Bibliografías temáticas / Marginal and peripheral forest population

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Literatura académica sobre el tema "Marginal and peripheral forest population"

Autor: Grafiati

Publicado: 10 de marzo de 2023

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Artículos de revistas sobre el tema "Marginal and peripheral forest population"

Eliades, Nicolas-George, Filippos Aravanopoulos y Andreas Christou. "Mediterranean Islands Hosting Marginal and Peripheral Forest Tree Populations: The Case of Pinus brutia Ten. in Cyprus". Forests 9, n.º 9 (24 de agosto de 2018): 514. http://dx.doi.org/10.3390/f9090514.

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Mediterranean islands have served as important Tertiary and glacial refuges, hosting important peripheral and ecologically marginal forest tree populations. These populations, presumably harboring unique gene complexes, are particularly interesting in the context of climate change. Pinus brutia Ten. is widespread in the eastern Mediterranean Basin and in Cyprus in particular it is the most common tree species. This study evaluated genetic patterns and morphoanatomical local adaptation along the species geographical distribution and altitudinal range in Cyprus. Analysis showed that the Cyprus population of P. brutia is a peripheral population with high genetic diversity, comprised of different subpopulations. Evidence suggests the presence of ongoing dynamic evolutionary processes among the different subpopulations, while the most relic and isolated subpopulations exhibited a decreased genetic diversity compared to the most compact subpopulations in the central area of the island. These results could be the consequence of the small size and prolonged isolation of the former. Comparing populations along an altitude gradient, higher genetic diversity was detected at the middle level. The phenotypic plasticity observed is particularly important for the adaptive potential of P. brutia in an island environment, since it allows rapid change in local environmental conditions.

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Kitamura, Keiko, Kentaro Uchiyama, Saneyoshi Ueno, Wataru Ishizuka, Ikutaro Tsuyama y Susumu Goto. "Geographical Gradients of Genetic Diversity and Differentiation among the Southernmost Marginal Populations of Abies sachalinensis Revealed by EST-SSR Polymorphism". Forests 11, n.º 2 (20 de febrero de 2020): 233. http://dx.doi.org/10.3390/f11020233.

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Research Highlights: We detected the longitudinal gradients of genetic diversity parameters, such as the number of alleles, effective number of alleles, heterozygosity, and inbreeding coefficient, and found that these might be attributable to climatic conditions, such as temperature and snow depth. Background and Objectives: Genetic diversity among local populations of a plant species at its distributional margin has long been of interest in ecological genetics. Populations at the distribution center grow well in favorable conditions, but those at the range margins are exposed to unfavorable environments, and the environmental conditions at establishment sites might reflect the genetic diversity of local populations. This is known as the central-marginal hypothesis in which marginal populations show lower genetic variation and higher differentiation than in central populations. In addition, genetic variation in a local population is influenced by phylogenetic constraints and the population history of selection under environmental constraints. In this study, we investigated this hypothesis in relation to Abies sachalinensis, a major conifer species in Hokkaido. Materials and Methods: A total of 1189 trees from 25 natural populations were analyzed using 19 EST-SSR loci. Results: The eastern populations, namely, those in the species distribution center, showed greater genetic diversity than did the western peripheral populations. Another important finding is that the southwestern marginal populations were genetically differentiated from the other populations. Conclusions: These differences might be due to genetic drift in the small and isolated populations at the range margin. Therefore, our results indicated that the central-marginal hypothesis held true for the southernmost A. sachalinensis populations in Hokkaido.

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Rottenberg, Aaron, Eviatar Nevo y Daniel Zohary. "Genetic variability in sexually dimorphic and monomorphic populations of Populus euphratica (Salicaceae)". Canadian Journal of Forest Research 30, n.º 3 (1 de marzo de 2000): 482–86. http://dx.doi.org/10.1139/x99-230.

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The genetic polymorphism of three populations of the dioecious riparian tree Populus euphratica Oliv. in Israel was examined with isozyme tests. Twelve enzyme systems revealed 20 putative loci, of which 13 were polymorphic. A centrally located population (comprising both females and males) was sampled, as well as two small peripheral and isolated stands: one comprised of only females and one containing males only. Genetic diversity values in P. euphratica were usually lower than those reported in other poplars and other species with similar life-history traits. The highest genetic diversity was found in the central, sexually dimorphic population; however, the sexually monomorphic (unisexual) marginal populations also manifested some genetic diversity, with the lowest values in the male population. Each of the unisexual populations could have originated from very few founder individuals of the same gender. The genetic variability detected in the unisexual populations may reflect somatic mutations accumulated in a vegetatively reproducing lineage over a long time span.

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Gafenco (Pleșca), Ioana Maria, Bogdan Ionuț Pleșca, Ecaterina Nicoleta Apostol y Neculae Șofletea. "Spring and Autumn Phenology in Sessile Oak (Quercus petraea) Near the Eastern Limit of Its Distribution Range". Forests 13, n.º 7 (17 de julio de 2022): 1125. http://dx.doi.org/10.3390/f13071125.

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Due to the visible and predictable influence of climate change on species’ spatial distributions, the conservation of marginal peripheral populations has become topical in forestry research. This study aimed to assess the spring (budburst, leaf development, and flowering) and autumn (leaf senescence) phenology of sessile oak (Quercus petraea), a species widespread across European forests close to its ranges’ eastern limit. This study was performed in Romania between spring 2017 and 2020, and it included a transect with three low-altitude populations, a reference population from its inner range, and a sessile oak comparative trial. The temperature was recorded to relate changes to phenophase dynamics. We identified small variations between the reference and peripheral populations associated with climatic conditions. In the peripheral populations, budburst timing had day-of-year (DOY) values <100, suggesting that sessile oak may be more susceptible to late spring frost. Furthermore, we found spring phenophase timing to be more constant than autumn senescence. Moreover, budburst in the sessile oak comparative trial had obvious longitudinal tendencies, with an east to west delay of 0.5–1.4 days per degree. In addition, budburst timing influenced leaf development and flowering, but not the onset of leaf senescence. These findings improve our understanding of the relationship between spring and autumn phenophase dynamics and enhance conservation strategies regarding sessile oak genetic resources.

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Osemeobo, Gbdebo Jonathan. "The Human Causes of Forest Depletion in Nigeria". Environmental Conservation 15, n.º 1 (1988): 17–28. http://dx.doi.org/10.1017/s0376892900028411.

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Human activities in Nigeria are not evenly distributed on the land surface, owing to marked differences in climatic, geological, demographic, and cultural, factors in different areas of Nigeria. The use of land is designed to optimize resources for diverse interest-groups, thus causing pressures to be exerted on the land in varied degrees. Because land-uses are neither influenced by capabilities of existing resources nor based on effective land-use policy, the economic development of land is not conducive to conservation of the environment. Indeed, the attempt to maximize the use of resources constitutes a serious impediment to future development, as most lands are either destroyed or rendered marginal for primary production.However, the best use to which land can be put is ultimately largely a political matter, and this is influenced by socio-economic factors at work in a given environment. Unfortunately, when the use of land is not in harmony with ecological approaches to development, the soils commonly depreciate to counter-productive levels. This is why, when land uses are in opposition, they pose serious questions regarding the extent to which they can adequately sustain life. There is plenty of evidence that the rate of forest depletion in the country may increase in relation to population increase, which is why, without adequate measures being taken, constraints in land-use could lead to shortened fallow periods, reduced crop-yields, overgrazing, indiscriminate burning of vegetation, excessive hunting, poor techniques of mineral exploitation, and application of unconserving agro-technical practices for food production.In the face of the above problems, however, adoption of alley cropping by smallholder farmers, establishment of woodlots for fuel-wood production in the vicinity of large towns, planting of timber trees in the periphery of cocoa and oil palm plantations, private-sector participation in reafforestation, and rehabilitation of mined areas with suitable vegetational forms, are some of the strategies that can reduce the rate of forest depletion in the country.

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Вехник, В. А. "АДАПТАЦИИ ВИДА К ОБИТАНИЮ НА ПЕРИФЕРИИ АРЕАЛА: ОБЗОР ОСОБЕННОСТЕЙ БИОЛОГИИ ПОЛЧКА (GLIS GLIS LINNAEUS, 1766) В САМОЙ ВОСТОЧНОЙ ПОПУЛЯЦИИ". Biosfera 14, n.º 1 (4 de abril de 2022): 43. http://dx.doi.org/10.24855/biosfera.v14i1.665.

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Marked peculiarities in the biology of a species that may be observed, possibly regardless of genetic changes, on the periphery of the species habitat may provide for species survival under extreme conditions. The same may be relevant to populations that are isolated, marginal, or remote from the main distribution range of a species. With this in mind, several biological features of the edible dormouse were studied. This rodent species features a vast distribution range in Europe and partly in Asia. Differentiation into subspecies is mostly not observed within the range. This allows comparing the biology of a single species over significantly distant areas. The range of biotope preferences of the dormice on the periphery of their distribution is wider than in the central areas. In the former cases, these rodents were found in forests featuring a significant proportion of birch and aspen in the forest stand. These observations are similar to those on the northern boundary of the dormouse distribution range in Poland and Lithuania. Some specific features of the diet of the species are associated with these habitats. In the Zhiguli Mts. (Russia) and Lithuania, the main diet includes birch seeds. At the same time, fruits and berries, which are of major importance in the other parts of dormice distribution range, are completely absent among the juicy forages. These differences probably underlie the development of a unique mechanism of reproduction control, which is not observed in other mammalian species. On the periphery of the distribution range, the number of sources of the basic forages for the highly specialized species under study is increased compared to the rest of the distribution area, and the reproductive activity of dormice is annual. However, upon the absence of a sufficient amount of the high-calorie food, mass embryonic resorption in most of females occurs. In addition, in the easternmost population, a higher territoriality is featured by females rearing offspring, and the phenomenon of communal nesting by related females is not observed. To confirm whether the genetic or environmental factors are at the base of the biological features described, large-scale population genetic studies are warranted. At the present stage, field studies allow tracing analogous features in other parts of the species habitat and thus help illustrating the ecological plasticity of the oligophagous species under suboptimal conditions.

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Bunnell, Fred L., R. Wayne Campbell y Kelly A. Squires. "Conservation priorities for peripheral species: the example of British Columbia". Canadian Journal of Forest Research 34, n.º 11 (1 de noviembre de 2004): 2240–47. http://dx.doi.org/10.1139/x04-102.

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Most jurisdictions must assign conservation priorities to peripheral species. British Columbia hosts more than 1300 peripheral taxa, about 900 of which appear on the Red and Blue Lists prepared by the province to guide conservation actions. Conversely, fewer than half of the endemic taxa, or taxa for which the province has major global stewardship responsibility, appear on provincial Red and Blue Lists. We examine why we conserve and list species, concluding that the primary scientific or practical reason is to sustain genetic variability. We consider two broad kinds of peripheral species: disjunct (geographically marginal) populations and continuous peripheral populations that straggle irregularly across provincial boundaries. Populations of both groups may be ecologically marginal, with λ < 1. We document the degree to which each group enters provincial Red and Blue Lists. Factors used to modify rankings of risk are correlated in a fashion that artificially biases continuous peripheral populations toward rankings of higher risk. Federal initiatives in recovery plans for most continuous peripheral species appear doomed to failure for sound biological reasons. We note alternative approaches to ranking species for conservation action and recommend that conservation efforts for peripheral species be focused on disjunct peripheral populations, rather than continuous peripheral populations.

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Roibu, Cătălin-Constantin, Ciprian Palaghianu, Viorica Nagavciuc, Monica Ionita, Victor Sfecla, Andrei Mursa, Alan Crivellaro et al. "The Response of Beech (Fagus sylvatica L.) Populations to Climate in the Easternmost Sites of Its European Distribution". Plants 11, n.º 23 (30 de noviembre de 2022): 3310. http://dx.doi.org/10.3390/plants11233310.

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In the context of forecasted climate change scenarios, the growth of forest tree species at their distribution margin is crucial to adapt current forest management strategies. Analyses of beech (Fagus sylvatica L.) growth have shown high plasticity, but easternmost beech populations have been rarely studied. To describe the response of the marginal beech population to the climate in the far east sites of its distribution, we first compiled new tree ring width chronologies. Then we analyzed climate–growth relationships for three marginal beech populations in the Republic of Moldova. We observed a relatively high growth rate in the marginal populations compared to core distribution sites. Our analyses further revealed a distinct and significant response of beech growth to all climatic variables, assessing for the first time the relationship between growth and vapor pressure deficit (VPD) which described how plant growth responds to drought. These results highlight that accumulated water deficit is an essential limiting factor of beech growth in this region. In conclusion, beech growth in the easternmost marginal population is drought-limited, and the sensitivity to VPD will need to be considered in future studies to update the forest management of other economic and ecologically important species.

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Koehler, Gary M. "Population and habitat characteristics of lynx and snowshoe hares in north central Washington". Canadian Journal of Zoology 68, n.º 5 (1 de mayo de 1990): 845–51. http://dx.doi.org/10.1139/z90-122.

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Lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) population characteristics and use of habitats were studied during 1985–1987 in north central Washington. Lynx used areas above 1463 m elevation that were dominated by lodgepole pine (Pinus contorta) and Engelmann spruce – subalpine fir (Picea engelmannii – Abies lasiocarpa) cover types. Snowshoe hares were the most common prey of lynx, with remains of snowshoe hare occurring in 23 of 29 scats. Counts of tracks and pellets showed snowshoe hares to be most abundant in 20-year-old lodgepole pine stands. Fire suppression and natural fire frequencies in the past 5 decades has limited the amount of these early successional forests, which are important as habitat for snowshoe hares. Marginal habitat conditions for snowshoe hares probably resulted in a scarcity of prey in the study area and may explain the relatively large home ranges of lynx (69 ± 28 km2 for five males and 39 ± 2 km2 for two females), low density of adults (2.3 lynx/100 km2), and high kitten mortality rates (88% for eight kittens in three litters). Demographic characteristics of lynx in the study area may be representative of lynx populations along the southern periphery of their range where habitat conditions are marginal for lynx and snowshoe hares.

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Marchi, M. y F. Ducci. "Some refinements on species distribution models using tree-level National Forest Inventories for supporting forest management and marginal forest population detection". iForest - Biogeosciences and Forestry 11, n.º 2 (30 de abril de 2018): 291–99. http://dx.doi.org/10.3832/ifor2441-011.

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Tesis sobre el tema "Marginal and peripheral forest population"

MARCHI, MAURIZIO, Fulvio Ducci y SUSANNA NOCENTINI. "Pinus nigra J.F. Arnold ssp. nigra var. italica: a study case of an isolated and altitudinally-marginal forest population in view of the Global Change". Doctoral thesis, 2015. http://hdl.handle.net/2158/987625.

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Capítulos de libros sobre el tema "Marginal and peripheral forest population"

Nayar, Renu, G. D. Sharma, Ritesh Kohale y S. J. Dhoble. "Analysis of Seasonal and Spatial Variations of Water Quality of Dulhara and Ved Ponds in Ratanpur, Chhattisgarh, India". En Water Pollution Sources and Purification: Challenges and Scope, 90–113. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050684122010007.

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Pollution load, rising population, and scarcity of water have drawn special attention for the management of water resources such as pond water. The present investigation was carried out at Dulahra and Ved ponds in Ratanpur, Bilaspur District. The seasonal deviations in water such as transparency, temperature, pH, dissolved oxygen, nitrate, phosphate, biological oxygen demand (BOD), total dissolved solids (TDS), and total suspended solids (TSS) were evaluated. In the contemporary study, the BOD standards were considerably higher than World Health Organization (WHO) standards (5 mg/l). The water samples were collected from each site at outer (about 100-150 meters) and internal (10 m from the shoreline) localities. The highest mean value of BOD, i.e., 32±4.6, was found at the north peripheral S-1 in the summertime. In the summer season, maximum mean BOD 39±2.1 was found at S-2 (West peripheral) in Ved Pond. It indicates the biological pollution load on the water body in the site of North peripheral in Dulhara pond and West peripheral in Ved Pond in the summer season. Low Secchi depth readings such as 20±1.0 at S-2 North peripheral site during summer seasons are indicative of reduced water clarity that is habitually related to the existence of suspended particles and algal tinges. We also found the maximum value of total suspended solids on the north side of the pond, where the transparency of water was also very low. A transparency value of 37.0±0.40 was noted at S-1 in the East marginal sites and 30±0.22 at the East inner sites in the rainy period at the Ved pond. The transparency of the water physique is exaggerated by the elements like planktonic growth, rainfall, the sun’s location in the sky, the angle of incidence of rays, cloudiness, electiveness, and turbidity due to deferred inert particulate material. Our outcomes suggest that the lowermost water transparency value was 16.0 ± 0.41 at S-1 in the North marginal sites for the duration of summer. The concentration of Calcium ions was much above the WHO recommended value of 75 mg/l at almost all the sites and both ponds during the study period. Numerous indicators and catalogues have been established in this particular study to evaluate water quality in intermediate water bodies. For transparency studies,low-cost Secchi disk was used.

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Atkinson, Martin E. "Development of the central nervous system". En Anatomy for Dental Students. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199234462.003.0027.

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The early development of the nervous system, the process of neurulation, has already been outlined in Chapter 8 and illustrated in Figure 8.4. To briefly recap, an area of dorsal ectoderm is induced by the underlying notochord to form the neural plate during the third week of development. The lateral edges of the neural plate rise to form the neural folds which eventually fold over and unite in the midline by the end of the fourth week to produce the neural tube. A distinct cell population on the crest of the neural folds, the neural crest, migrates from the forming neural tube to form various structures, including components of the peripheral nervous system. The closed neural tube consists of a large diameter anterior portion that will become the brain and a longer cylindrical posterior section, the future spinal cord. Initially, the neural plate is a single cell layer, but concentric layers of cells can be recognized by the time the neural tube has closed. An inner layer of ependymal cells surrounds the central spinal canal. Neuroblasts, the precursors of neurons, make up the bulk of the neural tube called the mantle layer; this will become the grey matter of the spinal cord. Neuroblasts do not extend processes until they have completed their differentiation. When the cells in a particular location are fully differentiated, the neuronal processes emerging from the neuroblasts form an outer marginal layer which ultimately becomes the white matter of the spinal cord. Figure 19.1B shows that the neural tube changes shape due to proliferation of cells in the mantle layer. This figure also indicates two midline structures in the roof and floor of the tube, known as the roof plate and floor plate. They are important in the determination of the types of neurons that develop from the mantle layer. The floor plate is induced by the expression of a protein product of a gene called sonic hedgehog (SHH) produced by the underlying notochord; the floor plate then expresses the same gene itself. Neuroblasts nearest to the floor plate receive a high dose of SHH protein and respond by differentiating into motor neurons; as seen in Figure 19.1B, these cells group together to form bilateral ventrolateral basal plates.

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Singh, Ashbindu. "International Activities Related to Dryland Degradation Assessment and Drought Early Warning". En Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0045.

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Land degradation usually occurs on drylands (arid, semiarid, and dry subhumid areas). According to the United Nations Convention to Combat Desertification held in Paris in 1994 (UNCCD, 1999), drylands are defined as those lands (other than polar and subpolar regions) where the ratio of annual precipitation to potential evapotranspiration falls within the range of 0.05–0.65. Land degradation causes reduction in the biological or economic productivity of those lands that may support cropland, rangelands, forest, and woodlands. Land degradation threatens culturally unique agropastoral and silvopastoral farming systems and nomadic and transhumance systems. The consequences of land degradation are widespread poverty, hunger, migration, and creation of a potential cycle of debt for the affected populations. Historical awareness of the land degradation was cited, mainly at the local and regional scales, by Plato in the 4th century B.C in the Mediterranean region, and in Mesopotamia and China (WRI, 2001). The occurrence of the “dust bowl” in the United States during the 1930s affected farms and agricultural productivity, and several famines and mass migrations, especially in Africa during the 1970s, were important landmarks of land degradation in the 20th century. It is estimated that more than 33% of the earth’s land surface and 2.6 billion people are affected by land degradation and desertification in more than 100 countries. About 73% of rangelands in dryland areas and 47% of marginal rain-fed croplands, together with a significant percentage of irrigated croplands, are currently degraded (WRI, 2001). In sub-Saharan Africa, land degradation is widespread (20–50% of the land) and affects some 200 million people. This region experiences poverty and frequent droughts on a scale not known anywhere else in the world. Land degradation is also severe and widespread in Asia, Latin America, as well as other regions of the globe. Continuous land degradation is accelerating the loss of agricultural productivity and food production in the world. Over the next 50 years, food production needs to triple in order to provide a nutritionally adequate diet for the world’s growing population. This will be difficult to achieve even under favorable circumstances.

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Skrobala, Viktor y Sofiya Marutyak. "PECULIARITIES OF THE TERRITORY OF THE CITY OF LVIV (UKRAINE) AND THEIR INFLUENCE ON THE HYDROLOGICAL REGIME AND EROSION PROCESSES". En European vector of development of the modern scientific researches. Publishing House “Baltija Publishing”, 2021. http://dx.doi.org/10.30525/978-9934-26-077-3-28.

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The object of research is the territory of the city of Lviv (Ukraine). Lviv (geographical coordinates: 49N50, 24E00) is the largest city in Western Ukraine, with a population of over 720,000 inhabitants. The city is located in the western part of the Volyn-Podilska Upland, on the line of the Main European Ridge of the Baltic and Black Sea basins. Subject of research is relief parameters (maximum, average and minimum heights, vertical dismemberment and steepness of the surface) and land use characteristics (building intensity, phytocenotic cover). The purpose of research is to study the features of the territory of Lviv from the standpoint of influence on the hydrological regime and erosion processes. Methodology. Peculiarities of the territory of Lviv were studied by processing topographic maps using aerial photography materials and route surveys. Morphometric analysis of the relief was performed on topographic maps of scale 1: 10000 by dividing the map into elementary squares with an area of 0.25 km2. The research covers an area of 100.25 km2 (401 elementary squares). Within the elementary squares, the maximum, average and minimum heights of the territory, the depth of local erosion bases, the average surface steepness, the intensity and nature of construction, and the features of vegetation were determined. Results. The territory of Lviv is characterized by a variety of relief conditions and related nature of surface use. On the basis of morphometric maps of maximum and minimum heights, vertical dismemberment and steepness of the surface, we can distinguish the flat peripheral part of the city and the middle band of elevations. The asymmetry of the territory of Lviv in relation to the watershed causes various potential dangers of erosion processes and related unproductive moisture losses. The intensity of construction increases from the periphery to the center, with the exception of modern multi-storey buildings of the Sykhiv massif and industrial areas in the western part of the city. Low specific weight of waterproof coatings is characterized by the eastern and northern parts of the city with a complex relief. The largest amount of greenery is concentrated in the eastern part of the city (Vysokyi Zamok Park, Shevchenkivskyi grove, Pohulyanka Forest Park, Lychakiv), where surfaces with maximum relative heights predominate. The great variety of the underlying surface on the territory of Lviv causes different conditions for the formation of surface runoff and associated unproductive moisture consumption. The high potential danger of erosion processes is primarily noted by the structural-denudation level of Roztochia, which is characterized by the highest values of surface steepness. Complex relief conditions, intensive anthropogenic impact determine the need for anti-erosion organization of the city and measures aimed at optimizing hydrological processes. Scientific novelty. One of the criteria that characterizes the degree of landscape transformation within the city is the intensity of construction, which is determined by the proportion of watertight areas in the overall balance of the territory. Peculiarities of spatial arrangement of elementary plots with different intensity of construction in combination with relief parameters and land use scheme are determined. Practical significance. Knowing the parameters of the terrain and the peculiarities of land use, it is possible to determine the potential intensity of erosion processes in the territory of Lviv, to assess the level of anthropogenic changes in the hydrological regime.

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"The lake trapping was continued twice monthly from February 1991, two years after the first filling of the stage 2A reservoir, until June 1993. The trapping locality at Toonpan was essentially the same as for the 1984–85 studies except that for Big Bay was moved a few hundred metres up the incline. Because the expansion from stage 1 to 2A involved extensive clearing of marginal scrub, grassland and forest, almost total control of five mosquito species utilizing tree holes and plant axils (Aedes alboscutellaris, Aedes mallochi, Aedes purpureus, Aedes quasirubithorax) or shaded pools (Uranotaenia nivipes) occurred. The transformation of temporary wetland with ti-trees (Melaleuca spp.), lilies (Nymphoides indica, Nymphaea gigantea) and submerged plants into an unvegetated muddy foreshore similarly reduced Mansonia spp. and Coquillettidia crassipes, whose larvae depend on attachment to arenchymatous or lacunate macrophytes. Larvae of these genera have pointed reinforced tips to their siphons which are used to pierce these plants to breathe. Because of the devastating nature of the inundation and the time required for new breeding habitat to re-establish, mosquito populations increased through to the end of 1993 but the mean abundance of adult Culex annulirostris had not changed significantly from stage 1 levels. The trend for this species and for Anopheles annulipes was upward, and one can only speculate on population levels when the marginal vegetation has fully established. Due to the extensive loss of marginal vegetation and the creation of expanses of shallow muddy pools, especially towards Toonpan, Anopheles amictus and Aedes normanensis populations increased by 36-fold and 282-fold, respectively (Figure 9.2). The ramifications of this are interesting as Aedes normanensis is well recognized as a vector of Ross River virus and Murray Valley encephalitis, especially inland where Anopheles amictus (probably another species complex) has been the source of Ross River, Barmah Forest and Edge Hill viruses. Control of mosquitoes is usually directed at removal of breeding habitat (source reduction) or aimed at larvae which often aggregate in large numbers in discrete sites. Aedes normanensis is ephemeral and its desiccation-resistant eggs characteristically hatch in response to wet season rainfall filling up temporary pools. Plague numbers appear one month and may be gone the next. More accurate definition of these breeding sites, particularly at Toonpan, Antill Creek and Ross River, is required before control options can be considered. As already mentioned, the clearing process created vast expanses of bare muddy pools, particularly at the north-eastern end (e.g. Toonpan). As the lake gradually receded during the dry season, ideal breeding sites were created and populations increased through spring (from September) and also in the late wet season (March to April) when dry sites were refilled by rainfall. Thus, although the land clearing had benefits in eliminating tropical itch mites and some minor mosquito species, it probably paved the way for population growth of Aedes normanensis and Anopheles amictus. This could possibly be considered a dubious swap, although time will tell. Little is known of their biology and their flight range, the latter being of obvious importance to recreational activity at the other end of the lake. Fortunately, however, they are mainly active at night." En Water Resources, 144–45. CRC Press, 1998. http://dx.doi.org/10.4324/9780203027851-32.

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Actas de conferencias sobre el tema "Marginal and peripheral forest population"

Esteves, Filipa, Joana Madureira, João Paulo Teixeira y Solange Costa. "Assessment of Potential Health Risks of Portuguese Wildland Firefighters’ Occupational Exposure: Biomonitoring Approach". En 4th Symposium on Occupational Safety and Health. FEUP, 2021. http://dx.doi.org/10.24840/978-972-752-279-8_0031-0036.

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Introduction:Worldwide, forest fires are among the most common forms of natural disasters. In the closing years of the last century there was an increase of the burned area in some parts of the globe, including in Europe. Portugal has been particularly affected by large forest fires and megafires, which have been occurred mainly in the central and northern regions. The proximity of firefighters to fire exposes them to high levels of toxic compounds making this occupation one of the most dangerous and leading International Agency for Research on Cancer to classified occupational firefighting activity as possibly carcinogenic to humans. Up to date, the existing studies are mainly focused on environmental monitoring, existing limited information regarding biomonitoring assessments during real scenarios of wildland fires combat. This study aims to evaluate the impact of firefighting occupational exposure at molecular and cellular levels, considering personal exposure levels. Early-effect biomarkers (e.g., micronucleus, DNA strand breaks and oxidative DNA damage) will be analyzed in order to understand the mechanisms of action through which woodsmoke may impact firefighters’ health, including the risk of cancer. Methodology:This ongoing prospective longitudinal study will comprise three different stages, specifically pre-exposure, exposure, and post-exposure to fire season. Around 200 wildland northern Portuguese firefighters will be involved in this study. Characterization of the study population will be conducted via questionnaires. Firefighters’ personal exposurelevels will be assessed by means of metabolites in exhaled breath, using an artificial olfactory system (e-nose technology). Buccal and urine samples will be used to measure genomic instability through micronucleus test in buccal epithelial cells and urothelial cells. DNA damage and oxidative DNA damage will be evaluated in peripheral blood lymphocytes using the comet assay. Statistical analysis will be performed to determine the relationship between personal exposure levels to toxic compounds and the early-effect biomarkers over the three different phases of the study. Expected results: The obtained results will support a more accurate and comprehensive assessment of occupational risks among wildland firefighters, crucial to prevent/reduce the associated health impacts. This work will contribute tothe establishment of recommendations/good practices to improve firefighters’ working conditions, allowing better definitions of policies and prevention strategies highly needed in this sector.

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