Infestation by the mite Harpirhynchus nidulans in the Bearded Tit Panurus biarmicus

Capsule Mites sometimes induced voluminous subcutaneous cysts in featherless parts.

Aims To describe the first reported infestation by the skin-dweller mite Harpirhynchus nidulans in Bearded Tits Panurus biarmicus and for the Timaliidae family, to detect possible fitness costs for the host and to determine the distribution of the parasite within the distribution range of the host.

Methods Parasites were identified using a microscope. Wing-length and body mass were recorded on both uninfected and infected birds captured at different times during the year. We also considered historical data, and contact was made with 32 European ringing stations to identify the distribution range of the parasite.

Results Subcutaneous reproduction of the mite Harpirhynchus nidulans induced the development of voluminous dermal nodules in Panurus biarmicus. There were no differences in body mass or wing-length with respect to infestation. In the south of France, prevalence changed from 10.6% in spring to 4.7% in autumn. Both sexes are equally parasitized. Occurrence of dermal cysts is reported from several southern European populations of Bearded Tits, whereas it seems to be absent from northern latitudes.

Conclusion The occurrence of a Harpirhynchus mite in wild bird populations is reported for the first time. We consider aspects of its biology, host–parasite system, host-specificity, co-adaptation of the mite reproductive cycle to the social dynamics of its host and metapopulational host–parasite dynamics.     

Fifteenth annual research symposium University of Glasgow, 1975

Background: All human land use (LU) affects the distribution of plant species; however, the impacts vary with the type/intensity of LU. For managing ecosystems, it is therefore essential to understand the effects of LU types on the distribution of plant species on a macroscale.

Aims: The objectives of our study were to quantify the effects of various LU types on the distribution of vascular plant species in Japan and to determine in particular the extent to which LU was an important factor for the distribution of common species.

Methods: Based on a logistic regression model and variation partitioning being applied to each plant species, we evaluated the partial deviance by six LU types, four climatic types and three topographic and geological factors for 647 plant species at 14,412 sites in Japan.

Results: The effect of LU was significant for species present at multiple sites. Of the six LU types, secondary vegetation and plantation were the most important factors determining species distribution for many species.

Conclusions: Our results suggest that distribution of the common species is largely affected by LU on macroscale. The design of LU relating to secondary vegetation and plantations will thus be important in determining changes in the vegetation composition within Japan.     

Anthropogenic Vegetation Contributions to Polynesia’s Social Heritage: The Legacy of Candlenut Tree (<Emphasis Type="Italic">Aleurites moluccana</Emphasis>) Forests and Bamboo (<Emphasis Type="Italic">Schizostachyum glaucifolium</Emphasis>) Groves on the Island of Tahiti

Anthropogenic Vegetation Contributions to Polynesia’s Social Heritage: The Legacy of Candlenut Tree ( Aleurites moluccana ) Forests and Bamboo ( Schizostachyum glaucifolium ) Groves on the Island of Tahiti. In the tropical oceanic islands of the Pacific, vegetation patterns and dynamics are the result of plant dispersal capacities, the physical characteristics of the islands’ ecosystems, and natural disturbances. However, humans have profoundly modified native landscapes through habitat destruction and the introduction of animal and plant species. The candlenut tree Aleurites moluccana (Euphorbiaceae) and the Polynesian bamboo Schizostachyum glaucifolium (Poaceae), intentionally introduced as useful plants by the first Polynesian migrants at least 1,000 years ago, are now widely naturalized in the high volcanic islands of the Society archipelago (French Polynesia), but with an intriguing patchy distribution. The present study consists of a comparative analysis between the most recent existing vegetation map and the known archeological sites on the island of Tahiti. Thirty-nine bamboo groves and 30 candlenut forests were identified and located using GIS and a Digital Elevation Model. The results show that the dispersal and distribution patterns of these two plant taxa are related to the presence and location of ancient sites of Polynesian occupation. The bamboo groves can be used as a bio-indicator of the presence of potential archeological sites. Their currently restricted distribution might reflect habitat requirements and poor dispersal capacities. The candlenut tree and the Polynesian bamboo are relicts of ancient Polynesian society that have persisted and remain integrated in the modern landscape. They can therefore be viewed as introduced species of high cultural heritage value.     

Trait dynamics of Mediterranean xerophytic shrub communities growing on stabilised inland dunes respond to nutrient and aridity gradients

Background: Understanding the processes that determine community assembly and their dynamics is a central issue in ecology. The analysis of functional diversity can improve our understanding of these dynamics by identifying community assembly processes.

Aims: We studied the effect of environment–community covariations on both functional diversity and functional structure of xerophytic shrub communities for inferring the community assembly processes shaping this vegetation type.

Methods: Functional diversity was quantified using (1) community-weighted mean of the studied traits, (2) functional groups, defined using Ward’s hierarchical agglomerative clustering method and (3) Rao’s quadratic entropy. Relationships between functional diversity and environmental gradients were identified by Spearman correlations and modelled using generalised additive models.

Results: Variations in community composition and functional diversity correlated with soil nutrient availability and aridity. Increasing nutrient availability resulted in both greater average plant height and higher abundance of plants with green photosynthetic organ colour, whereas the abundance of nanophanerophytes increases with aridity.

Conclusions: The species composition and trait structure of the studied Mediterranean xerophytic shrub communities varies along nutrient and aridity gradients. This supports the importance of environmental filters for the local assembly and dynamics of these inland dune communities.     

Impact of land use intensity and temperature on the reproductive performance of <Emphasis Type="Italic">Dactylis glomerata</Emphasis> populations in the southeastern Alps

An understanding of the processes and environmental conditions governing spatial variation in reproductive performance of plants can provide important information about the factors characterizing plant community structure and influencing fitness in natural plant populations, especially in the context of climate and land use change. In this study, 60 mountain populations of Dactylis glomerata distributed along a fertilization regime in varying grassland hay meadows were evaluated. Variations in field management, climate, soil fertility, vegetation structure, population density and species richness on reproductive performance were examined. The results indicated that field management and soil nutrient availability are the main variables influencing population density and reproductive output of D. glomerata. Moreover, the results show the effect of temperature on seed mass and resource investment in reproduction. Climate and soil change suggest a morphological differentiation of reproductive traits: (i) individuals grown on sites with higher soil nutrient availability or nutrient supply have larger inflorescences with a greater number and heavier seeds; (ii) individuals grown on warmer sites have heavier seeds. We conclude that if the climate warms and increases land use intensification in hay meadows in the Alps, this will have a pronounced positive impact on the reproductive performance of D. glomerata. Moreover, it can be hypothesized that the migration potential of D. glomerata towards higher altitudes may be likely in the near future in response to accelerated climate change.     

The identification of the seeds and fruits of common Scottish aquatic herbs

Background: There have been few quantitative observations of the attributes of native animal paths and no studies of their variation between vegetation types. These paths may be important in extending the local ranges of plant species.

Aims: To determine the incidence, cover and characteristics of native animal paths in different vegetation types, their relationships with other variables and the influence of paths on plant species distributions.

Methods: Randomly located line transects, and paired quadrats on and adjacent to paths, were used to record path and environmental attributes at 10 sites in each of 10 vegetation types. The relationships between path cover, number, width and depth and potential predictor variables were determined by using Pearsons product moment correlation.

Results: The mean cover of paths in plant communities varied between 6.5% and 12.6%. Path cover, number, width and depth varied between vegetation types. Penetration resistance, bare ground, scat density and plant species richness had higher values in path quadrats than in controls. Within particular vegetation types, several plant species were restricted to paths.

Conclusions: Animal trampling is an important influence on vegetation structure and the distribution of plant species in the study area.     

Habent Fata Sua: The Rise and Fall of Garden Plants

Background: Rare cactus in the Americas and other species worldwide are threatened species because of their high level of habitat specialisation, narrow distribution range and continuing population decline.

Aims: To identify management units (MUs) based on genetic variability and demographic structure in order to propose assertive conservation actions for Mammillaria crucigera and to provide a model case study for other species that are under similar threats.

Methods: We genotyped through eight microsatellite loci in 171 individuals and described demographic structures in six populations of this cactus based on plots of 1 m².

Results: Across populations with a mean density of 2.6 m^?2 and a total of ~500 individuals counted, 30% of the individuals were reproductive (diameter >2 cm). The total heterozygosity was low (H_O = 0.54), but the inbreeding coefficient (F_IS = 0.29) and the allele diversity (N_A = 20) were high. Four genetic groups were distinguished, although considering the demographic structure, we propose three MUs.

Conclusions: It is critical to maintain the genetic connectivity within and among MUs, which can only be achieved through cooperation between government authorities and local habitants to halt the degradation and further destruction of the remnant populations. Searching MUs allows the identification of critical areas for conservation issues for all species whose extant populations are in a fragmented landscape.     

Vegetation pattern of mountains in West Greenland – a baseline for long-term surveillance of global warming impacts

Background: Steep environmental gradients, coupled with predicted high temperature rises in the Arctic make arctic mountain vegetation highly suitable for surveillance of changes related to global warming. However, guidelines and baselines for such a purpose are widely lacking since arctic mountain vegetation has been little explored.

Aims: We explore options for long-term surveillance on the basis of a detailed analysis of extant plant community patterns and their underlying environmental conditions in the mountainous inland of West Greenland.

Methods: Distribution, abundance and site conditions of vegetation types were analysed, using 664 vegetation samples and detailed vegetation maps in four altitudinal belts.

Results: Most plant communities had a restricted elevation distribution and were confined to special habitats predominantly defined by mesotopography and soil moisture.

Conclusions: Based on the strong linkage to habitat conditions, horizontal and vertical changes of species distribution and vegetation pattern are excellent indicators for inferring underlying environmental changes on three different scales. The recommendations given concerning climate sensitive species and plant communities, ecotones for setting up observation sites as well as stratification of analysis by habitats can be the basis for establishing long-term surveillance programmes on arctic mountain vegetation.     

Correlates of distribution and nesting success in a Welsh upland Eurasian Curlew Numenius arquata population

Capsule: Habitat structure and composition explained spatial variation in breeding distribution and nesting success in a declining upland Eurasian Curlew Numenius arquata population in North Wales.

Aims: To identify environmental correlates of Curlew breeding distribution, nesting success and change in distribution.

Methods: Thirty random 1?km squares stratified by historical population trend were surveyed for Curlew density and nesting success, and habitat- and predation-related variables in a landscape containing agriculturally improved farmland, and moorland that was partly protected and subject to grazing reductions for nature conservation. Analyses tested for associations between Curlew measures and environmental variables.

Results: Curlew breeding density declined by 29% between 1994 and 2008, and was highest in squares comprising a mixture of moorland and agriculturally improved farmland, and in squares with lower vegetation density and higher cover of Nardus stricta (characteristic of rough grazing). Nesting success was positively associated with cover of Trichophorum germanicum (characteristic of mire). Vegetation density was lower than average in squares with the highest Curlew densities, while in the protected area vegetation density was higher than average.

Conclusion: Habitat and vegetation variables influenced Curlew distribution and nesting success in North Wales, largely in line with previous results but with no evidence for predator-related influences. Habitat condition for Curlew in the protected area could probably be increased through targeted increases in grazing alongside the protection of priority habitats.     

Spatiotemporal effects of Hurricane Ivan on an endemic epiphytic orchid: 10 years of follow-up

ABSTRACT

Background: Hurricanes have a strong influence on the ecological dynamics and structure of tropical forests. Orchid populations are especially vulnerable to these perturbations due to their canopy exposure and lack of underground storage organs and seed banks.

Aims: We evaluated the effects of Hurricane Ivan on the population of the endemic epiphytic orchid Encyclia bocourtii to propose a management strategy.

Methods: Using a pre- and post-hurricane dataset (2003–2013), we assessed the population asymptotic and transient dynamics. We also identified the individual size-stages that maximise population inertia and E. bocourtii’s spatial arrangement relative to phorophytes and other epiphytes.

Results: Hurricane Ivan severely affected the survival and growth of individuals of E. bocourtii, and caused an immediate decline of the population growth rate from λ = 1.05 to λ = 0.32, which was buffered by a population reactivity of ρ₁ = 1.42. Our stochastic model predicted an annual population decrease of 14%. We found an aggregated spatial pattern between E. bocourtii and its host trees, and a random pattern relative to other epiphytes.

Conclusion: Our findings suggest that E. bocourtii is not safe from local extinction. We propose the propagation and reintroduction of reproductive specimens, the relocation of surviving individuals, and the establishment of new plantations of phorophytes.     

Genetic variation relevant for the conservation of the narrow endemic Senecio carbonensis (Asteraceae) from the southern Andes

We studied morphological variation, reproductive biology and genetic structure of Senecio carbonensis, a narrow endemic from high elevations of the southern Andes, and compared it to Senecio peteroanus, a closely related widespread congeneric species. Using ANOVAs and discriminant analysis we showed that populations of S. carbonensis were more similar to each other in their morphology, had comparatively limited reproductive capacity and presented lower plant density and more reduced plant cover than populations of S. peteroanus. Similar high genetic variation was found at the population and species level in both species, based on isozyme variation at 14 and 11 putative gene loci that were resolved in S. carbonensis and S. peteroanus, respectively. The two species were genetically distinct. However, the small genetic distance between populations of each species suggests that either they were recently founded and that genetic drift did not have time to promote divergence, or that its effects are masked by significant current gene flow. These results show that ecological and reproductive characteristics of S. carbonensis may limit its extension and abundance. In contrast, high genetic variation at the population level is probably favored by self‐incompatibility. Despite the restricted geographical distribution and low plant density of S. carbonensis populations, genetic characteristics do not seem to be limiting their long‐term persistence. This information suggests that populations of S. carbonensis are not at risk of extinction as a result of genetic factors, although it is important to study and monitor population dynamics to further assess the degree of recruitment through time.     

Inter- and intraspecific variation in grass phytolith shape and size: a geometric morphometrics perspective

Background and AimsThe relative contributions of inter- and intraspecific variation to phytolith shape and size have only been investigated in a limited number of studies. However, a detailed understanding of phytolith variation patterns among populations or even within a single plant specimen is of key importance for the correct taxonomic identification of grass taxa in fossil samples and for the reconstruction of vegetation and environmental conditions in the past. In this study, we used geometric morphometric analysis for the quantification of different sources of phytolith shape and size variation.MethodsWe used landmark-based geometric morphometric methods for the analysis of phytolith shapes in two extant grass species (Brachypodium pinnatum and B. sylvaticum). For each species, 1200 phytoliths were analysed from 12 leaves originating from six plants growing in three populations. Phytolith shape and size data were subjected to multivariate Procrustes analysis of variance (ANOVA), multivariate regression, principal component analysis and linear discriminant analysis.Key ResultsInterspecific variation largely outweighed intraspecific variation with respect to phytolith shape. Individual phytolith shapes were classified with 83 % accuracy into their respective species. Conversely, variation in phytolith shapes within species but among populations, possibly related to environmental heterogeneity, was comparatively low.ConclusionsOur results imply that phytolith shape relatively closely corresponds to the taxonomic identity of closely related grass species. Moreover, our methodological approach, applied here in phytolith analysis for the first time, enabled the quantification and separation of variation that is not related to species discrimination. Our findings strengthen the role of grass phytoliths in the reconstruction of past vegetation dynamics.     

Genetic Diversity and Geographic Differentiation in the Threatened Species Dysosma pleiantha in China as Revealed by ISSR Analysis

Dysosma pleiantha, an important threatened medicinal plant species, is restricted in distribution to southeastern China. The species is capable of reproducing both sexually and asexually. In this study, inter-simple sequence repeat marker data were obtained and analyzed with respect to genetic variation and genetic structure. The extent of clonality, together with the clonal and sexual reproductive strategies, varied among sites, and the populations under harsh ecological conditions tended to have large clones with relatively low clonal diversity caused by vegetative reproduction. The ramets sharing the same genotype show a clumped distribution. Across all populations surveyed, average within-population diversity was remarkably low (e.g., 0.111 for Nei’s gene diversity), with populations from the nature reserves maintaining relatively high amounts of genetic diversity. Among all populations, high genetic differentiation (AMOVA: Φ_ST = 0.500; Nei’s genetic diversity: G _ST = 0.465, Bayesian analysis: Φ_B = 0.436) was detected, together with an isolation-by-distance pattern. Low seedling recruitment due to inbreeding, restricted gene flow, and genetic drift are proposed as determinant factors responsible for the low genetic diversity and high genetic differentiation observed.     

Living in a world of fire: the population dynamics of Mulinum spinosum in Northwestern Patagonia grasslands

Questions

How do fire frequency and fire size affect the long-term population dynamics of Mulinum spinosum? Which demographic parameters contribute most to the overall effect of fire on population growth? What is the relative importance of resprouting in sustaining population increase?

Location

Grass-shrub northwestern Patagonian steppe, Argentina.

Methods

We monitored five permanent plots excluded from grazing for 6 years. We measured shrub abundance, dimensions, reproductive status, seedling emergence, and the size structure of M. spinosum, a resprouting native shrub inhabiting the northwest Patagonian steppe. Data were used to parametrize a stochastic matrix model developed to explore the influence of fire frequency and fire size on long-term population dynamics. We analyzed hypothetical scenarios that included fire frequencies ranging from one per year up to exclusion.

Results

Except for annual fires, projections show growing populations regardless of fire frequency. For fire return intervals greater than 50 years, the population becomes independent of fires, with an annual population growth rate of 5.6%. The results suggest two relevant aspects of the population dynamics of this species: M. spinosum is well adapted to the current fire frequency and its resprouting capability will allow M. spinosum to survive and persist in the community, even under frequent fires.

Conclusions

Climate change models forecast an increase in summer temperature in NW Patagonia and, consequently, an enhanced fire frequency. Fire is a driver of M. spinosum encroachment that gets worse in overgrazed grasslands. Mulinum spinosum encroachment derivate in a relative replacement of palatable grasses by shrubs changes the ecosystem functionality and reduces productivity. Controlling this process is highly difficult and we suggest a change in the land use for the areas already deteriorated.

     

The forest–alpine ecotone: a multi-scale approach to spatial and temporal dynamics of treeline change at Niwot Ridge

Background: Current understanding of treeline or forest-alpine ecotone (FAE) dynamics does not fully explain past and present FAE patterns and their underlying processes, nor allow prediction of their response to climate change.

Aims: We address the overarching hypothesis that the FAE is a mosaic of distinct landscape units of vegetation and landforms that result in differential responses to climate change. We focus on climate-related, landscape and vegetation characteristics, but also consider the effect of landscape heterogeneity on biogeochemistry and overall resilience of the FAE to climate change.

Results: There are three distinct FAE land units at Niwot Ridge, generated by different interactions of climate with vegetation, landforms and topography. Within these FAEs, a process of self-organisation takes place from organism to patch to landscape scales, and is modulated by positive and negative feedback loops along an elevation gradient. The underlying controls cannot be attributed solely to temperature, but to a combination of interactions along a physical/biotic gradient.

Conclusions: FAE dynamics result from interactions among mechanisms and processes at the microsite, patch and landscape scales: (1) tree persistence; (2) forest patch establishment; (3) drivers of patch forest configurations and (4) resilience, increasing along a gradient of biotic control.     

Phenotypic plasticity of life history traits in relation to reproductive strategies in <Emphasis Type="Italic">Boa constrictor occidentalis</Emphasis>

The close connection between reproductive ecology and life history in snakes leads to trade-offs between reproductive and other life-history traits. Optimal energy allocation to growth and reproduction is a key factor to determine life history structure. Therefore, elucidating the relationship between body size variations and reproductive characters is essential for a better understanding of life-history plasticity. The aim of this work was to determine to what extent life-history differs among populations of Boa constrictor occidentalis and to identify possible life-history trade-offs between morphological and reproductive traits. We compared two populations from areas that are separated latitudinally, with different climatic conditions and vegetation landscape structure. Reproductive and morphological data of specimens were recorded. Although populations had a similar mean length of mature snakes, the frequency of some size classes tended to be different. Size at sexual maturity differed between populations for females, generating variations in the proportion of mature individuals. Reproductive threshold and follicular size also varied, but female reproductive frequency was similar between populations. Reproductive frequency of males varied between populations although their body condition was similar. We discussed two major issues: (1) implications of size at sexual maturity for body size and fecundity; (2) trade-offs in reproductive characters.     

The life history and population structure of Cycas armstrongii in monsoonal northern Australia

The cycad Cycas armstrongii is endemic to the north-western corner of the Northern Territory in Australia. Here we provide data on its life history and population structure from four populations across its range. Few plants reproduced before they were 1 m in height. There was considerable variation in the proportion of reproductive plants between sites and years, but the sex ratio in all populations was close to 1:1. The growth rate of plants was approximately 4.5 cm year⁻¹ which indicates that most plants are less than 100 years old and that the tallest individuals are likely to be little older than this. The annual fecundity of female plants ranged from 12 to 80 seeds; there was no evidence that fecundity varied with plant height. Dispersal was restricted generally to less than 1 m and the distribution of dispersal distances was fitted well by a gamma distribution. Recruitment occurred through both seedlings and vegetative sprouts and the proportion of juveniles (plants without trunks) in the populations varied between one-quarter and two-thirds. The data indicate that recruitment is episodic, but occurs more frequently under the current fire regime than amongst the canopy trees. It is shown that there is considerable variation in the dynamics of populations between sites and that the long term dynamics of a population cannot readily be inferred from an examination of the size structure at a single point in time. Received: 4 January 1997 / Accepted: 1 March 1997     

Forest floor photosynthesis and respiration in a drained peatland forest in southern Finland

Background: Although forest floor forms a large biomass pool in forested peatlands, little is known about its role in ecosystem carbon (C) dynamics.

Aim: We aimed to quantify forest floor photosynthesis (P _FF) and respiration (R _FF) as a part of overall C dynamics in a drained peatland forest in southern Finland.

Methods: We measured net forest floor CO₂ exchange with closed chambers and reconstructed seasonal CO₂ exchange in the prevailing plant communities.

Results: The vegetation was a mosaic of plant communities that differed in CO₂ exchange dynamics. The reconstructed growing season P _FF was highest in the Sphagnum community and lowest in the feather moss communities. On the contrary, R _FF was highest in the feather moss communities and lowest in the Sphagnum community. CO₂ assimilated by the forest floor was 20–30% of the total CO₂ assimilated by the forest. The forest floor was a net CO₂ source to the atmosphere, because respiration from ground vegetation, tree roots and decomposition of soil organic matter exceeded the photosynthesis of ground vegetation.

Conclusions: Tree stand dominates C fluxes in drained peatland forests. However, forest floor vegetation can have a noticeable role in the C cycle of peatlands drained for forestry. Similarly to natural mires, Sphagnum moss-dominated communities were the most efficient assimilators of C.     

Long-term change in the floristic composition and vegetation structure of Carnac Island, Western Australia

Aim To document changes in the floristic composition and vegetation structure of Carnac Island during a period of 40 years. This paper presents a synthesis of all available floristic and vegetational information. Location Carnac Island is 8 km offshore from Fremantle, south‐west Western Australia. Methods Comparison of lists of plant species for 1951, 1958/9, 1966/7, 1975/6 and 1995–6. Comparison of vegetation, based on structural and floristic elements, for 1951, 1965, 1972, 1984 and 1995. Results Floristic composition (both native and exotic species) changed most dramatically in the period 1975/6–1995/6, with a 37% reduction in number of plant species. The number of annual and perennial native species present in 1995/6 was most similar to that in 1951. The most remarkable change in the flora has been the increase in annual exotic species since 1951. Immigration and extinction rates were greatest in the periods 1951–58/9 and 1958/9–1966/7, respectively. Vegetation structure has also altered, involving a reduction in height of dominant species from 3–4 m to 1 m as Acacia rostellifera and Olearia axillaris have declined in distribution. The weed species Mesembryanthemum crystallinum (first recorded 1975) and Malva parviflora (1958) now dominate the vegetation of half the island. Main conclusions Five factors are considered to have contributed to botanical change: nesting seabird populations, eradication of the rabbit in 1969, drought, increased saltload from occasional cyclones in summer or autumn, and competition from increasing dominance of several weed species. Several of these factors have operated in opposing ways with respect to plant species richness and vegetation cover. Experimental studies are required to determine the strength of these interactions. Two weed species, Zantedeschia aethiopica (first recorded 1966) and Lycium ferocissimum (1992) have the potential to dominate the vegetation of the island.