A Holistic Landscape Description Reveals That Landscape Configuration Changes More over Time than Composition: Implications for Landscape Ecology Studies

International audienceBackground: Space-for-time substitution—that is, the assumption that spatial variations of a system can explain and predict the effect of temporal variations—is widely used in ecology. However, it is questionable whether it can validly be used to explain changes in biodiversity over time in response to land-cover changes.Hypothesis: ere, we hypothesize that different temporal vs spatial trajectories of landscape composition and configuration may limit space-for-time substitution in landscape ecology. Land-cover conversion changes not just the surface areas given over to particular types of land cover, but also affects isolation, patch size and heterogeneity. This means that a small change in land cover over time may have only minor repercussions on landscape composition but potentially major consequences for landscape configuration.Methods: sing land-cover maps of the Paris region for 1982 and 2003, we made a holistic description of the landscape disentangling landscape composition from configuration. After controlling for spatial variations, we analyzed and compared the amplitudes of changes in landscape composition and configuration over time.Results: For comparable spatial variations, landscape configuration varied more than twice as much as composition over time. Temporal changes in composition and configuration were not always spatially matched.Significance: The fact that landscape composition and configuration do not vary equally in space and time calls into question the use of space-for-time substitution in landscape ecology studies. The instability of landscapes over time appears to be attributable to configurational changes in the main. This may go some way to explaining why the landscape variables that account for changes over time in biodiversity are not the same ones that account for the spatial distribution of biodiversity

The heterogeneity of wooded-agricultural landscape mosaics influences woodland bird community assemblages

Context Landscape heterogeneity (the composition and configuration of different landcover types) plays a key role in shaping woodland bird assemblages in wooded-agricultural mosaics. Understanding how species respond to landscape factors could contribute to preventing further decline of woodland bird populations. Objective To investigate how woodland birds with different species traits respond to landscape heterogeneity, and to identify whether specific landcover types are important for maintaining diverse populations in wooded-agricultural environments. Methods Birds were sampled from woodlands in 58 2 x 2 km tetrads across southern Britain. Landscape heterogeneity was quantified for each tetrad. Bird assemblage response was determined using redundancy analysis combined with variation partitioning and response trait analyses. Results For woodland bird assemblages, the independent explanatory importance of landscape composition and landscape configuration variables were closely interrelated. When considered simultaneously during variation partitioning, the community response was better represented by compositional variables. Different species responded to different landscape features and this could be explained by traits relating to woodland association, foraging strata and nest location. Ubiquitous, generalist species, many of which were hole-nesters or ground foragers, correlated positively with urban landcover while specialists of broadleaved woodland avoided landscapes containing urban areas. Species typical of coniferous woodland correlated with large conifer plantations. Conclusions At the 2 x 2 km scale, there was evidence that the availability of resources provided by proximate landcover types was highly important for shaping woodland bird assemblages. Further research to disentangle the effects of composition and configuration at different spatial scales is advocated

Wind energy potential in Liguria region

In this work, the aim is to assess the current wind energy potential in the Liguria region, Italy, by the application of well assessed methodologies that are recalled within the paper. Data for a monitored period up to six and half years from 25 stations distributed over the four provinces of Liguria (i.e., La Spezia, Genoa, Savona and Imperia) have been analyzed. From the data obtained on the 25 stations, only 4 of them seem to be eligible for energy production, but, due to other constraints such as environmental protected areas, only one of them seems the only one where the wind potential \u2013 which has been quite stable in the years \u2013 can be effectively exploited. However, as usual in these cases, also due to the complex orography of Liguria region, a monitoring campaign on the field should be additionally performed on the site

Wind energy potential in Liguria region

In this work, the aim is to assess the current wind energy potential in the Liguria region, Italy, by the application of well assessed methodologies that are recalled within the paper. Data for a monitored period up to six and half years from 25 stations distributed over the four provinces of Liguria (i.e., La Spezia, Genoa, Savona and Imperia) have been analyzed. From the data obtained on the 25 stations, only 4 of them seem to be eligible for energy production, but, due to other constraints such as environmental protected areas, only one of them seems the only one where the wind potential - which has been quite stable in the years - can be effectively exploited. However, as usual in these cases, also due to the complex orography of Liguria region, a monitoring campaign on the field should be additionally performed on the site.

Rheological behaviour and concentration distribution of paraffin slurry in horizontal rectangular channel

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.The mathematical modeling of liquid-solid flows is very complex because the solid particles distribution in the carrier liquid is heterogeneous or even when moving beds occurs. In this paper, a mathematical modelling and a numerical simulation of the flow behaviour of the paraffin slurry in a horizontal rectangular channel are presented . The pressure drop was presented and analyzed. The diffusion equation was solved, and the concentrations of suspended solid particles in the mixture have been given for some values of the mixture's average velocity.ej201

Relative importance of the land-use composition and intensity for the bird community composition in anthropogenic landscapes

Humans are changing the biosphere by exerting pressure on land via different land uses with variable intensities. Quantifying the relative importance of the land-use composition and intensity for communities may provide valuable insights for understanding community dynamics in human-dominated landscapes. Here, we evaluate the relative importance of the land-use composition versus land-use intensity on the bird community structure in the highly human-dominated region surrounding Paris, France. The land-use composition was calculated from a land cover map, whereas the land-use intensity (reverse intensity) was represented by the primary productivity remaining after human appropriation (NPPremaining), which was estimated using remote sensing imagery. We used variance partitioning to evaluate the relative importance of the land-use composition versus intensity for explaining bird community species richness, total abundance, trophic levels, and habitat specialization in urban, farmland, and woodland habitats. The land-use composition and intensity affected specialization and richness more than trophic levels and abundance. The importance of the land-use intensity was slightly higher than that of the composition for richness, specialization, and trophic levels in farmland and urban areas, while the land-use composition was a stronger predictor of abundance. The intensity contributed more to the community indices in anthropogenic habitats (farmland and urban areas) than to those in woodlands. Richness, trophic levels, and specialization in woodlands tended to increase with the NPPremaining value. The heterogeneity of land uses and intensity levels in the landscape consistently promoted species richness but reduced habitat specialization and trophic levels. This study demonstrates the complementarity of NPPremaining to the land-use composition for understanding community structure in anthropogenic landscapes. Our results show, for the first time, that the productivity remaining after human appropriation is a determinant driver of animal community patterns, independent of the type of land use