Recent Shrinkage and Fragmentation of Bluegrass Landscape in Kentucky

The Bluegrass Region is an area in north-central Kentucky with unique natural and cultural significance, which possesses some of the most fertile soils in the world. Over recent decades, land use and land cover changes have threatened the protection of the unique natural, scenic, and historic resources in this region. In this study, we applied a fragmentation model and a set of landscape metrics together with the satellite-derived USDA Cropland Data Layer to examine the shrinkage and fragmentation of grassland in the Bluegrass Region, Kentucky during 2008–2018. Our results showed that recent land use change across the Bluegrass Region is characterized by grassland decline, cropland expansion, forest spread, and suburban sprawl. The grassland area decreased by 14.4%, with an interior (or intact) grassland shrinkage of 5%, during the study period. Land conversion from grassland to other land cover types has been widespread, with major grassland shrinkage occurring in the west and northeast of the Outer Bluegrass Region and relatively minor grassland conversion in the Inner Bluegrass Region. The number of patches increased from 108,338 to 126,874. The effective mesh size, which represents the degree of landscape fragmentation in a system, decreased from 6629.84 to 1816.58 for the entire Bluegrass Region. This study is the first attempt to quantify recent grassland shrinkage and fragmentation in the Bluegrass Region. Therefore, we call for more intensive monitoring and further conservation efforts to preserve the ecosystem services provided by the Bluegrass Region, which has both local and regional implications for climate mitigation, carbon sequestration, diversity conservation, and culture protection.

The Extent of Infrastructure Causing Fragmentation in the Hydrocarbon Basin in the Arid and Semi-Arid Zones of Patagonia (Argentina)

Fragmentation is a disruption in the connectivity of landscapes. The aims of this paper are (i) to quantitatively assess the fragmentation rates in three landscape units located in a hydrocarbon basin, and (ii) to model their behavior between 2001 and 2013 using landscape metrics at different scales of resolution. The following metrics were selected using principal component analysis (PCA): The Clumpiness Index (CLUMPY), patch density (PD), perimeter-area fractal dimension (PAFRAC) and effective mesh size (MESH). Results from our investigations pointed out that hydrocarbon activity increased the fragmentation at the sites. In particular, the CLUMPY index increased in all three landscape units, the average of PD decreased from 60 to 14 patches per 100 hectares, whereas the mean of MESH was quite constant, however, due to oil production, it decreased mainly in the coastal valleys. Finally, the PAFRAC also decreased at sites with oil production, being more evident in the plateau and coastal canyons. As a whole, outputs from our analyses clearly pointed out that the monitoring of landscape fragmentation trends in arid and semi-arid zones can be successfully achieved using metrics derived from satellite spectral information.

Influencia de la actividad petrolera y la ganadería ovina en la cubierta del suelo en una región árida y semiárida de la Patagonia Argentina

The Geography has provided the greatest theoretical body for the study of the configurations that occur over the geographical space. The generation of cartography that represents ground cover is one of the most important uses of remote sensing. Polygons were selected, with oil and livestock activity, in the landscape units: coastal canyons, plateaus and western valleys. The polygons were used to evaluate multi-temporal changes in land cover and plant communities over a period of 15 years. Supervised classifications and analysis of landscape metrics were made to examine the possible causes of these changes by comparing: i) polygons without oil or livestock activity (control), ii) polygons with oil and livestock activity, iii) polygons with oil activity and without livestock activity, and iv) polygons without oil activity and livestock activity. The results obtained indicated that the density of patches, the total edge, the edge density and the division index of the fragments increased in the three landscape units, between 2001 and 2016. The contagion index, however, decreased. An increase in bare soil was observed in the plateaus and in the western valleys, with a regression of the dominant plant communities. The density of patches in the sites without disturbance was the lowest, and in the sites with both disturbances acting simultaneously was maximum. In the sites without disturbance the effective mesh size was maximum, while in the sites with some disturbance it was smaller. When analyzing the effect of the disturbance on the elements of the landscape it was observed that the presence of the disturbance generates the highest density of patches and the minimum connectivity. The results show that there was a process of fragmentation in the coverage of the soil directed by the oil exploitation and sheep farming, which decrease the size of the patches and, therefore, the density of the same per unit area.

Research on heat transfer characteristics of fractal-generated turbulence based on large eddy simulation

Turbulence plays an important role in the fields of heat and mass transfer and enhanced chemical reaction. In order to explore the effect of grid-generated turbulence on flow heat transfer, in this paper, three different fractal grid structures with the same blocking ratio ?, effective mesh size Meff and thickness ratio tr= t max/t min (Case1: The grid cross-section is a triangle, Case2: the grid cross-section is an inverted triangle, Case3:the grid cross-section is square, Case4:no grid) and without the grid were simulated based on large eddy simulation. The aim of this simulation is to explain the evolution characteristics and heat transfer mechanism of turbulent flow field under the four cases. The results show that, in the same initial condition, Case 2 can generate the highest turbulence intensity and the feature of heat transfer on the cylindrical surface is more uniform. In Case 3, the boundary-layer in the flow field is separated earlier, and more vortices are excited to enhance the heat transfer than other cases in the boundary-layer region. The surface average Nusselt number is 1.3 times than that of Case 4.

ANÁLISE DO ESTADO DE DECOMPOSIÇÃO E FRAGMENTAÇÃO DA PAISAGEM COSTEIRA (ABORDAGEM GEOGRÁFICA) DO RIO GRANDE DO SUL – BRASIL / DECOMPOSITION AND FRAGMENTATION STATE ANALYSIS OF THE COASTAL LANDSCAPE (GEOGRAPHICAL APPROACH) OF RIO GRANDE DO SUL - BRAZIL

A Planície Costeira do Rio Grande do Sul é composta de um mosaico de ecossistemas frágeis e sua resiliência está relacionada diretamente à conservação da estrutura e função dos sistemas ecológicos. Sendo assim, a não-fragmentação de remanescentes naturais é um pré-requisito para a manutenção da integridade ecológica. O presente trabalho analisou a estrutura espacial da paisagem da Planície Costeira do Rio Grande do Sul a partir de índices métricos de Tamanho Efetivo de Malha e Área Nuclear que agrupados e classificados em 5 limiares qualitativos, de -10 a +10, representaram o estado de uso e ocupação da terra na paisagem costeira em 50 janelas de atenção. A integração das métricas aqui apresentadas permitiram identificar as estruturas fragmentadoras predominantes e possíveis refinamentos metodológicos a partir da constatação de que cultivos agrícolas dominam os processos ecológicos em todas as regiões litorâneas e a tendência de compactação dos remanescentes naturais afeta o diagnóstico de intensidade de uso da terra.Abstract:The Rio Grande do Sul Coastal Plain is composed by a mosaic of fragile ecosystems and its resilience is directly related to the conservation of the ecological systems structures and functions. Thus, non-fragmentation of natural remnants is a prerequisite for maintaining ecological integrity. The present work analyzed the Rio Grande do Sul Coastal Plain spatial structure through the landscape metric indexes of Effective Mesh Size and Nuclear Area. They were grouped and classified into 5 qualitative thresholds, from -10 to +10, representing the coastal landscape use and occupation among 50 attention windows. The integration of metrics presented herein allowed to identify the predominant fragmenting feature and possible methodological refinements, since agricultural crops dominated ecological processes in all coastal regions, while a trend for compaction of natural fragments affects the land use intensity diagnosis.Keywords: Effective Mesh Size; Core Area; Ecological Connection Matrix; Land Use Intensity

Avaliação da fragmentação da cobertura arbórea de Maringá/PR utilizando geotecnologias

A cobertura arbórea urbana desempenha um papel fundamental na manutenção do equilíbrio ambiental nas cidades. O uso de recursos e ferramentas gratuitas, que auxiliem os tomadores de decisão no planejamento e manejo das florestas urbanas, é uma tendência que deve ser incentivada. O objetivo deste trabalho foi avaliar a fragmentação e conectividade da cobertura arbórea urbana da cidade de Maringá/PR, por meio da aplicação do complemento LecoS de ecologia de paisagem, utilizando como base imagens e programas gratuitos. Para a extração das classes de uso e ocupação do solo, imagens RapidEye dos anos de 2012 e 2013 foram recortadas tomando como base a mancha urbana do município, e, em seguida, submetidas à classificação supervisionada. No programa livre Quantum GIS, aplicou-se a função Effective Mesh Size (meff) do complemento de ecologia de paisagens LecoS, a fim de obter as porcentagens de fragmentação da cobertura arbórea com base na área total da classe. Observou-se que a cobertura arbórea urbana de Maringá reduziu 11,4% entre 2012 e 2013 (de 14,9% para 13,2%), muito provavelmente devido ao manejo da vegetação (supressão). No entanto, a conectividade entre os fragmentos aumentou de 0,4% para 16,8% no mesmo período, indicando que lacunas na cobertura arbórea estão se fechando, tornando-a mais homogeneamente distribuída. Demais variações encontradas nas imagens são devidas à qualidade e à resolução espacial. É desejável que a cobertura arbórea esteja distribuída igualmente no tecido urbano, para que um número maior de habitantes desfrute dos benefícios trazidos pelas árvores às cidades.

Stirring and scalar transfer by grid-generated turbulence in the presence of a mean scalar gradient

The stirring of a passive scalar by grid-generated turbulence in the presence of a mean scalar gradient is studied by direct numerical simulations (DNS) for six different grids: one fractal square grid with three fractal iterations, one fractal square grid with four fractal iterations, one fractal I grid and three different regular grids. Our results can be summarised as follows. (i) For all these grids, the turbulence intensity averaged over time and over a plane parallel to the grid takes its peak value when the streamwise position of this plane is between $0.75M_{eff}$ and $1.5M_{eff}$ where $M_{eff}$ is the effective mesh size introduced by Hurst & Vassilicos (Phys. Fluids, vol. 19, 2007, 035103). (ii) Downstream of the location of this peak, the turbulence intensity averaged in this way is greatly enhanced by the fractal grids relative to the regular grids even though the fractal grids have comparable or even lower blockage ratios. The novelty of this result lies in the fact that it concerns turbulence intensities averaged over lateral planes (as well as time). (iii) The pressure drop is about the same across grids of the same blockage ratio whether fractal or not, but the pressure recovery is longer for the fractal grids. (iv) Even so, the fractal grids enhance turbulent scalar fluxes by up to an order of magnitude in the region downstream of the aforementioned peak and they also greatly enhance the streamwise growth of the fluctuating scalar variance in that region. (v) We demonstrate on a simple planar model problem that the cause of this phenomenon lies in the fractality of the grids. (vi) The turbulence scalar flux coefficient is constant far enough downstream of all the present grids and is significantly dependent on the nature and details of the turbulence-generating grid.