Beta diversity

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'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

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.

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  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  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). #

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.

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.

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.

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.

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.

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.

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.