Testing the higher-taxon approach: a case study of aquatic marcophytes in China’s northwest arid zone and its implications for conservation

Assessments of biodiversity are time-consuming and require a high level of expert knowledge. A reduced set of taxonomic ranks other than species has been proved to be useful for rapid and cost-effective assessment of biodiversity. However, few studies have examined how well this method performs for aquatic plant group that of enormous ecological importance. We studied the aquatic plant flora in the arid zone of China and examined whether the distribution of species α- and β-diversity could be predicted well from genus-, and family-levels. Analyses of 3 years field data showed that significant and positive relations exist between α-diversity of species and α-diversity of genera and family in both entire arid zone and five sub-zones. In contrast, β-diversity at species level is difficult to predict from β-diversity indexes at higher taxonomic level. The results indicate that higher-taxon α-diversity, especially at the generic level in our research, can be useful surrogates of species α-diversity for aquatic plants conservation.     

Short Rotation Coppice (SRC) Plantations Provide Additional Habitats for Vascular Plant Species in Agricultural Mosaic Landscapes

Increasing loss of biodiversity in agricultural landscapes is often debated in the bioenergy context, especially with respect to non-traditional crops that can be grown for energy production in the future. As promising renewable energy source and additional landscape element, the potential role of short rotation coppice (SRC) plantations to biodiversity is of great interest. We studied plant species richness in eight landscapes (225 km²) containing willow and poplar SRC plantations (1,600 m²) in Sweden and Germany, and the related SRC α-diversity to species richness in the landscapes (γ-diversity). Using matrix variables, spatial analyses of SRC plantations and landscapes were performed to explain the contribution of SRC α-diversity to γ-diversity. In accordance with the mosaic concept, multiple regression analyses revealed number of habitat types as a significant predictor for species richness: the higher the habitat type number, the higher the γ-diversity and the lower the proportion of SRC plantation α-diversity to γ-diversity. SRC plantation α-diversity was 6.9 % (±1.7 % SD) of species richness on the landscape scale. The contribution of SRC plantations increased with decreasing γ-diversity. SRC plantations were dominated more by species adapted to frequent disturbances and anthropo-zoogenic impacts than surrounding landscapes. We conclude that by providing habitats for plants with different requirements, SRC α-diversity has a significant share on γ-diversity in rural areas and can promote diversity in landscapes with low habitat heterogeneity and low species pools. However, plant diversity enrichment is mainly due to additional species typically present in disturbed and anthropogenic environments.     

Structure and diversity of shallow soft-bottom benthic macrofauna in the Gulf of Lions (NW Mediterranean)

Samples of soft-sediment macrobenthos from 92 sites between 10 and 50 m depth were used to assess (1) the main soft-bottom macrofauna communities in the Gulf of Lions, (2) the different components of the diversity of benthic macrofauna in this area, and (3) the relevance of the use of major taxonomic groups as surrogates for the analysis of the structure and diversity of total macrofauna. Three main communities were identified by cluster analysis and associated procedures. These communities corresponded well to the assemblages recently identified on the basis of polychaete composition. The α-diversity indices were in accordance with those reported for similar communities in the Mediterranean. Conversely, the β-diversity value was higher than the few other data available in the literature for marine soft-bottom macrofauna. The total number of species in the studied area estimated by the “total species accumulation curve” (TS) method was 2,319, which was only 10% higher than the number obtained by extrapolation of the species–area curve. The similarity matrix based on polychaetes correlated best with the one based on total macrofauna. Polychaetes and crustaceans were also the best surrogates of total macrofauna when assessing α-diversity (except in the case of Δ*). Conversely, molluscs were the best surrogates of total macrofauna β-diversity. Our results show that the choice of an optimal surrogate for total benthic macrofauna depends on the characteristic of the benthic macrofauna to be studied. Moreover, this choice is also dependent on the environment to be studied.     

Breeding bird assemblages of eastern Mediterranean shrublands: composition, organisation and patterns of diversity

The patterns of α-diversity and the structure and organisation of breeding bird assemblages were studied in four vegetation stages (characteristic of Mediterranean shrublands) on an eastern Mediterranean island (Crete, Greece): low phrygana, tall phrygana, low maquis and tall maquis. Phrygana differed significantly from maquis, in regard to the community metrics, composition and the homogeneity of bird assemblages. Moreover, detrended correspondence analysis ordered the census plots along a continuum of increasing vegetation height. On the other hand, within-maquis differences were few, while no significant differences were found within phrygana stages. Based upon the observed patterns, we recognise three vegetation groups: (1) phrygana, with low α-diversity and abundance and homogenous bird assemblages; (2) low maquis with relatively high α-diversity and heterogenous bird assemblages; and (3) tall maquis with relatively high α-diversity and heterogenous assemblages in which “woodland” bird species contribution is prominent.     

Diversity of Crenarchaeota in terrestrial hot springs in Tengchong, China

Diversity of Crenarchaeota was investigated in eight terrestrial hot springs (pH 2.8–7.7; temperature 44–96°C) located in Tengchong, China, using 16S rRNA gene phylogenetic analysis. A total of 826 crenarchaeotal clones were sequenced and a total of 47 operational taxonomic units (OTUs) were identified. Most (93%) of the identified OTUs were closely related (89–99%) to those retrieved from hot springs and other thermal environments. Our data showed that temperature may predominate over pH in affecting crenarchaeotal diversity in Tengchong hot springs. Crenarchaeotal diversity in moderate-temperature (59–77°C) hot springs was the highest, indicating that the moderately hot-temperature springs may provide optimal conditions for speciation of Crenarchaeota.     

Indicators of species richness at the local scale in an alpine region: a comparative approach between plant and invertebrate taxa

Studies investigating congruent variations in species richness patterns in alpine habitats are scarce. We investigated the potential of using the indicator taxa approach for species richness in alpine habitats of the Scandes (Norway). In four areas, we investigated seven functional and taxonomic terrestrial groups of organisms and evaluated their contribution to the species diversity. The function of each group as a surrogate for the overall species diversity or for the diversity of another taxon was analysed. Three groups of invertebrates (spiders without Lycosids, Lycosids only, and ground beetles), three groups of plants (shrubs, graminoids, and herbs), and lichens were used for a cross-taxon analysis of species diversity. Congruence in species richness was restricted to several significant results, with vascular plants and spiders (Araneae) being best suited as surrogate taxa in alpine habitats of the Scandes. In the cross-taxon analyses they showed strongest significant positive correlations, covering the total species richness of the alpine habitats best. Species counts in one group account for up to 70% of the variation in total species richness. We found only limited evidence for an ideal, efficient biodiversity indicator taxon that could be applied without restrictions at different alpine habitats in low and middle alpine areas. Thus, our results suggest that it is very important to use more than one taxon as indicator for species richness in terrestrial alpine habitats. This should facilitate future conservation planning in alpine areas.     

Contrasting Taxonomic and Phylogenetic Diversity Responses to Forest Modifications: Comparisons of Taxa and Successive Plant Life Stages in South African Scarp Forest

The degradation of natural forests to modified forests threatens subtropical and tropical biodiversity worldwide. Yet, species responses to forest modification vary considerably. Furthermore, effects of forest modification can differ, whether with respect to diversity components (taxonomic or phylogenetic) or to local (α-diversity) and regional (β-diversity) spatial scales. This real-world complexity has so far hampered our understanding of subtropical and tropical biodiversity patterns in human-modified forest landscapes. In a subtropical South African forest landscape, we studied the responses of three successive plant life stages (adult trees, saplings, seedlings) and of birds to five different types of forest modification distinguished by the degree of within-forest disturbance and forest loss. Responses of the two taxa differed markedly. Thus, the taxonomic α-diversity of birds was negatively correlated with the diversity of all plant life stages and, contrary to plant diversity, increased with forest disturbance. Conversely, forest disturbance reduced the phylogenetic α-diversity of all plant life stages but not that of birds. Forest loss neither affected taxonomic nor phylogenetic diversity of any taxon. On the regional scale, taxonomic but not phylogenetic β-diversity of both taxa was well predicted by variation in forest disturbance and forest loss. In contrast to adult trees, the phylogenetic diversity of saplings and seedlings showed signs of contemporary environmental filtering. In conclusion, forest modification in this subtropical landscape strongly shaped both local and regional biodiversity but with contrasting outcomes. Phylogenetic diversity of plants may be more threatened than that of mobile species such as birds. The reduced phylogenetic diversity of saplings and seedlings suggests losses in biodiversity that are not visible in adult trees, potentially indicating time-lags and contemporary shifts in forest regeneration. The different responses of taxonomic and phylogenetic diversity to forest modifications imply that biodiversity conservation in this subtropical landscape requires the preservation of natural and modified forests.     

Cross-scale analysis of the region effect on vascular plant species diversity in southern and northern European mountain ranges

Background

The divergent glacial histories of southern and northern Europe affect present-day species diversity at coarse-grained scales in these two regions, but do these effects also penetrate to the more fine-grained scales of local communities?

Methodology/Principal Findings

We carried out a cross-scale analysis to address this question for vascular plants in two mountain regions, the Alps in southern Europe and the Scandes in northern Europe, using environmentally paired vegetation plots in the two regions (n = 403 in each region) to quantify four diversity components: (i) total number of species occurring in a region (total γ-diversity), (ii) number of species that could occur in a target plot after environmental filtering (habitat-specific γ-diversity), (iii) pair-wise species compositional turnover between plots (plot-to-plot β-diversity) and (iv) number of species present per plot (plot α-diversity). We found strong region effects on total γ-diversity, habitat-specific γ-diversity and plot-to-plot β-diversity, with a greater diversity in the Alps even towards distances smaller than 50 m between plots. In contrast, there was a slightly greater plot α-diversity in the Scandes, but with a tendency towards contrasting region effects on high and low soil-acidity plots.

Conclusions/Significance

We conclude that there are strong regional differences between coarse-grained (landscape- to regional-scale) diversity components of the flora in the Alps and the Scandes mountain ranges, but that these differences do not necessarily penetrate to the finest-grained (plot-scale) diversity component, at least not on acidic soils. Our findings are consistent with the contrasting regional Quaternary histories, but we also consider alternative explanatory models. Notably, ecological sorting and habitat connectivity may play a role in the unexpected limited or reversed region effect on plot α-diversity, and may also affect the larger-scale diversity components. For instance, plot connectivity and/or selection for high dispersal ability may increase plot α-diversity and compensate for low total γ-diversity.     

Plant communities and landscape diversity along a Canadian Arctic river

Abstract. We analysed the structure and diversity of the vegetation along an Arctic river to determine the relationship between species richness and plant community structure. We examined whether variation in species richness along the corridor is structured as (1) an increase in the number of communities due to increasing landscape heterogeneity, (2) an increase in the floristic distinctiveness (β-diversity) of communities, or (3) an increase in within-community richness (α-diversity) as species-poor communities are replaced by species-rich communities. We described 24 community types and analysed the relationship between site vascular species richness (γ-diversity) and β-diversity, α-diversity, site environmental heterogeneity, and the number of distinct plant communities. We also measured diversity patterns of vascular, bryophyte, and lichen species within communities and examined their relationship to community-level estimates of environmental factors. We found that an increase in site species richness correlated with an increase in the number of communities (r²= 0.323, P= 0.0173) and β-diversity (r²= 0.388, P= 0.0075), rather than an increase in the α-diversity of individual communities. Moisture and pH controlled most of the differences in composition between communities. Measures of species richness and correlations with moisture and pH within communities differed among vascular, bryophyte, and lichen species. Bryophyte richness was positively correlated with moisture (r²= 0.862, P= 0.0010) and lichen richness was negatively correlated with moisture (r²= 0.809, P= 0.0031). Vascular plants had a peak in richness at pH 6.5 (r²= 0.214, P < 0.0001). We conclude that site variation in vascular richness in this region is controlled by landscape heterogeneity, and structured as variation in the number and distinctiveness of recognizable plant communities.     

Historical divergence vs. contemporary gene flow: evolutionary history of the calcicole Ranunculus alpestris group (Ranunculaceae) in the European Alps and the Carpathians

Although many species have similar total distributional ranges, they might be restricted to very different habitats and might have different phylogeographical histories. In the European Alps, our excellent knowledge of the evolutionary history of silicate‐dwelling (silicicole) plants is contrasted by a virtual lack of data from limestone‐dwelling (calcicole) plants. These two categories exhibit fundamentally different distribution patterns within the Alps and are expected to differ strongly with respect to their glacial history. The calcicole Ranunculus alpestris group comprises three diploid species of alpine habitats. Ranunculus alpestris s. str. is distributed over the southern European mountain system, while R. bilobus and R. traunfellneri are southern Alpine narrow endemics. To explore their phylogenetic relationships and phylogeographical history, we investigated the correlation between information given by nuclear and chloroplast DNA data. Analyses of amplified fragment length polymorphism fingerprints and matK sequences gave incongruent results, indicative for reticulate evolution. Our data highlight historical episodes of range fragmentation and expansion, occasional long‐distance dispersal and on‐going gene flow as important processes shaping the genetic structure of the group. Genetic divergence, expressed as a rarity index (‘frequency‐down‐weighted marker values’) seems a better indicator of historical processes than patterns of genetic diversity, which rather mirror contemporary processes as connectivity of populations and population sizes. Three phylogeographical subgroups have been found within the R. alpestris group, neither following taxonomy nor geography. Genetic heterogeneity in the Southern Alps contrasts with Northern Alpine uniformity. The Carpathians have been stepwise‐colonised from the Eastern Alpine lineage, resulting in a marked diversity loss in the Southern Carpathians. The main divergence within the group, separating the ancestor of the two endemic species from R. alpestris s. str., predates the Quaternary. Therefore, range shifts produced by palaeoclimatic oscillations seem to have acted on the genetic structure of R. alpestris group on a more regional level, e.g. triggering an allopatric separation of R. traunfellneri from R. bilobus.     

Macroinvertebrate Diversity in Alpine Lakes: Effects of Altitude and Catchment Properties

Lakes are common features of alpine landscapes, and the attention given to alpine lakes has increased recently in response to increased recognition of the important role that these freshwaters play as sensible indicators of climate change. Despite this general research interest, there is nevertheless a general lack of information about zoobenthos especially of lakes in the Alps, and only few published data are available, which has made it nearly impossible to draw general conclusions in respect to benthic community structure, profundal and/or littoral food webs. This paper aims to explore the relationships between main environmental/catchment properties of 55 lakes and their littoral benthic fauna across three regions of the Alps. We provide updated information on relative abundance, species richness, distribution and ecology of macroinvertebrates which occur and are typical in the littoral of high-mountain lakes of the Alps. These lakes were located in the Lago-Maggiore Watershed (Italy and Switzerland), in South Tyrol (Italy) and in North/East Tyrol (Austria), between 1840 and 2796 m a.s.l., in catchments undisturbed by human activities. As the studied lakes are situated above the tree line, they were characterised by low nutrient levels indicating an oligotrophic status. Lake water chemistry corresponded closely to the geo-lithology of the catchment and some parameters (especially nutrient concentrations) differed between the regions. The macroinvertebrates were dominated by insects which to a high degree were chironomid larvae and pupae. Other insect orders were typical cold stenotherm species of Ephemeroptera, Plecoptera and Trichoptera. Non-insect macroinvertebrates contributed to the 144 taxa found. Other than lake size and catchment area, the faunal parameters exhibited a clearer pattern along altitude. Macroinvertebrates per sample increased with higher elevation, reached their maximum in lakes between 2400 and 2600 m a.s.l., but decreased strongly above 2600 m. The altitudinal pattern of species richness and Shannon diversity resembled each other being highest between 2001 and 2200 m a.s.l., but decreased when going lower and higher, respectively. Various patterns and trends along altitude were also evident when individual groups were analysed within the individual sampling regions. The somewhat conflicting trends of various biocoenotic indices let assume that factors other than altitude are also responsible for the structure of faunal assemblages in the littoral of alpine lakes. Six variables (“bare rocks” and “nitrate”, “alkalinity”, “ammonia” and “peat bog”) were selected by the CCA analysis where these three groups of lakes were identified: (1) lakes with a higher alkalinity (higher pH, conductivity, ion concentration), a higher relative vegetation cover (compared to the “bare rocks” on the opposite side) and lower nitrate levels; (2) lakes with a higher portion of “bare rocks” in their catchments and higher nitrate levels; and (3) a smaller group of lakes with higher ammonia levels and a boggy environment. Geographical patterns seemed to have weak effects on the presence of taxa while catchment properties had evident impacts on macroinvertebrate communities in these lakes. In this way, the present study contributes to the overall understanding of environmental settings and effects on high mountain lake ecosystems and assists in refining research and conservation strategies for an important landscape aspect in the Alps.     

Patterns and drivers of phytodiversity in steppe grasslands of Central Podolia (Ukraine)

We asked: (i) Which environmental factors determine the level of α-diversity at several scales and β-diversity in steppic grasslands? (ii) How do the effects of environmental factors on α- and β-diversity vary between the different taxonomic groups (vascular plants, bryophytes, lichens)? We sampled nested-plot series ranging from 0.0001 to 100 m² and additional 10-m² plots, covering different vegetation types and management regimes in steppes and semi-natural dry grasslands of Central Podolia (Ukraine). We recorded all terricolous taxa and used topographic, soil, land-use and climatic variables as predictors. Richness-environment relationships at different scales and across taxonomic groups were assessed with multimodel inference. We also fitted power-law species-area relationships, using the exponent (z value) as a measure of β-diversity. In general, the richness values in the study region were intermediate compared to those known from similar grasslands throughout the Palaearctic, but for 1 cm² we found seven species of vascular plants, a new world record. Heat index was the most important factor for vascular plants and bryophytes (negative relation), while lichen diversity depended mainly on stone and rock cover (positive). The explanatory power of climate-related variables increased with increasing grain size, while anthropogenic burning was the most important factor for richness patterns at the finest grain sizes (positive effect). The z values showed more variation at the finest grain sizes, but no significant differences in their mean between scales. The results highlight the importance of integrating scale into ecological analyses and nature conservation assessments in order to understand and manage biological diversity in steppe ecosystems.     

Stygobiotic crustacean species richness: a question of numbers,a matter of scale

Species richness in ground water is still largely underestimated, and this situation stems from two different impediments: the Linnaean (i.e. the taxonomic) and the Wallacean (i.e. the biogeographical) shortfalls. Within this fragmented frame of knowledge of subterranean biodiversity, this review was aimed at (i) assessing species richness in ground water at different spatial scales, and its contribution to overall freshwater species richness at the continental scale; (ii) analysing the contribution of historical and ecological determinants in shaping spatial patterns of stygobiotic species richness across multiple spatial scales; (iii) analysing the role of β-diversity in shaping patterns of species richness at each scale analysed. From data of the present study, a nested hierarchy of environmental factors appeared to determine stygobiotic species richness. At the broad European scale, historical factors were the major determinants in explaining species richness patterns in ground water. In particular, Quaternary glaciations have strongly affected stygobiotic species richness, leading to a marked latitudinal gradient across Europe, whereas little effects were observed in surface fresh water. Most surface-dwelling fauna is of recent origin, and colonized this realm by means of post-glacial dispersal. Historical factors seemed to have also operated at the smaller stygoregional and regional scales, where different karstic and porous aquifers showed different values of species richness. Species richness at the small, local scale was more difficult to be explained, because the analyses revealed that point-diversity in ground water was rather low, and at increasing values of regional species richness, reached a plateau. This observation supports the coarse-grained role of truncated food webs and oligotrophy, potentially reflected in competition for food resources among co-occurring species, in shaping groundwater species diversity at the local scale. Alpha-diversity resulted decoupled from γ-diversity, suggesting that β-diversity accounted for the highest values of total species richness at the spatial scales analysed.     

Spatial and Temporal Patterns in Macrofaunal Diversity Components Relative to Sea Floor Landscape Structure

We examined temporal changes in macrofaunal α- and β-diversity over several spatial scales (within patches, among patches, across landscapes and across regions) in Long Island Sound on the northeast USA coast. Regional ε-diversity was estimated at 144 taxa, however γ-diversity fluctuated over time as did α- and β-diversity components. Based on additive partitioning, patch- and region-scale β-diversity components generally had the highest contributions to γ-diversity; lower percentages were found at within-patch and landscape scales. Multiplicative diversity partitioning indicated highest species turnover at within- and among patch scales. For all partition results, within-patch and patch-scale β-diversity increased sharply when hypoxia impacted benthic communities. Spatial variation in diversity components can be attributed to the collection of different patch types at varying spatial scales and their associated habitats across the benthic landscapes, as well as gradients in depth and other estuarine-scale characteristics. Temporal variation in diversity components across spatial scales may be related to seasonal changes in habitat heterogeneity, species population dynamics, and seasonal disturbances. Rare species were significant and temporally consistent components of macrofaunal diversity patterns over different spatial scales. Our findings agree with other marine and terrestrial studies that show diversity components vary significantly over different spatial scales and the importance of habitat/landscape heterogeneity in supporting diversity. However, our results indicate that the relative contributions of scale-specific β-diversity components can also change significantly over time. Thus, studies of diversity patterns across patches and landscapes based on data collected at one time, or assembled into a single data set from different times, may not capture the full suite of diversity patterns that occur over varying spatial scales and any time-specific determinants of those patterns. Many factors that shape and maintain sedimentary communities vary temporally, and appear to play an important role in determining and maintaining macrofaunal diversity over different spatial scales.     

Cross-taxon congruence of α and β diversity among five leaf litter arthropod groups in Colombia

In this study α and β diversity patterns of five leaf litter arthropod groups (ants, predatory ants, oribatid mites, spiders and other arachnids) were described and compared in 39 sampling patches of a transformed landscape in southwestern Colombia, that represented five vegetation types: secondary forest, riparian forest, giant bamboo forest, pasture and sugarcane crop. It was also assessed whether some taxa could be used as diversity surrogates. A total of 6,765 individuals grouped in 290 morphospecies were collected. Species richness in all groups was lower in highly transformed vegetation types (pasture, sugarcane crop) than in native ones (forests). In contrast, there were no clear tendencies of β diversity among vegetation types. Considering sampling patches, 0.1–42% of the variation in α diversity of one taxonomic group could be explained from the α diversity of another, and 0.2–33% of the variation of β diversity of a given taxon was explained by that in other groups. Contrary to recent findings, we concluded that patterns of α diversity are more congruent than patterns of β diversity. This fact could be attributed to a sampling effect that promotes congruence in α diversity and to a lack of a clear regional ecological gradient that could promote congruent patterns of β diversity. We did not find evidence for an ideal diversity surrogate although diversity patterns of predatory ants had the greatest congruencies. These results support earlier multi-taxon evaluations in that conservation planning should not be based on only one leaf litter arthropod group.     

Does the Existence of Bird's Nest Ferns Enhance the Diversity of Oribatid (Acari: Oribatida) Communities in a Subtropical Forest?

We examined the effects of the presence of bird's nest ferns on the species diversity of oribatid mites in the whole forest in terms of the three categories of species diversity (α-, β-, and γ-diversity) in a subtropical forest in south-western Japan. The species diversity (1 − D) of oribatid communities in the ferns was significantly lower than those in bark of trees and the forest-floor litter and soil, and was similar to that in the branches. The oribatid faunas in the litter in and the roots of the fern were more similar to those in both the forest-floor litter and soil than to the faunas in the other arboreal habitats. However, the ferns can be colonized by endemic oribatid species specialized to such environments. The number of oribatid species estimated for a hypothetical stand with no ferns was about 180 species from 80 samples; this value did not differ significantly from that in another hypothetical stand with ferns (ca. 190 species). Thus, the species richness of oribatid communities estimated for the whole forest (the γ-diversity) was not affected by the presence or absence of bird's nest ferns. The α- and β-diversities of oribatid communities on bird's nest ferns were lower than those in other habitats, and they might not dramatically raise the overall γ-diversity of invertebrate communities in the whole forest. The bird's nest ferns, however, can generate a unique habitat for specialized species, and this would help to maintain species diversities of invertebrates at the whole-forest scale in subtropical forests.     

Distribution and ecology of rotifer communities in high-altitude alpine sites — a multivariate approach

The distribution and ecology of benthic, periphytic and planktonic rotifers were investigated in a wide range of alpine waterbodies in Austria. A total of 162 substrate classified samples was taken at 60 sampling sites situated between 1824 m and 2753 m a.s.l. in the Central Alps (predominantly gneiss) and between 1290 m and 1643 m a.s.l. in the Northeastern Calcareous Alps. Multivariate analysis allowed the recognition of distinct sampling site groups. Different groups of taxa were identified on the basis of their total frequencies of occurrence and frequency of co-occurrence. Several species were shown to have distributions restricted to particular groups of habitats. Habitat complexity, as indicated by taxon diversity and density of submersed vegetation, pH, conductivity, and temperature seem to be the principal components affecting community composition and distribution of single species in alpine waterbodies. Highest diversities were measured in limestone solution lakes and acid bog ponds on primary bedrock.     

Scale dependence of plant species richness in a network of protected areas

Despite the widely recognised importance of reserve networks, their effectiveness in encompassing and maintaining biodiversity is still debated. Species diversity is one of the most affordable measures of biodiversity, but it is difficult to survey such data over large scales. This research aimed to perform a sample-based assessment of species richness of groups of plants with different conservation value (alien species, protected species, and all species) within a reserve network, testing the use of partitioning as a tool for assessing diversity at different spatial scales, from the plot to the entire network. Plant diversity patterns differed for the groups of species for most of the investigated spatial scales. Despite these patterns assumed divergent tendencies when different species groups were considered, most of the species richness within the network was given by larger scale β-diversity for both alien and protected species, as well for all species. Diversity partitioning proved an effective tool to quantify the role of spatial scales in structuring the total species richness of the network, and is helpful in planning reserve networks.     

The impact of overgrazing on dung beetle diversity in the Italian Maritime Alps

Dung beetles (Coleoptera: Scarabaeidae) are undoubtedly the most typical and ecologically relevant insects of grazed alpine habitats because they provide valuable ecological services such as biological pest control and soil fertilization. Despite the great ecological contribution of these insects to pasture ecosystem functioning, little is known about their direct or indirect relationships with pastoral activities. The main aim of the study was to assess whether dung beetle diversity was influenced by different intensities of cattle grazing. Dung beetle communities of two adjacent alpine valleys within the Maritime Alps Natural Park (north-western Italian Alps), representing overgrazed and ungrazed pastures, were studied by pitfall trapping. A hierarchical design (three levels: valleys, transects, and replicates) was established for additive partitioning of γ-diversity and Indicator Species Analysis. Evenness and Shannon diversity were significantly higher at the ungrazed than at the overgrazed site because abundances were much more evenly distributed at the former than at the latter site (where one species was dominant over all the others). Dung beetle abundance and species richness of the overgrazed graminaceous pasture vegetation types were in most cases significantly lower than those of the ungrazed nongraminaceous vegetation type. In the additive partitioning of γ -diversity analysis relative to the whole study area, the randomization procedure indicated that the contribution of β to γ-diversity was significantly different from that expected by chance, suggesting that one or more environmental factors has intervened to change the partition of total diversity in the system considered. The analysis of the preferences and fidelity of species (Indicator Species Analysis) showed that only one species chose overgrazed pastures; all the others positively selected the ungrazed site, or the only ungrazed pasture vegetation type (Rumicetum alpini Beger) occurring at the overgrazed site. Results conformed to evidences that overgrazing represents a serious threat to the conservation of alpine dung beetles. To conserve local dung beetle assemblages, especially in protected areas, cattle overgrazing should be avoided. This does not mean, however, that pastoral activities are incompatible with biodiversity conservation. The contemporaneous presence of wild ungulates and low intensity extensive pastoral activities may be useful to preserve both local dung beetle assemblages and alpine pasture ecosystems.