Is vascular plant species diversity a predictor of bryophyte species diversity in Mediterranean forests?

This study aimed to (i) investigate the congruence among the species composition and diversity of bryophytes and vascular plants in forests; (ii) test if site prioritization for conservation aims by the maximization of the pooled number of vascular plant species is effective to maximize the pooled number of bryophyte species. The study was performed in six forests in Tuscany, Italy. Four-hundred and twenty vascular plant species (61 of which were woody) and 128 bryophyte species were recorded in 109 plots. Despite the good predictive value of the compositional patterns of both woody plants and total vascular with respect to the compositional pattern of bryophytes, the species richness of the latter was only marginally related to the species richness of the former two. Bryophyte rare species were not spatially related to rare plant species and neither coincided with the sites of highest plant species richness. The species accumulation curves of bryophytes behaved differently with respect to those of woody plants or total vascular plants. Reserve selection analysis based on the maximization of the pooled species richness of either woody plants or total vascular plants were not effective in maximizing the pooled species richness of bryophytes. This study indicates that species diversity of vascular plants is not likely to be a good indicator of the bryophyte species diversity in Mediterranean forests.     

Are local patterns of anthropoid primate diversity related to patterns of diversity at a larger scale?

Aims (1) To determine the relationship between local and regional anthropoid primate species richness. (2) To establish the spatial and temporal scale at which the ultimate processes influencing patterns of primate species coexistence operate. Location Continental landmasses of Africa, South America and Asia (India to China, and all islands as far south as New Guinea). Methods The local–regional species richness relationship for anthropoid primates is estimated by regressing local richness against regional richness (independent variable). Local richness is estimated in small, replicate local assemblages sampled in regions that vary in total species richness. A strong linear relationship is taken as evidence that local assemblages are unsaturated and local richness results from proportional sampling of the regional pool. An asymptotic curvilinear relationship is interpreted to reflect saturated communities, where strong biotic interactions limit local richness and local processes structure the species assemblage. As a further test of the assumption of local assemblage saturation, we looked for density compensation in high‐density local primate assemblages. Results The local–regional species richness relationship was linear for Africa and South America, and the slope of the relationship did not differ between the two continents. For Asia, curvilinearity best described the relationship between local and regional richness. Asian primate assemblages appear to be saturated and this is confirmed by density compensation among Asian primates. However, density compensation was also observed among African primates. The apparent assemblage saturation in Asia is not a species–area phenomenon related to the small size of the isolated islands and their forest blocks, since similar low local species richness occurs in large forests on mainland and/or peninsular Asia. Main conclusions In Africa and South America local primate assemblage composition appears to reflect the influence of biogeographic processes operating on regional spatial scales and historical time scales. In Asia the composition of primate assemblages are by‐and‐large subject to ecological constraint operating over a relatively small spatial and temporal scale. The possible local influence of the El Niño Southern Oscillations on the evolution and selection of life‐history characteristics among Asian primates, and in determining local patterns of primate species coexistence, warrants closer inspection.     

Modeling of mosaic patterns in chimeric liver and adrenal cortex: algorithmic organogenesis?

If organogenesis were a completely deterministic process, then the amount of information required to store the spatial position and fate of every cell in vertebrate organisms would be larger than the total information that could be contained in their genomes. This suggests that the instructions of developmental mechanisms involved in organogenesis, coded in DNA, must be at least in part procedural or algorithmically based. Chimeric mosaic patterns in rat livers have been shown to be isotropic and to have fractal profiles (D approximately 1.3) whereas adrenal gland mosaics show a less irregular radial pattern, with lower fractal dimension (D approximately 1.2) than in the liver. These findings suggested a possible model of parenchyma generation. We propose that during organogenesis in both liver and adrenal cortex, the same basic mechanism is directed to organ mass enlargement, whereas the differences observed in mosaic patterns between the organs could be due to the control of a single parameter, namely, a form of contact inhibition. Computer simulations in two dimensions returned comparable results in both the fractal dimension value of mosaic patches and appearance of the mosaic 'tissues', as observed histologically in chimeras. This suggests that position information and locomotion of cells would not be required to produce the mosaic pattern observed in chimeras.     

Plant composition and diversity at edges in a semi-natural forest–grassland mosaic

Plant Ecology - As key components of landscapes, edges have received considerable scientific attention in anthropogenic ecosystems. However, edges in natural and semi-natural forest–grassland...     

Summer and autumn activity patterns in the Vicuña

Airborne input of minerals essential for plant growth is significantly more important for the Amazonian rain forest than elsewhere. Annual rates have been calculated to an average of 26.9 kg/ha/yr for phosphate phosphorus and 12.6 kg/ha/yr for potassium. Other nutrients show a similar amount. If these values are representative for Amazonia as a whole, the total amount of nutrient influx via the air (dry input and precipitation) attains a magnitude, which may be well above the level for assuming a local South American source of origin. Phosphate and potassium alone give an average of 15 to 25 million tons per year. It is concluded, therefore, that dust from the Sahara carried by the trade winds provides the bulk of this mineral input, thus influencing the stability and productivity of the Amazonian rain forest. If this conclusion holds true, the pleistocene forest dynamics in Amazonia should have been influenced not only by changes in the amount of rain fall, but also by the transatlantic transport of nutrients.     

Which components of plant diversity are most correlated with ecosystem properties? A case study in a restored wetland in northern China

The relationship between plant diversity and ecosystem services is a controversial topic in ecology that may be due, at least in part, to the variety of methods used to define and quantify diversity. This study examined the relationship between plant diversity and 11 ecosystem properties of a restored wetland in northern China by considering four primary components of diversity (dominance, richness, evenness, and divergence). Each diversity component was expressed by eight taxonomic and functional diversity indices respectively. Results showed that trait-based functional diversity had a stronger correlation with ecosystem processes than non-trait taxonomic diversity did. Among the four components of diversity, dominance (in terms of mean trait value index) was the best in explaining the variation in ecosystem processing. Richness and divergence also had significant correlations with ecosystem properties in some instances. By contrast, evenness had no significant correlation with most of the studied ecosystem properties. Our results indicated that wetland ecosystem properties are significantly related to certain traits of the dominant species. Thus, the dominant species and functional traits should be considered before the number of species in managing diversity and enhancing certain ecosystem functions of wetlands, especially in the case of conservation.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Contrasted levels of genetic diversity in a benthic Mediterranean octocoral: Consequences of different demographic histories?

Understanding the factors explaining the observed patterns of genetic diversity is an important question in evolutionary biology. We provide the first data on the genetic structure of a Mediterranean octocoral, the yellow gorgonian Eunicella cavolini, along with insights into the demographic history of this species. We sampled populations in four areas of the Mediterranean Sea: continental France, Algeria, Turkey, and the Balearic and Corsica islands. Along French coasts, three sites were sampled at two depths (20 and 40 m). We demonstrated a high genetic structure in this species (overall F_ST = 0.13), and most pairwise differentiation tests were significant. We did not detect any difference between depths at the same site. Clustering analyses revealed four differentiated groups corresponding to the main geographical areas. The levels of allelic richness and heterozygosity were significantly different between regions, with highest diversity in Algeria and lowest levels in Turkey. The highest levels of private allelic richness were observed in Algeria followed by Turkey. Such contrasted patterns of genetic diversity were not observed in other Mediterranean octocorals and could be the result of different evolutionary histories. We also provide new empirical evidence of contrasting results between tests and model‐based studies of demographic history. Our results have important consequences for the management of this species.     

Migratory behaviour of the Schreiber's bat: when, where and why do cave bats migrate in a Mediterranean region?

Regional migrations are important elements of the biology of bats, but remain poorly understood. We obtained a large dataset of recoveries of ringed Miniopterus schreibersii to study the patterns and drivers of migration of a Mediterranean cave-dwelling bat. In spite of the mildness of Mediterranean winters, in average years bats hibernated, and few movements were recorded during this period. After hibernation, females migrated to spring roosts, and again to maternity roosts just before parturition. This late arrival at nurseries could be a strategy to avoid a harmful build-up of parasites. Soon after the juveniles were weaned, the mothers migrated to the roosts where they spent autumn and sometimes also winter. Juveniles remained in the warm nurseries longer, presumably because high roost temperatures speed up growth. The pattern of migration of males was similar to that of females, but they left hibernacula later and remained more mobile during the maternity season. They also arrived at the hibernacula later, possibly because they needed time to build up fat stores after the energetically costly mating season. Maternity colonies spent the yearly cycle in well-defined home ranges (mean=19 030 km²), which overlapped greatly. Bats were furthest from the maternity sites during hibernation, but even then 80% remained within 90 km of them. Each hibernaculum attracted bats from multiple nurseries, from within a mean range of 10 770 km². We tested two potential drivers for migration – temperature in the roosts and at the foraging areas – but our results supported only the first one. Bats migrated to reach the roosts most thermally suited for each phase of their life cycle, indicating that roost temperature and associated metabolic advantages are key drivers for regional migrations of cave-dwelling bats.     

Spatial and temporal distribution patterns of nitrogen in marsh soils from an inland alkaline wetland – A case study of Fulaowenpao wetland, China

Samples of surface (0–10 cm) and subsurface soils (10–20 cm) were collected using a grid sampling method in July and September in order to study the spatial and temporal distribution patterns of all forms of nitrogen and total nitrogen (TN) and the relationships between nitrogen concentrations and selected soil properties in Fulaowenpao wetland, a typical inland alkaline wetland. Results showed that there existed obvious heterogeneity at spatial and temporal scales. Generally, higher spatial variability for nitrate nitrogen (NO₃^-–N), ammonium nitrogen (NH₄⁺–N) and available nitrogen (AN) were observed compared to organic nitrogen (Org-N) and TN. At the spatial scale, concentrations of NO₃^-–N, NH₄⁺–N and AN in surface soils were higher than those in subsurface soils, but no significant differences were observed between both soil layers (p < 0.05). However, concentrations of Org-N and TN were significantly higher in surface soils compared to subsurface soils (p < 0.05), and both of them had similar spatial distribution patterns. At the temporal scale, with the exception of NH₄⁺–N in both soil layers and NO₃^-–N in subsurface soils, concentrations of all the other forms of nitrogen and TN were generally higher in September than them in July, while there were no significant differences between both sampling periods (p < 0.05) except for AN (p < 0.01) in both soil layers. Correlation analysis showed that AN, Org-N and TN were significantly and positively correlated with soil organic matter, total phosphorous, and clay contents, while they were significantly negatively correlated with soil pH values; NO₃^-–N was also correlated with soil organic matter and total phosphorous, however, NH₄⁺–N was only closely lined to water contents.     

The mosaic diversity of field layer vegetation in the natural and exploited forests of Białowieża

The main focus of the study was to find out whether and how the forestry management in the Biaowiea Forest has influenced the mosaic diversity of field layer vegetation and habitat heterogeneity in the temperate hard wood forest (Tilio-Carpinetum). Five belt-transects represent natural and semi-natural old-growths in Biaowiea National Park (BNP), the commercial forest (CF), and secondary stands in the CF. Along the transects, distinct patches of field layer vegetation were identified and delimited, and their species composition was assessed. Along central lines of the transects the environmental data was collected from sample points established at regular intervals: soil pH and the distances to the 4 closest trees, their species, and dbh (diameter at the breast height=135 cm). The group of patches (on average 50 per transect) was subjected to the dichotomous classification in order to identify a number of characteristic types of microphytocoenoses – synusiae. Beta-diversity of the vegetation was expressed with the Simpson diversity index calculated on the basis of areas occupied by synusiae. The most structurally diversified were the transects representing natural old-growths in the BNP. A calculation of similarity coefficients between the transects on the basis of their mosaic composition displayed sharper differences between old-growth and secondary communities in summer than those found in spring. Forestry management has seriously modified the tree species composition in two studied stands, through planting oak or initiating succession. This resulted, both in plantation and pioneer stand, in loss of the main components of natural old-growths: hornbeam (Carpinus betulus), Norway spruce (Picea abies), lime (Tilia cordata) and maple (Acer platanoides). Significantly a wider range of soil pH values in natural old-growths coincided with a higher diversity of herbaceous mosaics comparing to secondary stands. The elimination of spruce (the species being most commonly blown down, projecting an acid canopy shadow) in two studied areas, elimination of dead wood, and destruction of humus layers through ploughing, could contribute to a reduction of specific microenvironments. A lower mosaic diversity of secondary stands coinciding with the unification of environmental conditions along the transects may indicate that forestry management can lead to the disappearance of a highly structural character in natural forest communities.Nomenclature: Flora europaea; Sokoowski (1993).     

Does interspecific competition drive patterns of habitat use in desert bat communities?

Bodies of water are a key foraging habitat for insectivorous bats. Since water is a scarce and limiting resource in arid environments, bodies of open water may have a structuring effect on desert bat communities, resulting in temporal or spatial partitioning of bat activity. Using acoustic monitoring, we studied the spatial and temporal activity patterns of insectivorous bats over desert ponds, and hypothesised that sympatric bat species partition the foraging space above ponds based on interspecific competitive interactions. We used indirect measures of competition (niche overlap and competition coefficients from the regression method) and tested for differences in pond habitat selection and peak activity time over ponds. We examined the effect of changes in the activity of bat species on their potential competitors. We found that interspecific competition affects bat community structure and activity patterns. Competing species partitioned their use of ponds spatially, whereby each species was associated with different pond size and hydroperiod (the number of months a pond holds water) categories, as well as temporally, whereby their activity peaked at different hours of the night. The drying out of temporary ponds increased temporal partitioning over permanent ponds. Differences in the activity of species over ponds in response to the presence or absence of their competitors lend further support to the role of interspecific competition in structuring desert bat communities. We suggest that habitat use and night activity pattern of insectivorous bats in arid environments reflect the trade-offs between selection of preferred pond type or activity time and constraints posed by competitive interactions.     

Plant–plant interactions and local patterns of diversity from semi-arid to subalpine Mediterranean plant communities

An understanding of the diversity spatial organization in plant communities provides essential information for management and conservation planning. In this study we investigated, using a multi-species approach, how plant–plant interactions determine the local structure and composition of diversity in a set of Mediterranean plant communities, ranging from semi-arid to subalpine habitats. Specifically, we evaluated the spatial pattern of diversity (i.e., diversity aggregation or segregation) in the local neighborhood of perennial plant species using the ISAR (individual species–area relationship) method. We also assessed the local pattern of beta-diversity (i.e., the spatial heterogeneity in species composition among local assemblages), including the contribution of species turnover (i.e., species replacement) and nestedness (i.e., differences in species richness) to the overall local beta-diversity. Our results showed that local diversity segregation decreased in the less productive plant communities. Also, we found that graminoids largely acted as diversity segregators, while forbs showed more diverse neighborhoods than expected in less productive study sites. Interestingly, not all shrub and dwarf shrub species aggregated diversity in their surroundings. Finally, an increase in nestedness was associated with less segregated diversity patterns in the local neighborhood of shrub species, underlining their role in creating diversity islands in less productive environmental conditions. Our results provide further insights into the effect of plant–plant interactions in shaping the structure and composition of diversity in Mediterranean plant communities, and highlight the species and groups of species that management and conservation strategies should focus on in order to prevent a loss of biodiversity.

     

Spatial and temporal distribution patterns of nitrogen in marsh soils from an inland alkaline wetland – A case study of Fulaowenpao wetland, China

Samples of surface (0–10 cm) and subsurface soils (10–20 cm) were collected using a grid sampling method in July and September in order to study the spatial and temporal distribution patterns of all forms of nitrogen and total nitrogen (TN) and the relationships between nitrogen concentrations and selected soil properties in Fulaowenpao wetland, a typical inland alkaline wetland. Results showed that there existed obvious heterogeneity at spatial and temporal scales. Generally, higher spatial variability for nitrate nitrogen (NO₃^-–N), ammonium nitrogen (NH₄⁺–N) and available nitrogen (AN) were observed compared to organic nitrogen (Org-N) and TN. At the spatial scale, concentrations of NO₃^-–N, NH₄⁺–N and AN in surface soils were higher than those in subsurface soils, but no significant differences were observed between both soil layers (p < 0.05). However, concentrations of Org-N and TN were significantly higher in surface soils compared to subsurface soils (p < 0.05), and both of them had similar spatial distribution patterns. At the temporal scale, with the exception of NH₄⁺–N in both soil layers and NO₃^-–N in subsurface soils, concentrations of all the other forms of nitrogen and TN were generally higher in September than them in July, while there were no significant differences between both sampling periods (p < 0.05) except for AN (p < 0.01) in both soil layers. Correlation analysis showed that AN, Org-N and TN were significantly and positively correlated with soil organic matter, total phosphorous, and clay contents, while they were significantly negatively correlated with soil pH values; NO₃^-–N was also correlated with soil organic matter and total phosphorous, however, NH₄⁺–N was only closely lined to water contents.     

Quantifying threats in a Mediterranean wetland: are there any changes in their evaluation during a training course?

“Threats analysis” is a conservation discipline directed to identify, quantify, rank, map the human-induced threats occurring in a specific study area, assessing their spatial-temporal regime (e.g., the extension and intensity on specific targets of conservation concern). This approach may be particularly useful in order to define the priorities in the management strategies to be adopted by nature reserves, especially those that are situated in human-altered multi-disturbed contexts. In a remnant Mediterranean wetland of central Italy, where 15 human-induced threats were identified, we compared the assessment given for two regime parameters (scope and severity) of each threat by a panels of not-expert students (n = 13) during different phases of a training academic course, thus evaluating perception modifications during three steps. We applied an experience-based method, then comparing the assessments obtained during the training course with the values obtained previously from a panel of experts (n = 10). Two direct threats (pollution and alien species) significantly changed their mean values in scope during the three steps, and three threats (habitat conversion, garbage, and aircraft) significantly changed as for severity. Students tended to significantly correct their responses in such a way to progressively match with the experts’ responses for a set of threats either for scope (habitat conversion, linear infrastructures, grazing, garbage, fires on reed-beds) or severity (pollution, garbage, fires on reed-beds). Despite the responses were not clear for some threats (aircraft), we suppose that students could assign a initial emphasis towards more charismatic threats as pollution, garbage, fires that instead locally did not appear of priority concern, while threats being uneasily detected (as alien species) were underestimated. Our study showed that a training course with field surveys allows to better define and contextualize the threats affecting a given area, reducing the perception effect that each student had prior to the beginning of the course, when their education information was mainly mass-media based.     

Are patterns in the taxonomic,biological and ecological traits of water beetles congruent in Mediterranean ecosystems?

1. Coleoptera species show considerable diversity in life histories and ecological strategies, which makes possible their wide distribution in freshwater habitats, including highly stressed ones such as saline or temporary waterbodies. Explaining how particular combinations of traits allow species to occupy distinctive habitats is a central question in ecology. 2. A total of 212 sites, sampled over a wide range of inland aquatic habitats in the south‐eastern Iberian Peninsula, yielded 272 species belonging to 68 genera and 11 families. The affinities of genera for 11 biological and 11 ecological traits, gathered from literature and the authors’ own expertise, were used to assess the degree of congruence between taxonomic, biological and ecological traits. 3. Taxonomic richness was significantly related to the number of both biological and ecological trait categories, with the richest families also showing the highest functional and ecological diversity. A fuzzy correspondence analysis performed on the abundance‐weighed array of biological traits separated genera according to categories of diet, feeding habits, respiration, reproduction and locomotion. A similar analysis of ecological traits revealed that preferences related to longitudinal distribution (headwater to mouth), local habitat and current velocity best discriminated genera. At the family level, there was a distinctive functional grouping of genera based on biological traits. Only Elmidae showed noticeable homogeneity across genera for both biological and ecological traits. 4. Co‐inertia analysis demonstrated a significant match between biological and ecological traits (Rv‐correlation = 0.35, P < 0.001). Elmidae genera displayed the highest concordance, whereas Hydraenidae demonstrated the lowest. 5. These results indicate that the predominance of habitat filtering processes in headwater streams yields biological trait conservatism (as shown by Elmidae genera), as well as trait convergence for some specific traits (for instance, respiration) among certain Dytiscidae genera and other typical rheophilic taxa, whereas other biotic factors, such as competition among species, appear more prominent in less stressed habitats. Further knowledge of traits, especially regarding physiological capabilities, is needed to better understand water beetle life history strategies.     

Does diversity beget diversity? A case study of crops and weeds

Abstract. The ecological literature is ambiguous as to whether the initial diversity of a plant community facilitates or deters the diversity of colonizing species. We experimentally planted annual crop species in monoculture and polyculture, and examined the resulting weed communities. The species composition of weeds was similar among treatments, but the species richness of weeds was significantly higher in the polycultures than in the monocultures. This supports the ‘diversity begets diversity’ hypothesis. Environmental microheterogeneity, diversity promoters, and ecological equivalency do not seem able to explain the observed patterns.     

‘Rigid’ internal timing in the circadian rhythm of flight activity in a tropical bat

Summary The timing of the emergence activity of a colony of the bat Taphozous melanopogon occupying a cave environment in Madurai (lat. 9°58 N, long. 78°10 E) and consisting of approximately 150–180 animals of both sexes was studies at 10-day intervals for one year. Even though the time of sunset during the eyar varied over a range of 41 min, the bats displayed an astonishingly rigid time of emergence that was restricted to a narrow gate of 16 min from 18:25 to 18:41 h. The timing of the termination of the activity was less precise in all seasons. Light/dark cycles are clearly the Zeitgeber. Even so, the bats began flying when it was very dark (0.1 lx) during shorter days, and they flew out as the sun was disappearing in the evening horizon (50 or more lx) during long days. Evidently there is no invariant, fixed lower threshold intensity that uniformly elicits the onset of activity throughout the year as reported earlier by other authors (Aschoff, 1969; Erkert, 1974). It is proposed that the bats undergo a systematic seasonal shift in the threshold sensitivity to light in response to the photic Zeitgeber of the environment. The result is a remarkable precision in terms of the hours of the civil/calendar day in the emergence of Taphozous melanopogon.