scholarly journals Dynamics of vegetation structure in a fragmented landscape in Minas Gerais, Brazil

2019 ◽  
Vol 79 (4) ◽  
pp. 678-685 ◽  
Author(s):  
N. V. Salomão ◽  
M. D. D. Silva ◽  
E. L. M. Machado
Keyword(s):  
Edge Effect ◽  
Fire Resistance ◽  
Edge Effects ◽  
Vegetation Structure ◽  
Patch Dynamics ◽  
Minas Gerais ◽  
Fragmented Landscape ◽  
Landscape Changes ◽  
Dynamics Of Vegetation

Abstract Considering that area and edge effects are the most important factors that lead to landscape changes from the fragmentation of terrestrial communities, the present study aimed to analyze changes in the structure of vegetation classes of a fragmented landscape. The methodology employed was based on a model of patch dynamics for the years between 1979 and 2015. The analysis was performed with quantitative (area, shape and edge effect) and qualitative (low declivity of the terrain, fire resistance and tolerance to variation in light) variables of the classes of vegetation. Processes of retraction and expansion of the vegetation classes were identified, as well as the alteration of the structure of the fragments, which resulted in the intensification of the edge effect.

scholarly journals Effects of habitat edges on vegetation structure and the vulnerable golden-brown mouse lemur (Microcebus ravelobensis) in northwestern Madagascar

BMC Ecology ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Bertrand Andriatsitohaina ◽  
Daniel Romero-Mujalli ◽  
Malcolm S. Ramsay ◽  
Frederik Kiene ◽  
Solofonirina Rasoloharijaona ◽  
...  
Keyword(s):  
Body Mass ◽  
Edge Effects ◽  
Vegetation Structure ◽  
Species Abundance ◽  
Tree Height ◽  
Logistic Function ◽  
Study Region ◽  
Large Trees ◽  
Significant Difference ◽  
Vegetation Parameters

Abstract Background Edge effects can influence species composition and community structure as a result of changes in microenvironment and edaphic variables. We investigated effects of habitat edges on vegetation structure, abundance and body mass of one vulnerable Microcebus species in northwestern Madagascar. We trapped mouse lemurs along four 1000-m transects (total of 2424 trap nights) that ran perpendicular to the forest edge. We installed 16 pairs of 20 m2 vegetation plots along each transect and measured nine vegetation parameters. To determine the responses of the vegetation and animals to an increasing distance to the edge, we tested the fit of four alternative mathematical functions (linear, power, logistic and unimodal) to the data and derived the depth of edge influence (DEI) for all parameters. Results Logistic and unimodal functions best explained edge responses of vegetation parameters, and the logistic function performed best for abundance and body mass of M. ravelobensis. The DEI varied between 50 m (no. of seedlings, no. of liana, dbh of large trees [dbh ≥ 10 cm]) and 460 m (tree height of large trees) for the vegetation parameters, whereas it was 340 m for M. ravelobensis abundance and 390 m for body mass, corresponding best to the DEI of small tree [dbh < 10 cm] density (360 m). Small trees were significantly taller and the density of seedlings was higher in the interior than in the edge habitat. However, there was no significant difference in M. ravelobensis abundance and body mass between interior and edge habitats, suggesting that M. ravelobensis did not show a strong edge response in the study region. Finally, regression analyses revealed three negative (species abundance and three vegetation parameters) and two positive relationships (body mass and two vegetation parameters), suggesting an impact of vegetation structure on M. ravelobensis which may be partly independent of edge effects. Conclusions A comparison of our results with previous findings reveals that edge effects are variable in space in a small nocturnal primate from Madagascar. Such an ecological plasticity could be extremely relevant for mitigating species responses to habitat loss and anthropogenic disturbances.

scholarly journals Tentative Investigations on Reducing the Edge Effects in Pre-Polishing the Optics

2020 ◽  
Vol 10 (15) ◽  
pp. 5286
Author(s):  
Xiaolong Ke ◽  
Lei Qiu ◽  
Chunjin Wang ◽  
Zhenzhong Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Edge Effect ◽  
Edge Effects ◽  
Material Removal ◽  
Processing Time ◽  
Grinding Process ◽  
Element Analysis ◽  
Edge Zone ◽  
The Finite Element Analysis

The material removal depth in the pre-polishing stage of the precision optics is usually tens of microns to remove the subsurface damage and grinding marks left by the previous grinding process. This processing of the upstand edge takes a large part of the time at this stage. The purpose of this paper is to develop a method that can reduce the edge effect and largely shorten the processing time of the pre-polishing stage adopting the semirigid (SR) bonnet. The generation of the edge effect is presented based on the finite element analysis of the contact pressure at the edge zone firstly. Then, some experimentations on the edge effect are conducted, and the results proved that the SR bonnet tool can overhang the workpiece edge in the pre-polishing stage to reduce the width and height of the upstand edge to largely shorten the subsequent processing time of it. In addition, there exists a perfect overhang ratio, which generates the upstand edge with the smallest width and height, with no damage to the bonnet tool in the meantime. In addition, one combination of the pre-polishing parameters is concluded according to this method, which can be safely adopted in practical process.

scholarly journals Dendrochronology and growth of Copaifera langsdorffii wood in the vegetation dynamics of the Pirapitinga Ecological Station, state of Minas Gerais, Brazil

FLORESTA ◽  
2018 ◽  
Vol 48 (1) ◽  
pp. 49 ◽  
Author(s):  
Daniel Costa de Carvalho ◽  
Marcos Gervasio Gervasio Pereira ◽  
Jair Figueiredo do Carmo ◽  
José Henrique Camargo Pace ◽  
Leonardo Davi Silveira Augusto Baptista da Silva ◽  
...  
Keyword(s):  
Vegetation Type ◽  
Pearson Correlation ◽  
Minas Gerais ◽  
Average Sensitivity ◽  
Growth Rings ◽  
Copaifera Langsdorffii ◽  
Environmental Variations ◽  
Lower Population ◽  
Lower Population Density ◽  
Dynamics Of Vegetation

This study aims to build a chronology of the growth rings of Copaifera langsdorffii (copaíba) in order to understand the dynamics of vegetation types that occur on a river island in the Cerrado biome. For this purpose, we selected 30 trees of copaíba established in a vegetation of Mata Seca Sempre-Verde in the Pirapitinga Ecological Station (EEP), state of Minas Gerais, Brazil. Two radial samples from each tree were collected by an auger. The samples were treated by mechanical polishing for better visualization of the growth rings, and consequently further delineation and measurement. Later, the width of the growth rings was verified in order to generate a master time series of the specie. To check the influence of meteorological factors, we used the Pearson correlation (p < 0.05). The results showed that the population of copaíba in the EEP presented dendrochronologyc potential, which was confirmed by the high values of wide growth rings correlation within and between trees. The dendrochronologyc analysis revealed that copaíba trees were already present before the dam filling, but with lower population density than today. It was also possible to infer that the development of the vegetation type Mata Seca Sempre-Verde occurred since the decade of the 1970. The average sensitivity was enough to consider the species sensitive to environmental variations. Precipitation and temperature only influenced positively the growth rings in the transition from dry to wet seasons. The results revealed information about the dynamics of the local vegetation, elucidating the changes that occurred in the environment in which the population of copaíba is established.

Recovery Dynamics of Vegetation and Soil Properties in Karst Rocky Desertification Areas in Guizhou, China

2012 ◽  
Vol 518-523 ◽  
pp. 4532-4544 ◽  
Author(s):  
Hong Yan Liu ◽  
Fang Liu
Keyword(s):  
Soil Fertility ◽  
Soil Properties ◽  
Vegetation Structure ◽  
Vegetation Recovery ◽  
Native Forest ◽  
Forming Process ◽  
Karst Rocky Desertification ◽  
Rocky Desertification ◽  
Available Nitrogen ◽  
Dynamics Of Vegetation

Abstract. Dynamics of vegetation and soil properties responses to vegetation recovery in the selected 72 Karst desertification sites in Guizhou, China were studied. Six typical and representative vegetation types along a chronosequence of vegetation recovery (corn land, sparse grass, regeneration forest, shrub, grass and shrub, and native forest with 0, 3-5, 10-15, 20-30, 30-40, and >100 yrs, respectively) were selected for the study of the plant species, vegetation features as well as soil physical & chemical properties in order to assess interaction between soil properties and vegetation structure. It was found that vegetation species had dry-resistant characteristics because of their extensive exposure to the basement rocks and thinness soil. Grass community was always coarse grass, shrub was generally dominated by vines, thorn bushes and tree species were almost leather-like, single and mini-type leaf plants. Factor analysis showed that the 3 factors, soil fertility, pH and clay, explain 67.97 % of total variance among the 19 soil property parameters. Soil fertility changed significantly effects included the increasing of soil organic matter, total and available nitrogen, humic acid, CEC, fuvic acid, exchange Ca, porosity and total P but decreasing bulk density. This trend was followed by enhancing of bio-enrichment capacity along the chronosequence of vegetation recovering process. Soil pH had no significant correlation with the vegetation recovery stages because it was determined by soil forming process and characteristic of parent materials. The factor clay only decreased slightly in the recovery stages. Cluster analysis indicated that vegetation structure could develop within short time under anthropocentric interfering, but soil fertility only accumulated with annual litter decomposing. We can conclude that recovery of vegetation community structure proceeded restoration of soil function.

Biodiversity responses to vegetation structure in a fragmented landscape: ant communities in a peri-urban coastal dune system

2016 ◽  
Vol 20 (3) ◽  
pp. 485-495 ◽  
Author(s):  
Sophie L. Cross ◽  
Adam T. Cross ◽  
David J. Merritt ◽  
Kingsley W. Dixon ◽  
Alan N. Andersen
Keyword(s):  
Vegetation Structure ◽  
Coastal Dune ◽  
Fragmented Landscape ◽  
Dune System ◽  
Ant Communities ◽  
Coastal Dune System

Spider diversity responds strongly to edge effects but weakly to vegetation structure in riparian forests of Southern Brazil

2014 ◽  
Vol 8 (2) ◽  
pp. 123-133 ◽  
Author(s):  
Everton Nei Lopes Rodrigues ◽  
Milton De Souza Mendonça ◽  
Luiz Ernesto Costa-Schmidt
Keyword(s):  
Edge Effects ◽  
Vegetation Structure ◽  
Riparian Forests ◽  
Southern Brazil

Free-Edge Effects in Composite Laminates

2007 ◽  
Vol 60 (5) ◽  
pp. 217-245 ◽  
Author(s):  
Christian Mittelstedt ◽  
Wilfried Becker
Keyword(s):  
Stress Concentration ◽  
Edge Effect ◽  
Edge Effects ◽  
Composite Laminates ◽  
Relevant Literature ◽  
Free Edge ◽  
Experimental Investigations ◽  
Singular Stress ◽  
Concentration Problem ◽  
Concentration Phenomena

There are many technical applications in the field of lightweight construction as, for example, in aerospace engineering, where stress concentration phenomena play an important role in the design of layered structural elements (so-called laminates) consisting of plies of fiber reinforced plastics or other materials. A well known stress concentration problem rich in research tradition is the so-called free-edge effect. Mainly explained by the mismatch of the elastic material properties between two adjacent dissimilar laminate layers, the free-edge effect is characterized by the concentrated occurrence of three-dimensional and singular stress fields at the free edges in the interfaces between two layers of composite laminates. In the present contribution, a survey on relevant literature from more than three decades of scientific research on free-edge effects is given. The cited references date back to 1967 and deal with approximate closed-form analyses, as well as numerical investigations by the finite element method, the finite difference method, and several other numerical techniques. The progress in research on the stress singularities which arise is also reviewed, and references on experimental investigations are cited. Related problems are also briefly addressed. The paper closes with concluding remarks and an outlook on future investigations. In all, 292 references are included.

Edge effects on yield, yield components and other traits in mechanized durum wheat and barley trials

1983 ◽  
Vol 101 (2) ◽  
pp. 383-387 ◽  
Author(s):  
A. Hadjichristodoulou
Keyword(s):  
Grain Yield ◽  
Durum Wheat ◽  
Edge Effect ◽  
Edge Effects ◽  
Yield Components ◽  
Straw Yield ◽  
Varietal Differences ◽  
Arid Conditions ◽  
1000 Grain Weight ◽  
Semi Arid

SUMMARYA series of trials were conducted during 1979–82 under semi-arid conditions in a Mediterranean-type environment to study the edge effects in mechanized durum wheat and barley variety trials when uncropped pathways are left between plots. Varietal differences in edge effects on grain yield were in most trials not significant. Thus, edge effects do not distort significantly the relative ranking of varieties.Edge effects were significant for all traits studied and higher in grain and straw yields. These effects were also higher in drier seasons. The overestimation of grain yield from whole plots was 13–18% in relatively high rainfall seasons and 29% in a dry season. In two seasons the scores on the two outer rows were higher than on the two central rows by 89 and 117 % for grain yield, by 72 and 73% for straw yield, by 44 and 48% for numbers of tillers, by 6% for 1000-grain weight and by 14 and 40% for number of grains per tiller. The edge effect was not confined to the outer rows, but it extended to the inner rows of the plot; the magnitude of this effect varied with season and trait.Rows adjacent to the pathway and unprotected from wind had a lower value for all traits than the opposite rows of the pathway, which were protected by the inner rows.

Voles looking for an edge: habitat selection across forest ecotones

2000 ◽  
Vol 78 (12) ◽  
pp. 2174-2183 ◽  
Author(s):  
Steven R Kingston ◽  
Douglas W Morris
Keyword(s):  
Habitat Selection ◽  
Edge Effect ◽  
Edge Effects ◽  
Selection Effect ◽  
Habitat Model ◽  
The Other ◽  
Controlled Experiments ◽  
Habitat Boundaries ◽  
Forest Habitats ◽  
Null Expectation

We searched for the presence of "edge effects" in the occupation of adjacent boreal-forest habitats by red-backed voles (Clethrionomys gapperi). First, we reviewed four models that differ in their predictions of abundance at habitat boundaries. Three of the models predicted an edge effect, while the so-called matrix or habitat model served as a null expectation. We then developed a protocol to detect, objectively, the ecotone between two habitats that is necessary to differentiate among the four models. The protocol revealed both abrupt and gradual ecotones along transects crossing conifer to cutover and conifer to deciduous habitats. Though vole density was almost always higher on one side of the ecotone than on the other, we were unable to detect an edge effect of any kind. Vole density within ecotones was intermediate to that on each side (refuting the existence of an ecotone effect). There were also no differences in the pattern of density between abrupt and gradual ecotones (refuting the existence of a permeability effect), and no consistent pattern of vole density away from either type of ecotone (refuting the existence of a habitat-selection effect). Simulations that manipulated vole densities along the transects suggested, however, that the habitats may have been too similar to allow a habitat-selection effect to be detected. We suspect that our result will be common to moderately generalised species, and we recommend that controlled experiments be carried out to evaluate the conditions under which habitat-selecting species may exhibit edge effects.

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