• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 35
  • 16
  • 14
  • 11
  • 4
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 85
  • 54
  • 28
  • 26
  • 20
  • 19
  • 19
  • 18
  • 16
  • 13
  • 11
  • 9
  • 9
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Altitude, litter quality and availability of root derived resources as determinants of decomposition processes and soil microarthropod community composition in tropical montane rainforests in Southern Ecuador

Marian, Franca 19 August 2016 (has links)
No description available.
32

Fenologia reprodutiva da palmito Euterpe edulis (Arecaceae) e sua influência na abundância de aves frugívoras na floresta Atlântica /

Castro, Everaldo Rodrigo de. January 2007 (has links)
Resumo: O palmito Euterpe edulis é uma das espécies de árvores dominates na Floresta Atlântica, e seus frutos constituem uma parte importante da dieta de várias espécies de aves frugívoras. O presente estudo foi desenvolvido em três tipos de Floresta Atlântica (restinga, planície e encosta), na Ilha do Cardoso (Cananéia, São Paulo), durante três anos de observação. Os objetivos foram (1) comparar a fenologia reprodutiva do palmito nos três tipos florestais, e determinar quais os fatores ambientais que estariam influenciando os padrões encontrados; (2) estudar a oferta de frutos e consumo dos mesmos pelas aves frugívoras (em particular, duas espécies de aves Turdus flavipes e Turdus albicollis), e avaliar a relação da abundância destas aves com a oferta de frutos da comuniade arbórea e do palmito E. edulis. Nós avaliamos o consumo de frutos das aves e monitoramos a fenologia de frutificação do palmito e da comunidade arbórea nos três tipos florestais, comparando mensalmente com os dados de censo das aves, de agosto 2001 a julho 2004. Nós também estimamos no mesmo período à produção de frutos e sementes coletados no chão da floresta para o palmito e para a comunidade arbórea. A fenologia de frutificação do palmito foi anual e sazonal nos três tipos florestais, com as fases fruto imaturo e verde correlacionadas com o comprimento do dia, precipitação, e temperaturas, importantes fatores para o desenvolvimento dos frutos. A biomasa de frutos e sementes de palmito coletados no chão diferiram significativamene entre os tipos florestais, sendo maiores estas diferenças entre as florestas restinga e planície. Estas diferenças na produtividade foram relacionadas a densidade do palmito em cada área e a fertilidade de solo. Sobre a dieta das aves... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The palm Euterpe edulis is one of the most common species in Atlantic Brazilian Tropical Rainforest, and its fruits are an important part on the diet of several frugivorous birds' species. This study had been developed in three Atlantic Rainforest types (restinga, lowland and premontane), located in Cardoso Island (Cananéia, São Paulo state), during three years of study. The objectives were: (1) to compare the reproductive phenology of the palm in three forest types, determining which environmental factors could be affecting the patterns found; (2) to study the available number of fruits and the consume of them by the frugivorous birds (mainly, two birds species Turdus flavipes and Turdus albicollis), and to evaluate the abundance relation of these birds with the available number of fruits in the arboreal community and the palm E. edulis. The fruits consume of the birds had been evaluated, and the reproductive phenology of the palm as well the arboreal community in the three types of forest had been monitored. The bird's census data had been compared from August 2001 to July 2004. The palm and the arboreal community production of fruits and seeds taken on the ground of the forest had been estimated during the same period. The reproductive phenology of the palm was annual and seasonal in the three types of forest, having its unripe fruit phases co-related to the day length, precipitation, and temperatures which are important aspects to the fruit development. The palm fruit and seed biomass taken on the ground of the forest differs meaningfully within the forest types, such difference is bigger when considered the restinga and lowland forest. This productivity differences were related to the palm density in each area and the soil fertility. About the bird’s diet, 600 records of feeding had been observed, and the families which got the biggest... (Complete abstract click electronic access below) / Orientador: Mauro Galetti / Coorientador: Leonor Patrícia Cerdeira Morellato / Banca: Sandra Bos Mikich / Banca: Adelar Mantovani / Banca: Mercival Roberto Francisco / Banca: Valesca Bononi Ziparro / Doutor
33

Altitudinal Variability of Quiet-time Plasma Drifts in the Equatorial Ionosphere

Hui, Debrup 01 May 2015 (has links)
The plasma drifts or electric fields and their structures in the ionosphere affect the accuracy of the present-day space-based systems. For the first time, we have used ionospheric plasma drift data from Jicamarca radar measurements to study the climatology of altitudinal variations of vertical and zonal plasma drifts in low latitudes during daytime. We used data from 1998 to 2014 to derive these climatological values in bimonthly bins from 150 km to 600 km. For the vertical plasma drifts, we observed the drifts increasing with altitudes in the morning and slowly changing to drifts decreasing with altitude in the afternoon hours. The drifts change mostly linearly from E- to F-region altitudes except in the morning hours of May-June when the gradients are very small. The zonal drifts show a highly nonlinear increase in the westward drifts at the lower altitudes and then increase slowly at the higher altitudes. We see a break in the slopes at lower altitudes during the morning hours of March-April and May-June. The E-region zonal drifts, unlike vertical drifts, show a very large variability compared to F-region drifts. We also explored the altitudinal profiles of vertical drifts during late afternoon and evening hours when the electrodynamic properties in the ionosphere change rapidly. For the first time using drifts up to 2000 km, we have shown the drifts increase and decrease below and above the F-region peak before becoming height independent. These structures arise to satisfy the curl-free condition of electric fields in low latitudes. The altitudinal gradients of vertical drifts are balanced by a time derivative of the zonal drifts to satisfy the curl-free condition of electric fields. We have shown how these structures evolve with local time around the dusk sector and change with solar flux. During solar minimum, the peak region can go well below 200 km. The present-day electric field models do not incorporate these gradients, particularly in the evening sectors when they change very rapidly. Very often their results do not match with the observations. Including these gradients along with proper magnetic field models will improve the model results and accuracy of our navigation, communication, and positioning systems.
34

Altitudinal Variation in the Life History of Anurans in Southeast Queensland

Morrison, Fiona Clare, n/a January 2002 (has links)
Global declines and disappearances of amphibians from high altitude, pristine habitats have been reported in recent years. To date the cause of many of these declines and/or disappearances has not been identified. Although it is well documented that life history characteristics of temperate amphibians are influenced by altitude (due to systematic variation of temperature with altitude), little work has been carried out on the effects of altitude on Australian anurans. This lack of ecological data is a major impediment to identifying the causal factors responsible for amphibian declines. Due to differences in life history characteristics, high altitude populations may be less resilient than their lowland counterparts and subsequently may be more vulnerable to extinction. Consequently, the main aim of this study was to determine whether altitude influenced life history characteristics and ultimately population resilience of anurans in the southeast Queensland region. Six anuran species; Litoria chloris, L. lesueuri, L. pearsoniana (Anura: Hylidae), Mixophyes fasciolatus, M. fleayi and M. iteratus (Anura: Myobatrachidae) were studied over three field seasons (1997-1999) in 18 sites of varying altitude (100-950m) in the southeast Queensland region. The life history characteristics examined were: activity and breeding season length, fecundity and egg size, number of clutches produced per season, tadpole growth and development rates, longevity, age at maturity, reproductive life span, average lifetime fecundity, survival and recapture rates. The data were collected using a combination of field-based surveys (body sizes, clutch sizes, and survival and recapture rates), museum specimen dissections (clutch and egg sizes), reciprocal transplant field experiments (tadpole growth and development rates) and skeletochronology (longevity, age at maturity, reproductive lifespan and average lifetime fecundity). On average, high altitude populations of all species had shorter breeding and activity seasons than low altitude populations (up to 10 weeks less in some cases). The magnitude of the difference in breeding season length varied among years depending on the average temperature and rainfall for the year; i.e. differences appeared greater in warmer and wetter years. Within a population males had longer breeding and activity seasons than females. Although breeding season length varied with altitude, the number of nights that individuals were active within the breeding season did not vary; i.e. low altitude populations were not active for more nights despite having a longer breeding season. This result was attributed to the absence of a relationship between individual activity and environmental variables (air temperature, rainfall, etc.) in many of the populations. Generally, intraspecific clutch size did not vary significantly with altitude. This result was due to the absence of a significant relationship between female body size and altitude (as clutch size is proportional to female body size). Egg size also did not vary with altitude however, suggesting egg size may be canalized (i.e. fixed) in these species. Results also suggest that females of these species only produce one clutch of eggs per season. Interspecific differences in reproductive characteristics largely reflected differences in reproductive mode, larval habitat and female body size. Altitude negatively influenced growth and development rates in L. chloris and development rates in L. pearsoniana. Tadpoles raised at high altitudes were also generally larger at each Gosner Development Stage in both species. The results of the reciprocal transplant experiments suggested that most of the variation in growth and development rates was due to environmental factors (water temperature) rather than genetic or maternal factors. Altitude or genetic factors did not significantly affect tadpole survival in either species. The results suggest that tadpoles occurring at high altitudes take longer to reach metamorphosis and do so at a larger size than their lowland counterparts. With the exception of L. lesueuri, skeletochronology was suitable for age estimation in the study species. Altitude had a significant effect on the age at maturity or longevity in some of the species, however there were trends toward older individuals and older ages at maturity in high altitude populations for the remaining species. Females were generally older than males for all species and in the case of longer-lived species (i.e. Mixophyes spp.) also tended to be older when breeding for the first time. The large overlap of body sizes of individuals of different ages demonstrates that body size is a poor indicator of age in these species. This is the first study to estimate average lifetime fecundity for more than one amphibian species and/or population. The results suggest that the absence of significant altitudinal variation in the average lifetime fecundity of different populations is due to tradeoffs made by females (current reproduction vs. survival). There was no significant altitudinal variation in annual survival and recapture rates in any of the species, and generally there was no difference in the survival and recapture rates of males and females in each population. Within a year, monthly survival and recapture rates were more variable at low than high altitudes and this was attributed to the longer breeding season of low altitude populations. The results did not support previous studies that suggested there was a size bias in survival and recapture rates. The shorter breeding seasons, slower growth and development rates, older age at maturity and greater longevity found in the high altitude study populations will result in increased generation time in those populations. In turn, increased generation time can cause high altitude populations to be less resilient (i.e. population takes longer to return to equilibrium after a disturbance away from equilibrium) (Pimm et al. 1988, Pimm 1991) and ultimately more vulnerable or prone to extinction or decline. The majority of unexplained global amphibian declines have occurred at high altitudes in tropical and subtropical areas. These latitudinal patterns may be explained by the narrow range of environmental tolerances exhibited by tropical organisms resulting in mountains being effectively “higher” in the tropics. Consequently, high altitude tropical species are likely to be even more vulnerable than temperate species occurring at similar altitudes. Further work on the effects of geographic variation, especially interactions between altitude and latitude are needed to evaluate the hypotheses for the causes of these declines and disappearances.
35

Le gradient altitudinal sur les sommets tabulaires de Guyane, basé sur l'étude des Arecaceae, des Melastomataceae et des Ptéridophytes

Delnatte, Cesar 15 October 2010 (has links) (PDF)
L'Amazonie, bien qu'elle soit essentiellement couverte par une forêt de basse altitude, possède quelques reliefs. Les travaux précédents ont montré que la Guyane en présentait deux types : les inselbergs et les sommets tabulaires sur roches basiques. Sur ces derniers, la végétation y est relativement uniforme entre les reliefs d'altitude et de nature géomorphologique comparables. Notre travail vise principalement à étudier la composition floristique le long d'un gradient altitudinal en s'appuyant sur plusieurs bioindicateurs. Pour ce faire, notre étude s'appuie sur l'utilisation de trois groupes de végétaux vasculaires : les Arecaceae, les Melastomataceae et les Ptéridophytes. L'étude confirme une variation de la composition à 500 mètres d'altitude mais également à des altitudes inférieures et supérieures en fonction des groupes étudiés.
36

Avaluació regional de la dinàmica recent de l'ecotò bosc subalpí-prats alpins als Pirineus

Batllori Presas, Enric 28 May 2008 (has links)
El límit altitudinal del bosc, o ecotò superior bosc-prat alpí, constitueix per definició, la frontera entre l'estatge subalpí i l'estatge alpí separant, per tant, sistemes ecològics adjacents. És una de les fronteres més aparents entre sistemes ecològics que s'origina degut a l'increment gradual de l'adversitat de les condicions climàtiques en altitud i que, finalment, comporta el límit biològic per al creixement dels vegetals en port arbori. La formació de boscos arreu del planeta, en absència de pertorbacions naturals o antròpiques (p.e., tales, incendis, pastures), està limitada per condicions climàtiques excessivament seques, humides o fredes. En el cas de la transició natural bosc subalpí-prat alpí, que s'observa a tots els sistemes muntanyosos del planeta suficientment alts, les causes de la seva formació (llindar tèrmic, balanç de carboni,...) és un tema encara avui de debat on no hi ha un consens generalitzat. Però independentment del factor causant del límit altitudinal del bosc, els factors abiòtics controlen en últim terme els processos ecològics que hi tenen lloc. És per això, que els ecotons han estat motiu d'estudi des de fa molt temps, ja que es consideren paradigmàtics per l'anàlisi de la resposta dels patrons de distribució de la vegetació a les fluctuacions climàtiques. La seva importància com a monitors de canvis climàtics recau en el fet que les respostes dels ecosistemes degut a la variació ambiental són detectats primerament a les zones de frontera.Aquesta tesi ha estat realitzada al límit superior del bosc del sector central i oriental dels Pirineus catalans i d'Andorra. L'espècie dominant a totes les localitats estudiades, i a bona part dels Pirineus, és el pi negre (Pinus uncinata). Els resultats obtinguts mostren que tot i la importància de les condicions locals en la dinàmica del límit superior del bosc, hi ha una sincronització en el creixement radial i, en menor mesura, en el reclutament d'individus entre localitats a escala regional. Aquest fet evidencia la presència d'un factor comú extern, el macroclima, que modula la dinàmica de l'ecotò bosc-prats alpins a escala regional dels Pirineus. S'ha detectat una densificació del límit superior del bosc a escala regional durant la segona meitat del segle XX, que s'ha produït en paral·lel a l'increment de les temperatures (canvi climàtic). Però en base al patró de la transició en l'edat i la mida dels individus, el canvi d'usos del sòl hauria estat el factor determinant de l'augment del caràcter forestal en alguns dels ecotons estudiats. Tot i la densificació regional de la zona de l'ecotò des de 1950s, l'estructura demogràfica recent (1971-2000) i la dinàmica del límit de l'arbre de les diverses localitats estudiades evidencien l'existència de respostes diferencials a curt termini entre localitats. Aquest resultat emfatitza la importància de les condicions locals en la modulació de la dinàmica dels ecotons. L'anàlisi del patró espacial de la regeneració sembla indicar que la distribució dels llocs segurs de reclutament, que estan condicionats per la distribució espacial dels elements responsables dels processos de facilitació a nivell microambiental, determinarien la distribució espacial de la regeneració del pi negre a l'ecotò. Per tant, els processos de regeneració recent a l'ecotò superior de Pinus uncinata no han estat condicionats per limitacions reproductives de l'espècie ni per una manca d'hàbitat favorable per a l'establiment de nous individus. Tot i això, el previsible increment dels fenòmens d'estrés hídric a escala regional al sud d'Europa (IPCC 2007), degut a augments de temperatura sense anar acompanyats d'augments en el règim de precipitació, i la probable disminució de la precipitació hivernal en forma de neu, poden aturar i revertir els processos de densificació de la zona de l'ecotò observats durant el segle XX. / The altitudinal limit of forest growth, the alpine treeline ecotone, constitutes the boundary between the subalpine and alpine belts, and thus separates distinct ecological systems. The treeline ecotone is one of the most striking borders between ecosystems that result from the altitudinal increase of climate harshness, which finally leads to the altitudinal limit of tree-like growth. Irrespective of the ultimate cause of the alpine treeline, where abiotic factors limits population processes, ecotones have been focus of scientific research for long since they are regarded as suitable monitors of the influence of climatic variability on species distribution. This is due to the fact that climatic variability effects are first detected in transition zones between ecosystems.This thesis is focused on the alpine "Pinus uncinata" treeline in the Iberian eastern Pyrenees: Catalan Pyrenees (NE Spain) and Andorra. The demographic and spatial analyses of the alpine ecotone at a regional scale evidence that, in spite of the importance of local conditions on the alpine treeline dynamics, there is an important degree of synchronization in tree growth and, to a lesser extent, recruitment processes among treelines at a regional scale. This evidences the presence of an external factor, the macroclimate, that modulates the dynamics of such populations. The treeline densification observed, at a regional scale, during the second half of the 20th century occurred in parallel to temperature rises (climate warming). But based on the transition pattern in tree age and size along the ecotone, land use changes may have triggered the afforestation processes observed in some of the treelines studied. Our results suggest that recent alpine "Pinus uncinata" treeline recruitment, at a regional scale, was not limited by reproductive constraints or by the lack of suitable habitat for regeneration. However, the predicted increase of drought stress events at southern Europe as a result of increased temperature without precipitation increments, together with the expected reduction of snow precipitation in winter, may distort or even reverse the observed treeline densification trends during the 20th century.
37

Why do Birds Migrate? The Role of Food, Habitat, Predation, and Competition

Boyle, Alice January 2006 (has links)
The ultimate causes of bird migration are largely unknown despite more than a century of research. By studying partially migratory short-distance tropical migrants and by employing comparative methods, some difficulties in testing hypotheses for evolution of migration can be overcome. Using comparative methods I tested the evolutionary precursor hypothesis, a major hypothesis for why migration evolved in some lineages and not in others. The results of this study conflicted with many assumptions and predictions of the evolutionary precursor hypothesis. Most importantly, migratory behavior was not related to diet and habitat in simple ways. The interaction between diet and habitat, as well as consistent associations between flocking behavior and migration suggested that food variability is poorly captured by the surrogates embodied in the evolutionary precursor hypothesis. I then employed comparative methods to studying tropical altitudinal migration. Comparisons of diets and fruit preferences between species pairs showed that migrants are more frugivorous, eat a broader diversity of fruits, and have diets that more strongly resemble their preferences than do residents. Although providing evidence that food limitation plays a role in altitudinal migration, these results do not support the hypothesis that interspecific competition explains variation in migratory behavior. Next, I provided the first test of a predation-based hypothesis to explain altitudinal migration. Migrants breed at higher elevations than where they spend their non-breeding season. Thus, birds may migrate uphill to escape high nest predation risk at lower elevations. Results from this experimental study are largely consistent with this hypothesis, but anomalies between predicted and observed patterns suggest that either migration of lowland birds occurs in response to other factors, or that anthropogenic change has altered the tradeoffs involved in migratory decisions. Finally, I focus on a single migrant species and evaluate (a) two food-based hypotheses to explain the destination of migration movements, and (b) mechanisms underlying intra-specific differences in migratory strategy. Food can explain why Corapipo altera migrate uphill, but not why they migrate downhill. My data on sex bias and body condition leads to a new hypothesis explaining the complete annual cycle of this tropical migrant bird.
38

Changements temporels de v??g??tation sur quatre d??cennies le long d'un gradient altitudinal: Effets du r??chauffement climatique

Savage, Jos??e January 2014 (has links)
Depuis les 100 derni??res ann??es, la temp??rature de la Terre a fortement augment?? en raison des changements climatiques. Par exemple, le sud du Qu??bec a connu des anomalies d???environ +1,2 ??C depuis 1970. Or, deux cons??quences possibles d???une telle augmentation de temp??rature sont (i) le d??placement des distributions g??ographiques des esp??ces vers des latitudes ou altitudes plus froides, et (2) une modification des communaut??s favorisant les esp??ces adapt??es au chaud. ?? l?????t?? 2012, l???inventaire floristique effectu?? par Gilles Marcotte et Miroslav Grandtner en 1970 a ??t?? reproduit dans le Parc du Mont-M??gantic. Ce site d?????tude se distingue par un fort gradient altitudinal et une transition abrupte entre la for??t de feuillus et la for??t bor??ale, ce qui en fait un site propice ?? l?????tude des questions reli??es au climat. Ainsi, 48 parcelles de 0,1 et 0,2 acres (~400 et 800 m2) ont ??t?? inventori??es ?? 42 ans d???intervalle sur l???ensemble du parc. Ce m??moire vise donc ?? d??terminer s???il y a eu des changements dans les communaut??s v??g??tales du Mont-M??gantic, et si oui, si ces changements vont dans la direction pr??dite par le r??chauffement climatique. Les r??sultats sugg??rent un effet visible du r??chauffement climatique puisque les esp??ces se sont en moyenne d??plac??es vers le sommet de fa??on notable, toutes strates confondues (8,5 ?? 1,6 m par d??cennie). De plus, cette augmentation de l???altitude moyenne des esp??ces est coh??rente avec une augmentation des Community Temperature Indices (CTI) et des Community Moisture Indices (CMI) des parcelles (0,2 ?? 0,1 ??C et -0,13 ?? 0,05 unit??s arbitraires d???humidit??, respectivement, en 42 ans), sugg??rant une repr??sentation l??g??rement accrue des esp??ces adapt??es au chaud et au sec. Ces r??sultats sont coh??rents avec le r??chauffement r??gional observ??, puisque celui-ci peut r??duire la disponibilit?? de l???eau. Par contre, un r??le potentiel du changement de r??gime de lumi??re a ??t?? mis en ??vidence, particuli??rement pour les herbac??es, qui sembleraient affect??es par une ouverture accrue de la canop??e par rapport ?? 1970. Finalement, consid??rant que la variation spatiale des CTI est ??quivalente au gradiant adiabatique de temp??rature (-0,55 ??C/100 m d???altitude), nos r??sultats indiquent que les esp??ces v??g??tales du Mont-M??gantic subissent probablement un retard les emp??chant de se d??placer de mani??re ?? suivre l???augmentation de temp??rature observ??e. Les conclusions de ce m??moire soulignent que le r??chauffement climatique peut mener ?? des changements visibles dans les communaut??s v??g??tales, et ce, m??me lorsque ces communaut??s sont relativement bien prot??g??es.
39

Estudo da Comunidade de anfíbios anuros ao longo de um gradiente altitudinal na Ilha Grande, Angra dos Reis, RJ. Rio de Janeiro 2010 / Community study of anurans along an altitudonal gradient in Ilha Grande, Angra dos reis, RJ

Pablo Goyannes de Araújo 03 February 2010 (has links)
Este estudo investigou a variação altitudinal da comunidade de anfíbios anuros em uma montanha de floresta Atlântica da Ilha Grande, avaliando a ocorrência, distribuição, organização e riqueza de anuros nas diferentes altitudes. Estabelecemos seis faixas de altitude para realização do estudo: 150, 300, 450, 600, 750 e 900 metros acima do nível do mar. Utilizamos duas metodologias de amostragem: o método de parcelas grandes (5 x 5 metros) e o método de transecção, entre janeiro de 2008 e março de 2009. Os dados indicaram que na região de Mata Atlântica do Pico do Papagaio ocorre uma considerável riqueza de espécies de anuros, a qual varia dependendo da faixa de altitude ao longo do gradiente altitudinal do morro. Houve em geral uma tendência a um decréscimo da riqueza com aumento da altitude, com exceção da altitude de 900 metros, onde a riqueza teve um aumento quando comparado à faixa altitudinal imediatamente abaixo. Nossos dados mostram ainda que ao longo de todo o gradiente altitudinal do morro, as maiores riquezas de anuros em geral ocorrem nas faixas de altitudes de 150 e 300 metros. Nossos dados indicaram para a região estudada uma considerável densidade de anuros, que além de variar significativamente entre as estações seca e chuvosa, foi influenciada negativamente pela altitude: na medida em que houve um aumento da altitude ocorreu uma correspondente diminuição na densidade geral de anuros da comunidade componente. A anurofauna da região do Pico do Papagaio apresentou uma queda abrupta na abundância a partir dos 450 metros de altitude, com grande dominância, em termos numéricos, de três espécies com desenvolvimento direto. Nossos dados mostraram haver uma variação sazonal na abundância e, nas densidades de anuros na região do Pico do Papagaio. Concluímos que a região de Mata Atlântica do Pico do Papagaio possui uma elevada riqueza de espécies de anuros, a qual varia ao longo do gradiente altitudinal com os maiores valores de riqueza e abundâncias encontradas entre as faixas de 150 e 300 metros, o que pode ser favorecido pela menor inclinação do terreno, pela maior ocorrência de cursos dágua e pela elevada pluviosidade que ocorre nestas faixas altitudinais na Ilha Grande. A considerável similaridade na comunidade componente de anuros entre as altitudes de 150 e 300 pode resultar da similaridade estrutural da vegetação entre estas faixas de altitudes. A região em geral teve uma alta densidade de anuros, que além de variar sazonalmente, foi negativamente influenciada pela altitude. A observada redução na abundância dos anuros a partir dos 450 metros de altitude pareceu favorecer espécies com desenvolvimento direto. / This study aimed to investigate the altitudinal variation of the community of amphibians in a mountain of Atlantic forest of Ilha Grande, evaluating the occurrence, distribution, organization and richness of frogs at different altitudes. We established six tracks of altitude for the study: 150, 300, 450, 600, 750 and 900 meters above sea level. We use two sampling methods: the method of plots (5 x 5 meters) and the method of transection between January 2008 and March 2009. The data indicated that in the Atlantic forest of Pico do Papagaio there is a considerable richness of frog species, which varies depending on the range of altitude along the altitudinal gradient of the hill. There was a general tendency to a decrease in richness with increasing altitude, except for the altitude of 900 meters, where richness has increased compared to the altitudinal range immediately below. Our data also show that throughout the altitudinal gradient of the hill, the highest frog richness in general occur from 150 to 300 meters. Our data indicated that the density of frogs, varied significantly between the dry and rainy seasons, was negatively influenced by altitude: with an increase in altitude there was a corresponding decrease in overall density of anurans. The frogs in the region of Papagaio showed a sharp drop in abundance above 450 meters, with high dominance, in terms of numbers, of three species with direct development. Our data showed a seasonal variation in the abundances and densities of frogs in the region of Pico do Papagaio. We conclude that the Atlantic Forest region of Pico do Papagaio has a high species richness of frogs, which varies along the altitudinal gradient with the greatest richness and abundance found between 150 and 300 meters, which can be favored by the lower slope, the higher occurrence of water courses and the high rainfall that occurs in these altitudinal zones at Ilha Grande. The considerable similarity in the community component of frogs between the altitudes of 150 and 300 can result from the structural similarity of vegetation between these altitudes. The region in general had a high density of frogs, which also vary seasonally, and was negatively influenced by altitude. The observed reduction in abundance of frogs from 450 meters upward seemed to favor species with direct development.
40

Diversidade e distribuição de Solanaceae em formações vegetais altomontanas no sul do Brasil

Vendruscolo, Giovana Secretti January 2009 (has links)
A família Solanaceae possui ampla distribuição geográfica e ocorre em diversos ambientes, sendo a maioria das espécies colonizadoras de ambientes abertos. A família possui representantes herbáceos, arbustivos, arbóreos, escandentes e epifíticos. O objetivo deste estudo foi analisar a diversidade e a distribuição de espécies de Solanaceae em formações vegetais altomontanas nos Aparados da Serra Geral, que ocorrem acima de 900 m, localizados no extremo sudeste de Santa Catarina e no extremo nordeste do Rio Grande do Sul (27°48' - 29°21'S e 49°15' - 50°10'W). Foram realizadas 12 saídas a campo, sendo percorridas todas as formações vegetais e consultadas exsicatas de 23 herbários, referentes aos municípios da região de estudo. Primeiramente, foi feita uma chave para identificação dos gêneros e espécies. Foram consideradas para a região de estudo cinco formações vegetais, oito estações de coleta e 10 faixas altitudinais que foram submetidas a técnicas multivariadas de ordenação e classificação para detectar padrões de distribuição geográfica. Análises de modelos de distribuição de espécies foram utilizadas para estabelecer a área potencial para as 17 espécies com maior ocorrência e avaliar quais as variáveis ambientais que influenciam esta distribuição. No levantamento foram encontrados 12 gêneros e 72 espécies de Solanaceae. A maior riqueza de espécies foi encontrada na Floresta Ombrófila Mista. A forma de vida predominante foi arbustiva e melitofilia e quiropterocoria foram as síndromes de polinização e dispersão mais comuns, respectivamente. O principal fator relacionado com a distribuição das espécies nas formações vegetais foi a luminosidade. A distribuição das espécies em faixas altitudinais evidenciou um decréscimo de espécies com o aumento da altitude e revelou um gradiente altitudinal de riqueza, também apresentado na distribuição das espécies em estações. Três grupos florísticos foram encontrados conforme a altitude, um formado entre 900 e 1.190 m, um segundo grupo entre 1.200 e 1.490 m e o terceiro grupo entre 1.500 e 1.822 m. A maioria das 17 espécies possui uma distribuição potencial ampla. As variáveis relacionadas com temperatura e precipitação atmosférica de estações mais quentes e úmidas foram as que mais influenciaram os modelos de distribuição gerados. / The family Solanaceae has wide geographical distribution and occurs in different environments. The majority of species colonizes open areas. The family present herbaceous, shrubs, trees, lianas and epiphytic representatives. The proposal of this study was to examine the diversity and distribution of Solanaceae species in "Aparados the Serra Geral" which are upper montane plant formations above 900 m in Santa Catarina and Rio Grande do Sul states, Brazil (27°48 '- 29°21' S and 49°15' - 50°10' W). We performed all plant formations in 12 travels to the field and analysed exsiccate of 23 herbaria referring to the study region. First, we made an identification key to the genera and species. We considered five vegetation types, eigth montane stations and 10 altitudinal belts that were submitted to ordination and classification techniques to detect patterns of geographical distribution. Analysis of models of species distribution were used to establish the potential area for 17 species with higher occurrence and to assess the role of environmental variables on their distribution. A total of 12 genera and 72 species of Solanaceae were found. The greatest richness of species was found in the Araucaria angustifolia forest. The predomintant life-form were shrubby and melittophily and quiropterocory were the most common pollination and dispersal syndromes, respectively. The main factor related to the species distribution was luminosity. The species distribution in altitudinal belts showed a decreasing number of species according to higher altitudes. We also verified a gradient based on species distributions and the formation of three species-groups, one related from 900 to 1.190 m, a second group from 1.200 to 1.490 m and a third group from 1.500 to 1.822 m. Most of the 17 species has a wide distribution potential. The variables related to temperature and precipitation of hot and wet seasons were the most influencing factors for the generated models.

Page generated in 0.0327 seconds