Home About us Contact
|
Home About us Contact | ||
|
|
||
Anthropogenic Origin (anthropogenic + origin)
Selected AbstractsAssemblages of soil macrofauna across a Scottish land-use intensification gradient: influences of habitat quality, heterogeneity and areaJOURNAL OF APPLIED ECOLOGY, Issue 6 2005PAUL EGGLETON Summary 1Land-use intensification strongly influences biodiversity by altering habitat heterogeneity, the distribution of habitat types and their extent. This study explores these effects within mixed semi-natural/agricultural mosaic habitats in Scotland, examining the effect of land-use intensification on the soil macrofauna at point (m2), landscape (km2) and regional (> 1 km2) scales. 2The soil macrofauna in six 1-km2 sampling areas (land-use units; LUU) were sampled using a combined hand-sorting and Winkler bag extraction technique. Within each LUU, 16 1-m2 samples were taken in each of 2 successive years. Each LUU had a mixture of land-use types, representing an agricultural intensification gradient. 3The following hypotheses were tested: (i) the study area sustains a number of distinct habitats as defined by soil macrofaunal composition; (ii) a greater number of restricted range species are found in semi-natural habitats; (iii) local (point) species density is related to habitat type; (iv) overall levels of species richness per habitat at regional scales are related to species-area effects; and (v) landscape-level species density is correlated with habitat heterogeneity. 4Initial analysis revealed five distinct habitat types: Caledonian forest (semi-natural pine forest), closed canopy woodland (pine plantation and broadleaved woodland), riparian habitats (wet woodland and grassland), pasture (improved grassland) and arable (crop fields). 5As hypothesized, the Caledonian habitat contained a greater number of restricted-range species than the other habitats. However, conifer plantations contained more restricted range species than expected, given their anthropogenic origin. Species density per m2 was most strongly affected by habitat type. At the regional level, the size of the species pool was correlated with the size of habitat areas. There were more species overall in LUU with greater habitat heterogeneity. 6Synthesis and applications. Caledonian pine forests have high species densities and contain species of conservation value. Mixed conifer plantations also appear to have a surprisingly high invertebrate conservation value. In contrast, intensively managed agricultural habitats have low species densities and conservation value. Generally, mixed land-use areas have higher species densities than single land-use areas. This emphasizes the need for careful management of forest systems within the matrix of agricultural habitats to maximize landscape diversity. [source] Late Quaternary vegetation, climate and fire dynamics inferred from the El Tiro record in the southeastern Ecuadorian Andes,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2008Holger Niemann Abstract In order to study the stability and dynamics of mountain rainforest and paramo ecosystems, including the biodiversity of these ecosystems, the Holocene and late Pleistocene climate and fire variability, and human impact in the southeastern Ecuadorian Andes, we present a high-resolution pollen record from El Tiro Pass (2810,m elevation), Podocarpus National Park. Palaeoenvironmental changes, investigated by pollen, spores and charcoal analysis, inferred from a 127,cm long core spanning the last ca. 21,000,cal. yr BP, indicate that grass-paramo was the main vegetation type at the El Tiro Pass during the late Pleistocene period. The grass-paramo was rich in Poaceae, Plantago rigida and Plantago australis, reflecting cold and moist climatic conditions. During the early Holocene, from 11,200 to 8900,cal. yr BP, subparamo and upper mountain rainforest vegetation expanded slightly, indicating a slow warming of climatic conditions during this period. From 8900 to 3300,cal. yr BP an upper mountain rainforest developed at the study site, indicated by an increase in Hedyosmun, Podocarpaceae, Myrsine and Ilex. This suggests a warmer climate than the present day at this elevation. The modern subparamo vegetation became established since 3300,cal. yr BP at El Tiro Pass. Fires, probably anthropogenic origin, were very rare during the late Pleistocene but became frequent after 8000,cal. yr BP. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mental retardation and prenatal methylmercury toxicityAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2006Leonardo Trasande MD Abstract Background Methylmercury (MeHg) is a developmental neurotoxicant; exposure results principally from consumption of seafood contaminated by mercury (Hg). In this analysis, the burden of mental retardation (MR) associated with methylmercury exposure in the 2000 U.S. birth cohort is estimated, and the portion of this burden attributable to mercury (Hg) emissions from coal-fired power plants is identified. Methods The aggregate loss in cognition associated with MeHg exposure in the 2000 U.S. birth cohort was estimated using two previously published dose-response models that relate increases in cord blood Hg concentrations with decrements in IQ. MeHg exposure was assumed not to be correlated with native cognitive ability. Previously published estimates were used to estimate economic costs of MR caused by MeHg. Results Downward shifts in IQ resulting from prenatal exposure to MeHg of anthropogenic origin are associated with 1,566 excess cases of MR annually (range: 376,14,293). This represents 3.2% of MR cases in the US (range: 0.8%,29.2%). The MR costs associated with decreases in IQ in these children amount to $2.0 billion/year (range: $0.5,17.9 billion). Hg from American power plants accounts for 231 of the excess MR cases/year (range: 28,2,109), or 0.5% (range: 0.06%,4.3%) of all MR. These cases cost $289 million (range: $35 million,2.6 billion). Conclusions Toxic injury to the fetal brain caused by Hg emitted from coal-fired power plants exacts a significant human and economic toll on American children. Am. J. Ind. Med. 49:153,158, 2006. © 2006 Wiley-Liss, Inc. [source] Genetic variability of Austropotamobius italicus in the Marches region: implications for conservationAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2010Rosaria Cataudella Abstract 1.Ten populations of Austropotamobius italicus from the Marches region (Central Italy), two populations from the Appennines of Calabria and Basilicata (Southern Italy) and four populations from Friuli Venezia Giulia region were sampled to elucidate the geographical pattern of genetic variability in relation to recent and historical factors. 2.A total of nine COI haplotypes belonging to three separate lineages have been characterized. Both lineage A (Northern Marches region) and C (Friuli Venezia Giulia region) were represented by one haplotype and were related to the Istria 1 peninsula and SouthAlps/Western Balkans lineages respectively. The lineage B included seven haplotypes belonging to the Appenines lineage. 3.Two hypotheses on the origin of individuals belonging to the Istrian lineage in Marches are discussed: (i) a natural colonization from the Istria peninsula refugia by migrating westwards across the bridge between the Istria peninsula and Italy, (ii) an anthropogenic origin. Based on 16S rRNA sequences, the taxonomic status of lineage B and C, defined from COI mtDNA markers, belongs to A. i. meridionalis and that of lineage A belongs to A. i. carsicus. The existence of a complex geographic structure between Marches populations (,st=0.66) of A. i. meridionalis should be further considered in conservation management. Copyright © 2010 John Wiley & Sons, Ltd. [source] Low genetic variability of the white-clawed crayfish in the Iberian Peninsula: its origin and management implicationsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2008Javier Diéguez-Uribeondo Abstract 1.A study on the genetic variability of the white-clawed crayfish was carried out based on mitochondrial cytochrome oxidase subunit I gene sequences. The sequences applied were more informative regarding white-clawed crayfish genetic variability than others previously used. 2.Two haplotypes were found to exist in the Iberian Peninsula. The haplotypes exhibit a strong geographic subdivision (,ST=0.83). One of the Iberian haplotypes was similar to north Italian haplotypes and the second differed in only one mutation. This pattern of genetic variability contrasts with those found in glacial refugial areas of France, Italy and the Balkan Peninsula. 3.Two hypotheses on the origin of the white-clawed crayfish in the Iberian Peninsula are discussed: (i) one based on an anthropogenic origin, and (ii) a second based on a successive number of postglacial ancient and recent bottlenecks, i.e. the disjunction between Iberian and Italian populations of white-clawed crayfish species is due to competition between A. italicus and A. pallipes, in addition to the impact of crayfish plague and human translocations. 4.New references for the white-clawed crayfish in the Iberian Peninsula were found in medieval and Arabic texts. The results show that this species has been thriving in this peninsula since ancient periods and that its indigenous status should not be questioned. 5.Conservation action and plans should consider the low genetic diversity as a limitation for farm-raising specimens more adapted and resistant to changing environments and diseases. Copyright © 2007 John Wiley & Sons, Ltd. [source] Ground-penetrating radar survey to map the location of buried structures under two churchesARCHAEOLOGICAL PROSPECTION, Issue 4 2002Giovanni LeucciArticle first published online: 21 NOV 200 Abstract The range of ground-penetrating-radar (GPR) applications is very wide and diverse. Ground-penetrating radar provides high-resolution continuous profiles, and it has been used in various fields such as environmental, geology, geotechnical engineering, archaeology, etc. Two surveys with GPR were undertaken inside two churches (the church of St Oronzo and the church of Immacolata) at Novoli village, located a few kilometres northwest of Lecce (Italy). The purpose of the two surveys was to obtain information about the existence of ancient structures beneath the two churches. No document or writing exists to confirm the presence of structures under the two churches. However, there are several oral testimonies handed down over the centuries that suggest the presence of these ancient structures. Both surveys were carried out using a GSSI Sir System2, incorporating 500 MHz centre frequency antenna. The GPR time slices were constructed from closely spaced parallel profiles. The time slices, computed from averaging radar reflections over vertical time windows several nanoseconds thick, are used to map subsoil features associated with the structures, probably of anthropogenic origin. To facilitate the interpretation of the results, a three-dimensional image was constructed using closely spaced parallel profiles, which are linearly interpolated. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||