Beta diversity Research Papers - Academia.edu (original) (raw)

Understanding how landscape characteristics affect biodiversity patterns and ecological processes at local and landscape scales is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest eight hypotheses, which we hope will encourage more systematic research on Teja Tscharntke and others the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. We organize the eight hypotheses under four overarching themes. Section A: 'landscape moderation of biodiversity patterns' includes (1) the landscape species pool hypothesis-the size of the landscape-wide species pool moderates local (alpha) biodiversity, and (2) the dominance of beta diversity hypothesis-landscapemoderated dissimilarity of local communities determines landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. Section B: 'landscape moderation of population dynamics' includes (3) the cross-habitat spillover hypothesis-landscape-moderated spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes and (4) the landscape-moderated concentration and dilution hypothesis-spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations with functional consequences. Section C: 'landscape moderation of functional trait selection' includes (5) the landscape-moderated functional trait selection hypothesis-landscape moderation of species trait selection shapes the functional role and trajectory of community assembly, and (6) the landscape-moderated insurance hypothesis-landscape complexity provides spatial and temporal insurance, i.e. high resilience and stability of ecological processes in changing environments. Section D: 'landscape constraints on conservation management' includes (7) the intermediate landscape-complexity hypothesis-landscapemoderated effectiveness of local conservation management is highest in structurally simple, rather than in cleared (i.e. extremely simplified) or in complex landscapes, and (8) the landscape-moderated biodiversity versus ecosystem service management hypothesis-landscape-moderated biodiversity conservation to optimize functional diversity and related ecosystem services will not protect endangered species. Shifting our research focus from local to landscape-moderated effects on biodiversity will be critical to developing solutions for future biodiversity and ecosystem service management.

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- Landscape Ecology, Environmental Monitoring, Biodiversity, Global Environmental Change

Aim Virtually all studies exploring the use of taxonomic surrogates in assessing patterns of diversity have focused on clear shifts in the location of samples in multivariate space. The potential use of coarser levels of taxonomic resolution to detect patterns of variability in multivariate space, corresponding to β-diversity in the case of presence/absence data, remains unexplored. Here we considered five ecological data sets of highly diverse marine molluscan assemblages to test the hypothesis that patterns in compositional heterogeneity would be maintained at coarser levels of taxonomic resolution. Location Italy, Norway, New Zealand and the Arctic. Methods We used multivariate dispersion based on the Jaccard resemblance measure of presence/absence data as a measure of β-diversity to test the null hypothesis that patterns of heterogeneity in species composition for molluscs would be maintained at coarser levels of taxonomic resolution. Tests to compare β-diversities among groups (based on distances to centroids and using 9999 permutations) were carried out separately for each of five data sets at the species level and then for each of genus, family, order and class levels. Results Differences in multivariate dispersion at the species level (heterogeneity in the identities of species) were maintained for genera and for families, but not at coarser levels of taxonomic resolution (order or class). These results were consistent across all data sets, despite differences in their spatial scale and extent, geographical location, environmental and habitat features (benthic soft sediments, rocky reefs or kelp holdfasts). Main conclusions These results suggest that either genera or families may be used as effective taxonomic surrogates to detect spatial differences in β-diversity for molluscs. The use of surrogates can provide considerable sampling efficiencies for biodiversity assessments. We consider, however, that a degree of caution and more work is needed, as heterogeneity at the species level may not be reflected by taxonomic surrogates at smaller spatial scales.

- by Antonio Terlizzi
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- Diversity, Biological Sciences, Beta diversity, Environmental Sciences

Humankind's innate curiosity makes us wonder whether life is or was present on other planetary bodies such as Mars. The EuroGeoMars 2009 campaign was organized at the Mars Desert Research Station (MDRS) to perform multidisciplinary astrobiology research. MDRS in southeast Utah is situated in a cold arid desert with mineralogy and erosion processes comparable to those on Mars. Insight into the microbial community composition of this terrestrial Mars analogue provides essential information for the search for life on Mars: including sampling and life detection methodology optimization and what kind of organisms to expect. Soil samples were collected from different locations. Culture-independent molecular analyses directed at ribosomal RNA genes revealed the presence of all three domains of life (Archaea, Bacteria and Eukarya), but these were not detected in all samples. Spiking experiments revealed that this appears to relate to low DNA recovery, due to adsorption or degradation. Bacteria were most frequently detected and showed high alpha-and beta-diversity. Members of the Actinobacteria, Proteobacteria, Bacteroidetes and Gemmatimonadetes phyla were found in the majority of samples. Archaea alpha-and beta-diversity was very low. For Eukarya, a diverse range of organisms was identified, such as fungi, green algae and several phyla of Protozoa. Phylogenetic analysis revealed an extraordinary variety of putative extremophiles, mainly Bacteria but also Archaea and Eukarya. These comprised radioresistant, endolithic, chasmolithic, xerophilic, hypolithic, thermophilic, thermoacidophilic, psychrophilic, halophilic, haloalkaliphilic and alkaliphilic micro-organisms. Overall, our data revealed large difference in occurrence and diversity over short distances, indicating the need for high-sampling frequency at similar sites. DNA extraction methods need to be optimized to improve extraction efficiencies.

- by Pascale Ehrenfreund
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- Geology, Astrobiology, Beta diversity, DNA Extraction

Forest canopies support diverse assemblages of free-living mites. Recent studies suggest mite species complementarity between canopy and terrestrial soils is as high as 80-90%. However, confounding variation in habitat quality and resource patchiness between ground and canopy has not been controlled in previous comparative studies. We used experimental litter bags with standardized microhabitat structure and resource quality to contrast the colonization dynamics of 129 mite species utilizing needle accumulations on the ground vs in the canopy of Abies amabilis trees in a temperate montane forest in Canada. Mite abundance and species richness per litter bag were five to eight times greater on the ground than in the canopy, and composition differed markedly at family-, genus-, and species-level. Seventy-seven species (57%) were restricted to either ground or canopy litter bags, but many of these species were rare (n<5 individuals). Of 49 'common' species, 30.6% were entirely restricted to one habitat, which is considerably lower than most published estimates. In total, 87.5% of canopy specialists had rare vagrants on the ground, whereas only 51.9% of ground specialists had rare vagrants in the canopy. Canonical correspondence analysis of mite community structure showed high species turnover through time and a high degree of specialization for early-, mid-, and late-successional stages of litter decomposition, in both ground and canopy mites. In addition, distinct assemblages of ground-specialist mites dominated each elevation (800, 1000, and 1200 m), whereas few canopyspecialist mites had defined elevational preferences. This suggests that canopy mites may have greater tolerance for wide variation in environmental conditions than soil mites. The degree of species turnover between adjacent mountains also differed markedly, with 46.5% turnover of ground species, but 63.4% turnover of canopy species between the two montane areas. While ground and canopy assemblages are similar in total biodiversity, it appears that local mite richness (alpha diversity) is higher on the ground, whereas species turnover between sites (beta diversity) is higher in the canopy.

- by Valerie Behan-pelletier
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- Ecology, Population Dynamics, Biodiversity, Comparative Study

Distribution patterns of vascular plants with diameter at breast height (dbh) ≥ 2.5 cm were studied on the basis of compositional data from 30 small plots located in a rain-forest area in Colombian Amazonia. The research questions were: How are distribution patterns of species in relation to local abundance in plots? Do understorey species (defined as species with individuals that never attained dbh ≥ 10 cm anywhere) show better correlations with soils and environment than canopy species (defined as species with individuals that attained dbh ≥ 10 cm)? Are patterns found in the entire range of landscape units comparable to those found in well-drained uplands alone? Species that occurred in more than one plot showed higher local abundances. This pattern was consistent among environmental generalists and specialists. Locally rare species (with only one individual in a plot) occurred mostly in well-drained uplands. Considering all landscape units, Mantel tests showed substantial correla...

- by Alvaro Duque
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- Tropical Ecology, Ecology, Beta diversity, Rain forest

Alpha and beta arthropods diversity from the different environments of Parque Nacional Los Cardones, Salta, Argentina. The essential role of the National Parks is to protect nature, in order to prevent the deterioration and loss of the ecosystem under protection. Very few records about the diversity of arthropods are known from Los Cardones National Park, where three eco-regions are protected: Puna and Monte eco-regions and the High Andean Grassland of the Yungas. Here, we aimed to compare the alpha and beta diversity of arthropods in these eco-regions, and to prove if sites from the same ecoregion, show greater similarity between them in their assemblages, than with sites of the other eco-regions. We also identified arthropod orders with higher species richness, and indicated the families that contribute the most to the registered beta diversity. Three sampling sites were established on each eco-region and the arthropods were sampled using pitfall traps and suction samples. We evaluated the obtained inventory through nonparametric estimators of species richness, and compared diversity among eco-regions through "diversity profiles" and "effective number of species". Beta diversity was assessed by different methods such as the Morisita Index, nonmetric multidimentional scaling analysis, a multiple permutation procedure, and a Similarity Percentage analysis. We recorded 469 spp/morphospecies and recognized three arthropod orders (spiders, dipterans and hymenopterans) that are diverse and abundant in the Park. Besides, the diversity in Los Cardones National Park was found to be high, but it was observed higher in the High Andean Grassland of the Yungas, and lower in the Puna. The inventory obtained was good, reached up to the 81% of the species richness estimated by nonparametric estimators. Each eco-region of the park showed a very particular arthropod community that was tested by a multi-response permutation procedure. The species turnover between eco-regions was high, so that the different environments of the protected area are contributing to the maintenance of the regional diversity of arthropods in the park. The assemblages of arthropods belonging to the same eco-region sites showed greater similarity among themselves than with those of more distant sites. This represents the first attempt for biodiversity studies in these areas, but more evaluations are required to detail on the possible climate change and human impacts in the ecosystem.

- by jose corronca
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- Beta diversity, Arthropods, Alpha Diversity, Revista de Biología Tropical

The Lulanda forest cover a portion of the Udzungwa mountains in Mufindi district, Tanzania, ranging from 1480 -1640 meters above sea level. The forest consists of three forest patches dominated by Parinari excelsa and a corridor between two of them that is being regenerated to a forest under the help of the Tanzania Forest Conservation Group (TFCG). A capture-mark-recapture study was carried out to document the small mammal species found in Lulanda forest patches and corridor. There is a considerable difference in small mammal species composition between the montane forest and the corridor with a higher diversity in the corridor.

- by Alex Kisingo
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- Tropical Ecology, Ecology, Beta diversity, Small Mammals

Measures of species diversity are valuable tools for assessing ecosystem health. However, most assessments have addressed individual sites or regional taxon pools, with few comparisons of differences in assemblage composition within or among regions. We examined the effects of anthropogenic disturbance on local richness (a diversity) and species turnover (b diversity) of benthic macroinvertebrates in small streams within and between 2 ecoregions (Northern Piedmont vs Southeastern Plains ecoregions) of the Patuxent River basin (Maryland, USA). Regional species pools did not differ between ecoregions (Piedmont = 166 taxa, Plains = 162 taxa); however, local richness was lower in the Plains (mean = 17.4 taxa/stream) compared to the Piedmont (mean = 22.2 taxa/stream). When streams were categorized into disturbance classes (low, medium, high), local richness did not differ among categories for either region. However, at the entire Patuxent scale, local richness tended to decrease with % impervious cover in a watershed. Variation in species composition, analyzed with nonmetric multidimensional scaling (nMDS), differed significantly between Piedmont and Plains streams, and Plains streams had higher b diversity than Piedmont streams. When partitioned by disturbance category and region, b diversity differed only between the low-disturbance sites (Plains . Piedmont). Relationships between b diversity and environmental variables varied by region. b diversity was weakly negatively related to % row-crop cover in a watershed at the entire Patuxent scale. For the Piedmont region, b diversity tended to decrease with % forest, % pasture, and % row-crop cover in a watershed. Such negative relationships between b diversity and landuse variables indicate a possible homogenization of the assemblage. The incongruence between diversity measures and composition measures, together with differing effects of anthropogenic land use on b diversity in the 2 regions, emphasizes the need to incorporate both a and b diversity and regional environmental factors in conservation/land management studies.

- by Richard Mitchell
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- Ecology, Beta diversity, Scale, Fisheries Sciences

Forests characterized by mixed-severity fires occupy a broad moisture gradient between lower elevation forests typified by low-severity fires and higher elevation forests in which high-severity, stand replacing fires are the norm. Mixed-severity forest types are poorly documented and little understood but likely occupy significant areas in the western United States. By definition, mixed-severity types have high beta diversity at meso-scales, encompassing patches of both high and low severity and gradients in between. Studies of mixed-severity types reveal complex landscapes in which patch sizes follow a power law distribution with many small and few large patches. Forest types characterized by mixed severity can be classified according to the modal proportion of high to low severity patches, which increases from relatively dry to relatively mesic site conditions. Mixed-severity regimes are produced by interactions between top-down forcing by climate and bottom-up shaping by topography and the flammability of vegetation, although specific effects may vary widely across the region, especially the relation between aspect and fire severity. History is important in shaping fire behavior in mixed-severity landscapes, as patterns laid down by previous fires can play a significant role in shaping future fires. Like low-severity forests in the western United States, many dry mixed-severity types experienced significant increases in stand density during the 20th century, threatening forest health and biodiversity, however not all understory development in mixed-severity forests increases the threat of severe wild fires. In general, current landscapes have been homogenized, reducing beta diversity and increasing the probability of large fires and insect outbreaks. Further loss of old, fire tolerant trees is of particular concern, but understory diversity has been reduced as well. High stand densities on relatively dry sites increase water use and therefore susceptibility to drought and insect outbreaks, exacerbating a trend of increasing regional drying. The need to restore beta diversity while protecting habitat for closed-forest specialists such as the northern spotted owl call for landscape-level approaches to ecological restoration.

- by Paul Hessburg
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- Landscape Ecology, Fire Ecology, Forest Ecology And Management, Forest Ecology

The spatial and temporal distribution and diversity of sediment-dwelling foraminifera are reasonably well known, but encrusting (hard-substrate dwelling) foraminifera are little studied. Encrusting foraminifera are common in the world&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;s oceans, attached to floating debris or marine animals in the water column to living on rocks, sand grains and organisms in benthic environments from shallow to deep marine regions. With projected

- by Carlton Brett and +1
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- Evolutionary Biology, Geology, Ecology, Beta diversity

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos norte y sur. Los análisis de atenuación y de PAE revelaron la existencia de tres grupos principales de áreas: uno ubicado en la sección sur, que comprende desde el este de Oaxaca hasta el sur de Chiapas; otro en la porción norte, abarcando desde el norte de Sonora hasta el norte de Nayarit y Jalisco; y un último para la porción central, desde el sur de Jalisco y el noroeste de Colima hasta el este de Oaxaca, así como la existencia de varios subgrupos al interior de estos. Palabras Clave: Biogeografía, oeste de México, avifauna, análisis de parsimonia de endemismos, regionalización.

- by Erick Alejandro García Trejo and +1
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- Diversity, Biogeography, Beta diversity
- by Gianfranco Sartoni and +3
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- Evolutionary Biology, Zoology, Natural History, Multivariate Analysis

Small organisms provide the bulk of biodiversity. Here, we look at rewilding from their perspective. As an umbrella group for other terrestrial invertebrates, we focus on the diverse group of Lepidoptera. More specifically, we set out to explore their response to farmland abandonment. So far, studies have warned against farmland abandonment, which is for instance listed as one of the key threats to European butterfly diversity. Here, partly based on a case study within the Peneda mountain range, we argue (i) that the majority of Lepidoptera is to a greater or lesser extent forest-dependent, (ii) that effects on species composition should be considered at regional rather than smaller scales, and (iii) that habitat resource heterogeneity at multiple spatial scales is key. As such, we believe that rewilding does offer opportunities to Lepidoptera. However, we recommend rewilding not to be equalled to a hands-off approach, but rather to a goal-driven conservation management approaches. It should monitor, and where necessary intervene to provide habitat heterogeneity at multiple spatial scales, in order to cater for the whole gradient of sedentary to mobile species. Given that sufficient levels of habitat heterogeneity are maintained, Lepidoptera are one of probably many taxa that are likely to benefit from rewilding processes on European marginal farmland. The resulting improved species composition will help achieve European species conservation targets. It may also lead to more viable populations of moths, butterflies and other invertebrates, which will foster more resilient food-webs and increased ecosystem functioning.

Almost half a century after Whittaker (Ecol

- by Gerald Jurasinski
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- Ecology, Environmental Monitoring, Biodiversity, Literature Review

The environmental heterogeneity of a natural protected area is major driver of the spatial distribution of biodiversity within its territory. The goal of this study was to determine the effect of
geomorphological heterogeneity on the spatial variation of oak forest diversity, floristic composition and structure at the El Tepozteco National Park (Morelos, Mexico). Floristic composition and vegetation structural attributes were recorded in 10 sampling plots randomly distributed in each one of six geomorphological units occurring in the park. In total, 343 plant species were identified, with plant richness by unit varying from 60 species in the oldest lava field to 151 in the El Tepozteco mountain range. Estimated richness with Chao 2 algorithm for the entire oak forest was 448.2 species, a larger value than those calculated for geomorphological units separately (94.3 to 284.6 species). Vegetation structure also varied greatly between units. The
largest basal area values (60.5 m2/ha) and vegetation height (22.8 m) corresponded to the oldest lava field, while the smallest (19.6 m2/ha and 9.0 m, respectively) were recorded in the most recent one. A canonical correspondence analysis showed that geomorphological heterogeneity better explains the variation of understory diversity than that of canopy. These results show that the park’s geomorphological heterogeneity is partially responsible for the regional high biodiversity. Likewise, it was proved that structure, floristic composition and plant diversity vary greatly between the various park’s oak forests, which may help identify priority areas upon which to focus future conservation efforts in this natural protected area.

- by Sebastian Block
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- Vegetation Ecology, Natural protected areas, Plant Diversity, Beta diversity

Conservation biological control in agroecosystems requires a landscape management perspective, because most arthropod species experience their habitat at spatial scales beyond the plot level, and there is spillover of natural enemies across the crop-noncrop interface. The species pool in the surrounding landscape and the distance of crop from natural habitat are important for the conservation of enemy diversity and, in particular, the conservation of poorly-dispersing and specialized enemies. Hence, structurally complex landscapes with high habitat connectivity may enhance the probability of pest regulation. In contrast, generalist and highly vagile enemies may even profit from the high primary productivity of crops at a landscape scale and their abundance may partly compensate for losses in enemy diversity. Conservation biological control also needs a multitrophic perspective. For example, entomopathogenic fungi, plant pathogens and endophytes as well as below-and above-ground microorganisms are known to influence pest-enemy interactions in ways that vary across spatiotemporal scales. Enemy distribution in agricultural landscapes is determined by beta diversity among patches. The diversity needed for conservation biological control may occur where patch heterogeneity at larger spatial scales is high. However, enemy communities in managed systems are more similar across space and time than those in natural systems, emphasizing the importance of natural habitat for a spillover of diverse enemies. According to the insurance hypothesis, species richness can buffer against spatiotemporal disturbances, thereby insuring functioning in changing environments. Seemingly redundant enemy species may become important under global change. Complex landscapes characterized by highly connected crop-noncrop mosaics may be best for long-term conservation biological control and sustainable crop production, but experimental evidence for detailed recommendations to design the composition and configuration of agricultural landscapes that maintain a diversity of generalist and specialist natural enemies is still needed.

- by thomas crist
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- Zoology, Spatial Ecology, Agroecosystems, Biological Control

We compared patterns of understorey vegetation and abiotic factors in old-growth forests with low management intensity and young forests with high management intensity. CCA showed that disturbance gradient was the main axis of community variation, while local light availability (ISF, indirect site factor) and soil conditions (nitrate content) were also of some importance. Young stands demonstrated a significantly higher heterogeneity of vegetation with increased pattern diversity (1 À Jaccard similarity among 1 m Â 1 m plots, also called beta diversity), variation in species richness and variation in the cover of both vascular plants and bryophytes. Young stands also showed a higher variation of soil nitrate content and lower average vascular plant cover. We concluded that the understorey vegetation in young stands with high intensity management is, contrary to our literature-based expectation, more heterogeneous in space than that in old stands with low management intensity. The relationship between environmental heterogeneity and diversity has been discussed extensively, but there is a scarcity of quantitative relationships documented in natural vegetation. We found that species richness in 4 m Â 4 m plots was positively dependent on the variability of light availability (ISF) within plot. Pattern diversity was positively dependent on the variation of microtopography and the availability of direct radiation (DSF, direct site factor). #

- by Heikki Kalle and +1
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- Forest Ecology And Management, Biodiversity, Forest Ecology, Heterogeneity

The aim of this paper is to investigate differences in plant species composition between managed and unmanaged forests, and to assess if these difference give rise to a higher plant diversity in the unmanaged forest. Furthermore our aim is to relate forest structure to differences in plant species composition, identifying the structural attributes more strongly related to the unmanaged forest vegetation. We compared an old-growth forest and a managed highforest in the Abruzzo Lazio and Molise National Park (Central Italy). Plant species composition and diversity, deadwood components and live structure have been analyzed. We used permutational multivariate analysis of variance to test the response of species composition to management factor; furthermore, we compared species richness and beta diversity. Redundancy analysis has been used to relate plant species abundances to structural variables; the importance of dead and living wood components has been compared through variation partitioning. Plant species composition proved to be significantly different in the two sites, and the old-growth stand showed a higher plant diversity. From a structural point of view, we found differences especially in the amount and quality of deadwood, and in the diameter class distribution. These variables are also the most important in determining the old-growth stand plant species composition according to redundancy analysis. Variation partitioning confirmed the greater importance of the deadwood variables. Our results suggest that including deadwood surveys in traditional forest inventories could help in finding forests with both structural and floristic old-growth properties to be considered in conservation programmes. The imitation of natural dynamics, through the creation of gaps avoiding deadwood removal, could be an effective strategy for restoring oldgrowth conditions, also in terms of plant diversity.

- by marco marchetti
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- Plant Biology, Ecology, Plant Diversity, Beta diversity

Meiobenthic data from two microtidal sandy beaches of the eastern Mediterranean (Crete, Greece) were used to investigate patterns of both alpha and beta diversity in space and time. Copepod assemblages and environmental variables related to sediment characteristics, morphodynamics and food were studied over a year at four distinct habitats at each beach; the retention, resurgence and saturation zones of Salvat's intertidal scheme (midlittoral zone), and the surf zone of the sublittoral. Αlpha diversity analysis indicated similar species richness at both beaches when the whole 13-month data set was considered but was higher at the sheltered site when each sampling period was examined separately. Both beaches supported higher diversity in the sublittoral zone. Species richness increased seawards at the midlittoral zone of the sheltered site whereas, no pattern was evident at the exposed site, where the intense hydrodynamic conditions homogenized the sediments. Beta diversity increased markedly towards the sublittoral, indicating greater differences in alpha diversity between the sublittoral and the midlittoral zone. Species turnover was more variable at the exposed beach and at the most landward stations, where environmental conditions change often between extremes. A proportion of the variation in alpha diversity was explained by food availability at both beaches and additionally by grain size at the sheltered site. However, no environmental variable explained beta diversity patterns. Although the results of our study support the hypothesis of Multicausal Environmental Severity proposed for sandy beach macrofauna, we believe the classic Intermediate Disturbance Hypothesis is a more appropriate framework for the meiofauna communities of the studied sites.

- by Anastasios Eleftheriou and +1
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- Oceanography, Beta diversity, Environmental Variables, Grain size

Aim Researchers measuring beta diversity have rarely concerned themselves with the problems of how complete the species lists of studied communities are, and of how the varying degrees of completeness can actually change estimates of beta diversity. No comprehensive assessment has been made regarding the behaviour of most beta diversity indices when applied to incomplete samples, a situation which is more common than usually recognized. Our objective was to assess the behaviour and robustness of a number of beta diversity measures for incidence data from undersampled communities.

- by Paulo Borges
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- Biological Sciences, Beta diversity, Environmental Sciences

The goal of this paper is to provide a general description of the terrestrial arthropod fauna of arid areas of SE Iberian Peninsula. The available data show that invertebrate communities in these environments are dominated by arthropods and that the composition of the assemblages are similar to those described in other arid regions of the world. The number of species of different arthropod groups (Coleoptera, Hymenoptera, Orthoptera, Lepidoptera, Araneae) in these environments show that arid regions of SE Iberian Peninsula are inhabited by a diverse terrestrial arthropod fauna. An ecological feature of arthropod communities in arid zones of SE Spain is the spatial and temporal variability of assemblage composition at different scales, a characteristic of faunal assemblages in arid environments. Similarity in composition of assemblages between sites (Beta diversity) shows a high variability in faunal composition between apparently similar environments. The distribution patterns of species show that 8.4e9.6% of the species in these environments are local and SE Iberian Peninsula endemics. A number of eremic Mediterranean or Palaearctic species are also associated exclusively with these environments, highlighting the singularity of the invertebrate fauna in these arid habitats. Differences in assemblage composition of arid areas with more mesic surrounding environments show that arid zones of SE Spain are inhabited by a distinct fauna, increasing faunal diversity in SE Spain. A recent analysis of endangered and threatened invertebrate species in southern Spain recognizes the arid environments of SE Spain as priority areas for conservation, where habitat loss and fragmentation, changes in agricultural and grazing uses, and inadequate management constitute the main threats. We conclude that the fauna of the SE Iberian arid zones represents an important component of the high ecological diversity of the Mediterranean ecosystem in SE Spain, not only because of their arthropod diversity but also due to the important implications that these areas have for conservation in the entire SE region of the Iberian Peninsula.

- by Alberto Tinaut and +2
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- Earth Sciences, Arid environments, Biological Sciences, Beta diversity

Experimental studies demonstrating that nitrogen (N) enrichment reduces plant diversity within individual plots have led to the conclusion that anthropogenic N enrichment is a threat to global biodiversity. These conclusions overlook the influence of spatial scale, however, as N enrichment may alter b diversity (i.e., how similar plots are in their species composition), which would likely alter the degree to which N-induced changes in diversity within localities translate to changes in diversity at larger scales that are relevant to policy and management. Currently, it is unclear how N enrichment affects biodiversity at scales larger than a small plot. We synthesized data from 18 N-enrichment experiments across North America to examine the effects of N enrichment on plant species diversity at three spatial scales: small (within plots), intermediate (among plots), and large (within and among plots). We found that N enrichment reduced plant diversity within plots by an average of 25% (ranging from a reduction of 61% to an increase of 5%) and frequently enhanced b diversity. The extent to which N enrichment altered b diversity, however, varied substantially among sites (from a 22% increase to an 18% reduction) and was contingent on site productivity. Specifically, N enrichment enhanced b diversity at low-productivity sites but reduced b diversity at high-productivity sites. N-induced changes in b diversity generally reduced the extent of species loss at larger scales to an average of 22% (ranging from a reduction of 54% to an increase of 18%). Our results demonstrate that N enrichment often reduces biodiversity at both local and regional scales, but that a focus on the effects of N enrichment on biodiversity at small spatial scales may often overestimate (and sometimes underestimate) declines in regional biodiversity by failing to recognize the effects of N on b diversity.

- by Elsa Cleland
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- Biomass, Productivity, Ecology, Biodiversity

- by Yann Clough and +1
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- Landscape Ecology, Environmental Monitoring, Biodiversity, Global Environmental Change

This article presents an analysis of plant species richness and diversity and its association with climatic and soil variables along a 1300-m elevation gradient on the Cerro Tláloc Mountain in the northern Sierra Nevada in Mexico. Two 1000-m 2 tree sampling plots were created at each of 21 selected sampling sites, as well as two 250-m 2 plots for shrubs and six 9-m 2 plots for herbaceous plants. Species richness and diversity were estimated for each plant life form, and beta diversity between sites was estimated along the gradient. The relationship between species richness and diversity and environmental variables was modelled using simple linear correlation and regression trees. Species richness and diversity showed a unimodal pattern with a bias towards high values in the lower half of the elevation gradient under study. This response was consistent for all three life forms. Beta diversity increased steadily along the elevation gradient, being lower between contiguous sites at intermediate elevations and high -the species replacement rate was nearly 100% -between sites at the extremes of the gradient. Few species were adapted to the full spectrum of environmental variation along the elevation gradient studied. The regression tree suggests that differences in species richness are mainly influenced by elevation (temperature and humidity) and soil variables, namely A 2 permanent wilting point, organic matter and horizon field capacity and A 1 horizon Mg 2+ .

- by lauro López-Mata
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- Diversity, Temperate Forests, Biological Sciences, Beta diversity

Spatial associations among overstory and understory species tend to increase on gradients from wet to dry cli- mates. This shift in the strength of spatial associations has usually been attributed to shared abiotic requirements between canopy species and understory assemblages within communities and/or to an increase in habitat hetero- geneity in dry climates and therefore higher beta diversity. On another

- by Dan Gafta
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- Plant Ecology, Plant Biology, Ecology, Correspondence Analysis

This study aimed to: (1) assess differences between two quantitative sampling methods of soil microarthropods (visual census vs. stone washing) in ice-free areas located along a latitudinal gradient (from 72°37′S to 74°42′S) in northern Victoria Land (Antarctica); (2) furnish preliminary results on the abundance and diversity of mites and springtails in the studied areas. Visual census yielded reliable density estimates for adult collembolans and larger prostigmatic mites but did not detect small species. The study updates the distribution of several mites, including the southernmost record of an Oribatida species at global scale. Species composition was correlated with latitude but the uneven abundance distribution and local high beta-diversity probably reflect habitat fragmentation and population isolation. Under this circumstance nested sampling design should be usefully employed. Priorities and suitable methods for studying terrestrial microarthropod communities in continental Antarctica are discussed.

- by roberto bargagli
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- Biological Sciences, Beta diversity, Sampling methods, Habitat fragmentation

The sensitivity of global carbon and water cycling to climate variability is coupled directly to land cover and the distribution of vegetation. To investigate biogeochemistryclimate interactions, earth system models require a representation of vegetation distributions that are either prescribed from remote sensing data or simulated via biogeography models. However, the abstraction of earth system state variables in models means that data products derived from remote sensing need to be post-processed for model-data assimilation. Dynamic global vegetation models (DGVM) rely on the concept of plant functional types (PFT) to group shared traits of thousands of plant species into usually only 10-20 classes. Available databases of observed PFT distributions must be relevant to existing satellite sensors and their derived products, and to the present day distribution of managed lands. Here, we develop four PFT datasets based on land-cover information from three satellite sensors (EOS-MODIS 1 km and 0.5 km, SPOT4-VEGETATION 1 km, and ENVISAT-MERIS 0.3 km spatial resolution) that are merged with spatially-consistent Köppen-Geiger climate zones. Using a beta (ß) diversity metric to assess reclassification similarity, we find that the greatest uncertainty in PFT classifications occur most frequently between cropland and grassland categories, and in dryland systems between shrubland, grassland and forest categories because of differences in the minimum threshold required for forest cover. The biogeographybiogeochemistry DGVM, LPJmL, is used in diagnostic mode with the four PFT datasets prescribed to quantify the effect of land-cover uncertainty on climatic sensitivity of gross primary productivity (GPP) and transpiration fluxes. Our results show that land-cover uncertainty has large effects in arid regions, contributing up to 30 % (20 %) uncertainty in the sensitivity of GPP (transpiration) to precipitation. The

- by H Lischke
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- Earth Sciences, Remote Sensing, Climate variability, Data Assimilation

We aim to analyze the spatial patterns of the vegetation at local and landscape scale during a scenario characterized by abnormally dry period (2007)(2008) and a reference scenario (1976)(1977). We used the frequency occurrence of the species and the number of species belonging to five life forms to compare the two temporal scenarios. In five water bodies of Esteros del Iberá we surveyed vascular aquatic macrophytes and the wetland plants during spring-summer with up to three samples of 20 m 2 each. A total of 161 species were found during the two study periods (120 and 117 species respectively). Cyperaceae and Poaceae were the most species-rich families at both periods. At waterbody scale, beta diversity showed a high spatial heterogeneity and at wetland scale, the turnover rate of S is low. At both scenarios, the vegetation composition showed relevant differences between the sub-rounded lakes and the elongated waterbodies. The floristic composition and the life forms spectra were affected by the change in the water supply. The knowledge of the baseline of the spatial and temporal variability of this particular wetland is key to support future assessments of the ecosystem response to the global change.

- by S. Casco and +1
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- Ecology, Global change, Biodiversity Conservation, Beta diversity

The habitat heterogeneity hypothesis states that an increase in habitat heterogeneity leads to an increase in species diversity. We tested this hypothesis for a community of small mammals in the semiarid, sand-shinnery-oak ecosystem of the southwestern United States. We used indices of differentiation diversity to quantify differences between two habitat types (blowouts in a sand-shinnery-oak matrix) in terms of species diversity. The Wilson-Shmida index (beta(T)) considers species composition only, whereas the Morisita-Horn index (C(mH)) also takes species abundances into account. We constructed null models to test the hypothesis that differentiation diversity between habitat types is greater than that produced by stochastic processes. Two models were constructed, one based on the random placement of species and one based on the random placement of individuals. No evidence supported the hypothesis that habitat heterogeneity enhances diversity of a landscape by increasing the number of species in an area. Indeed, paired habitats were more similar than chance alone would dictate in terms of species identities. In contrast, habitat heterogeneity affects diversity by significantly altering the relative proportions of species in contrasting habitat types. Because seeds differentially accumulate at the interface between blowouts and matrix, the high productivity of the edge may actually homogenize habitat types in terms of species richness. Nonetheless, blowouts might best be considered to be microhabitats which enhance or complement the value of the matrix even though the species which use either habitat type are identical.

- by Michael Cramer
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- Community Ecology, Beta diversity, Species Diversity, Null Model

The goal of this research is to evaluate how the assemblages of aquatic macrophytes in marginal floodplain habitats, with different degrees of connectivity to the main river, respond to water level fluctuations. Samples were carried out quarterly (May 2000 to March 2002 in seven lagoons of the Upper Paraná River floodplain (22°30′ and 22°45′-S and 53°15′ and 53°30′-W) with different degrees of connectivity (connected and disconnected to the main river). In each lagoon, a shore-pelagic zone transect was marked and at every 2 m the depth and the cover of each aquatic macrophyte species were recorded (Domin-Krajina scale) in a quadrat of 0.25 m 2 . A total of 29 aquatic macrophyte species and an unusual decrease in water level were recorded in August 2001. Drawdown had a negative impact on species richness, only in connected lagoons, which was shown by a positive relationship between depth and species number (r-Spearman = 0.86; P < 0.01). Depth affected Beta diversity positively (r-Spearman = 0.79; P < 0.05). Drawdown affected the connected and disconnected lagoons differently, which can be attributed to their different morphometry. In this period, 'habitat contraction' was higher on connected lagoons. Positive correlation between mean species number and depth, and between beta diversity and depth, are factors that support this affirmation. Indicator species analysis showed that for disconnected lagoons, Oxycaryum cubense (Cyperaceae), Polygonum meissnerianum (Polygonaceae) and P. ferrugineum, with indicator values (IndVal) of 53, 30 and 25%, respectively, were indicator species. Salvinia spp. (Salvinaceae) (62%), P. acuminatum (44%) and the Ricciaceae Ricciocarpus natans (0%) were the indicator species of the connected lagoons.

The cerrado has been identified as one of the richest and most threatened biomes of the world, but few phytogeographical studies have been undertaken in the region. A total of 70 land systems based on climate, landscape and soils have been identified in the region, but it remains to be seen if the distribution and structure of the plant communities support these divisions. The aim of this work was to compare the floristic and structural similarity of cerrado sensu stricto within and between three physiographic units, named Pratinha, Veadeiros and São Francisco, which contain six land systems in central Brazil and cover 10 degrees of latitude and five degrees of longitude. The woody vegetation of 15 selected sites of the cerrado sensu stricto physiognomy was surveyed under a standardized methodology. The number of species per site varied from 55 to 97, with most sites having around 60 to 70 species, and Shannon´s diversity indices ranged from 3.44 to 3.73, with most sites around 3.5 suggesting high alpha diversity. Sørensen´s floristic similarity index was high, with all Figures above 0.5 between the sites in the same land system in each physiographic unit but low between sites in different land systems in the Veadeiros. Czekanowski similarity indices were lower than Sørensen's in the comparisons due to a high structural differentiation between the sites. There is a large overlap in species occurrence in the sites but the size of their populations is very different at each site. Therefore, the high beta diversity is mostly due to differences in abundance of species between sites. The sites were separated by physiographic units, considering the first three divisions of TWINSPAN classification. The first axis of DCA ordination showed a gradient going from the cerrado on deep soils in Pratinha, through to those on sandy soils in São Francisco and ending on the shallower soils of the Veadeiros. Land systems conformed well with the floristic and structural variations of the vegetation, indicating their potential use in designing a network of conservation areas in the cerrado region and as a basis for decision-making on management.

- by Bruno Machado Teles Walter and +1
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- Plant Ecology, Decision Making, Plant Biology, Ecology

Riparian forests are classified as endangered ecosystems in general, particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works. The modification of this important habitat is continuing, with little attention being paid to the ecological or human consequences of these changes. The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso. All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m. Density, dominance, frequency and species and family importance values were computed to characterize the species composition. Different diversity indices were calculated to examine the heterogeneity of riparian forests. A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests. The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests. Similarity in tree species composition between riparian forests was low, which indicates high beta diversity and reflects differences in habitat conditions and topography. The structural characteristics varied significantly along the phytogeographical gradient and between the different types of riparian forests. The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals. Considering the ecological Foundation project: This work was financially supported by University of Frankfurt and BIOTA West project The online version is available at Responsible editor: Chai Ruihai importance of riparian forest, there is a need to delineate and classify them along watercourses throughout the country.

- by Oumarou Sambaré and +1
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- Forestry, Beta diversity, Burkina Faso, Species Diversity
- by Cabezudo, Baltasar
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- Ecology, Plant Diversity, Spatial autocorrelation, Beta diversity

We tested the hypothesis that coffee systems with organic management have higher spider diversity by comparing a control (rainforest area) and two coffee systems, one with organic and the other with conventional management. Spiders were sampled every two weeks over three months during the dry season and three months during the rainy season in 2000. Spider alpha diversity was analyzed using Shannon and Simpson indices. We also used the Cody index for beta diversity and cluster analysis for analyzing changes in species abundance hierarchies. 2261 individuals were collected (including juveniles and adults) representing 20 families, 56 genera and 97 species. In most cases the alpha diversity indices showed no relation between management gradient and spider diversity. When compared across seasons, spider diversity differed significantly only in organic management. Species turnover among the three sites (Cody index) was highest between the two coffee farms but not so clearly in the dry vs. rainy season; the conventional management shared the fewest species with the forest. Cluster analysis showed changes in abundance hierarchy related to management type. Our results did not support the proposed hypothesis of a direct positive correlation between management gradient and alpha spider diversity. In contrast, beta diversity showed that management and seasons influenced species composition.

- by Miguel Pinkus
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- Zoology, Agroecosystems, Arachnology, Beta diversity

Gostaria de agradecer em primeiro lugar, às minhas orientadoras, Sandra Müller e Suzana Martins, que me apoiaram na construção dessa dissertação. Sem os conselhos e as contribuições delas não teria sido possível realizar esse trabalho. Sandra, obrigada por ter aceito entrar no mundo dos liquens para me orientar! Não tenho palavras para agradecer toda a tua dedicação! Suzana, serei eternamente tua "cria", foi tu que me ensinou grande parte do que hoje sei sobre liquens, e agradeço, de coração, por ter sempre me dado todo o apoio! À Fabiane Lucheta, minha super companheira de campo, que além de ser uma amiga muito especial, ainda foi uma ajudante de campo super eficiente! Obrigada amiga pela força, pelo incentivo e pelas horas (e horas!) de conversa. Sem a tua ajuda nada disso teria sido possível! Agradeço também a outra amiga, e também companheira de campo, Laura Capelatti, que igualmente foi uma super ajudante, além de uma ótima botânica! A Iporã Haeser, que esteve sempre à disposição de nos levar de um canto a outro de Maquiné, mesmo tendo o seu trabalho para fazer por lá também. Obrigada querido, vou ser eternamente grata por toda ajuda e pelo companheirismo de sempre! Aos meus colegas de laboratório Kátia Zanini, Rafael Machado, Betânia Azambuja e Grasiela Casas, pelas sugestões, pela amizade e pelos muitos ensinamentos ecológicos e estatísticos! E em especial à Adriane Muelbert que além de me dar muitas dicas estatísticas, ainda se tornou uma super amiga! Obrigada! Um grande obrigada a Rodrigo Bergamin pela identificação das plantas! Aos meus colegas de mestrado, em especial à Anne Gomes Sacco, por estar sempre solícita a uma troca de ideias, fossem elas ecológicas ou não. Além de colega, se tornou uma grande amiga! Ao Programa de Pós Graduação em Ecologia e à Universidade Federal do Rio Grande do Sul por todo o auxílio logístico e financeiro e por permitir que este trabalho fosse desenvolvido.

- by Fabiane Lucheta
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- Beta diversity, Biological Indicators

A standardized sampling method was used to evaluate turnover ( diversity) among cactus species assemblages along a 798 km long latitudinal megatransect across the Chihuahuan Desert Region, from north-central Mexico to southern Texas. A total of 71 cactus species were found along the megatransect, 66.2% of which appeared at low frequencies, mostly as a consequence of their highly discontinuous distribution pattern. At the scale the study was conducted, there was always species turnover among cactus assemblages. The rate of turnover among contiguous sites primarily Xuctuated from low to medium, but when all site combinations were considered (contiguous and non-contiguous), medium diversity values were predominant ( = 0.331-0.66); however, 25.4% of the site pair combinations registered high values ( = 0.661-1.0). Our results showed that turnover among cactus species assemblages in the CDR does not consist for the most part of a process of species succession in the geographic space. Instead, we concluded that the continuous spatial changes in cactus species composition are primarily explained by the commonly intermittent distribution patterns of the species, by the presence in the megatransect of species at the margin of their distribution range, and, to a lesser extent, by the existence of narrowly endemic species.

- by Hector Meneses Hernandez
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- Ecology, Biodiversity, Low Frequency, Biodiversity Conservation

Species composition and diversity of bryophyte communities occurring on dead beech trees were analyzed in five European countries (Slovenia, Hungary, The Netherlands, Belgium and Denmark). Altogether 1.009 trees were inventoried in 19 beech dominated forest reserves. The differences in the composition of bryophyte communities were high among countries and it overwhelms the effect of decay stages, which affect the species composition at local scale. Well decayed trees were dominated by epixylic species in Slovenia, while in other countries the proportion of opportunistic bryophytes was much higher and in Atlantic countries uproot species are also common. In Slovenia hepatics, in Hungary and Denmark pleurocarps, and in The Netherlands and Belgium acrocarps were the most frequent. Diversity of communities differed considerably among regions. Slovenian sites were the hotspot of bryophyte diversity characterized by high species richness (both tree and country level) and a high fraction of rare and threatened species. This richness is most likely caused by the combination of high air humidity combined with a very high degree of naturalness of the Slovenian sites. The diversity of Hungarian stands was intermediate reflecting the relatively high naturalness of the study sites, as well as a rather continental climate sub-optimal for epixylic liverworts. Atlantic forests have deteriorated bryophyte communities on dead trees, dominated by a few opportunistic species. This is partly a result of habitat fragmentation and past and recent management of forest. Most of the stands the amount and quality of dead wood is not suitable for species rich epixylic bryophyte communities.

A recent increase in studies of b diversity has yielded a confusing array of concepts, measures and methods. Here, we provide a roadmap of the most widely used and ecologically relevant approaches for analysis through a series of mission statements. We distinguish two types of b diversity: directional turnover along a gradient vs. nondirectional variation. Different measures emphasize different properties of ecological data. Such properties include the degree of emphasis on presence ⁄ absence vs. relative abundance information and the inclusion vs. exclusion of joint absences. Judicious use of multiple measures in concert can uncover the underlying nature of patterns in b diversity for a given dataset. A case study of Indonesian coral assemblages shows the utility of a multi-faceted approach. We advocate careful consideration of relevant questions, matched by appropriate analyses. The rigorous application of null models will also help to reveal potential processes driving observed patterns in b diversity.

- by Sandy P. Harrison
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- Community Ecology, Coral Reefs, Indonesia, Ecology

We studied temporal and spatial dynamics of extremely diverse moth ensembles (Lepidoptera: Pyraloidea) along a gradient of forest disturbance ranging from undisturbed primary tropical rain forest to different kinds of modified forest and open cultivated land at the margin of Mount Kinabalu National Park (Sabah, East Malaysia). We sampled moths by light trapping during two periods (March-May and August-September 1997). We collected a total of 7724 individuals representing 680 species during 78 light-trapping nights at six study sites. Species diversity (Fisher's a) of ensembles in undisturbed primary forest was distinctly higher than in disturbed or secondary forest. More pyraloid moths were attracted in undisturbed primary forest. Samples from disturbed primary or old-growth secondary forest were statistically indistinguishable from the undisturbed primary forest ensemble in regard to species composition. Thus, pyraloid ensembles from disturbed forest with tall trees remaining appeared to represent impoverished subsets of the undisturbed primary forest community. The more heavily disturbed sites had a distinct fauna and showed a stronger faunal differentiation among each other. Four species of the genus Eoophyla, in which aquatic larvae feed on algae in fast-running streams benefited prominently from forest disturbance. Temporal variation of ensembles was remarkably concordant across the disturbance gradient. Relative abundance variation of the commonest species was identical at all sites. Overall, pyraloid moths responded more sensitively to anthropogenic habitat alteration than most other moth taxa studied thus far in tropical regions and allowed for an analysis of diversity patterns at a high temporal resolution.

- by Konrad Fiedler
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- Biological Sciences, Beta diversity, Environmental Sciences, Alpha Diversity

The variations in the size, composition and diversity of the germinable soil seed bank were studied along an altitudinal gradient in the northwestern Red Sea region. The standing vegetation and the germinable seed bank were studied in 58 stands distributed along the altitudinal range from sea level to coastal mountain peaks. The classification of the germinable seed bank by the two-way indicator species analysis (TWINSPAN) led to the recognition of five groups representing different altitudinal ranges. Detrended correspondence analysis (DCA) shows that these groups are clearly distinguished by the first two DCA axes. The results demonstrate significant associations between the floristic composition of the seed bank and the edaphic factors such as CaCO 3 , electrical conductivity, organic carbon and soil texture. Species richness, Shannon index of diversity and the size of the germinable seed bank show a hump-shaped curve along the altitudinal gradient, whereas evenness shows a weak increase with elevation increasing. Beta diversity of the seed bank declines with altitude increasing. The similarity between the standing vegetation and the seed bank approaches a U-shaped pattern along the elevation gradient. About 34.8% of the species that constitute the standing vegetation are vulnerable to elimination from the standing vegetation because they are not represented in the seed bank. Soil seed bank can be used for restoration of the vegetation at some of the degraded sites.

- by Ahmad K Hegazy
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- Sea Level, Beta diversity, Red Sea, Seed bank

Aim To analyse the zoogeography of the shallow-water holothuroids of the western Indian Ocean (WIO). Based on this analysis we ask to what extent differences in species' ability to disperse across potential barriers provide an explanation... more

- by Yves Samyn
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- Earth Sciences, Biogeography, Biological Sciences, Beta diversity

Aim By dissolving natural physical barriers to movement, human-mediated species introductions have dramatically reshuffled the present-day biogeography of freshwater fishes. The present study investigates whether the antiquity of Australia's freshwater ichthyofauna has been altered by the widespread invasion of non-indigenous fish species.

- by mark kennard
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- Ecology, Beta diversity, Freshwater Fish, Species Invasion

Abstract: Beta diversity, or the turnover in species composition among sampling sites in a region, is an important criterion for obtaining adequate representation of regional biodiversity in systems of protected areas. Recently, the additive model for partitioning regional (gamma) diversity (in opposition to the multiplicative model) has been proposed because it allows a direct measure of the contribution of beta diversity to gamma diversity. We determined avian beta diversity along latitudinal (among neighboring river drainages) and elevational axes in a 1347-km2 region on the western slope of the Central Cordillera of the Colombian Andes, where a regional system of protected areas is being designed. We then compared avian beta diversity between sites based on rapid versus long-term (>1 year) inventories and between fragmented sites versus continuous forest. Overall, beta diversity represented 63.1% of gamma diversity among 16 sites. Elevational differences in species composition accounted for 43.3% of regional diversity, whereas differences among drainages accounted for 19.8%. A complementary cluster analysis showed that sites grouped by elevational zones. Rapid inventories overestimated beta diversity because of sampling effects, but the effect was biologically small. Estimators of species richness derived from species accumulation curves provided a useful alternative to compensate for undersampling in short-term surveys. Forest fragmentation increased beta diversity because of differential local extinction of populations. Nevertheless, in our region, forest fragments contributed to gamma diversity because they contained complementary sets of species. More importantly, they contained populations of special-interest species. Although the region is relatively small, our analyses indicate that spatial differentiation of the biota is an important factor for deciding number and location of protected areas in the Andean region.Resumen: La diversidad beta, o recambio en la composición de especies entre sitios de muestreo en una región, es un criterio importante para alcanzar una adecuada representación de la biodiversidad regional en sistemas de áreas protegidas. Recientemente, el modelo aditivo para la partición de la diversidad gama o diversidad regional (en oposición al modelo multiplicativo) ha sido promocionado pues permite una medida directa de la contribución de la diversidad beta a la diversidad gama. En este estudio determinamos la diversidad beta de aves a lo largo de ejes latitudinales (entre cuencas hidrográficas vecinas) y altitudinales en una región de 1347 km2 en la vertiente occidental de la cordillera Central de los Andes de Colombia, donde se está construyendo un sistema regional de áreas protegidas. También comparamos la diversidad beta de aves entre sitios caracterizados con muestreos rápidos versus inventarios a largo plazo (>1 año) y entre sitios con bosques fragmentados versus bosques continuos. En total, la diversidad beta representó el 63.1% de la diversidad gama encontrada entre 16 localidades. Las diferencias altitudinales en composición de especies representaron el 43.3% de la diversidad regional, mientras que las diferencias entre cuencas representaron el 19.8%. Un análisis de agrupamiento complementario también mostró la diferenciación de especies por elevaciones pues las localidades se agruparon por cinturones altitudinales. Los inventarios rápidos sobre-estimaron la diversidad beta debido al efecto de muestreo incompleto, pero el efecto fue biológicamente pequeño. Los estimadores de riqueza de especies derivados de las curvas de acumulación de especies proveyeron una alternativa útil para compensar el submuestreo en los inventarios rápidos. La fragmentación de bosques aumentó la diversidad beta debido a extinción local diferencial de poblaciones. Sin embargo, en nuestra región los fragmentos de bosque contribuyen a la diversidad gama porque contienen conjuntos complementarios de especies. Además, estos fragmentos contienen poblaciones de especies de interés especial. Aunque la región es relativamente pequeña, nuestros análisis indican que la diferenciación espacial de la biota es un factor importante a la hora de tomar decisiones sobre el número y la localización de áreas protegidas en la región andina.Resumen: La diversidad beta, o recambio en la composición de especies entre sitios de muestreo en una región, es un criterio importante para alcanzar una adecuada representación de la biodiversidad regional en sistemas de áreas protegidas. Recientemente, el modelo aditivo para la partición de la diversidad gama o diversidad regional (en oposición al modelo multiplicativo) ha sido promocionado pues permite una medida directa de la contribución de la diversidad beta a la diversidad gama. En este estudio determinamos la diversidad beta de aves a lo largo de ejes latitudinales (entre cuencas hidrográficas vecinas) y altitudinales en una región de 1347 km2 en la vertiente occidental de la cordillera Central de los Andes de Colombia, donde se está construyendo un sistema regional de áreas protegidas. También comparamos la diversidad beta de aves entre sitios caracterizados con muestreos rápidos versus inventarios a largo plazo (>1 año) y entre sitios con bosques fragmentados versus bosques continuos. En total, la diversidad beta representó el 63.1% de la diversidad gama encontrada entre 16 localidades. Las diferencias altitudinales en composición de especies representaron el 43.3% de la diversidad regional, mientras que las diferencias entre cuencas representaron el 19.8%. Un análisis de agrupamiento complementario también mostró la diferenciación de especies por elevaciones pues las localidades se agruparon por cinturones altitudinales. Los inventarios rápidos sobre-estimaron la diversidad beta debido al efecto de muestreo incompleto, pero el efecto fue biológicamente pequeño. Los estimadores de riqueza de especies derivados de las curvas de acumulación de especies proveyeron una alternativa útil para compensar el submuestreo en los inventarios rápidos. La fragmentación de bosques aumentó la diversidad beta debido a extinción local diferencial de poblaciones. Sin embargo, en nuestra región los fragmentos de bosque contribuyen a la diversidad gama porque contienen conjuntos complementarios de especies. Además, estos fragmentos contienen poblaciones de especies de interés especial. Aunque la región es relativamente pequeña, nuestros análisis indican que la diferenciación espacial de la biota es un factor importante a la hora de tomar decisiones sobre el número y la localización de áreas protegidas en la región andina.

- by Carlos Valderrama and +1
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- Geography, Conservation Biology, Conservation, Colombia

Although wetland restoration has been a key part of U.S. environmental policy for 20 years (i.e., ''no net loss''), there is little long-term data on restorations to guide planning and assessment. Understanding how restored wetland communities deviate from natural conditions, and how long those deviations persist, can provide important insights into the mechanisms of recovery and improve restoration practice. This study reports the results from a 19-year survey of 37 restored prairie pothole wetlands in northern Iowa, southern Minnesota, and southeastern South Dakota. Complete floristic surveys were performed for each of the wetlands in 1989, 1990, 1991, 2000, and 2007. The accumulation of wetland species across all sites was greatest during the first 12 years after reflooding (14.4 species/year), after which the rate declined to 1.6 species/year. Proximity to natural wetlands and a semi-permanent water regime favored species accumulations during the first 12 years, but changes since then are primarily linked to water regime. Semi-permanent wetlands have experienced fewer major gains and losses in species richness, whereas temporary and seasonal wetlands have been less stable. From 2000 to 2007, extinctions exceeded colonizations in all wetlands, resulting in a convergence of beta diversity. Although 77% of the species considered common to natural wetlands in the region established in these restorations, 70% of those considered infrequent have not. The likelihood that these restorations will eventually support many additional species appears low, given the presence of barriers to recovery, especially the dominance of invasive perennials (e.g., Phalaris arundinacea and Typha angustifolia/x glauca) on all sites and the low colonization efficiency of wet prairie, sedge meadow, and woody perennial species. Management, such as active revegetation of these low efficiency species guilds, particularly sedge meadow and wet prairie perennials, and invasive species control is needed to ensure that restored prairie wetlands support the region's biodiversity. The important barriers to the recovery of prairie pothole restoration: isolation, infrequent flooding, and invasive species, are all factors that do not self-correct over time and need to be addressed during planning by establishing sound practices for initial implementation and longterm vegetation management.

- by Susan Galatowitsch
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- Earth Sciences, Wetlands, Environmental policy, Invasive Species

Lakes and reservoirs disrupt the longitudinal connectivity of streams, considerably affecting benthic macroinvertebrate assemblages and diversity. Changes in assemblage composition within fragments can result from habitat alteration and reduced dispersal between fragments. We investigated the effects of habitat fragmentation in 10 Alpine streams, examining 69 taxa of benthic macroinvertebrates from 22 sites in fragmented and freeflowing streams. Total taxon richness (a-diversity) ranged from 6 to 27 in individual sites, and total richness was not significantly affected by fragmentation. However, Ephemeroptera and Diptera (excluding Simuliidae) richness was significantly reduced in stream fragments. Beta-diversity indicated a high degree of taxon turnover among sites within streams, but was not significantly different be-

- by Piet Spaak
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- Earth Sciences, Biological Sciences, Aquatic Insects, Beta diversity

We examined the spatial and temporal variation of species diversity and genetic diversity in a metacommunity comprising 16 species of freshwater gastropods. We monitored species abundance at five localities of the Ain river floodplain in southeastern France, over a period of four years. Using 190 AFLP loci, we monitored the genetic diversity of Radix balthica, one of the most abundant gastropod species of the metacommunity, twice during that period. An exceptionally intense drought occurred during the last two years and differentially affected the study sites. This allowed us to test the effect of natural disturbances on changes in both genetic and species diversity. Overall, local (alpha) diversity declined as reflected by lower values of gene diversity H S and evenness. In parallel, the among-sites (beta) diversity increased at both the genetic (F ST ) and species (F STC ) levels. These results suggest that disturbances can lead to similar changes in genetic and community structure through the combined effects of selective and neutral processes.

- by E. Castella
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- Genetics, Population Genetics, Population Dynamics, Biodiversity