical Australia. Two introduced biocontrol agents have spatial effects on both plant fecundity and the probability of recolonisation after senescence. We incorporated biocontrol effects into IWM models with disturbance, mechanical control, herbicide and fire. The models were parameterised from experimental and field data. 3. Models indicate that the reduction in fecundity is not the most important impact of biocontrol; rather it is through defoliation at the edges of stands allowing grasses to out-compete M. pigra seedlings. We demonstrate that biocontrol alone is only successful at low disturbance and seedling survival and even then, current biocontrol agents would take decades to reduce a stand to

Trichogramma zahiri Polaszek sp. n. is described from Bangladesh. It has been collected at several localities from the major pest of rice Dicladispa armigera (Olivier) on which it has an important controlling impact. Trichogramma zahiri is compared with known Trichogramma species from the region, and diagnostic differences are presented. Data on developmental period, adult longevity, egg-laying frequency, host egg age preference and seasonal parasitism rate are presented and discussed. Other records of parasitoids of D. armigera are briefly reviewed and discussed.

Scotch broom (Cytisus scoparius) is a serious weed of natural and pastoral ecosystems and is invasive in many countries worldwide. Eight polymorphic microsatellite loci were developed and characterized for this species. The number of alleles per locus ranged from five to 23. The range of observed heterozygosity was between 0.207 and 0.928. These microsatellite markers will be useful tools for studies of population genetics in the native and invasive range of this species.

International audience; Genetic diversity and the way a species is introduced influence the capacity of populations of invasive species to persist in, and adapt to, their new environment. The diversity of introduced populations affects their evolutionary potential, which is particularly important for species that have invaded a wide range of habitats and climates, such as European gorse, Ulex europaeus. This species originated in the Iberian peninsula and colonised Europe in the Neolithic; over the course of the past two centuries it was introduced to, and has become invasive in, other continents. We characterised neutral genetic diversity and its structure in the native range and in invaded regions. By coupling these results with historical data, we have identified the way in which gorse populations were introduced and the consequences of introduction history on genetic diversity. Our study is based on the genotyping of individuals from 18 populations at six microsatellite loci. As U. europaeus is an allohexaploid species, we used recently developed tools that take into account genotypic ambiguity. Our results show that genetic diversity in gorse is very high and mainly contained within populations. We confirm that colonisation occurred in two stages. During the first stage, gorse spread out naturally from Spain towards northern Europe, losing some genetic diversity. During the second stage, gorse was introduced by humans into different regions of the world, from northern Europe. These introductions resulted in the loss of rare alleles but did not significantly reduce genetic diversity and thus the evolutionary potential of this invasive species.

In herbaceous ecosystems worldwide, biodiversity has been negatively impacted by changed grazing regimes and nutrient enrichment. Altered disturbance regimes are thought to favour invasive species that have a high phenotypic plasticity, although most studies measure plasticity under controlled conditions in the greenhouse and then assume plasticity is an advantage in the field. Here, we compare trait plasticity between three co-occurring, C(4) perennial grass species, an invader Eragrostis curvula, and natives Eragrostis sororia and Aristida personata to grazing and fertilizer in a three-year field trial. We measured abundances and several leaf traits known to correlate with strategies used by plants to fix carbon and acquire resources, i.e. specific leaf area (SLA), leaf dry matter content (LDMC), leaf nutrient concentrations (N, C:N, P), assimilation rates (Amax) and photosynthetic nitrogen use efficiency (PNUE). In the control treatment (grazed only), trait values for SLA, leaf C:N ratios, Amax and PNUE differed significantly between the three grass species. When trait values were compared across treatments, E. curvula showed higher trait plasticity than the native grasses, and this correlated with an increase in abundance across all but the grazed/fertilized treatment. The native grasses showed little trait plasticity in response to the treatments. Aristida personata decreased significantly in the treatments where E. curvula increased, and E. sororia abundance increased possibly due to increased rainfall and not in response to treatments or invader abundance. Overall, we found that plasticity did not favour an increase in abundance of E. curvula under the grazed/fertilized treatment likely because leaf nutrient contents increased and subsequently its' palatability to consumers. E. curvula also displayed a higher resource use efficiency than the native grasses. These findings suggest resource conditions and disturbance regimes can be manipulated to disadvantage the success of even plastic exotic species.

Opportunities for dual restoration and carbon benefits from naturally regenerating woody ecosystems in agricultural landscapes have been highlighted recently. The restoration capacity of woody ecosystems depends on the magnitude and duration of ecosystem modification, i.e., the "agricultural legacy." However, this legacy may not influence carbon sequestration in the same way as restoration because carbon potential depends primarily on biomass accumulation, with little consideration of other attributes and functions of the ecosystem. Our present study simultaneously assesses the restoration and carbon potential of Acacia harpophylla regrowth, an extensive regrowth ecosystem in northeastern Australia. We used a landscape-scale survey of A. harpophylla regrowth to test the following hypotheses: (1) management history, in combination with climatic and edaphic factors, has long-term effects on stem densities, and (2) higher-density stands have lower restoration and carbon potential, which is also influenced by climatic and edaphic factors. We focused on the restoration of forest structure, which was characterized using stem density, aboveground biomass, stem heights, and stem diameters. Data were analyzed using multilevel models within the hierarchical Bayesian model (HBM) framework. We found strong support for both hypotheses. Repeated attempts at clearing Brigalow (A. harpophylla ecosystem) regrowth increases stem densities, and these densities remain high over the long term, particularly in high-rainfall areas and on gilgaied, high-clay soils (hypothesis 1). In models testing hypothesis 2, interactions between stem density and stand age indicate that higher-density stands have slower biomass accumulation and structural development in the long term. After accounting for stem density and stand age, annual rainfall had a positive effect on biomass accumulation and structural development. Other climate and soil variables were retained in the various models but had weaker effects. Spatial extrapolations of the HBMs indicated that the central and eastern parts of the study region are most suitable for biomass accumulation; however, these may not correspond to the areas that historically supported the highest biomass Brigalow forests. We conclude that carbon and restoration goals are largely congruent within areas of similar climate. At the regional scale, however, spatial prioritization of restoration and carbon projects may only be aligned where carbon benefits will be high.

Invasive plants have negative impacts on ecosystems worldwide. Several ecological studies have identified disturbance as a causative mechanism of plant invasions. Changes to natural disturbances and/or newly imposed disturbances can favour an invader over native species especially those that are better adapted to prior conditions. # 2. To link the disturbance ecology of invasives to their management, we investigated the benefit of incorporating actions that manipulate disturbance (natural or imposed) into control efforts. We developed a simple model that describes the dynamics of an invader whose establishment is preferentially favoured by disturbance. # 3. The model includes the probability of disturbance differentially affecting sites occupied by natives and invaders. Invaded sites are disturbed by alternative control measures, which act to kill and/or remove above-ground biomass and reduce the seed bank. We couched the model in a decision theory tool, stochastic dynamic programming, and applied it to the management of Mimosa pigra, a pan-tropical invasive perennial shrub. # 4. We found that targeting the above-ground biomass of the invader (current population) was optimal when the probability of disturbance of native sites and the invader seed bank size were low to moderate. When both the rate of disturbance of native sites and invader seed banks were high, the best measure was that with the highest probability of reducing the seed bank (future populations). This measure was optimal despite its trade-off of having the highest probability of reinvasion. # 5. Synthesis and applications. Manipulation of disturbance regimes in both native and invaded sites can simplify control efforts. If there is a high probability that native vegetation will be disturbed, then management efforts should focus on future populations by attempting to reduce the size of the invader seed bank. This complicates control, as seed bank size is difficult to measure and reducing it requires intensive actions, which are likely to also negatively affect the seed bank of native species. If, however, the probability of disturbance of native sites can be reduced, practitioners can shift control from future populations to the current population, which is more straightforward to implement and monitor

Knowledge of the introduction history of invasive plants informs on theories of invasiveness and assists in the invasives management. For the highly successful invasive shrub Scotch broom, Cytisus scoparius, we analysed a combination of nuclear and chloroplast microsatellites for eight native source regions and eight independent invasion events in four countries across three continents. We found that two exotic Australian populations came from different sources, one of which was derived from multiple native populations, as was an invasive sample from California. An invasive population from New Zealand appeared to be predominantly sourced from a single population, either from the native or exotic ranges. Four invasive populations from Chile were genetically differentiated from the native range samples analysed here and so their source of introduction could not be confirmed, but high levels of differentiation between the Chilean populations suggested a combination of different sources. This extensive global data set of replicated introductions also enabled tests of key theories of invasiveness in relation to genetic diversity. We conclude that invasive populations have similar levels of high genetic diversity to native ranges; levels of admixture may vary across invasive populations so admixture does not appear to have been an essential requirement for invasion; invasive and native populations exhibit similar level of genetic structure indicating similar gene flow dynamics for both types of populations. High levels of diversity and multiple source populations for invasive populations observed here discount founder effects or drift as likely explanations for previously observed seed size differences between ranges. The high levels of genetic diversity, differential and source admixture identified for most exotic populations are likely to limit the ability to source biocontrol agents from the native region of origin of invasive populations.

Eucalyptus melanophloia and E. populnea dominate large areas of savanna in eastern Australia. Under aboriginal management, fires probably occurred under a broad range of conditions, but under pastoral management, burning is avoided when soil moisture is low. This experiment subjected E. melanophloia and E. populnea seedlings to burning and moisture stress, to examine whether this change in burning regime could affect seedling survivorship. The findings suggest survivorship rates are 87–93% for unstressed seedlings with relatively large lignotubers (>12 mm2 plan area) and 56–66% for unstressed seedlings with small lignotubers. There was no substantial interactive effect between moisture stress and burning for E. melanophloia, but such an interaction was apparent for E. populnea, such that moisture stress multiplied the effect of burning. The timing of burning in relation to soil-moisture conditions may have an enduring effect on woodland structure where E. populnea is dominant. E. melanophloia seedlings are more resistant to burning, especially with moisture stress, and fire may not be limiting structural development in woodlands where this species dominates. However, a more detailed understanding of species demography is required, including the conditions required for germination, causes of seedling mortality and the time taken for seedlings to develop fire resistance in the field.

We explored the spatial structure of seed size variation and tested whether seed size differed between native and exotic populations in two invasive species. Seed of Cytisus scoparius (Scotch broom) is significantly heavier in its exotic range, whereas seed of Ulex europaeus (European gorse) is no different between ranges. This result suggests that seed size in C. scoparius is either adaptively or phenotypically responsive to conditions in its exotic range or that plants with large seeds were preferentially introduced. We found that modern ornamental broom seed was no bigger than seed from natural or naturalized populations, suggesting that large seed size in the exotic range is not due to preferential introduction of ornamental varieties with large seeds. Most previous studies of trait differences between native and exotic ranges in invasive species have not taken variation throughout the ranges into account. This is the most comprehensive survey of seed size variation in any species, and the first time that variation in a trait of an invasive species has been studied from individual plant level up to global ranges. Demographic rates can be affected by seed attributes making this study an important first step in understanding how population processes may differ between native and exotic ranges.