Competence of <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Frankliniella intonsa</Emphasis> strains as vectors for <Emphasis Type="Italic">Chrysanthemum stem necrosis virus</Emphasis>

The vector competence of Frankliniella occidentalis for Chrysanthemum stem necrosis virus (CSNV) was evaluated. Three vector strains with distinct competences for Tomato spotted wilt virus (TSWV) transmission were investigated, including an artificially selected strain (TsH) that has a particularly high competence (>90 %). Newly hatched larvae of F. occidentalis were given an acquisition access period of 5 days on CSNV-infected D. stramonium leaves, and reared to maturity. Their transmission efficiencies were examined using a leaf disk assay using Petunia x hybrida leaves. Following the leaf disk assay, the virus accumulation in the vectors was examined via a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of their bodies. The results showed that the CSNV acquisition and transmission efficiency of the TsH strain did not differ from those of the others, indicating that the competence of F. occidentalis as a vector for CSNV is not related to that for TSWV. The CSNV transmission and acquisition efficiencies of two F. intonsa strains (Hiroshima and Fukuoka) were also evaluated. In Hiroshima strain, 35 % of adults were viruliferous, but only two transmitters (3 %) were observed. In Fukuoka strain, 6 % were viruliferous, and no transmitters were observed. These results indicate that F. intonsa cannot be a major vector for CSNV. The accumulation of CSNV in the adults of F. occidentalis and F. intonsa evaluated using DAS-ELISA showed a significant difference in ELISA values among transmitter, viruliferous non-transmitter, and non-viruliferous individuals. These results clearly demonstrated that only transmitters that accumulated a threshold quantity of virus can transmit CSNV to plants.     

First report of celery stunt anthracnose caused by <Emphasis Type="Italic">Colletotrichum simmondsii</Emphasis> in Japan

A new disease was found in Japan, on celery (Apium graveolens var. dulce) having severe chlorotic leaf spot, stunt, and dwarf with leaf curl. A spore suspension from the fungus isolated from affected plants induced identical symptoms 14 days after plants were sprayed. Identification and molecular characterization showed that the causal agent is Colletotrichum simmondsii. This report is the first of stunt anthracnose on celery caused by C. simmondsii. We propose the name “stunt anthracnose” for the new disease. Colletotrichum acutatum sensu lato, as reference pathogen of celery anthracnose, should be changed to C. fioriniae based on morphological and molecular characteristics.     

Spatial assessment of aesthetic services in a complex mountain region: combining visual landscape properties with crowdsourced geographic information

Context

Human and natural systems interact at multiple scales which are context specific in relation to ecosystem service supply. Scenic beauty is recognised as a cultural ecosystem service whose aesthetic value is perceived at a holistic landscape level.

Objectives

In this study we provide methodological advancements for assessing the relationship between landscape visual character and scenic beauty based on crowdsourced geographic information. The final aim is to demonstrate, through a case study application, an empirical method for mapping the scenic beauty of complex mountain landscapes from the perspective of observers which are realistically exposed to the environment being evaluated.

Methods

We propose a viewshed based approach which relies on visual indicators and the location of visitors retrieved by public image storage analysis. A cluster analysis was used to integrate visual characters of the landscape and visiting users’ preferences.

Results

Four different typologies of landscapes were finally characterized by distinct values of visual indicators. The spatial distribution of the landscape typologies presented a clustered pattern, allowing a regionalization of the landscape characters. The analysis of the visiting users’ provenance revealed that visual scale, naturalness and ephemera attract mainly foreign users, while imageability, complexity and historicity attract mostly domestic and local users.

Conclusions

The combination of crowdsourced images with visual indicators allows a systematic analysis of landscape scenic beauty properties. In all, by understanding how specific landscape characters contributes to aesthetic service provision we provide a tool for facilitating the visualization and interpretation of complex landscape characters.

     

The concept of habitat specificity revisited

Habitat specificity indices reflect richness (α) and/or distinctiveness (β) components of diversity. The latter may be defined by α and γ (landscape) diversity in two alternative ways: multiplicatively () and additively (). We demonstrate that the original habitat specificity concept of Wagner and Edwards (Landscape Ecol 16:121–131, 2001) consists of three independent components: core habitat specificity (uniqueness of the species composition), patch area and patch species richness. We describe habitat specificity as a family of indices that may include either area or richness components, or none or both, and open for use of different types of mean in calculation of core habitat specificity. Core habitat specificity is a beta diversity measure: the effective number of completely distinct communities in the landscape. Habitat specificity weighted by species number is a gamma diversity measure: the effective number of species that a patch contributes to landscape richness. We compared 12 habitat specificity indices by theoretical reasoning and by use of field data (vascular plant species in SE Norwegian agricultural landscapes). Habitat specificity indices are strongly influenced by weights for patch area and patch species richness, and the relative contribution of rare vs. common species (type of mean). The relevance of properties emphasized by each habitat specificity index for evaluation of patches in a biodiversity context is discussed. Core habitat specificity is emphasized as an ecologically interpretable measure that specifically addresses patch uniqueness while habitat specificity weighted by species number combines species richness and species composition in ways relevant for conservation biological assessment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Bird response to disturbance varies with forest productivity in the northwestern United States

Huston’s Dynamic Equilibrium Hypothesis predicts that the response of biodiversity to disturbance varies with productivity. Because disturbance is thought to break competitive advantage of dominant species in productive ecosystems, species richness is predicted to increase with disturbance frequency in productive systems. Recovery of plant biomass following disturbance is also predicted to be faster in productive systems. Here we provide the first test of Huston’s hypothesis in the context of setting harvest rates in managed forests for achieving biodiversity objectives. We examined predictions relating to vegetation and bird response to disturbance and succession in productive and less productive forests in western Oregon and Washington, USA. We found that measurements of understory cover and shrub diversity were higher in young, productive stands than less productive stands of similar age. Later-seral forests in productive environments (mean age = 67 years) had less variable and more complete canopy closure than similar-age forests in less favorable settings. At the stand scale, bird abundance and richness decreased with canopy closure in highly productive forests whereas bird abundance and richness increased with canopy closure in less productive forests. At the landscape scale, bird abundance and richness within stands increased with increasing levels of disturbance in the surrounding landscape within highly productive forests, whereas bird abundance and richness decreased with increasing disturbance in the surrounding landscape within less productive forests. Our results indicate that bird response to disturbance varies across levels of productivity and suggest that bird species abundance and associated species richness will be maximized through relatively more frequent disturbance in highly productive systems.     

Historical influences dominate the composition of regenerating plant communities in abandoned citrus groves in north-central Florida

The question of what determines plant community composition is fundamental to the study of plant community ecology. We examined the relative roles of historical land use, landscape context, and the biophysical environment as determinants of plant community composition in regenerating citrus groves in north-central Florida. Results were interpreted in light of plant functional traits. Herbaceous and woody plants responded differently to broad-scale variables; herbs correlated most strongly with surrounding land cover at a scale of 8 km, while the only significant determinant of woody species distributions was local land use history. There were significant correlations between herbaceous species and spatial context, habitat isolation, environmental variables, and historical variables. Partial Mantel tests indicated that each variable provided a unique contribution in explaining some of the variation in the herbaceous dataset. The correlation between woody plants and local historical variables remained significant even with other effects corrected for. In the herbaceous community, species composition was linked to functional traits much as expected from classical theory. While spatial influences in our study system are important for both woody and herbaceous plants, the primary determinant of plant community composition in regenerating citrus groves is historical land use. Our results suggest that the fine-scale mechanisms of local competition, tolerance and facilitation invoked by many classical studies may ultimately be less important than land use history in understanding current plant community composition in regenerating agricultural areas.     

Multi-scale predictive habitat suitability modeling based on hierarchically delineated patches: an example for yellow-billed cuckoos nesting in riparian forests,California, USA

The discipline of landscape ecology recognizes the importance of measuring habitat suitability variables at spatial scales relevant to specific organisms. This paper uses a novel multi-scale hierarchical patch delineation method, PatchMorph, to measure landscape patch characteristics at two distinct spatial scales and statistically relate them to the presence of state-listed endangered yellow-billed cuckoos (Coccyzus americanus occidentalis) nesting in forest patches along the Sacramento River, California, USA. The landscape patch characteristics calculated were: patch thickness, area of cottonwood forest, area of riparian scrub, area of other mixed riparian forest, and total patch area. A third, regional spatial variable, delineating the north and south portions of study area was also analyzed for the effect of regional processes. Using field surveys, the landscape characteristics were related to patch occupancy by yellow-billed cuckoos. The area of cottonwood forest measured at the finest spatial scale of patches was found to be the most important factor determining yellow-billed cuckoo presence in the forest patches, while no patch characteristics at the larger scale of habitat patches were important. The regional spatial variable was important in two of the three analysis techniques. Model validation using an independent data set of surveys (conducted 1987–1990) found 76–82% model accuracy for all the statistical techniques used. Our results show that the spatial scale at which habitat characteristics are measured influences the suitability of forest patches. This multi-scale patch and model selection approach to habitat suitability analysis can readily be generalized for use with other organisms and systems.     

Intermediate landscape disturbance maximizes metapopulation density

The viability of metapopulations in fragmented landscapes has become a central theme in conservation biology. Landscape fragmentation is increasingly recognized as a dynamical process: in many situations, the quality of local habitats must be expected to undergo continual changes. Here we assess the implications of such recurrent local disturbances for the equilibrium density of metapopulations. Using a spatially explicit lattice model in which the considered metapopulation as well as the underlying landscape pattern change dynamically, we show that equilibrium metapopulation density is maximized at intermediate frequencies of local landscape disturbance. On both sides around this maximum, the metapopulation may go extinct. We show how the position and shape of the intermediate viability maximum is responding to changes in the landscape’s overall habitat quality and the population’s propensity for local extinction. We interpret our findings in terms of a dual effect of intensified landscape disturbances, which on the one hand exterminate local populations and on the other hand enhance a metapopulation’s capacity for spreading between habitat clusters.     

基于核蛋白激酶基因内含子5序列研究雀形目18种鸟类分子系统发育关系(英文)

The 18 species of bird studied originally are known to belong to muscicapids, robins and sylviids of passerines, but some dis- putations are always present in their classification systems. In this experiment, phylogenetic relationships of 18 species of passerines were studied using Adenylate Kinase lntron 5 （AKS） sequences and DNA techniques. Through sequences analysis in comparison with each other, phylogenetic tree figures of 18 species of passerines were constructed using Neighbor-Joining （N J） and Maximum-Parsimony （MP） meth- ods . The results showed that sylviids should be listed as an independent family, while robins and flycatchers should be listed into Musci- capidae. Since the phylogenetic relationships between long-tailed tits and old world warblers are closer than that between long-tailed tits and parids, the long-tailed tits should be independent of paridae and be categorized into aegithalidae. Muscicapidae and Paridae are known to be two monophylitic families, but Sylviidae is not a monophyletic group. AK5 sequences had better efficacy in resolving close relationships of interspecies among intrageneric groups.     

Ecological and economical significance of homestead forest to the household of the offshore island in Bangladesh

An explanatory survey was conducted to assess the contribution of plant diversity to the ecological and socio-economic condition of the rural household in the offshore island of Bangladesh.Assessment was done by means of multistage random sampling.The homestead sizes of the study area were classified into 3 groups viz,large (>0.25 ha),medium (0.05-0.25 ha) and small (<0.05 ha) based on the result obtained from a preliminary survey,and a total of 45 homesteads,15 from each group,were selected randomly for the study.The average annual income from homestead's plant diversity varied from Tk 5730.00 (US$95.5) to Tk 17500.00 (US$291.67).The rural people were mainly dependent on their homegarden for woodfuel and nutritional requirement as forest was unavailable in the island.The rural people here also cultivated the plant species as a safety measure from frequent cyclone.Constraints hindering the development of homestead plantation were identified and suggestions were given such as the adequate supply of seedlings of fast growing native species and conservation of endangered species to meet the demand of the household as well as to keep ecological balance.