scholarly journals Diferenciación florística en afloramientos calizos del sur de México y el centro de Brasil: un enfoque de diversidad beta

2019 ◽  
Vol 84 ◽  
pp. 45
Author(s):  
Eduardo A. Pérez García ◽  
Anderson C. Sevilha ◽  
Jorge A. Meave ◽  
Aldicir Scariot
Keyword(s):  
Environmental Gradient ◽  
Distance Effect ◽  
Floristic Composition ◽  
Spatial Arrangement ◽  
Central Brazil ◽  
Β Diversity ◽  
Structural Variables ◽  
Order Of Magnitude ◽  
Edaphic Gradient ◽  
Study Sites

We studied the spatial arrangement of floristic diversity in two systems of limestone outcrops, located in two distant Neotropical sites: the region of Nizanda (S Mexico) and the Paranã Valley (Central Brazil). We addressed the question whether their vegetation could display a similar zonation, and we explored the relative effects of distance and an environmental gradient on α-, β- and γ-diversities. The limestone outcrops at both sites are similar in size and in elevation, but strongly differ in between-outcrop distance by an order of magnitude. At each study site three individual limestone outcrops were selected; in each of them three plant communities along the edaphic gradient were distinguished (a xerophytic scrub and two tropical dry forests types, one of which had a more xeric character than the other), and sampled for structural variables and floristic composition in 100-m2 plots. At both study sites, structural variables responded similarly to the edaphic gradient. Species density was larger in Nizanda for both α- and γ-diversity, but the largest value of β-diversity was obtained in Paranã. The edaphic gradient produced larger mean β-diversity values than the simple distance effect, with the interaction of both factors resulting in an even larger β-diversity. Classification analyses by site showed larger floristic similarities between the two xerophytic communities than those existing between them and the more mesic forests. The spatial arrangement of diversity showed that both α- and γ-diversity were smaller for the xerophytic communities. As hypothesized, the more extreme changes in community physiognomy were associated with larger β-diversity values

Diversity metrics, species turnovers and nestedness of bird assemblages in a deep karst sinkhole

2017 ◽  
Vol 63 (2) ◽  
pp. 8-16 ◽  
Author(s):  
Corrado Battisti ◽  
Marco Giardini ◽  
Francesca Marini ◽  
Lorena Di Rocco ◽  
Giuseppe Dodaro ◽  
...  
Keyword(s):  
Species Richness ◽  
Random Distribution ◽  
Diversity Index ◽  
Species Turnover ◽  
Floristic Composition ◽  
Bird Assemblages ◽  
Β Diversity ◽  
Stick Model ◽  
Karst Sinkhole

We reported a study on breeding birds occurring inside an 80 m-deep karst sinkhole, with the characterization of the assemblages recorded along its semi-vertical slopes from the upper edge until the bottom. The internal sides of the sinkhole have been vertically subdivided in four belts about 20 m high. The highest belt (at the upper edge of the cenote) showed the highest values in mean number of bird detections, mean and normalized species richness, and Shannon diversity index. The averaged values of number of detections and species richness significantly differ among belts. Species turnover (Cody’s β-diversity) was maximum between the highest belts. Whittaker plots showed a marked difference among assemblages shaping from broken-stick model to geometric series, and explicited a spatial progressive stress with a disruption in evenness towards the deepest belts. Bird assemblages evidenced a nested subset structure with deeper belts containing successive subsets of the species occurring in the upper belts. We hypothesize that, at least during the daytime in breeding season, the observed non-random distribution of species along the vertical stratification is likely due to (i) the progressive simplification both of the floristic composition and vegetation structure, and (ii) the paucity of sunlight as resources from the upper edge to the inner side of the cenote.

scholarly journals Phyllostomidae assemblage (Chiroptera: Mammalia) in altitudinal forests at the Parque Estadual do Ibitipoca, Southeast of Minas Gerais, Brazil

2016 ◽  
Vol 106 (0) ◽  
Author(s):  
Rodrigo M. Mello ◽  
Pedro H. Nobre ◽  
Marco A. Manhães ◽  
Alexmar S. Rodrigues
Keyword(s):  
Species Composition ◽  
Floristic Composition ◽  
Abundant Species ◽  
Minas Gerais ◽  
Forest Types ◽  
Mountainous Areas ◽  
Ecological Relevance ◽  
Forest Region ◽  
Study Sites ◽  
Artibeus Lituratus

ABSTRACT Many studies have demonstrated the ecological relevance and great biodiversity of bats in Brazil. However, mountainous areas have been disproportionately less sampled, mainly in the Southeast. The aim of this study was to identify and compare the richness and diversity of Phyllostomidae, the most diverse bat family, in different forest types in Parque Estadual do Ibitipoca, trying to understand the causes of possible differences. The Parque Estadual do Ibitipoca is inserted in the Serra da Mantiqueira's domain, in an Atlantic Forest region known as "Zona da Mata", state of Minas Gerais, with an altitudinal range between 1200-1784 meters. The study was conducted in two forest types, classified as "Nanofloresta Nebular" and "Floresta Nebular", whose respective data on richness and diversity were compared. The bats were captured with 8-10 mist nets for 14 months (April 2011 to May 2012) and four nights per month totaling 62,171.25 m2h of capture effort. A total of 392 captures (12 species) belonging to the Phyllostomidae family were obtained. The most abundant species were Sturnira lilium (59.9%), Platyrrhinus lineatus (11.3%), Artibeus lituratus (8.7%) and Carollia perspicillata (7.6%). The two sampled areas presented differences in bat richness, diversity and species composition, and this difference was predominantly influenced by S. lilium. It is likely that the observed difference in the assembly of bats between the two study sites depends on the variation in floristic composition. The records of A. lituratus and P. lineatus in a few months of the year and close to Ficus mexiae bearing ripe fruits suggests that at least these species move to the park for a few periods of the year in search of food resources, possibly moving through the altitudinal landscapes.

scholarly journals Zonation in a cryptic Antarctic intertidal macrofaunal community

2012 ◽  
Vol 25 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Catherine L. Waller
Keyword(s):  
Outer Surface ◽  
Intertidal Zone ◽  
General View ◽  
Annual Cycles ◽  
West Antarctic ◽  
Order Of Magnitude ◽  
Size Of Animals ◽  
Study Sites ◽  
Macrofaunal Community ◽  
The Antarctic

AbstractDespite the general view that the Antarctic intertidal conditions are too extreme to support obvious signs of macrofaunal life, recent studies have shown that intertidal communities can survive over annual cycles. The current study investigates distribution of taxa within a boulder cobble matrix, beneath the outer, scoured surface of the intertidal zone at Adelaide Island, west Antarctic Peninsula. The intertidal zone at the study sites comprised compacted, flattened cobble pavements, which have been shown to be highly stable over time. Community structure was investigated using univariate and multivariate approaches. Virtually no macrofauna were present on the outer surface, but richness, diversity, abundance and size of animals increased with depth into the rock matrix. Abundance of taxa increased by an order of magnitude between the outer surface and the lowest level sampled. These findings show that the Antarctic intertidal is not always the uninhabitable environment currently perceived, and that under these highly variable environmental conditions at least some species have the capacity to survive.

scholarly journals Relating Hydrodynamic Forcing and Topographic Response for Tide-Dominated Sandy Beaches

2020 ◽  
Vol 8 (3) ◽  
pp. 151 ◽  
Author(s):  
Evelien Brand ◽  
Anne-Lise Montreuil ◽  
Rik Houthuys ◽  
Margaret Chen
Keyword(s):  
Intertidal Zone ◽  
Spring Tide ◽  
Field Measurements ◽  
Sandy Beaches ◽  
Tidal Currents ◽  
Sediment Supply ◽  
Wave Steepness ◽  
Natural Sediment ◽  
Order Of Magnitude ◽  
Study Sites

To relate hydrodynamic forcing and topographic response for a tide-dominated sandy beach, extensive field measurements were carried out in the intertidal zone. Hydrodynamics and beach topography were monitored during a total of 12 weeks at two different study sites: one with a featureless intertidal zone and one with intertidal bars. The results of both study sites indicate that the intertidal beach grows when wave steepness is small, whereas it erodes when wave steepness is large. Spring-neap variations in tidal current direction heavily distort this trend: strong spring tidal currents transport sediment away from the beach, resulting in enhanced erosion. Tide-induced beach volume changes are on the same order of magnitude as wave-induced changes. Besides waves and tides, the effect of variations in the amount of sediment supply is substantial, with enhanced accretion when the sediment supply is large. The effect of variations in sediment supply on the intertidal beach topography is subordinate to the effect of waves and tide, though. From this study, it is concluded that larger waves are primarily erosive, but they can also enhance the natural sediment supply. Furthermore, it is found that tidal currents can be equally important as waves in shaping the beach topography, especially during spring tide on macrotidal beaches.

scholarly journals Taxonomic and Functional Response of Millipedes (Diplopoda) to Urban Soil Disturbance in a Metropolitan Area

Insects ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 25 ◽  
Author(s):  
Zsolt Tóth ◽  
Elisabeth Hornung
Keyword(s):  
Metropolitan Area ◽  
Species Turnover ◽  
Chemical Properties ◽  
Soil Disturbance ◽  
Danube River ◽  
Functional Responses ◽  
Β Diversity ◽  
Functional Richness ◽  
Study Sites ◽  
And Function

Urbanization, as a major cause of local species extinction and biotic homogenization, drastically alters soil life. Millipedes are a key group of soil macrodetritivores and significantly influence soil quality, mainly through their essential role in nutrient cycling. Therefore, studying their taxonomic and functional responses to urban disturbance is crucial, as they contribute to the provision of several soil-related ecosystem services in cities. Differently degraded rural, urban forests and other woody patches (e.g., parks, gardens, and cemeteries) were sampled on Buda and Pest sides of the Budapest metropolitan area divided by the Danube River. We measured the most relevant physical and chemical properties of topsoil to characterize habitats. We applied an urbanization index based on vegetation cover and built-up area of the study sites to quantify urban intensity. The composition of the assemblages was determined by the division of the city along the Danube. Urbanization was associated with a reduction in species and functional richness of millipedes on both sides of Budapest. β diversity and species turnover increased with urban intensity. Urban disturbance was the main driver in assembly of taxonomic and functional community composition. A new species (Cylindroiulus caeruleocinctus (Wood, 1864)) to the fauna of Budapest was found. Detritivore invertebrates depend on leaf litter and other dead organic matter types, therefore microsites providing these resources greatly improve their survival. Due to increasing urban disturbance, it is recommended to provide appropriate detritus and shelter sites as part of the management of green spaces in order to maintain species richness, abundance, and function of species.

Identifying resilient Eastern Massasauga Rattlesnake (Sistrurus catenatus) peatland hummock hibernacula

2018 ◽  
Vol 96 (9) ◽  
pp. 1024-1031 ◽  
Author(s):  
A.G. Smolarz ◽  
P.A. Moore ◽  
C.E. Markle ◽  
J.M. Waddington
Keyword(s):  
Water Table ◽  
Spatial Arrangement ◽  
Subsurface Temperature ◽  
Contributing Factors ◽  
Northern Limit ◽  
Deep Freezing ◽  
Sistrurus Catenatus ◽  
Eastern Massasauga Rattlesnake ◽  
Study Sites ◽  
Water Table Rise

At the northern limit of the Eastern Massasauga Rattlesnake’s (Sistrurus catenatus (Rafinesque, 1818)) range, individuals spend up to half the year overwintering. In hummock hibernacula found in peatlands, it is likely that subsurface temperature and water table position are contributing factors dictating habitat suitability. As a step towards assessing the vulnerability of hibernacula to anthropogenic changes, we combined subsurface temperature and water table dynamics to assess the likelihood that unflooded and unfrozen conditions were present in hummock hibernacula. Our results indicate that taller hummocks are more resilient to an advancing frost line and fluctuating water table by providing a larger area and duration of unfrozen and unflooded conditions, and a critical overwintering depth that is farther from the hummock surface. In two study sites along eastern Georgian Bay, an unflooded and unfrozen zone was present for over 90% of the overwintering period for hummocks taller than 25–27 cm. Our findings highlight the vulnerability of peatland hummocks to variability of winter weather where deep freezing and (or) water table rise may nonlinearly reduce resilience. This suggests that height is not the only component affecting the suitability of hummock hibernacula and that further research should examine the structure and spatial arrangement of hummocks within a peatland.

scholarly journals Impacts of Human Activities on Tree Species Composition Along the Forest Savanna Boundary in Nigeria

2016 ◽  
Vol 47 (2) ◽  
pp. 115 ◽  
Author(s):  
Christiana Ndidi Egbinola
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Human Activities ◽  
Detrended Correspondence Analysis ◽  
Floristic Composition ◽  
Forest Species ◽  
Tree Species Composition ◽  
Study Sites ◽  
The Impact ◽  
The Relationship

The study investigated the tree species composition along the forest-savanna boundary in Oyo state of Nigeria with the aim of assessing the impact of human activities on the floristic composition. A transect was placed along the study area and species data was collected from quadrats placed in study plots within different study sites. Detrended Correspondence Analysis (DCA) was used to determine vegetation assemblages, while both correlation and the analysis of variance (ANOVA) were used to show the relationship between species in the different study sites. Results of the DCA revealed three species assemblages, an area with only forest species, another with only savanna species and a third with both forest/savanna species. ANOVA results further revealed that within the forest and savanna assemblages, species in mature and successional sites were alike. The study therefore revealed that human activities’ within the region is leading to the establishment of savanna species and an elimination of forest species.

Geotubes vs. mulching for post-fire erosion mitigation in eucalypt vs. pine plantations in Central Portugal vs. Galicia

2021 ◽  
Author(s):  
Ana Isabel Machado ◽  
Bruna Oliveira ◽  
Dalila Serpa ◽  
Martha Santos ◽  
Fátima Jesus ◽  
...  
Keyword(s):  
Sediment Traps ◽  
Mitigation Measures ◽  
Runoff Generation ◽  
Monthly Basis ◽  
Erosion Rates ◽  
The Usa ◽  
Order Of Magnitude ◽  
Central Portugal ◽  
Erosion Mitigation ◽  
Study Sites

<p>Wildfires are well-known to negative affect forest both directly and indirectly, due to fire-enhanced runoff generation and the associated losses of wildfire ash, soil, organic matter and nutrients. In turn, post-fire runoff and erosion can, promote eutrophication and contamination of downstream surface water bodies. A variety of erosion mitigation measures have been tested in recently burnt areas, with especially mulching with straw having been applied in operational post-fire land management in the USA and Galicia. The present work, evaluates the effectiveness of a new erosion mitigation strategy, using geotubes filled with mycotechnosols and straw, and compares it to that of mulching. This was done for the two prevalent forest types in central Portugal and Galicia, i.e. an eucalypt plantation in Central Portugal and a pine plantation in Galicia that both burnt during the summer of 2019.  Both study sites were instrumented with 9 bounded erosion plots of 16m<sup>2</sup> with sediment traps at the bottom of the plots, divided over three blocks. The three treatments of doing nothing, mulching and geotubes were applied to one plot per block. In total, 4 geotubes were placed in each plot to create a barrier in the middle of the plot and at the bottom, just before the sediment deposition zone at the plot outlet. Mulching was done with chopped eucalypt bark at the eucalypt site and with pine needles at the pine site, at application rates of roughly 250 g m<sup>-2</sup>. Eroded sediments were collected on a bi-weekly to monthly basis, depending on occurrence of rain, during the first post-fire hydrological year. The results showed that the erosion rates of the control plots differed about one order of magnitude between the two sites, amounting to  an average of 11 Mg  ha<sup>-1 </sup>y-<sup>1</sup> at the pine site as opposed to 1.0 Mg ha<sup>-1</sup> y-<sup>1</sup>  at the eucalypt site. This discrepancy was probably related to soil type (derived from granite vs. schist) and stoniness. Mulching was somewhat more effective than the geotubes at the pines site, with reduction in average annual erosion rates of 84 and 77%, respectively. The opposite was true at the eucalypt site, with annual erosion reductions of on average 75 and 62%. The use of geotubes would therefore seem a further option for forest and water resources managers to decrease markedly the risks of both elevated and reduced soil (fertility) losses from recently burnt hillslopes and the associated risks for downstream values.</p>

scholarly journals Divergent responses of β‐diversity among organism groups to a strong environmental gradient

Ecosphere ◽  
2016 ◽  
Vol 7 (10) ◽  
Author(s):  
Micael Jonsson ◽  
Tord Snäll ◽  
Johan Asplund ◽  
Karina E. Clemmensen ◽  
Anders Dahlberg ◽  
...  
Keyword(s):  
Environmental Gradient ◽  
Β Diversity

Force-Assembled Fe3O4 Particle Chains in Polyurethane Matrix

2016 ◽  
Vol 851 ◽  
pp. 221-225
Author(s):  
Marek Zboncak ◽  
Frantisek Ondreas ◽  
Josef Jancar
Keyword(s):  
Magnetic Field ◽  
Self Assembly ◽  
Spatial Arrangement ◽  
Precise Control ◽  
Electro Magnetic Field ◽  
Wide Range ◽  
Structural Variables ◽  
Simple Change ◽  
Electro Magnetic ◽  
Polyurethane Matrix

Despite substantial research efforts, the potential of polymer nanocomposites has still not been fully revealed, mainly due to poor control over the dispersion and alignment of nanoparticles (NPs). Since nanocomposite properties are controlled by the structural variables, it is crucial to achieve control over the NP assembly process.Self-assembly of NPs offers limited control over the NP spatial arrangement. This process results in a poorly controlled variation of simple structures such as agglomerates, clusters and dispersed NPs with the resulting structure strongly dependent a on wide range of thermodynamic parameters.On the other hand, force-assembly exploits interactions between particles induced by external force fields overcoming the thermodynamic ones. Stimulus of external electric, magnetic or electro-magnetic field is applied as the main force controlling the assembly of NPs. Understanding this process gives us the opportunity to create prescribed NP structures with controlled shape, size, and anisotropy by simple change of the force field. Precise control of structure formation on different length scales (from nanoto macro) gives us the opportunity to imitate hierarchical biological structures possessing unique balance of stiffness and toughness.Here, we report on magnetic field force assembly of Fe3O4 nanoparticles in the polyurethane matrix. Resulting NP chain structures were several NP wide and tens of micrometers long aligned along the magnetic force lines. Without the magnetic field, NP agglomerates of random size and shape were formed due to their self-assembly.

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