1,720,965 research outputs found
Use of microarthropods to evaluate the impact of fire on soil biological quality
No full textEdaphic (i.e. soil dwelling) microarthropods play crucial roles in soil ecosystem services. Fire is a widespread form of disturbance with severe effects on soil invertebrates. Research on the effects of fire on soil arthropods, however, has been mostly focused on surface-active species. Information on the effects of fire on strictly edaphic invertebrates is limited. Thanks to their variable degree of specialization to the edaphic life, soil microarthropods can be used to evaluate soil quality and how it is affected by disturbance. We used an index of soil biological quality based on microarthropods (QBS-ar) to assess the effects of wildfire in three habitats (a natural beechwood, a grassland and a conifer reforestation) in a burnt upland plain in Central Italy, one year after the fire event. Fire affected significantly soil biology quality. In all habitats, burnt soils had a biological quality about 1.4 lower than the respective unburnt soils. Sampling period did not affect QBS-ar values. QBS-ar values varied among habitat types, being highest in the beechwood, lowest in the pinewood, and intermediate in the grassland. These findings indicate that the QBS-ar approach can be profitably used to evaluate the impact of fire on soil biology quality and stress the poor performance of planted conifers in terms of soil quality
Influence of urbanization on the avian species-area relationship: insights from the breeding birds of Rome
Full text linkThe species-area relationship (SAR) is one of the most investigated patterns in ecology and conservation biology, yet there is no study testing how different levels of urbanization influence its shape. Here we tested the impact of urbanization on avian SARs along a rural-urban gradient using the breeding birds of Rome (Central Italy). We divided the city into 360 cells of 1 km2. Each cell was classified as rural, suburban or urban using the proportion of impervious surface calculated from remote sensing data. For each of these three landscape categories, we constructed a SAR as a species accumulation curve (Gleason function) using bird species distribution data. SAR intercepts (i.e. the number of species per unit area) decreased from rural to urban areas, which indicates that urbanization depressed the number of species, reflecting the loss of specialized species strictly associated with natural habitats. The slope was highest for the rural curve, indicating that natural landscapes have the highest turnover due to their higher habitat heterogeneity. A higher slope for the urban cells, compared to the suburban ones, can be explained by the presence of green spaces embedded in the built-up matrix which host different avian communities. Previous studies that compared whole cities with natural areas failed to find differences in the respective SARs. Our study, which constructed SARs for different levels of urbanization, indicated significant changes in the SARs along the rural-urban gradient. Further analyses in other cities and taxa will be useful to test how general are our findings
On the occurrence of porpita porpita in the tyrrhenian sea: COI and ITS2 DNA barcoding identification (cnidaria, hydrozoa)
No full textWildfire does not affect the dung beetle diversity of high-altitude Mediterranean habitats
No full textWildfires represent an important factor in the disturbance in Mediterranean ecosystems, although the effects of wildfires on the insect communities of mountain environments remain largely unknown. This research investigated the effect of fire on dung beetles in a Mediterranean high-altitude area, located in Central Italy (1500 m elevation). Sampling in each of the three main vegetation types of the study area (conifer plantation, beechwood forest and grassland) used pitfall traps during Spring to Autumn. For each habitat, three burnt and three unburnt sites were sampled. We considered the following community structure parameters: abundance, richness, Shannon diversity and Simpson diversity. Effects of fire, habitat and sampling period were investigated using generalised mixed-effects models. Abundance, species richness and diversity were higher in the grassland than in the two forest habitats and June was the month with the lowest values because of the late emergence of insects at high altitudes. Fire negatively affected dung beetle abundance, but not diversity. Forest habitats were less favourable to dung beetle recolonisation than the secondary grassland. Thus, dung beetles are sensitive to vegetation type, but not to fire, possibly because of their high recolonisation capabilities and preference for open habitats
Variations in plant richness, biogeographical composition, and life forms along an elevational gradient in a mediterranean mountain
Full text linkDespite the increasing interest in elevational patterns in biodiversity, few studies have investigated variations in life forms and biogeographical composition, especially in the Mediterranean biome. We investigated elevational patterns in species richness, biogeographical composition (chorotypes) and life forms (Raunkiaer classification) along an elevational gradient in a Mediterranean mountain (Central Italy). We found a general hump‐shaped pattern of species richness, which can be explained by harsher conditions at the lowest and highest elevations. This pattern is distinctly related to prevalence at mid elevations of species with European and Euro‐Asiatic distribution, which are favored by a temperate climate. Phanerophytes and geophytes (which are mainly associated with woods) were concentrated at mid elevations where woodlands prevail. Hemicrypto-phytes increased with elevation, consistently with their ability to cope with high altitude climatic conditions. Mediterranean species declined with elevation because they are negatively affected by decreasing temperatures. Chamaephytes showed a U‐shaped pattern, suggesting they are able to cope with arid and cold conditions at the extremes of the gradient. Endemics increased with elevation because of their association with mountainous areas as key places for endemism evolution. These results illustrate how elevational patterns in species richness, biogeographical composition and life forms are interrelated and demonstrate reciprocal insights for understanding current vegetation settings
Taxonomic variation in levels of endemism: a case study of Italian tenebrionid beetles
No full text1. Levels of endemism are usually expressed as percentage of endemics among all species recorded in a given area. Endemism levels also vary among taxa, yet inter-taxon variation in endemism levels has received much less attention. 2. We used the Italian tenebrionids to investigate how endemism levels vary among different but related lineages. We evaluated endemism variations among taxonomic levels both as a percentage of endemics to the number of species included in a given taxon (i.e., the tendency of a taxon to produce endemics) and as a percentage to the total number of species (i.e., the importance of that taxon to the overall endemic component). We also considered the residuals of regression lines of endemics against non-endemics. We tested the influence of phylogenetic position, lifestyle and body size on the percentage of endemics within genera. 3. Use of percentages and residuals gave similar outcomes. Pimeliinae were the subfamily with the highest level of endemism. Erodiini, Pimeliini, Tentyriini, Asidini, Opatrini and Pedinini were among the tribes with the highest endemism levels. Asida, Pimelia, Tentyria and Opatrum were the genera with the highest levels of endemism. 4. Phylogenetic position and body size affected significantly endemism levels, with genera including larger species being also those with higher endemism, whereas lifestyle was not significant. This suggests that endemism in the Italian tenebrionid beetles is phylogenetically constrained and that lines including larger species (which are possibly less subject to passive dispersal) tend to be richer in endemics, independently from their lifestyle
Diversity patterns of dung beetles along a mediterranean elevational gradient
Full text linkMost studies of biodiversity–elevational patterns do not take species abundance into con-sideration. Hill numbers are a unified family of indices that use species abundance and allow a complete characterization of species assemblages through diversity profiles. Studies on dung beetle responses to elevation were essentially based on species richness and produced inconsistent results because of the non-distinction between different habitats and the use of gradients dispersed over wide areas. We analyzed dung beetle diversity in a Mediterranean mountain (central Italy) for different habitats (woodlands vs. grasslands) and taxonomic groups (scarabaeids and aphodiids). Scar-abaeids were the most abundant. Since scarabaeids are able to construct subterranean nests, this indicates that the warm and dry summer climatic conditions of high elevations favor species capable of protecting their larvae from desiccation. Dung beetles were more abundant and diversified in grasslands than in woodlands, which is consistent with their preference for open habitats. In the woodlands, diversity increased with increasing elevation because of increasing tree thinning, whereas, in the grasslands, diversity decreased with elevation because of increasingly harsher environmental conditions. These results indicate a trade-off in the beetle response to elevation between the positive effects of increasing the availability of more suitable habitats and the decrease of optimal environmental conditions
Comparison of soil biology quality in organically and conventionally managed agro-ecosystems using microarthropods
Full text linkSince management practices profoundly influence soil characteristics, the adoption of sustainable agro-ecological practices is essential for soil health conservation. We compared soil health in organic and conventional fields in the Abruzzi region (central Italy) by using (1) the soil biology quality (QBS) index (which expresses the level of specialisation in soil environment shown by microarthropods) and (2) microarthropod diversity expressed by Hill numbers. QBS values were calculated using both the original formulation based on only presence/absence data and a new abundance-based version. We found that organic management improves soil biology quality, which encourages the use of organic farming to maintain soil health. Including arthropod abundance in QBS calculation does not change the main outcomes, which supports the use of its original, speedier formulation. We also found that agricultural fields included in protected areas had greater soil health, which shows the importance of the matrix in determining agricultural soil health and highlights the importance of land protection in preserving biodiversity even in managed soils. Finally, we found that soil biology quality and microarthropod community structure are distinctly influenced by certain physical and chemical characteristics of the soil, which supports the use of microarthropods as biological indicators
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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