Habitat Species Diversity Research Articles

Different components of plant diversity suggest the protection of a large area for the conservation of a riparian ecosystem

AbstractRiparian ecosystems host an high level of biodiversity but anthropic activities have deeply altered their naturalness and functionality. The present study was carried out in a protected area along a recently regulated tract of the upper River Tiber (Tuscany, central Italy). The study’s aim is to explore different components of plant diversity (species richness, species composition, β-diversity) in the riparian habitats to determine the most relevant conservation issues. Twelve transects were allocated along the riparian zone and a stratified random sampling was performed on the habitat detected along the transects with 184 plots of 1 x 1 m. Species richness was analysed by the use of set of species-richness estimators. The different patterns of plant diversity were analysed by NMDS, Indicator Species Analysis and SDR with symplex analysis. Five habitat types were detected in the study area. Three well-represented habitats (riparian woodlands, shrublands and dry bars) showed a higher number of species; flooded banks and marshlands were much less common and were also less species rich. Species composition and indicator species analysis showed however that marshlands were the richest in taxa having high conservation value and in indicator species. The habitats differed greatly in species composition; β-diversity analysis showed a low number of shared species between the habitats. High values of species replacement and low similarity values were recorded between the plots within the habitats. The study shows some differences between quantitative and qualitative patterns of biodiversity in the study area. The results suggest that to maintain habitat species diversity, the best conservation strategy for the study area is to protect as large an area as possible

Swiss Biodiversity Monitoring BDM (Z9 Mosses)

Switzerland is one of the first countries in the world to monitor its biological diversity. The Federal Office for the environment (FOEN) has launched a programme for this purpose called Biodiversity Monitoring in Switzerland (BDM). In conjunction with the BDM programme, experts contracted by the Federal Government will regularly count animals and plants in numerous predetermined areas in the field. Whereas numerical qualitative objectives are accepted in most areas of environmental protection (emissions thresholds in air pollution control, for example), there are so far no targets for how biodiversity should change. Biodiversity monitoring helps us to define specific targets for nature conservation policy and to establish whether the measures that have been implemented are enabling us to reach these targets. Mosses are surveyed for the state indicator Z9 (species diversity in habitats). This report describes the available content in the vegetation-plot database of the Swiss Biodiversity Monitoring BDM (Z9 Mosses) (GIVD ID EU-CH-010).

Swiss Biodiversity Monitoring BDM (Z9 Plants)

Switzerland is one of the first countries in the world to monitor its biological diversity. The Federal Office for the environment (FOEN) has launched a programme for this purpose called Biodiversity Monitoring in Switzerland (BDM). In conjunction with the BDM programme, experts contracted by the Federal Government will regularly count animals and plants in numerous predetermined areas in the field. Whereas numerical qualitative objectives are accepted in most areas of environmental protection (emissions thresholds in air pollution control, for example), there are so far no targets for how biodiversity should change. Biodiversity monitoring helps us to define specific targets for nature conservation policy and to establish whether the measures that have been implemented are enabling us to reach these targets. Plants are surveyed for the state indicators Z7 (species diversity in landscapes) and Z9 (species diversity in habitats). This report describes the available content in the vegetation-plot database of the Swiss Biodiversity Monitoring BDM (Z9 Plants) (GIVD ID EU-CH-002).

Geographic range expansion of Oxyops vitiosa (Coleoptera: Curculionidae) to the Bahamian Archipelago

Geographic range expansion of Oxyops vitiosa (Coleoptera: Curculionidae) to the Bahamian Archipelago

The nature of savanna heterogeneity in the Orinoco Basin

Detrended Canonical Correspondence Analysis (DCCA) was used to describe the relationship between savanna environments and vegetation community composition in the Orinoco Basin. TWINSPAN derived three major types of savanna vegetation, each with its own floristic and physiognomic features. The first group reflected a plant association with species of Trachypogon occurring in moderately infertile soils with low water availability and high bulk density. This group is distributed mostly on hilltops and dissected plains of the northern Orinoco savannas. The second group has the highest species diversity in habitats occurring in the northern Orinoco with extremely infertile soils. The third group, on the other hand, has a considerable number of species belonging to the Leguminosae and Cyperaceae families and linked to the habitats of the eastern Colombian savannas with the highest soil water availability, a shorter dry season and higher precipitation. The regional analysis of the Orinoco savannas suggests edaphic controls to be important. Changes in the underlying geology have affected topography and soil formation, which results in variation in water and nutrient status. The moisture regime and hydrological features are acting as the major regional determinants, while nutrient levels and distinctive surface soil properties provide the subregional determinants. The local boundary, at any given site, is strongly determined by nutrient shortage and acidity. Also, biogeographic and floristic considerations were taken into account to explain differences in species composition.

Species Diversity and Community Organization in Desert Seed‐Eating Ants

Patterns of species diversity and community organization in desert seed—eating ants were studied in 10 habitats on a longitudinal gradient of increasing rainfall extending from southeastern California, through southern Arizona, and into southwestern New Mexico. Local communities of harvester ants include 2—7 common species, and at least 15 species from five genera of Myrmecines compose the total species pool in these deserts. Ant species diversity is highly correlated with mean annual precipitation, an index of productivity in arid regions. Communities are structured on the basis of competition for food, and interspecific differences in worker body sizes and colony foraging strategies represent important mechanisms of resource allocation. Seed size preferences, measured for native seeds in food choice experiments with seeds of different size but uniform nutritional quality, are highly correlated with worker body sizes. Species of similar body size can coexist within local habitats if they differ in foraging strategy. Interspecific aggression and territorial defense and microhabitat partitioning all appear to be relatively unimportant in these and communities. Patterns of species diversity and community organization in harvest ants are strikingly similar to those reported for communities of seed—eating rodents that occupy many of the same desert habitats. Separate regressions of within—habitat species diversity against the precipitation index of productivity for the two groups correspond closely in slope, intercept, and proportion of explained variation. Resource allocation on the basis of seed size characterizes local communities of both ants and rodents. Parallels between these two groups suggest that limits to specialization and overlap may be specified by parameters such as resource abundance and predictability that effect unrelated taxa similarly.