The Experts below are selected from a list of 64161 Experts worldwide ranked by ideXlab platform
I Gouttevin - One of the best experts on this subject based on the ideXlab platform.
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how the insulating properties of snow affect soil carbon distribution in the continental pan arctic Area
Journal of Geophysical Research, 2012Co-Authors: I Gouttevin, Martin Menegoz, Florent Domine, Gerhard Krinner, Charles D Koven, P Ciais, Charles TarnocaiAbstract:[1] We demonstrate the effect of an ecosystem differentiated insulation by snow on the soil thermal regime and on the Terrestrial soil carbon distribution in the pan-Arctic Area. This is done by means of a sensitivity study performed with the land surface model ORCHIDEE, which furthermore provides a first quantification of this effect. Based on field campaigns reporting higher thermal conductivities and densities for the tundra snowpack than for taiga snow, two distributions of near-equilibrium soil carbon stocks are computed, one relying on uniform snow thermal properties and the other using ecosystem-differentiated snow thermal properties. Those modeled distributions strongly depend on soil temperature through decomposition processes. Considering higher insulation by snow in taiga Areas induces warmer soil temperatures by up to 12 K in winter at 50 cm depth. This warmer soil signal persists over summer with a temperature difference of up to 4 K at 50 cm depth, especially in Areas exhibiting a thick, enduring snow cover. These thermal changes have implications on the modeled soil carbon stocks, which are reduced by 8% in the pan-Arctic continental Area when the vegetation-induced variations of snow thermal properties are accounted for. This is the result of diverse and spatially heterogeneous ecosystem processes: where higher soil temperatures lift nitrogen limitation on plant productivity, tree plant functional types thrive whereas light limitation and enhanced water stress are the new constrains on lower vegetation, resulting in a reduced net productivity at the pan-Arctic scale. Concomitantly, higher soil temperatures yield increased respiration rates (+22% over the study Area) and result in reduced permafrost extent and deeper active layers which expose greater volumes of soil to microbial decomposition. The three effects combine to produce lower soil carbon stocks in the pan-Arctic Terrestrial Area. Our study highlights the role of snow in combination with vegetation in shaping the distribution of soil carbon and permafrost at high latitudes.
Murray K. Clayton - One of the best experts on this subject based on the ideXlab platform.
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Building patterns and landscape fragmentation in northern Wisconsin, USA
Landscape Ecology, 2007Co-Authors: Charlotte E. Gonzalez-abraham, Volker C. Radeloff, Roger B. Hammer, Todd J. Hawbaker, Susan I. Stewart, Murray K. ClaytonAbstract:Housing growth is prevalent in rural Areas in the United States and landscape fragmentation is one of its many effects. Since the 1930s, rural sprawl has been increasing in Areas rich in recreational amenities. The question is how housing growth has affected landscape fragmentation. We thus tested three hypotheses relating land cover and land ownership to density and spatial pattern of buildings, and examined whether building density or spatial pattern of buildings was a better predictor for landscape fragmentation. Housing locations were mapped from 117 1:24,000-scale USGS topographic maps across northern Wisconsin. Patch-level landscape metrics were calculated on the Terrestrial Area remaining after applying 50, 100 and 250 m disturbance zones around each building. Our results showed that building density and the spatial pattern of buildings were affected mostly by lake Area, public land ownership, and the abundance of coniferous forest, agricultural land, and grassland. A full 40% of the houses were within 100 m of lakeshores. The clustering of buildings within 100 m of lakeshores limited fragmentation farther away. In contrast, agricultural and grassland Areas were correlated with higher building density, higher fragmentation, and more dispersed building pattern possible legacies of agricultural settlement patterns. Understanding which factors influence building density and fragmentation is useful for landscape level planning and ecosystem management in northern Wisconsin and Areas that share similar social and environmental constraints.
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road development housing growth and landscape fragmentation in northern wisconsin 1937 1999
Ecological Applications, 2006Co-Authors: Todd J. Hawbaker, Volker C. Radeloff, Roger B. Hammer, Murray K. Clayton, Charlotte E GonzalezabrahamAbstract:Roads remove habitat, alter adjacent Areas, and interrupt and redirect ecological flows. They subdivide wildlife populations, foster invasive species spread, change the hydrologic network, and increase human use of adjacent Areas. At broad scales, these impacts cumulate and define landscape patterns. The goal of this study was to improve our understanding of the dynamics of road networks over time, and their effects on landscape patterns, and identify significant relationships between road changes and other land-use changes. We mapped roads from aerial photographs from five dates between 1937 and 1999 in 17 townships in predominantly forested landscapes in northern Wisconsin, USA. Patch-level landscape metrics were calculated on Terrestrial Area outside of a 15-m road-effect zone. We used generalized least-squares regression models to relate changes in road density and landscape pattern to concurrent changes in housing density. Rates of change and relationships were compared among three ecological regions...
Arkadiusz Fröhlich - One of the best experts on this subject based on the ideXlab platform.
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Habitat type, food resources, noise and light pollution explain the species composition, abundance and stability of a winter bird assemblage in an urban environment
Urban Ecosystems, 2017Co-Authors: Michał Ciach, Arkadiusz FröhlichAbstract:At present, urban Areas cover almost 3% of the Earth’s Terrestrial Area, and this proportion is constantly increasing. Although urbanization leads to a decline in biodiversity, at the same time it creates extensive habitats that are exploited by an assemblage of organisms, including birds. The species composition and density of birds nesting in towns and cities are determined by the types of buildings, the structure and maturity of urban greenery, and habitat diversity. In contrast, the habitat traits shaping the community of birds wintering in urban Areas are not known. The aim of this work was to assess the influence of habitat structure, food resources and the urban effects (pollution, noise, artificial light) on an assemblage of birds overwintering in an urban Area. It was carried out in 2014 and 2015 in the city of Kraków (southern Poland), on 56 randomly chosen sample plots, in which the composition, density and interseasonal similarity of bird assemblage were assessed with line transect method. A total of 64 bird species (mean = 17.7 ± 4.9 SD species/plot) was recorded. The mean density was 89.6 ind./km ±63.3 SD. The most numerous species were Great Tit Parus major , Magpie Pica pica , Blackbird Turdus merula , Blue Tit Cyanistes caeruleus , Rook Corvus frugilegus , Fieldfare Turdus pilaris and House Sparrow Passer domesticus . Noise adversely affected species numbers and density, but artificial light acted positively on the density of birds and their interseasonal stability. The species richness and density of birds were also determined by the number of food sources available (e.g. bird-feeders). In addition, the greater the proportion of open Areas, the fewer species were recorded. In contrast, the more urban greenery there was, the greater the density of the entire bird assemblage. Urban infrastructure (buildings, roads, refuse tips) had a positive effect on the interseasonal stabilization of the species composition of wintering birds. The results of this work indicate that the urban effect, i.e. noise and light pollution, apart from purely habitat factors, provide a good explanation for the species richness, density and stability of bird assemblage wintering in urban Areas.
Charles Tarnocai - One of the best experts on this subject based on the ideXlab platform.
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how the insulating properties of snow affect soil carbon distribution in the continental pan arctic Area
Journal of Geophysical Research, 2012Co-Authors: I Gouttevin, Martin Menegoz, Florent Domine, Gerhard Krinner, Charles D Koven, P Ciais, Charles TarnocaiAbstract:[1] We demonstrate the effect of an ecosystem differentiated insulation by snow on the soil thermal regime and on the Terrestrial soil carbon distribution in the pan-Arctic Area. This is done by means of a sensitivity study performed with the land surface model ORCHIDEE, which furthermore provides a first quantification of this effect. Based on field campaigns reporting higher thermal conductivities and densities for the tundra snowpack than for taiga snow, two distributions of near-equilibrium soil carbon stocks are computed, one relying on uniform snow thermal properties and the other using ecosystem-differentiated snow thermal properties. Those modeled distributions strongly depend on soil temperature through decomposition processes. Considering higher insulation by snow in taiga Areas induces warmer soil temperatures by up to 12 K in winter at 50 cm depth. This warmer soil signal persists over summer with a temperature difference of up to 4 K at 50 cm depth, especially in Areas exhibiting a thick, enduring snow cover. These thermal changes have implications on the modeled soil carbon stocks, which are reduced by 8% in the pan-Arctic continental Area when the vegetation-induced variations of snow thermal properties are accounted for. This is the result of diverse and spatially heterogeneous ecosystem processes: where higher soil temperatures lift nitrogen limitation on plant productivity, tree plant functional types thrive whereas light limitation and enhanced water stress are the new constrains on lower vegetation, resulting in a reduced net productivity at the pan-Arctic scale. Concomitantly, higher soil temperatures yield increased respiration rates (+22% over the study Area) and result in reduced permafrost extent and deeper active layers which expose greater volumes of soil to microbial decomposition. The three effects combine to produce lower soil carbon stocks in the pan-Arctic Terrestrial Area. Our study highlights the role of snow in combination with vegetation in shaping the distribution of soil carbon and permafrost at high latitudes.
Laurent Godet - One of the best experts on this subject based on the ideXlab platform.
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The influence of salina landscape structures on Terrestrial bird distribution in the Guérande basin (Northwestern France)
Bird Study, 2012Co-Authors: Christophe Dominik, Loic Ménanteau, Céline Chadenas, Laurent GodetAbstract:Capsule The salinas of the Guerande basin show highly fragmented landscapes that significantly structure the distribution of Terrestrial birds. Aim To test the potential influence of landscape structures of a fragmented landscape on the distribution of Terrestrial birds. Methods The salinas were mapped using a Geographical Information System and landscape metrics were calculated to quantify landscape structures. Birds were surveyed with a point count method. Multivariate analyses and multiple linear regressions were used to test for potential links between landscape metrics and bird distribution. Results The landscape structures of the salinas influenced bird assemblages significantly. The core of the salinas, with more-fragmented and less-diverse landscapes, contained the lowest abundance, richness and diversity of birds, but this assemblage tended to be homogeneous and distinct. Bird abundance, richness and diversity mainly increased with landscape richness and diversity, the Terrestrial Area available ...
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The influence of salina landscape structures on Terrestrial bird distribution in the Guérande basin (Northwestern France)
Bird Study, 2012Co-Authors: Christophe Dominik, Loic Ménanteau, Céline Chadenas, Laurent GodetAbstract:Capsule. The salinas of the Guérande basin show highly fragmented landscapes that significantly structure the distribution of Terrestrial birds. Aim. To test the potential influence of landscape structures of a fragmented landscape on the distribution of Terrestrial birds. Methods. The salinas were mapped using a Geographical Information System and landscape metrics were calculated to quantify landscape structures. Birds were surveyed with a point count method. Multivariate analyses and multiple linear regressions were used to test for potential links between landscape metrics and bird distribution. Results. The landscape structures of the salinas influenced bird assemblages significantly. The core of the salinas, with more-fragmented and less-diverse landscapes, contained the lowest abundance, richness and diversity of birds, but this assemblage tended to be homogeneous and distinct. Bird abundance, richness and diversity mainly increased with landscape richness and diversity, the Terrestrial Area available and the proximity to the continental domain. Conclusion. This study is the first to demonstrate and quantify the influence of salina landscape structures on Terrestrial bird assemblages.