Variations in the Landscape Along the High-Speed Rail Route

The development carried out in the last decades is degrading the ecosystems, damaging the existing biodiversity. One of the elements that is having the most impact on the deterioration of natural areas is the construction of transport infrastructures, among which are high-speed routes. These linear infrastructures are contributing to the deterioration of biodiversity enclaves, which contribute to providing highly relevant ecosystem services. Among these deteriorations are the processes of fragmentation and alteration of the landscape. This chapter analyses a situation that occurs in Spanish territory related to high-speed railways. This transport system began in Spain on the occasion of the Universal Exhibition of Seville 1992. By this transport activity, the changes suffered in the landscape are calculated and analysed through Corine land cover data since its inception until the last report of 2018.

Limited effect of a highway barrier on the genetic structure of a gypsum soil specialist

Background Gypsum ecosystems are edaphic islands surrounded by a matrix that is inhospitable to gypsum soil plant specialists. These naturally fragmented landscapes are currently exacerbated due to man-made disturbances, jeopardising their valuable biodiversity. Concomitant action of other fragmentation drivers such as linear infrastructures may increase the already high threat to these specialists. Although some evidence suggest that gypsophytes are not evolutionary dead-ends and can respond to fragmentation by means of phenotypic plasticity, the simultaneous action of barriers to genetic flow can pose a severe hazard to their viability. Here, we evaluated the effect of a highway with heavy traffic on the genetic flow and diversity in the species Lepidium subulatum, a dominant Iberian shrubby gypsophyte. Methods We tested the possible existence of bottlenecks, and estimated the genetic diversity, gene flow and genetic structure in the remnant populations, exploring in detail the effect of a highway as a possible barrier. Results Results showed variability in genetic diversity, migrants and structure. The highway had a low impact on the species since populations can retain high levels of genetic diversity and genetic parameter, like FST and FIS, did not seem to be affected. The presence of some level of genetic flow in both sides along the highway could explain the relatively high genetic diversity in the habitat remnants. Discussion Natural fragmentation and their exacerbation by agriculture and linear infrastructures seem to be negligible for this species and do not limit its viability. The biological features, demographic dynamics and population structures of gypsum species seem to be a valuable, adaptive pre-requisite to be a soil specialist and to maintain its competitiveness with other species in such adverse stressful conditions.

Red inalámbrica de sensores con topología lineal sin capa de red

A particular case of wireless sensor networks are those that have a linear topology. These networks are used in monitoring large-scale linear infrastructures that are characterized by having thousands of sensor nodes, hundreds of hops and great lengths. The requirements for routing in linear topologies are minimal relative to the requirements of other topologies. There are currently several network architectures and routing protocols for wireless sensor networks, which have been created based on the application that will run on the nodes. Routing protocols designed for mesh, tree, and star topologies are very complex when applied to linear multi-hop topologies, resulting in large processing delays. This article defines the relevance of the existence of the network level in the network architecture with linear topology, for which the functions of the network protocols that are applicable to linear topologies are analyzed. Finally, it is justified that the network level is not necessary in wireless sensor networks with linear topology, and as a consequence, the network levels that the new network architecture should have are proposed.

Changes in grassland management and linear infrastructures associated to the decline of an endangered bird population

European grassland birds are experiencing major population declines, mainly due to changes in farmland management. We analyzed the role of habitat availability, grazing management and linear infrastructures (roads and power lines) in explaining spatial and temporal variation in the population density of little bustards (Tetrax tetrax) in Portugal, during a decade in which the species population size halved. We used data from 51 areas (totaling ca. 1,50,000 ha) that were sampled in two different periods (2003–2006 and 2016). In 2003–2006, when the species occurred at high densities, habitat availability was the only factor affecting spatial variation in bustard density. In the 2016 survey, variation in density was explained by habitat availability and livestock management, with reduced bird numbers in areas with higher proportions of cattle. Population declines across the study period were steeper in areas that initially held higher densities of bustards and in areas with a higher proportion of cattle in the total stocking rate. Areas with higher densities of power lines also registered greater density declines, probably due to avoidance behavior and to increased mortality. Overall, our results show little bustards are currently lacking high quality grassland habitat, whose persistence depends on extensive grazing regimes and low linear infrastructure densities.

Response of vertebrate scavengers to power line and road rights-of-way and its implications for bird fatality estimates

Linear infrastructures, such as power lines and roads, are an important source of bird mortality. However, little is known on the potential effect of these infrastructures on local scavenger guilds, their foraging activity and the resulting bird carcass removal patterns. This is an important source of bias in studies aiming to quantify bird fatalities due to linear infrastructures. We used camera-traps to record scavenger identity and persistence patterns of bird carcasses placed close to linear infrastructure and nearby controls in two Mediterranean agricultural regions. We found that linear infrastructure influence on scavenger identity varied depending on the region. Contrary to expectations, linear infrastructure presence had either none or a positive effect on carcass persistence, meaning that carcasses placed within power line or road rights-of-way were not removed faster than the ones placed in controls. We conclude that linear infrastructure effect on vertebrate scavenging patterns is likely to be region-specific, and that reliable correction factors for carcass removal-bias in bird fatality estimates require site-specific experiments to characterize local scavenging processes.