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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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Harwell, R. L. y C. W. Dangerfield Jr. "Multiple use on marginal land: A case for cattle and loblolly pine". Forestry Chronicle 67, n.º 3 (1 de junio de 1991): 249–53. http://dx.doi.org/10.5558/tfc67249-3.
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Almost 20 million non-forest, cropland acres in the south-eastern United States can be classified as marginal. Demand projections for forest products call for a 40% increase by year 2030. Recently more land is being logged than regenerated. Land multiple use management, combining trees, cattle and wildlife, adjusts cash flows forward mitigating negative cash flow period associated with conventional forest production. Profit opportunities for smaller landowners are increased. Modification of tree population and spacing, allowing inclusion of hay and pasture, increases net present value (NPV) of agroforestry over traditional forestry. Model results show an increase in NPV from $554 to $948 per acre when beef cattle are added to loblolly pines on marginal lands. Key words: agroforestry, pines, cattle, NPV, multiple use
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Oddou-Muratorio, Sylvie, Cathleen Petit-Cailleux, Valentin Journé, Matthieu Lingrand, Jean-André Magdalou, Christophe Hurson, Joseph Garrigue, Hendrik Davi y Elodie Magnanou. "Crown defoliation decreases reproduction and wood growth in a marginal European beech population". Annals of Botany 128, n.º 2 (29 de abril de 2021): 193–204. http://dx.doi.org/10.1093/aob/mcab054.
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Abstract Background and Aims Abiotic and biotic stresses related to climate change have been associated with increased crown defoliation, decreased growth and a higher risk of mortality in many forest tree species, but the impact of stresses on tree reproduction and forest regeneration remains understudied. At the dry, warm margin of species distributions, flowering, pollination and seed maturation are expected to be affected by drought, late frost and other stresses, eventually resulting in reproduction failure. Moreover, inter-individual variation in reproductive performance versus other performance traits (growth, survival) could have important consequences for population dynamics. This study investigated the relationships among individual crown defoliation, growth and reproduction in a drought-prone population of European beech, Fagus sylvatica. Methods We used a spatially explicit mating model and marker-based parentage analyses to estimate effective female and male fecundities of 432 reproductive trees, which were also monitored for basal area increment and crown defoliation over 9 years. Key Results Female and male fecundities varied markedly between individuals, more than did growth. Both female fecundity and growth decreased with increasing crown defoliation and competition, and increased with size. Moreover, the negative effect of defoliation on female fecundity was size-dependent, with a slower decline in female fecundity with increasing defoliation for the large individuals. Finally, a trade-off between growth and female fecundity was observed in response to defoliation: some large trees maintained significant female fecundity at the expense of reduced growth in response to defoliation, while some other defoliated trees maintained high growth at the expense of reduced female fecundity. Conclusions Our results suggest that, while decreasing their growth, some large defoliated trees still contribute to reproduction through seed production and pollination. This non-coordinated decline of growth and fecundity at individual level in response to stress may compromise the evolution of stress-resistance traits at population level, and increase forest tree vulnerability.
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Marchi, Maurizio, Susanna Nocentini y Fulvio Ducci. "Future scenarios and conservation strategies for a rear-edge marginal population of Pinus nigra Arnold in Italian central Apennines". Forest Systems 25, n.º 3 (2 de diciembre de 2016): e072. http://dx.doi.org/10.5424/fs/2016253-09476.
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Aim of study: To forecast the effects of climate change on the spatial distribution of Black pine of Villetta Barrea in its natural range and to define a possible conservation strategy for the speciesArea of study: A rear-edge marginal population of Pinus nigra spp. nigra in Abruzzo region, central Italian ApenninesMatherials and Methods: For its adaptive and genetic traits this population is considered endemic of the Italian peninsula and represents a rear-edge marginal population of nigra subspecies. The spatial distribution of the tree in the administrative Region (Abruzzo) was used to define the ecological traits while three modelling techniques (GLM, GAM, Random Forest) were used to build a Species distribution model according to two climatic scenarios.Main results: The marginal population's range was predicted to shift at higher elevations as consequence of climatic adaptation. Many zones, represented by the higher part of the mountains surrounding the study area (currently bare and inhospitable for trees), were identified as suitable in future for the species. However, in the case of a rapid climate change, this marginal population may not be able to move as fast as necessary. An in-situ adaptive management integrated with an assisted migration protocol might be considered to enforce the natural regeneration and improve the richness and variability of the genetic pool.Research highlights: Most of the genetic richness is held in small populations at the borders of natural distribution of forest species. Monitoring this MAP could be useful to understand the adaptive processes of the species and could support the future management of many other within-core populations.Keywords: Species Distribution Models; Mediterranean forests; Abruzzo; climate change; altitudinal shift.
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Beatty, William S., James C. Beasley y Olin E. Rhodes. "Habitat selection by a generalist mesopredator near its historical range boundary". Canadian Journal of Zoology 92, n.º 1 (enero de 2014): 41–48. http://dx.doi.org/10.1139/cjz-2013-0225.
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The Virginia opossum (Didelphis virginiana Kerr, 1792) has expanded its geographic range northward since European settlement, which has been attributed to its ability to exploit anthropogenic resources. To examine the utility of anthropogenic resources to this species, we monitored 61 opossums from 2009 to 2010 with very high frequency (VHF) telemetry in a fragmented agricultural ecosystem in northern Indiana, USA, at the periphery of the opossum’s historical distribution. We examined the influence of anthropogenic (agricultural areas, developed land, roads), disturbed (corridor, forest edge, grassland, water), and native (forest, shrub land) habitats on habitat selection at the second- and third-order scales across three seasons. At the second-order scale, areas proximate to agricultural fields and developed land were selected in the breeding and postbreeding seasons, respectively. Areas proximate to roads were selected at both spatial scales during all seasons except winter at the third-order scale. Areas near forest with high forest-edge density were selected throughout the year at both spatial scales, but confidence intervals for forest during the postbreeding season marginally overlapped zero (third-order scale). Although anthropogenic habitats provide novel resources for opossums, forest and forest edge remain essential components to populations near their historical distributional limit in agricultural ecosystems.
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Akoum, Riad, Wassim Serhal y Hussein Farhat. "Disseminated Gastric MALT Lymphoma with Monoclonal Gammopathy, t(11;18)(q21;q21), and Subsequent Development of T-Large Granular Lymphocytic Leukemia: A Case Report and Review of the Literature". Case Reports in Medicine 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/953297.
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Background. Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is a well-characterized entity that may share clinical and morphological findings with other low-grade non-Hodgkin’s lymphomas. Dissemination of MALT-type lymphoma to bone marrow and peripheral blood simultaneously with the presence of T-large granular cell leukemia (T-LGL) has rarely been reported.Case Presentation. This is the case of a 42-year-old male who presented with a gastric MALT-type lymphoma, disseminated to the bone marrow and the peripheral blood with high serum IgM levels and t(11;18)(q21;q21). The morphological, immunophenotypical and, immunohistochemical studies of the successive bone marrow and peripheral blood samples had revealed the coexistence of two distinct lymphoma cell populations: a B-cell, marginal zone type population expressing CD19, CD20, CD22, CD79b, IgM, and kappa light chain, and a T-large granular cell population, developed after treatment with rituximab expressing CD3, CD8, CD5, CD7, and CD45.Conclusion. Based on the analysis of this unusual case we performed an extensive review of the literature to elucidate the relationship between T-LGL and B-cell lymphomas and to emphasize the importance of paraprotein analysis at diagnosis of gastric MALT lymphoma.
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Tsui, Hubert, Geoff Paltser, Hibret Adissu, Michael Dosch y Armand Keating. "Making “Sense” Of Persistent Polyclonal B Cell Lymphocytosis". Blood 122, n.º 21 (15 de noviembre de 2013): 3500. http://dx.doi.org/10.1182/blood.v122.21.3500.3500.
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Abstract Neuronal regulation of the hematopoietic stem cell niche includes elements of the sympathetic nervous system however, a role for sensory neurons has not been explored. While investigating sensory nerves in hematopoiesis, we unexpectedly found mice deficient in the neurotransmitter substance P (Tac-1-/-) to exhibit peripheral blood lymphocytosis that is persistent from 8 weeks to at least 35 weeks of age. Flow cytometry showed the increased population to be comprised of polyclonal B-lymphocytes. Hematopathology review demonstrated abnormal peripheral blood bi-nucleated lymphocytes and enlarged splenic marginal zones. Lymph nodes were not affected. To confirm that sensory nerve disruption and not hematopoietically derived substance P was the cause, wildtype C57BL/6 mice were chemically denervated and found to exhibit similar peripheral blood lymphocytosis. By immunohistochemistry, sensory nerves synapsed at splenic marginal zones, consistent with previous reports and providing a neuro-anatomical link for the observed lymphoid hyperplasia. A human correlate to this hematological phenotype featuring long-term peripheral polyclonal B cell lymphocytosis, bi-nucleated lymphocytes and expanded splenic marginal zones is Persistent Polyclonal B-cell Lymphocytosis (PPBL), a rare disorder affecting predominantly female chronic smokers. The pathoetiology of this disorder is unknown but its strong association with smoking supports a novel hypothesis where chronic smoking leads to respiratory tract sensory nerve desensitization with possibly more systemic effects, including on the spleen, thereby mimicking the substance P deficient environment of Tac-1-/- mice. Indeed, pulmonary function tests on chronic smokers have shown a sub-population of patients with hyporeactivity to respiratory sensory nerve stimulation, explained molecularly by increased activation thresholds. It will be interesting to determine if PPBL patients fall into this category. In Tac-1-/- mice, further characterization of the expanded B cell population, immunoglobulin profiles, VDJ utilization and effect of neurokinin-1 receptor modulators is proposed. These results support a neuroimmune regulatory network involving sensory nerves with potential relevance in both lymphoid homeostasis and lymphoproliferative disease. Disclosures: No relevant conflicts of interest to declare.
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Mazerolle, Marc J., Mathilde Lapointe St-Pierre, Louis Imbeau y Gilles Joanisse. "Woodland salamander population structure and body condition under irregular shelterwood systems". Canadian Journal of Forest Research 51, n.º 9 (septiembre de 2021): 1281–91. http://dx.doi.org/10.1139/cjfr-2020-0405.
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Ecosystem-based management aims to preserve old-growth forest attributes using techniques mimicking natural disturbances. One such technique is irregular shelterwood logging, but its impacts on forest floor organisms are poorly known. Our objective was to quantify the effects of three different treatments of irregular shelterwood on population structure and the body condition of the eastern red-backed salamander (Plethodon cinereus) 5–6 years following harvesting. A total of 64 sites in western Québec were sampled using artificial refugia and quadrat searches. Large salamanders (>32 mm) were more abundant in the gap treatment than in strip, uniform, or control treatments. Small salamanders (≤32 mm) followed the same pattern, although the differences were marginal. For a given treatment, small salamanders were as abundant as large salamanders. Salamander body condition differed between the 2 years of sampling but did not differ among treatments, regardless of salamander size. We conclude that environmental conditions in irregular shelterwood treatments 5–6 years following harvesting support populations of small vertebrates on the forest floor.
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Wells, S. M., A. B. Kantor y A. M. Stall. "CD43 (S7) expression identifies peripheral B cell subsets." Journal of Immunology 153, n.º 12 (15 de diciembre de 1994): 5503–15. http://dx.doi.org/10.4049/jimmunol.153.12.5503.
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Abstract CD43 (leukosialin) expression has previously been demonstrated on the surface of developing B cells in mouse bone marrow and on plasma cells induced in vitro, but not on peripheral B cells in spleen. Here we show that CD43, as recognized by mAb S7, is indeed expressed on a small population of splenic B cells. Flow cytometric phenotyping of normal mice and radiation chimeras reveals that CD43/S7 is expressed on virtually all (> 90 to 95%) splenic B-1 cells and the majority of peritoneal B-1 cells, but not on conventional B cells. The expression of CD43/S7, in conjunction with other cell surface markers, clearly distinguishes B-1 cells from follicular, marginal zone, and immature B cells in the unstimulated adult spleen and permits further phenotyping of these subsets. The phenotype of splenic and peritoneal B-1 cells in normal BALB/c and BAB/25 mice is essentially identical with the exception that all peritoneal B-1 cells express CD11b (Mac-1) and some lack CD43/S7 and heat stable Ag (as detected by the mAb 53-10) expression. Although splenic B-1, marginal zone, and immature B cells share many phenotypic characteristics, these studies show that, in addition to CD43, they differ with respect to the expression levels of a variety of Ags including heat stable Ag, B220, and the B cell activation Ag B7.
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Safriel, Uriel N., Sergei Volis y Salit Kark. "CORE AND PERIPHERAL POPULATIONS AND GLOBAL CLIMATE CHANGE". Israel Journal of Plant Sciences 42, n.º 4 (13 de mayo de 1994): 331–45. http://dx.doi.org/10.1080/07929978.1994.10676584.
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Environmental conditions outside the periphery of a species' distribution prevent population persistence, hence peripheral populations live under conditions different from those of core populations. Peripheral areas are characterized by variable and unstable conditions, relative to core areas. Peripheral populations are expected to be genetically more variable, since the variable conditions induce fluctuating selection, which maintains high genetic diversity. Alternatively, due to marginal ecological conditions at the periphery, populations there are small and isolated; the within-population diversity is low, but the between-population genetic diversity is high due to genetic drift. It is also likely that peripheral populations evolve resistance to extreme conditions. Thus, peripheral populations rather than core ones may be resistant to environmental extremes and changes, such as global climate change induced by the anthropogenically emitted “greenhouse gases”. They should be treated as a biogenetic resource used for rehabilitation and restoration of damaged ecosystems. Climatic transition zones are characterized by a high incidence of species represented by peripheral populations, and therefore should be conserved now as repositories of these resources, to be used in the future for mitigating undesirable effects of global climate change. Preliminary research revealed high phenotypic variability and high genetic diversity in peripheral populations relative to core populations of wild barley and the chukar partridge, respectively.
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Boroń, Piotr, Joanna Zalewska-Gałosz, Agnieszka Sutkowska, Bogdan Zemanek y Józef Mitka. "ISSR analysis points to relict character of Aconitum bucovinense Zapał. (Ranunculaceae) at the range margin". Acta Societatis Botanicorum Poloniae 80, n.º 4 (2011): 315–26. http://dx.doi.org/10.5586/asbp.2011.042.
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<p><em>Aconitum bucovinense</em>, a high-mountain species endemic to the Eastern and Southern Carpathians, including the Apuseni Mountains, is legally protected and classified in the Polish Red Data Book of Plants. It attains its NW geographical range in two peripheral populations in the Western Bieszczady Mountains (Polish Eastern Carpathians), isolated by a distance of 13.1 km. PCR-ISSR analysis has been used to elucidate the within- and among-populational levels of species genetic diversity. A UPGMA and block clustering showed discreteness of the populations and subpopulations based on ISSR banding pattern. Analysis of Molecular Variance (AMOVA) revealed significant divergence (<em>P </em>= 0.024) of the two marginal populations and highly significant (<em>P </em>< 0.001) differentiation of subpopulations within populations. The theta index calculated for the two marginal populations and the core population in the Carpathians was 0.131 ±0.030 S.D. Most of the population-genetic diversity indices of the marginal populations were not different from those in the core area but the Shannon’s and rarity indices were lower in the marginal populations. It seems that founder effect and subsequent genetic bottleneck resulted in a fine-scale population genetic structure. The marginal populations under study need a relevant recovery program to maintain their genetic diversity.</p>
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Regmi, Punya P. y Karl E. Weber. "Sustainable Agricultural Development for Small Farmers in Nepal: Myth or Reality?" Outlook on Agriculture 25, n.º 2 (junio de 1996): 89–94. http://dx.doi.org/10.1177/003072709602500204.
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Small and marginal farmers in Nepal mostly depend on their farms and the forests for their livelihoods. But continued population growth and increasing demands for food, shelter and cloth have stepped up the pressure on land and other natural resources. Furthermore, there is evidence that farmers have been extending the agricultural production area largely by clearing vast tracts of virgin forest, which are a precious natural resource. This has been creating both environmental and economic problems. Because small and marginal farmers have to survive below the subsistence level, in self-perpetuating dismal conditions, ‘sustainable agricultural development’ for them remains a myth rather than a reality.
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Baek, Seungil, Joongbin Lim y Wonkook Kim. "Analysis on the Fire Progression and Severity Variation of the Massive Forest Fire Occurred in Uljin, Korea, 2022". Forests 13, n.º 12 (19 de diciembre de 2022): 2185. http://dx.doi.org/10.3390/f13122185.
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Analysis of the progression of forest fires is critical in understanding fire regimes and managing the risk of active fires. Major fire events in Korea mostly occur in the eastern mountainous areas (Gangwon Province), where the wind and moisture conditions are prone to fire in the late winter season. Despite the significance of the fire events in the area both in terms of frequency and severity, their spatial progression characteristics and their dependency on forest types have not been sufficiently analyzed so far, particularly with satellite data. This study first derived the severity map for the Uljin fire which occurred in March 2022, using a series of satellite images acquired over the fire period with very high frequency (every 5 days), and analyzed the characteristics of spatio-temporal progression in terms of forest types. The analysis revealed that the core fire area expanded very rapidly in the first few days, followed by an intensification phase that elevated severity in the active areas with marginal expansion in the peripheral areas. The analysis of the progression showed that the fire did not expand selectively by the forest type, despite the clear difference in their severity levels in the burned areas, where coniferous forest exhibited 3 times higher severity than deciduous forest.
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Hao, Zhenyue y Klaus Rajewsky. "Homeostasis of Peripheral B Cells in the Absence of B Cell Influx from the Bone Marrow". Journal of Experimental Medicine 194, n.º 8 (15 de octubre de 2001): 1151–64. http://dx.doi.org/10.1084/jem.194.8.1151.
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To study homeostasis of peripheral B lymphocytes in the absence of B cell influx from the bone marrow, we generated a mouse mutant in which the recombination-activating gene (RAG)-2 can be inducibly deleted. When RAG-2 was deleted at the age of 8–10 wk, splenic naive follicular B cells were gradually lost over a year of observation, with a half-life of ∼4.5 mo. By contrast, the pool of marginal zone B cells in the spleen and of B-1 cells in the peritoneal cavity were kept at normal level. In lymph nodes, ∼90% of the B cells were lost within 4 mo, and B cell numbers remained constant thereafter. Mice in which RAG-2 was deleted at birth maintained a small population of activated B cells with an increased proportion of marginal zone B cells. Additionally, an increase of the pool of IgM secreting cells and B-1a cells was observed.
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Alemu, Molla Mekonnen. "Soil Seed Bank and Natural Regeneration of Trees". Journal of Sustainable Development 9, n.º 2 (18 de marzo de 2016): 73. http://dx.doi.org/10.5539/jsd.v9n2p73.
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The current trend of natural resources utilization, such as soils is getting incompatible with the natural, biological, physical and chemical processes of ecosystems. Excessive pressure of increasing agricultural production has exerted a negative impact on soil and its associated resources development. As the agricultural frontiers are getting exhausted in terms of productivity, immediate need has been developed to bring previously considered marginal and peripheral lands under cultivation by clearing forest resources by posing a sever threat to different ecosystems. Forest plantations are generally considered as efficient ways for the sustained development, rehabilitation and protection of land resources. Forest plantations will also provide other ecosystem services like, timber and associated products, control of soil erosion, edible fruits, shelter for wildlife, moderating climate and weather and carbon sequestration. Apart from this, forest plantations will serve a natural medium for the succession of the forest in the understory by moderating the microclimate and by creating the conducive environment for the proper functioning of dispersal agents and the soil seed bank regeneration process. The objective of this article is, therefore, to outline the soil seed bank elements and the natural regeneration process of trees as knowledge about soil seed bank and regeneration process plays a vital role in the proper management of forest development activities and understanding of forest dynamics.
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Fernández-García, José María. "The Middle-spotted Woodpecker Leiopicus medius in the Basque Country, Northern Spain: review of current ecological status". Ornis Hungarica 24, n.º 1 (1 de junio de 2016): 42–54. http://dx.doi.org/10.1515/orhu-2016-0002.
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Abstract Despite previous inventories and atlas of the avifauna in the Basque Country, Northern Spain, the dense population of the Middle-spotted Woodpecker Leiopicus medius in the Izki forest was not discovered until the 1990’s. This population mainly occupies a 3,700 ha Quercus pyrenaica forest, showing an average density of 0.89 territories/10 ha. The occurrence and abundance of territories is positively associated to the density of large caducifolious Quercus trees (>35 cm diameter). While nesting trees are apparently easily available, large trees for foraging could be a more limiting resource, given the historical exploitation regime of the forest. There are several other massifs in the region with smaller populations, but the functional connectivity, demographic and dispersal dynamics relating the core Izki and the peripheral areas have not been investigated. The conservation relevance of the Izki population in the Spanish context is high and given the need to understand the effects of forest management, future research should include spatial ecology, breeding performance as well as population monitoring.
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Mulwa, Moses, Mike Teucher, Werner Ulrich y Jan Christian Habel. "Bird communities in a degraded forest biodiversity hotspot of East Africa". Biodiversity and Conservation 30, n.º 8-9 (10 de mayo de 2021): 2305–18. http://dx.doi.org/10.1007/s10531-021-02190-y.
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AbstractTropical forests suffer severe habitat destruction. Thus, tropical forests frequently consist today of only a few small remnants that are often embedded within a matrix of agricultural fields and tree plantations. Forest specialist species have experienced severe population declines under these circumstances. We studied bird communities based on census plots set up in a near-natural forest block, as well as degraded forest patches, tree plantations, and agricultural fields, across the Taita Hills in southern Kenya. We classified each bird species according its ecology and behavior. We quantified the land cover and landscape configuration around each census plot. Typical forest species were mainly observed in the near-natural forest block, and to a lower extent in degraded forest patches. Plantations were almost devoid of birds. Bird communities of small forest fragments were more similar to that of agricultural land than the near-natural forest block. Most frugivorous, insectivorous and nectarivorous birds occurred in forest habitats, while granivorous bird species dominated the bird communities of agricultural land. The surrounding landscape had a marginal impact on bird species composition at local sites. Our study showed that the preservation of near-natural cloud forest, including small forest patches, is essential for the conservation of forest-dependent species, and that plantations do not serve as surrogate habitats.
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Rawstron, Andy C., Chi Doughty, Ruth M. de Tute, Fiona Bennett, Selina Denman, Peter Hillmen y Andrew Jack. "CD5-Negative Monoclonal B-Cell Lymphocytosis (MBL) Is Detectable In 9% of Adults Aged Over 40 but Phenotypes Associated with Clinically Common Non-Hodgkin Lymphomas Are Infrequent (<2%)". Blood 116, n.º 21 (19 de noviembre de 2010): 2002. http://dx.doi.org/10.1182/blood.v116.21.2002.2002.
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Abstract Abstract 2002 Introduction: Monoclonal B-cells with a Chronic Lymphocytic Leukemia (CLL) phenotype are detectable in more than 10% of adults in the general population using high sensitivity flow cytometry assays designed to detect minimal residual disease after treatment. However, the prevalence of MBL with a phenotype corresponding to other B-lymphoproliferative disorders (B-LPD) is less than 2% of the general population even using the most sensitive assays. No studies have reported CD10+ MBL whereas several studies have demonstrated that the t(14;18) is frequently detectable in the general population at a level which should be detectable by flow cytometry. The lack of CD10+ MBL may indicate that the t(14;18) alone rarely results in the expansion of a clonal B-cell population in the blood, or that currently available assays are inadequate for detecting circulating follicular lymphoma. We have previously investigated 66 markers to determine the best candidates for diagnosis and monitoring B-LPD, which were then tested in over 1500 cases. We have developed a single-tube assay to screen for residual disease that can detect lymphoma cells when they represent as few as 1 in 10,000 leucocytes. The aim of this study was to asses the frequency with which lymphoma-phenotype monoclonal B-cells are detected in the general population using a high sensitivity assay. Methods: Cells from 679 individuals (342 male, 337 female, median age 64, range 40–99) with a normal blood count and no current or prior history of cancer were incubated with antibodies to Kappa, Lambda, CD19, CD20, CD5, CD10, LAIR1, CXCR5 and 0.5 million cells were acquired using a BD FACSCanto II cytometer. In cases with detectable MBL further phenotyping was performed and B-cells were selected and stored for FISH and molecular clonality studies. Results: MBL was detected 129/679 cases (19.0%): CLL-type MBL in 86/679 cases (12.7%), non-CLL MBL in 60/679 cases (8.8%) with both CLL-type and non-CLL MBL were present in 17/679 cases (2.5%). Within the non-CLL MBL group, in 21/60 cases the monoclonal B cells had no additional features to confirm a neoplastic population and it was not possible to ascertain whether these were neoplastic cells or a reactive population with a highly skewed kappa/lambda ratio. Of the remaining 39 specimens: none showed evidence of germinal centre differentiation; 12 (1.7% of total) showed a phenotype most consistent with marginal zone lymphoma/lymphoplasmacytic lymphoma; and 27 cases expressed strong levels of LAIR1 coupled with strong CD19 and CD20 and an extended phenotype that is relatively rare in clinical B-LPD, restricted to hairy cell leukemia and a small proportion (<15%) of marginal zone lymphomas. Conclusions: Using an assay designed for detection of residual disease in lymphoma it was possible to detect non-CLL phenotype MBL in 8.8% of individuals over 60 years of age with normal blood counts and no history of cancer. Only a small number of these cases had a phenotype comparable to follicular lymphoma or marginal zone lymphoma, which constitute the majority of clinically significant indolent B-LPD. The complete absence of cases with a germinal centre phenotype contrasts with the high frequency of detection of BCL2-IGH rearrangement by PCR in the peripheral blood of healthy individuals. The flow cytometry assay used in this study readily detects circulating cells with appropriate phenotype in patients known to have follicular lymphoma, diffuse large B-cell lymphoma or marginal zone lymphoma/lymphoplasmacytic lymphoma and the data indicate a high specificity for peripheral blood based diagnosis and monitoring in these conditions. The most clinically prevalent lymphomas are rarely detectable in peripheral blood in individuals without lymphadenopathy but there is a surprisingly frequent development in the general population of both CLL and a restricted subset of marginal zone lymphomas which may indicate a common developmental pathway. Disclosures: No relevant conflicts of interest to declare.
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Scotti, Marco y Ferenc Jordán. "The structural importance of less abundant species in Prince William Sound food web". Israel Journal of Ecology and Evolution 61, n.º 2 (5 de mayo de 2015): 77–89. http://dx.doi.org/10.1080/15659801.2015.1067972.
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Rarity of species is often considered to set priorities for biodiversity conservation. Less abundant species are expected to be at higher risk of extinction and make significant contribution to food web functioning. However, the relationship between species abundance and position in food webs is still unclear. Here we tested possible correlations between species abundance and structural position in Prince William Sound food web. Species abundance was inferred from biomass data and structural position was characterized by 13 centrality indices.We found that less abundant species have higher trophic positions and display more generalist feeding strategies. However, positive correlations link most of the centrality indices to population size. Thus, being locally rare translates into more peripheral food web positions and implies marginal roles in the spread of indirect effects. Species characterized by largest population size are responsible for the transfer of largest amounts of biomass and regulate the transmission of indirect effects. Less abundant species are of marginal structural importance and are exposed to impacts mediated by larger populations. In Prince William Sound ecosystem, rarity is associated with critical food web positions and does not simply reflect a marginal contribution to biodiversity.We suggest that knowing the food web position of rare species might help to formulate more effective, system-level solutions for their conservation, rather than simply focusing on the direct treatment of symptoms.
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Dale, Svein y Geir Hardeng. "Changes in the breeding bird communities on mires and in surrounding forests in southeastern Norway during a 40-year period (1976–2015)". Ornis Norvegica 39 (18 de mayo de 2016): 11. http://dx.doi.org/10.15845/on.v39i0.996.
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The breeding bird communities of 18 mires and surrounding forests in southeastern Norway were censused in 1976–77 and in 2015. We found that 53% of the mire species with sufficient data for analyses showed significant changes. Red-throated Diver Gavia stellata, Common Crane Grus grus, Wood Sandpiper Tringa glareola and Tree Pipit Anthus trivialis increased, whereas Northern Lapwing Vanellus vanellus, Black-headed Gull Chroicocephalus ridibundus, Meadow Pipit Anthus pratensis and Yellow Wagtail Motacilla flava decreased. There were also near significant decreases of Eurasian Curlew Numenius arquata and Eurasian Skylark Alauda arvensis. Population changes did not differ between short- and long-distance migrants. Species with marginal populations on mires declined more than mire specialist species, suggesting an indirect negative influence of problems in other habitats. Overall, there was a significant 19% decline in number of mire species, but a non-significant 7% increase in number of individuals. The bird community in the forests surrounding the mires showed significant population changes for 42% of the species with sufficient data for analyses, with increases in many resident forest species, but less so for migrants. Overall, there was a near significant 12% increase in number of forest species, and a significant 28% increase in number of individuals. Mire- and forest-associated species did not differ in population trends. Among short-distance migrants (mire and forest species combined), species wintering in agricultural habitats had more negative population changes than species wintering in other habitats. Thus, the breeding bird community on and around mires in this part of Norway has undergone large changes during the last 40 years. We discuss our results in relation to general trends of bird communities in northern Europe.
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Dinata, Marta, Fitridawati Fitridawati y Lusi Dwi Putri. "The Study Trees Potential for Forest in Universitas Lancang Kuning Pekanbaru". EKSAKTA: Berkala Ilmiah Bidang MIPA 20, n.º 1 (30 de abril de 2019): 77–85. http://dx.doi.org/10.24036/eksakta/vol20-iss1/176.
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The location of the study of Potential tree species for Peripheral Forest Development is determined by Lancang Kuning University, which is on Yos Sudarso road KM 8 Rumbai Pekanbaru, which is a fragmented habitat. The method used is census through measurement of area, structure observation, population enumeration, measurement of three dimensions. Calculating tree species diversity (H '), Assessing the suitability criteria of a type of tree for each type of green edge path area refers to the method of analyzing an integrated research plan, the important value index for the highest vegetation is acacia (Acacia auriculiformis) with a value amounting to 73.11. Acacia (Acacia auriculiformis) type of tree is less suitable. This is because the population is too high, where the debris that falls hard to decompose causes a thick pile when trampled slipperily and endangers safety, which eventually leaves litter accumulation causing soil conditions on the slopes to become soft because it is moist and has the potential to become landslides.
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Burchall, Leondra N. "Emphasis on the Public". Public Historian 32, n.º 4 (2010): 62–68. http://dx.doi.org/10.1525/tph.2010.32.4.62.
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Abstract St. George's, Bermuda received World Heritage status in 2000, and today many of the island's majority Black population still don't know what that means. Is it because we aren't educating or marketing this ““achievement”” or do the peripheral voices and marginal communities view the designation as unimportant or an imposition? This case study examines the importance of examining the disparity in how we, and our public, interpret and value history. My job is to examine these acts of inclusion/exclusion and shift the balance with programs like ““Bringing History to Life,”” a student summer workshop series that uses different mediums to interrogate history.
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Pezo-Lanfranco, Luis, Sabine Eggers, Cecilia Petronilho, Alice Toso, Dione da Rocha Bandeira, Matthew Von Tersch, Adriana M. P. dos Santos, Beatriz Ramos da Costa, Roberta Meyer y André Carlo Colonese. "Middle Holocene plant cultivation on the Atlantic Forest coast of Brazil?" Royal Society Open Science 5, n.º 9 (septiembre de 2018): 180432. http://dx.doi.org/10.1098/rsos.180432.
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This work provides robust oral pathology and stable isotope evidence on Bayesian mixing model for an unexpectedly high consumption of carbohydrates by a Middle Holocene coastal population of the Atlantic Forest of South America, an area traditionally viewed as peripheral to early centres of food production on the continent. A diversified economy with substantial consumption of plant resources was in place at the shellmound (or sambaqui ) of Morro do Ouro, in Babitonga Bay, and supported a dense population at ca 4500 cal BP. This dietary composition is unique when compared with that of other contemporary and later groups in the region, including peoples who used ceramics and domesticated crops. The results corroborate independent dietary evidence, such as stone tool artefacts for plant processing and plant microremains in dental calculus of the same individuals, and suggest plant cultivation possibly took place in this region at the same time as the development of early agriculture in Amazonia and the La Plata Basin. Our study situates the Atlantic Forest coast of Brazil on the map of early plant management in the Neotropics.
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GONZÁLEZ, MANUEL ANTONIO, BENITO FUERTES, BEATRIZ BLANCO-FONTAO y ÁNGEL DE FRUTOS. "The edge also matters: human threats in a rare Mediterranean habitat for Cantabrian Capercaillie". Bird Conservation International 27, n.º 4 (11 de enero de 2017): 582–93. http://dx.doi.org/10.1017/s0959270916000587.
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SummaryNature reserves focused on the protection of an endangered species are often restricted to the core of the species’ distribution, leaving peripheral populations unprotected due to a lack of specific knowledge. This study describes the factors that potentially contribute to degradation of habitats of a peripheral population of the endangered Cantabrian Capercaillie Tetrao urogallus cantabricus. Using presence/absence data, we compared forest fragmentation, fire risk, and distance from leks to human infrastructure. Forest fragments in which Cantabrian Capercaillie were detected were significantly larger, closer to the nearest occupied fragments, and had a higher proximity index than fragments in which no presence was detected. Eighteen percent of the area of fragments in which Cantabrian Capercaillie presence was detected were placed in the high risk of fire category. Human infrastructure represents a permanent loss of Mediterranean habitat for the Cantabrian Capercaillie. The study area is highly modified by human activities; a priority conservation measure should be inclusion within the Natura 2000 network.
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Narmontas, Martynas, Petras Rupšys y Edmundas Petrauskas. "Construction of Reducible Stochastic Differential Equation Systems for Tree Height–Diameter Connections". Mathematics 8, n.º 8 (14 de agosto de 2020): 1363. http://dx.doi.org/10.3390/math8081363.
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This study proposes a general bivariate stochastic differential equation model of population growth which includes random forces governing the dynamics of the bivariate distribution of size variables. The dynamics of the bivariate probability density function of the size variables in a population are described by the mixed-effect parameters Vasicek, Gompertz, Bertalanffy, and the gamma-type bivariate stochastic differential equations (SDEs). The newly derived bivariate probability density function and its marginal univariate, as well as the conditional univariate function, can be applied for the modeling of population attributes such as the mean value, quantiles, and much more. The models presented here are the basis for further developments toward the tree diameter–height and height–diameter relationships for general purpose in forest management. The present study experimentally confirms the effectiveness of using bivariate SDEs to reconstruct diameter–height and height–diameter relationships by using measurements obtained from mountain pine tree (Pinus mugo Turra) species dataset in Lithuania.
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Morrow, Matthew, Antonio Valentin, Richard Little, Robert Yarchoan y George N. Pavlakis. "A Splenic Marginal Zone-Like Peripheral Blood CD27+B220−B Cell Population Is Preferentially Depleted in HIV Type 1-Infected Individuals". AIDS Research and Human Retroviruses 24, n.º 4 (abril de 2008): 621–33. http://dx.doi.org/10.1089/aid.2007.0186.
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Casazza, Gabriele, Carmelo Macrì, Davide Dagnino, Maria Guerrina, Marianick Juin, Luigi Minuto, John D. Thompson, Alex Baumel y Frédéric Médail. "When ecological marginality is not geographically peripheral: exploring genetic predictions of the centre-periphery hypothesis in the endemic plantLilium pomponium". PeerJ 9 (10 de marzo de 2021): e11039. http://dx.doi.org/10.7717/peerj.11039.
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BackgroundQuantifying variation of genetic traits over the geographical range of species is crucial for understanding the factors driving their range dynamics. The center-periphery hypothesis postulates, and many studies support, the idea that genetic diversity decreases and genetic differentiation increases toward the geographical periphery due to population isolation. The effects of environmental marginality on genetic variation has however received much less attention.MethodsWe tested the concordance between geographical and environmental gradients and the genetic predictions of center-periphery hypothesis for endemicLilium pomponiumin the southern Alps.ResultsWe found little evidence for concordance between genetic variation and both geographical and environmental gradients. Although the prediction of increased differentiation at range limits is met, genetic diversity does not decrease towards the geographical periphery. Increased differentiation among peripheral populations, that are not ecologically marginal, may be explained by a decrease in habitat availability that reduces population connectivity. In contrast, a decrease of genetic diversity along environmental but not geographical gradients may be due to the presence of low quality habitats in the different parts of the range of a species that reduce effective population size or increase environmental constraints. As a result, environmental factors may affect population dynamics irrespective of distance from the geographical center of the range. In such situations of discordance between geographical and environmental gradients, the predictions of decreasing genetic diversity and increasing differentiation toward the geographical periphery may not be respected.
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Franceschetti, Silvia, Annarita Conconi, Kathrin Aprile Von Hohenstaufen, Gloria Margiotta Casaluci, Anastasios Stathis, Alden Moccia, Michele Ghielmini et al. "Histologic Transformation in Marginal Zone Lymphomas". Blood 120, n.º 21 (16 de noviembre de 2012): 1571. http://dx.doi.org/10.1182/blood.v120.21.1571.1571.
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Abstract Abstract 1571 Background. Information concerning histologic transformation (HT) of marginal zone lymphomas (MZL) into aggressive entities is scant. We retrospectively analyzed the clinical variables at diagnosis and outcome, with special reference to HT, in a population of consecutive patients (pts) with confirmed diagnosis of MZL, including extranodal MZL (MALT lymphoma), splenic MZL (SMZL) and nodal MZL (NMZL). Patients and methods. The database of the Oncology Institute of Southern Switzerland (IOSI, Bellinzona) and of the Hematology Division of the Amedeo Avogadro University of Eastern Piedmont (Novara) includes 373 cases of MZL diagnosed and treated since 1979 to 2012: 186 MALT lymphomas (50%), 88 SMZL (23%), 36 NMZL (10%). Sixty-three patients (17%) could not be properly classified (uMZL): they presented with bone marrow infiltration with or without detectable involvement of peripheral blood but without splenomegaly and with apparently no other extranodal or nodal involved site. Results. Incidence was not significantly different according to sex (male: 47; female: 53%), median age at diagnosis was 68 years (20–94 years); 244 pts (65%) had stage III-IV disease. LDH was elevated in 45/212 (21%) tested pts, beta2-microglobulin in 108/205 (53%) tested pts. B symptoms were reported in 27/368 pts (7%). Five percent of pts had an ECOG performance status higher than 1. Serologic evidence of hepatitis C virus (HCV) infection was reported in 45/243 (19%) pts for whom the data was available. Among the 186 MALT lymphomas, 91 pts (49%) had a gastric localization, and 54 (29%) had multiple extranodal sites of disease involvement. Median overall survival (OS) and progression-free survival of the whole population were 15 years and 8 years, respectively. After a median follow-up of 5 years, HT was observed in 14 cases (4%, 95%CI:2%-6%). A diagnosis of diffuse large B cell lymphoma was documented in 12 pts (85.7% of patients undergoing HT), while in two cases the diagnosis was of classical Hodgkin lymphoma and mantle cell lymphoma, respectively. HT occurred after a median interval of 3 years (range: 1–12 years) after diagnosis. With respect to MZL type, HT occurred in 6% SMZL, 4% MALT lymphomas, 3% NMZL, and 2% uMZL (P=0.635). Risk of HT was 4% (95%CI, 2–8%) at 5 years, 6% (95%CI:3%-11%) at 10 years and 9% (95%CI, 5–16%) at 15 years; the rate of transformation tended to plateau from that point onward. At the time of HT, most pts had high LDH serum levels (8/11, 73%) and presence of B symptoms (6/10, 60%). After transformation, nine pts received anthracycline-containing regimens, and four pts were treated with high dose cytarabine regimens; in a single patient only supportive measures were adopted. In four pts, autologous stem cell transplantation was performed after induction. At a median follow-up of 12 months after HT, five of 14 pts died, all for lymphoma-related causes, with a 2-year post-transformation survival rate of 38% (95%CI:5%-74%). There was no significant association between the risk of HT and any of the clinical variables at diagnosis or frontline treatment strategies. Conclusions. This large retrospective series documents that the risk of HT is low across all MZL types. The incidence of HT in MZL is apparently lower than that of other indolent B cell malignancies, namely follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL). As also observed in FL and CLL, HT in MZL occurs relatively early during the clinical course, pointing to putative biological differences at diagnosis in MZL patients destined to transform. Disclosures: Off Label Use: Trial partially supported by a research grant by Celgene. Lenalidomide was provided free by Celgene. The use of Lenalidomide is off-label in untreated DLBCL. Bertoni:OncoEthix SA: Research Funding.
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Meyer-Bahlburg, Almut, Sarah F. Andrews, Karl O. A. Yu, Steven A. Porcelli y David J. Rawlings. "Characterization of a late transitional B cell population highly sensitive to BAFF-mediated homeostatic proliferation". Journal of Experimental Medicine 205, n.º 1 (7 de enero de 2008): 155–68. http://dx.doi.org/10.1084/jem.20071088.
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We have characterized a distinct, late transitional B cell subset, CD21int transitional 2 (T2) B cells. In contrast to early transitional B cells, CD21int T2 B cells exhibit augmented responses to a range of potential microenvironmental stimuli. Adoptive transfer studies demonstrate that this subset is an immediate precursor of both follicular mature and marginal zone (MZ) B cells. In vivo, a large percentage of CD21int T2 B cells has entered the cell cycle, and the cycling subpopulation exhibits further augmentation in mitogenic responses and B cell-activating factor of the TNF family (BAFF) receptor expression. Consistent with these features, CD21int T2 cells exhibit preferential responses to BAFF-facilitated homeostatic signals in vivo. In addition, we demonstrate that M167 B cell receptor (BCR) idiotypic-specific B cells are first selected within the cycling CD21int T2 population, ultimately leading to preferential enrichment of these cells within the MZ B cell compartment. These data, in association with the coordinate role for BAFF and microenvironmental cues in determining the mature BCR repertoire, imply that this subset functions as a unique selection point in peripheral B cell development.
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Magnussen, Steen. "Prediction of 2 × 2 tables of change from repeat cluster sampling of marginal counts". Canadian Journal of Forest Research 34, n.º 8 (1 de agosto de 2004): 1703–13. http://dx.doi.org/10.1139/x04-041.
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Repeat cluster sampling of a binary (0,1) attribute at time 1 (Y1) and time 2 (Y2) in a finite population of discrete units is considered. All clusters contain m units and a cluster provides the marginal count of ones and zeroes at the two time points only. From these counts, we seek to predict a 2 × 2 table of the rates of no change (π11 = E[Y1Y2], π00 = E[(1 Y1)(1 Y2)]) and change (π10 = E[Y1(1 Y2)], 01 = E[(1 Y1)Y2]). Two predictors are proposed; one is derived from the temporal correlation of marginal counts and the second from the odds ratio of no change that maximizes a (pseudo-) likelihood of a non-central, hypergeometric distribution. The bias of the first is positive when there is a positive intracluster correlation of Y1, Y2, and Y1Y2, while the bias of the second is negative when the odds ratio of no change is >1. A proposed combined estimator worked well in three examples of change analysis with paired, classified Landsat images of forest cover type and cluster sampling with 3 × 3 arrays of 30 m × 30 m units (pixels). 2 × 2 tables obtained from marginal counts were superior, in terms of mean absolute error, to estimates based on a direct unit-by-unit count when the time 2 image had a root mean square registration error of 0.5 pixel relative to the time 1 image. The proposed method is intended for settings where a direct unit-by-unit estimation of the 2 × 2 table is either compromised or when data (by design) consist of marginal counts from a repeat cluster sampling.
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Inogwabini, Bila-Isia, Bewa Matungila, Longwango Mbende, Mbenzo Abokome y Tshimanga wa Tshimanga. "Great apes in the Lake Tumba landscape, Democratic Republic of Congo: newly described populations". Oryx 41, n.º 4 (octubre de 2007): 532–38. http://dx.doi.org/10.1017/s0030605307414120.
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AbstractOver 8 months we surveyed the Lake Tumba landscape, Democratic Republic of Congo, walking 86 km of transects and 324 km of reconnaissance, to document the distribution and estimate the abundance of great apes. Five separate groups of bonobo Pan paniscus were located in the areas of Bolombo-Losombo, Mbala-Donkese, Ngombe-Botuali, Botuali-Ilombe, and Mompulenge–Mbanzi-Malebo–Nguomi, and one population of chimpanzees Pan troglodytes in the Bosobele-Lubengo area. Mean bonobo densities ranged from 0.27 individuals km-2 in the vicinity of Lake Tumba to 2.2 individuals km-2 in the Malebo-Nguomi area. In the latter they appear to be living at a higher density than reported for any other site. This may be due to the area's forest-savannah mosaic habitat, which may provide year-round fruit sources, with bonobos falling back on savannah fruits when forest resources are scarce. The bonobos of the Bolombo-Losombo area and the Bosobele-Lubengo chimpanzees have low relative abundances and live in marginal habitats of islands of terra firma within inundated forests.
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Toma, Andrea, Stephanie Poulain, Aurore Grelier, Magali Le Garff-Tavernier, Frederic Davi, Martine Brissard, Patrick Bonnemye et al. "Immunophenotypic Analysis Using CD80 and CD86 Staining Improves the Diagnosis of Waldenstrom's Macroglobulinemia by Evidencing a CD80+/CD86- Profile." Blood 114, n.º 22 (20 de noviembre de 2009): 4389. http://dx.doi.org/10.1182/blood.v114.22.4389.4389.
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Abstract Abstract 4389 The immunophenotypic characterization is an essential tool in the diagnosis of hematological malignancies but the immunophenotypic profile of Waldenstrom's macroglobulinemia (WM) B cells remains not clearly defined. In order to improve the diagnosis of WM by an immunophenotypic peripheral blood test, we studied within a multicentric protocol the expression of costimulatory molecules CD80 (B7.1) and CD86 (B7.2) on blood B-cells of WM patients diagnosed by monoclonal IgM in the serum and morphological lymphoplasmacytic bone marrow (BM) infiltration. Results were compared to those obtained in healthy controls and other chronic B-cell lymphoproliferative disorders (LPD). Immunophenotypic analysis was performed by flow cytometry using six-colour staining. The CD80 and CD86 staining was concomitant with usual analysis of standard antigens (kappa/lambda immunoglobulin light chains, CD20, CD19, CD79b, CD5, CD10, CD23, FMC7, CD38, CD25, CD43, CD11c, CD1c, CD27, IgM, IgD). We first analyzed 65 cases of WM and compared results to 13 healthy control subjects. Among the WM patients, 45 (69%) showed a monotypic kappa or lambda peripheral blood B-cell population with a Matutes score '3. In these patients, CD80 was always positive (>21% of B-cells) and CD86 negative (<18%). The mean responses obtained in WM compared to controls were: CD80 = 44.2±19.5% versus 13±4.6% (p<0.00001), CD86 = 5.4±5.3% versus 4.5±2.1% (p=0.18). Among the 20 patients without monotypic kappa or lambda B-cell population in peripheral blood, 13 showed a CD80+/CD86- profile (CD80 = 33±7.4%, CD86 = 7.6±4.4%). Six of them were studied by molecular aproach (PCR) showing the presence of a clonal B-cell population in all cases. Overall, 90% of WM patients showed a CD80+/CD86- profile in blood. Seven patients without peripheral monotypic kappa or lambda B-cell population evidenced a CD80-/CD86- profile; among them, one was tested by PCR and showed the lack of a clonal B-cell population in blood. We then studied other chronic B-cell LPD with peripheral blood neoplastic involvement by a monotypic kappa/lambda population, including 15 marginal zone lymphoma (MZL), 4 non-Hodgkin lymphomas (NHL) and 28 chronic lymphocytic leukemia (CLL). The mean expression of CD80 was 37±35.6%, 2.5±1.7%, 12.4±20.6%, and of CD86 30.5±38%, 19±27.5%, 15.4±19.3%, respectively. The expression of these antigens in MZL was heterogeneous, but a WM-type CD80+/CD86- profile was never observed in peripheral blood B cells. No NHL and 4 CLL (14%) exhibited a CD80+/CD86- profile. In conclusion, while immunophenotypic analysis usually performed with standard antigens does not allow to define a typical profile of WM, additional CD80 and CD86 staining in blood samples usefully improves the diagnosis of WM in the context of chronic B-cell LPD with peripheral blood involvement having a Matutes score '3. Furthermore, even in the absence of blood involvement detected by classical imunophenotypical aproach, the CD80 and CD86 staining may prove the presence of a peripheral blood monoclonal population, discriminating WM from other B-LPD with plasmatic IgM and lymphoplasmacytic BM infiltration, and diagnosing a WM in 90% of cases. Disclosures: No relevant conflicts of interest to declare.
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Li, Ling, Sergios Karatzos y Jack Saddler. "The potential of forest-derived bioenergy to contribute to China's future energy and transportation fuel requirements". Forestry Chronicle 88, n.º 05 (octubre de 2012): 547–52. http://dx.doi.org/10.5558/tfc2012-104.
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Increasing concerns of oil security, greenhouse gas emissions, and sustainability have encouraged nations to consider the contribution that agriculture/forestry for bioenergy (and biofuels in particular) could make as alternatives to current fossil-based energy and transportation fuels. Despite China's large population and geographical size, it has only relatively recently developed into a highly industrialized and energy-dependent economy. Coal is, and will remain, China's dominant energy source. However, over the last few years with China's growing middle class, increasing growth in production and sale of cars/trucks and a growing chemical based sector, oil and its derivatives are predicted to experience the fastest fossil fuel growth. China's ability to produce so-called “first-generation” or conventional biofuels from sugar, starch or vegetable oil based plants is very restricted because of “food vs. fuel” issues. Thus, biomass-based and forest-based biofuels, in particular, can form a medium-to-long-term solution that could contribute to China's national biofuels targets. Oilseed trees have been suggested as an initial forest-based biodiesel strategy with about 13 million ha of marginal land identified for possible plantation. It is also estimated that 17 million tonnes of cellulosic ethanol per annum could be derived from forest biomass that is currently available in China.
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Pongrácz, Ádám y Tamás Szitta. "Current situation and population trend of the lesser spotted eagle (Aquila pomarina) in Hungary". Slovak Raptor Journal 9, n.º 1 (30 de junio de 2015): 65–69. http://dx.doi.org/10.1515/srj-2015-0005.
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Abstract First reports on the population of the lesser spotted eagle in Hungary appeared between 1978 and 1982, and based on these data, we estimate that their population was about 90 pairs during that period. By 2014 this number had decreased to below 40 pairs. The species disappeared from its former nesting sites in the lowlands, riparian habitats and also in a few hilly and mountainous areas. The reasons for its decline appear complex in Hungary. Changes in agricultural practice are suspected of being one of the main reasons which are discussed in the article. We presume that populations of prey species were also negatively affected. Decrease in undisturbed forest stands older than 100 years was probably also a significant factor affecting nesting habitats. As a marginal population, it greatly depends on the larger ones in the surrounding countries, and it is also affected by mortality during migration. Positive changes in the past four years in agricultural land use have already caused a slight increase in their numbers. Main tasks for the near future should be the establishment of a special support scheme focusing on the species’ foraging habitats.
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Ali, S. K. M. y R. K. C. Kumara. "Study on factors responsible for high life expectancy in the elderly population in the peripheral area of northwest Sinharaja forest". Journal of the University of Ruhuna 1, n.º 2 (24 de febrero de 2014): 3. http://dx.doi.org/10.4038/jur.v1i2.6620.
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Golou Gizèle, ZANH, KPANGUI Kouassi Bruno, BARIMA Yao Sadaiou Sabas y Bogaert Jan. "Migration and Agricultural Practices in the Peripheral Areas of Côte d’Ivoire State-Owned Forests". Sustainability 11, n.º 22 (13 de noviembre de 2019): 6378. http://dx.doi.org/10.3390/su11226378.
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Côte d’Ivoire’s rural areas adjacent to the state-owned areas of the southern half of the country, such as classified forests, are experiencing significant migratory flows due to their agricultural potential. The population movements in these rural areas have changed the rural landscape. The general objective of this study was to identify the peasant innovations implemented in these rural areas adjacent to the state’s forest domains in a context of land saturation caused by migratory flows. This objective was elucidated from the case of the classified forest of Haut-Sassandra (CFHS). To achieve this, surveys were conducted in 11 villages on the periphery of the FCHS to determine the profile of planters and the main crops grown. Subsequently, floristic inventories were carried out on farms to analyse the diversity of associated species. Analyses showed that the rural populations of the CFHS are mainly composed of Allochthones (64%). Four innovative production systems were identified: a cashew-based production system, a cocoa-based production system, a coffee-based production system and a coffee- and cocoa-based production system. These farmer innovations based on agroforestry practices make it possible to restore impoverished lands and fight against climatic hazards. Consequently, these local practices deserve to be popularised in areas of strong land pressure as strategies to overcome the shortage of arable land and fluctuating prices of agricultural production.
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Andrieu, E., J. D. Thompson y M. Debussche. "The impact of forest spread on a marginal population of a protected peony (Paeonia officinalis L.): the importance of conserving the habitat mosaic". Biodiversity and Conservation 16, n.º 3 (20 de enero de 2007): 643–58. http://dx.doi.org/10.1007/s10531-005-2357-0.
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Widawati, Sri. "AKTIVITAS ENZIM PELARUT FOSFAT DAN EFEKTIVITAS MIKROBA ASAL WAMENA UNTUK MENUNJANG PERTANIAN RAMAH LINGKUNGAN PADA DAERAH MARGINAL". Jurnal Teknologi Lingkungan 11, n.º 3 (2 de diciembre de 2016): 481. http://dx.doi.org/10.29122/jtl.v11i3.1194.
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The activity of phosphate solubilizing enzyme and the effectivity of microbe from Wamena for support agriculture of environmental friendliness at marginal area. Phosphate dissolution of enzyme by microbial effective in compost plus from Wamena forest was stored in the freezer for 4 years, have been conducted in Ecofisiology laboratory,Microbiology devision, Research Center for Biology, Indonesian Institute of Science. This research was conducted to know the microbial affectivity and the activity of phosphate solubilizing enzyme of 20 microorganisms in inoculants stored 4 years in refrigerated room and to support soil fertility and biofertilizer agent in organic farming system. This research used plate count methode for counting the amount of microbial population, Scinner method was used toanalizer enzyme of alkaline and acid PME-ase,and statistical analysis use Duncan methode. The storage of 20 inoculants invected 20microorganisms for 4 years in refrigerated room showed that the microbial activity still high with the amount of mean population 107 and the activity of phosphate solubilizing enzyme with mean diameter of clear zone (holozone) 1 cm – 2 cm. The effectivity and the highest activity of phosphate solubilizing enzyme were : Azotobacter indicus (A), Bacillus panthothenticus (D), Bacillus megaterium (M), Bacillus thuringiensis (O), Ceratia sp. (R),Chromobacterium lividum (G), Chromobacterium violaceum (S), Flavobacterium breve(T), Klebsiella aerogenes (H), Pseudomonas fluorescent (J), Rhizobium legurxinosarium (L), and the lowest were: Streptomyces sp. (I) .Key word: Alkaline and acid PMEase, Phosphate solubilizing bacteria,Biofertolizer
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Marqués, Laura, J. Julio Camarero, Miguel A. Zavala, Markus Stoffel, Juan A. Ballesteros-Cánovas, Cesar Sancho-García y Jaime Madrigal-González. "Evaluating tree-to-tree competition during stand development in a relict Scots pine forest: how much does climate matter?" Trees 35, n.º 4 (10 de marzo de 2021): 1207–19. http://dx.doi.org/10.1007/s00468-021-02109-8.
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Abstract Key message Competitive interactions change over time and their influence on tree growth is intensified during drought events in marginal Scots pine populations. Abstract Competition is a key factor driving forest dynamics and stand structure during the course of stand development. Although the role of neighbourhood competition on stand dynamics has received increasing attention, the response of competition to environmental fluctuations and stand development remains poorly explored. We evaluated changes in competition during stand development in a dry-edge Scots pine relict population located in Central Spain. Typically, tree-to-tree interactions have been investigated through static competition measurements, which usually lack the temporal variation associated to natural forest development and environmental conditions. Here, we assessed how individual and neighbourhood components of competition evolved along a 35-year period, and we related competition dynamics to population structure and drought levels. On six plots, 508 trees were mapped and diameters at breast height (DBH) were measured. Two increment cores were taken from target trees to derive basal area increment (BAI), and neighbourhood was reconstructed back to 1980. Results provide insights into inter-annual variability in competition effects and their role on tree radial growth depending on climatic conditions. From the year 2005 onwards, both individual and neighbourhood components of competition showed a decoupled pattern over time. This effect was particularly pronounced during the extreme drought in 2012, in which the individual component decreased, whereas the neighbourhood component increased. In addition, climatic variability modulated the competition effects during stand development. This approach of evaluating competition dynamics proves to be promising for studying forest stand development and the influence of climate impacts on tree populations subjected to xeric conditions.
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Gomo, Gjermund, Jenny Mattisson, Lars Rød-Eriksen, Nina E. Eide y Morten Odden. "Spatiotemporal patterns of red fox scavenging in forest and tundra: the influence of prey fluctuations and winter conditions". Mammal Research 66, n.º 2 (26 de marzo de 2021): 257–65. http://dx.doi.org/10.1007/s13364-021-00566-7.
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AbstractConcern has been raised regarding red fox (Vulpes Vulpes) population increase and range expansion into alpine tundra, directly and indirectly enhanced by human activities, including carrion supply, and its negative impact on native fauna. In this study, we used cameras on bait stations and hunting remains to investigate how spatiotemporal patterns of red fox scavenging were influenced by abundance and accessibility of live prey, i.e., small rodent population cycles, snow depth, and primary productivity. We found contrasting patterns of scavenging between habitats during winter. In alpine areas, use of baits was highest post rodent peaks and when snow depth was low. This probably reflected relatively higher red fox abundance due to increased reproduction or migration of individuals from neighboring areas, possibly also enhanced by a diet shift. Contrastingly, red fox use of baits in the forest was highest during rodent low phase, and when snow was deep, indicating a higher dependency of carrion under these conditions. Scavenging patterns by red fox on the pulsed but predictable food resource from hunting remains in the autumn revealed no patterns throughout the rodent cycle. In this study, we showed that small rodent dynamics influenced red fox scavenging, at least in winter, but with contrasting patterns depending on environmental conditions. In marginal alpine areas, a numerical response to higher availability of rodents possible lead to the increase in bait visitation the proceeding winter, while in more productive forest areas, low availability of rodents induced a functional diet shift towards scavenging.
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Mossman, Catherine A. y Peter M. Waser. "Effects of habitat fragmentation on population genetic structure in the white-footed mouse (Peromyscus leucopus)". Canadian Journal of Zoology 79, n.º 2 (1 de febrero de 2001): 285–95. http://dx.doi.org/10.1139/z00-201.
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Habitat fragmentation may have significant consequences for population genetic structure because geographic distance and physical barriers may impede gene flow. In this study, we investigated whether habitat fragmentation affects fine-scale genetic structure of populations of the white-footed mouse (Peromyscus leucopus). We studied 27 populations of P. leucopus, 17 in continuous forest and 10 in isolated woodlots. Populations were trapped in pairs that were either 500 or 2000 m apart. We estimated genetic variation at eight P. leucopus specific microsatellite DNA loci. We discovered significant genetic variation within all populations, but no significant differences in numbers of alleles or heterozygosity between populations. For given population pairs, we found significant genetic differentiation even at very short distances, based on multilocus FST estimates. The amount of genetic differentiation between population pairs was similar in the two habitats. Distance had a marginal effect on genetic differentiation when comparing paired populations separated by 2000 m with those separated by 500 m. However, at a larger geographic scale, there was no evidence of isolation by distance. This study confirms that microsatellite-based studies have the potential to detect interpopulation differentiation at an extremely local scale, and suggests that habitat fragmentation has surprisingly few effects on P. leucopus genetic structure.