• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 72
  • 46
  • 6
  • 4
  • 4
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 177
  • 177
  • 50
  • 43
  • 37
  • 35
  • 28
  • 26
  • 23
  • 23
  • 20
  • 18
  • 17
  • 17
  • 16
  • 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.
121

Quantifying the ecological values of brigalow regrowth for woodland birds: a hierarchical landscape approach

Michiala Bowen Unknown Date (has links)
The conversion of native forests to pastures and crops is one of the most extensive causes of deforestation worldwide. Concomitant with agricultural landscape modification are the processes of habitat loss and fragmentation, which are major causes of species’ extinctions, population declines and altered ecosystem functions. However, in many tropical, sub-tropical and temperate regions, abandoned agricultural lands are reverting to regrowth or secondary forest, which represents an important opportunity for passive landscape restoration. Regrowth may be particularly important in highly modified landscapes, where the area of mature forest may be insufficient to support viable plant and animal communities without some form of restoration. Some studies of fauna populations in regrowth forest have found recovery of species richness within several decades, although recovery of species composition may take at least 100 years and some species may be permanently lost. While these findings are encouraging, they generally fail to account for the landscape context in which regrowth occurs and focus mainly on tropical forests. The aim of this thesis was to advance the understanding of fauna recovery in regrowth forests on abandoned agricultural land by: i) comparing woodland bird communities in a replicated chronosequence of semi-arid sub-tropical regrowth forests; and ii) quantifying how the ecological values of regrowth habitat vary among stand-, patch- and landscape-levels of ecological organisation. A review of 68 studies of fauna recovery in regrowth forests, revealed that current knowledge is limited by the predominance of studies conducted: in tropical rainforests; with minimal replication of sites; in landscapes within proximity of large tracts of relatively undisturbed mature forests; and with limited consideration of the influence of the spatial context on fauna recovery in regrowth forest. This study makes a significant contribution to understanding fauna recovery in regrowth forests by quantifying the recovery of estimated bird species richness to levels similar to mature forest, within a period of 30-60 years, in highly modified semi-arid agricultural landscapes in sub-tropical Australia. An ordination of the similarity in species composition among forest types also suggested that after 30-60 years regrowth bird communities are more similar to mature brigalow forest than the younger regrowth. This is important for the recovery of brigalow ecosystems, an endangered ecological community where regrowth is currently given minimal protection from further clearing. Comparisons of the importance of habitat attributes using model averaging and hierarchical partitioning of generalised linear models of the species richness of woodland birds showed that bird species richness was positively associated with patch age, and that stand-level factors such as grazing disturbance and the abundance of mistletoes (Amyema spp.) were also important. The spatial context of vegetation patches (size, shape and isolation) was equally important for bird species richness, with more species of woodland dependent, nectar/frugivores and non-ground foraging insectivores occurring in less modified landscape contexts, and the converse for generalist species, ground foraging insectivores and granivores. While a number of woodland dependent bird species known to be in decline in temperate woodlands of southern Australia were absent or rare in regrowth forests, several species (e.g., eastern yellow robin) also occupied regrowth habitats. This finding suggests that these more sensitive species may respond positively to landscape restoration through targeted retention of brigalow regrowth. The landscape-level amount of forest varied in importance among regrowth age classes and bird groups. In general, the amount and number of mature forest patches in the landscape were of lower importance than local attributes. However, the amount of mature forest and old regrowth (> 30 years) in the landscape did have an important positive influence on the number of woodland bird species and species’ abundance; suggesting that regrowth is making an important contribution to landscape recovery in the study area. Mistletoe abundance was strongly dependent on particular species of frugivores for seed dispersal (e.g., mistletoebird, spiny-cheeked honeyeater and painted honeyeater), and varied considerably among three sub-regions of the study area. In general, mistletoe abundance increased in linear patches and more highly modified landscapes but was also dependent on the abundance of seed dispersers and brigalow stand condition. These findings suggest that narrow linear patches in brigalow landscapes can have important conservation values for woodland birds. The study outcomes have important implications for research and management of regrowth vegetation, both within Australia and internationally. From an international perspective, the study highlights the need for greater consideration of the importance of regrowth forest in a landscape context for conserving and restoring fauna communities. From an Australian perspective, the study provides important baseline information for the conservation and management of woodland bird habitat in fragmented brigalow landscapes. Prior to this research, very little was known on the spatial ecology of woodland birds in the region. The study highlights the important conservation values of small and often linear mature brigalow patches for woodland birds and the considerable potential for restoration of habitat for a diverse range of species through the retention of regrowth vegetation. In particular, the research outcomes suggest that targeting the retention of regrowth towards increasing the size and reducing the isolation of mature brigalow forests may be an effective strategy to maximise biodiversity benefits. Brigalow regrowth stands will need to be retained for at least 60 years and probably longer to maintain viable woodland bird communities. For this to happen on a regional-scale, brigalow regrowth needs to be given greater recognition for potential biodiversity benefits either within a legislative framework or by incentive schemes to promote the long term persistence of regrowth habitat within the landscape.
122

Quantifying the ecological values of brigalow regrowth for woodland birds: a hierarchical landscape approach

Michiala Bowen Unknown Date (has links)
The conversion of native forests to pastures and crops is one of the most extensive causes of deforestation worldwide. Concomitant with agricultural landscape modification are the processes of habitat loss and fragmentation, which are major causes of species’ extinctions, population declines and altered ecosystem functions. However, in many tropical, sub-tropical and temperate regions, abandoned agricultural lands are reverting to regrowth or secondary forest, which represents an important opportunity for passive landscape restoration. Regrowth may be particularly important in highly modified landscapes, where the area of mature forest may be insufficient to support viable plant and animal communities without some form of restoration. Some studies of fauna populations in regrowth forest have found recovery of species richness within several decades, although recovery of species composition may take at least 100 years and some species may be permanently lost. While these findings are encouraging, they generally fail to account for the landscape context in which regrowth occurs and focus mainly on tropical forests. The aim of this thesis was to advance the understanding of fauna recovery in regrowth forests on abandoned agricultural land by: i) comparing woodland bird communities in a replicated chronosequence of semi-arid sub-tropical regrowth forests; and ii) quantifying how the ecological values of regrowth habitat vary among stand-, patch- and landscape-levels of ecological organisation. A review of 68 studies of fauna recovery in regrowth forests, revealed that current knowledge is limited by the predominance of studies conducted: in tropical rainforests; with minimal replication of sites; in landscapes within proximity of large tracts of relatively undisturbed mature forests; and with limited consideration of the influence of the spatial context on fauna recovery in regrowth forest. This study makes a significant contribution to understanding fauna recovery in regrowth forests by quantifying the recovery of estimated bird species richness to levels similar to mature forest, within a period of 30-60 years, in highly modified semi-arid agricultural landscapes in sub-tropical Australia. An ordination of the similarity in species composition among forest types also suggested that after 30-60 years regrowth bird communities are more similar to mature brigalow forest than the younger regrowth. This is important for the recovery of brigalow ecosystems, an endangered ecological community where regrowth is currently given minimal protection from further clearing. Comparisons of the importance of habitat attributes using model averaging and hierarchical partitioning of generalised linear models of the species richness of woodland birds showed that bird species richness was positively associated with patch age, and that stand-level factors such as grazing disturbance and the abundance of mistletoes (Amyema spp.) were also important. The spatial context of vegetation patches (size, shape and isolation) was equally important for bird species richness, with more species of woodland dependent, nectar/frugivores and non-ground foraging insectivores occurring in less modified landscape contexts, and the converse for generalist species, ground foraging insectivores and granivores. While a number of woodland dependent bird species known to be in decline in temperate woodlands of southern Australia were absent or rare in regrowth forests, several species (e.g., eastern yellow robin) also occupied regrowth habitats. This finding suggests that these more sensitive species may respond positively to landscape restoration through targeted retention of brigalow regrowth. The landscape-level amount of forest varied in importance among regrowth age classes and bird groups. In general, the amount and number of mature forest patches in the landscape were of lower importance than local attributes. However, the amount of mature forest and old regrowth (> 30 years) in the landscape did have an important positive influence on the number of woodland bird species and species’ abundance; suggesting that regrowth is making an important contribution to landscape recovery in the study area. Mistletoe abundance was strongly dependent on particular species of frugivores for seed dispersal (e.g., mistletoebird, spiny-cheeked honeyeater and painted honeyeater), and varied considerably among three sub-regions of the study area. In general, mistletoe abundance increased in linear patches and more highly modified landscapes but was also dependent on the abundance of seed dispersers and brigalow stand condition. These findings suggest that narrow linear patches in brigalow landscapes can have important conservation values for woodland birds. The study outcomes have important implications for research and management of regrowth vegetation, both within Australia and internationally. From an international perspective, the study highlights the need for greater consideration of the importance of regrowth forest in a landscape context for conserving and restoring fauna communities. From an Australian perspective, the study provides important baseline information for the conservation and management of woodland bird habitat in fragmented brigalow landscapes. Prior to this research, very little was known on the spatial ecology of woodland birds in the region. The study highlights the important conservation values of small and often linear mature brigalow patches for woodland birds and the considerable potential for restoration of habitat for a diverse range of species through the retention of regrowth vegetation. In particular, the research outcomes suggest that targeting the retention of regrowth towards increasing the size and reducing the isolation of mature brigalow forests may be an effective strategy to maximise biodiversity benefits. Brigalow regrowth stands will need to be retained for at least 60 years and probably longer to maintain viable woodland bird communities. For this to happen on a regional-scale, brigalow regrowth needs to be given greater recognition for potential biodiversity benefits either within a legislative framework or by incentive schemes to promote the long term persistence of regrowth habitat within the landscape.
123

Quantifying the ecological values of brigalow regrowth for woodland birds: a hierarchical landscape approach

Michiala Bowen Unknown Date (has links)
The conversion of native forests to pastures and crops is one of the most extensive causes of deforestation worldwide. Concomitant with agricultural landscape modification are the processes of habitat loss and fragmentation, which are major causes of species’ extinctions, population declines and altered ecosystem functions. However, in many tropical, sub-tropical and temperate regions, abandoned agricultural lands are reverting to regrowth or secondary forest, which represents an important opportunity for passive landscape restoration. Regrowth may be particularly important in highly modified landscapes, where the area of mature forest may be insufficient to support viable plant and animal communities without some form of restoration. Some studies of fauna populations in regrowth forest have found recovery of species richness within several decades, although recovery of species composition may take at least 100 years and some species may be permanently lost. While these findings are encouraging, they generally fail to account for the landscape context in which regrowth occurs and focus mainly on tropical forests. The aim of this thesis was to advance the understanding of fauna recovery in regrowth forests on abandoned agricultural land by: i) comparing woodland bird communities in a replicated chronosequence of semi-arid sub-tropical regrowth forests; and ii) quantifying how the ecological values of regrowth habitat vary among stand-, patch- and landscape-levels of ecological organisation. A review of 68 studies of fauna recovery in regrowth forests, revealed that current knowledge is limited by the predominance of studies conducted: in tropical rainforests; with minimal replication of sites; in landscapes within proximity of large tracts of relatively undisturbed mature forests; and with limited consideration of the influence of the spatial context on fauna recovery in regrowth forest. This study makes a significant contribution to understanding fauna recovery in regrowth forests by quantifying the recovery of estimated bird species richness to levels similar to mature forest, within a period of 30-60 years, in highly modified semi-arid agricultural landscapes in sub-tropical Australia. An ordination of the similarity in species composition among forest types also suggested that after 30-60 years regrowth bird communities are more similar to mature brigalow forest than the younger regrowth. This is important for the recovery of brigalow ecosystems, an endangered ecological community where regrowth is currently given minimal protection from further clearing. Comparisons of the importance of habitat attributes using model averaging and hierarchical partitioning of generalised linear models of the species richness of woodland birds showed that bird species richness was positively associated with patch age, and that stand-level factors such as grazing disturbance and the abundance of mistletoes (Amyema spp.) were also important. The spatial context of vegetation patches (size, shape and isolation) was equally important for bird species richness, with more species of woodland dependent, nectar/frugivores and non-ground foraging insectivores occurring in less modified landscape contexts, and the converse for generalist species, ground foraging insectivores and granivores. While a number of woodland dependent bird species known to be in decline in temperate woodlands of southern Australia were absent or rare in regrowth forests, several species (e.g., eastern yellow robin) also occupied regrowth habitats. This finding suggests that these more sensitive species may respond positively to landscape restoration through targeted retention of brigalow regrowth. The landscape-level amount of forest varied in importance among regrowth age classes and bird groups. In general, the amount and number of mature forest patches in the landscape were of lower importance than local attributes. However, the amount of mature forest and old regrowth (> 30 years) in the landscape did have an important positive influence on the number of woodland bird species and species’ abundance; suggesting that regrowth is making an important contribution to landscape recovery in the study area. Mistletoe abundance was strongly dependent on particular species of frugivores for seed dispersal (e.g., mistletoebird, spiny-cheeked honeyeater and painted honeyeater), and varied considerably among three sub-regions of the study area. In general, mistletoe abundance increased in linear patches and more highly modified landscapes but was also dependent on the abundance of seed dispersers and brigalow stand condition. These findings suggest that narrow linear patches in brigalow landscapes can have important conservation values for woodland birds. The study outcomes have important implications for research and management of regrowth vegetation, both within Australia and internationally. From an international perspective, the study highlights the need for greater consideration of the importance of regrowth forest in a landscape context for conserving and restoring fauna communities. From an Australian perspective, the study provides important baseline information for the conservation and management of woodland bird habitat in fragmented brigalow landscapes. Prior to this research, very little was known on the spatial ecology of woodland birds in the region. The study highlights the important conservation values of small and often linear mature brigalow patches for woodland birds and the considerable potential for restoration of habitat for a diverse range of species through the retention of regrowth vegetation. In particular, the research outcomes suggest that targeting the retention of regrowth towards increasing the size and reducing the isolation of mature brigalow forests may be an effective strategy to maximise biodiversity benefits. Brigalow regrowth stands will need to be retained for at least 60 years and probably longer to maintain viable woodland bird communities. For this to happen on a regional-scale, brigalow regrowth needs to be given greater recognition for potential biodiversity benefits either within a legislative framework or by incentive schemes to promote the long term persistence of regrowth habitat within the landscape.
124

Interactions between habitat fragmentation and invasions: factors driving exotic plant invasions in native forest remnants, West Coast, New Zealand.

Hutchison, Melissa Alice Sarah January 2009 (has links)
Habitat fragmentation and biological invasions are widely considered to be the most significant threats to global biodiversity, and synergistic interactions between these processes have the potential to cause even greater biodiversity loss than either acting alone. The objective of my study was to investigate the effects of fragmentation on plant communities in native forest fragments, and to examine potential interactions between these effects and invasions by exotic plants at multiple spatial scales. I examined edge, area and landscape effects on plant invasions using empirical data from fragmented landscapes on the West Coast of New Zealand. My research revealed significant interactions between the amount of native forest cover in the landscape and the strength of edge and area effects on plant communities in forest fragments. The dominance of exotic plants in the community was highest at forest edges and decreased towards fragment interiors, however the interiors of very small fragments were relatively more invaded by exotic plants than those in larger fragments, reflecting a significant interaction between edge and area effects. Similarly, exotic dominance increased in more heavily deforested landscapes, but this effect was only apparent in very small fragments (<2 ha). The combined effects of small fragment size and low forest cover in the landscape appear to have promoted invasions of exotic plants in very small remnants. I explored the mechanisms underlying edge-mediated invasions in forest fragments and examined whether propagule availability and/or habitat suitability may be limiting invasions into fragments. Experimental addition of exotic plant propagules revealed that landscape forest cover interacted with edge effects on germination, growth and flowering rates of two short-lived, herbaceous species, and this appeared to be driven by elevated light and soil phosphorus levels at edges in heavily deforested landscapes. I also examined the role of traits in influencing plant responses to forest fragmentation. Different traits were associated with exotic invasiveness in edge and interior habitats of forest fragments, indicating that the traits promoting invasiveness were context dependent. Traits also had a major influence on responses of native plants to forest fragmentation, with generalist species appearing to benefit from fragmentation, as they can utilise both forest and open habitats, whereas native forest specialists have been negatively impacted by fragmentation.
125

Metapopulation structure of the Western Spotted Frog (Heleioporus albopunctatus) in the fragmented landscape of the Western Australian wheatbelt

Davis, Robert A. January 2004 (has links)
[Truncated abstract] Amidst concern over the global phenomenon of declining amphibians, there is an increasing appreciation of the importance of understanding population dynamics at both local and regional scales. Data on the viability and persistence of species in landscapes altered by humans are scarce but an understanding of these dynamics is essential for enabling long-term species conservation in a modified world. Habitat loss, fragmentation and ensuing salinisation are of particular concern for species in Australia’s temperate agricultural regions where the rapid conversion of continuously vegetated landscapes to small fragments has occurred in less than 200 years. This thesis investigated the local and metapopulation structure of Heleioporus albopunctatus to determine the current population structure and likely future of this species in a highly degraded landscape: the wheat and sheep growing areas of southwestern Australia ... The life-history attributes of H. albopunctatus, including high fecundity, high adult longevity and low to moderate dispersal contribute to a robust regional metapopulation, responsive to changes, but with a strong chance of persistence over the long-term. H. albopunctatus appears to have adjusted to a radically modified landscape but its long-term persistence may be dependent on the existence of a small number of source populations that recruit in most years.
126

Composição da avifauna, frugivoria e dispersão de sementes por aves em áreas de floresta estacional semidecidual e cerrado, no Parque Estadual de Porto ferreira, São Paulo / Avifauna, frugivory and seed dispersal by birds in areas of semideciduous forest and savanna in the Porto ferreira state park, Sao Paulo

Athiê, Samira 29 October 2014 (has links)
Made available in DSpace on 2016-06-02T19:30:09Z (GMT). No. of bitstreams: 1 6453.pdf: 5537867 bytes, checksum: 57a708de759300745321cdff506b4e17 (MD5) Previous issue date: 2014-10-29 / Financiadora de Estudos e Projetos / In the São Paulo State predominated two large phytoecological formations: the semideciduous forests and the savanna. The extensive use of these areas mainly for cane sugar plantations and other monocultures, caused a high loss of habitats. While still play an important role in maintaining the biodiversity of the State, there is a lack of information on bird communities in this region. In this sense, we have developed a comprehensive study on the avifauna of Porto Ferreira State Park (PFSP), which protects one of the few stretches of ecological tension between semideciduous forest and savanna in São Paulo. In Chapter I, we analyze the composition and structure of PFSP&#8223;s bird community. We recorded 207 bird species in the area, between February 2011 and October 2013, including 15 threatened/near threatened species, 22 endemic to the Atlantic Forest and two endemic to savanna. We found that the PFSP has a bird richness similar to large fragments of the region, although the most sensitive species and more demanding in the resources exploitation are less abundant compared to generalist species and to the most conserved fragments of the surroundings. In Chap. II, we evaluated the interaction between frugivorous birds and PFSP&#8223;s ornithochoric plants. There was availability of attractive fruit throughout the year, with peak productivity between September and October, in line with the pre-reproductive period of birds and the arrival of migratory species. Despite the prevalence of generalist birds that disperse mainly small seeds of plants from the early succession stages, we found the PFSP has a diversified frugivorous bird-plant interaction network compared to other forest fragments of the State, due to the variety of available environments, connection with other surroundings fragments and its medium size and rounded shape, softening the matrix impact. In Chap. III, we evaluated the potential of bird perches in increasing the seed rain in an abandoned pasture within the PFSP limits. Therefore, we installed seed traps under natural perches (living trees) and artificial, noting the number of deposited seeds increased proportionally to the amount of landing perches structures. Natural perches also provided other resources for birds, such as fruits, insects and shelter, making them more attractive. We conclude that natural perches and artificial perches with more elaborate architecture showed greater efficiency in attracting seed-disperser birds and increasing the seed deposition, being the most recommended for this area recovery and for ecological restoration projects. / No interior do Estado de São Paulo predominavam duas grandes formações fitoecológicas: as Florestas Estacionais e o Cerrado. O uso extensivo dessas áreas principalmente para plantações de cana-de-açúcar e outras monoculturas, ocasionou uma elevada perda de habitats. Embora ainda desempenhe um importante papel na manutenção da biodiversidade do Estado, há carência de informações sobre a comunidades de aves dessa região. Neste sentido, desenvolvemos um estudo amplo sobre a avifauna do Parque Estadual de Porto Ferreira (PEPF), que protege um dos poucos trechos de tensão ecológica entre Floresta Estacional Semidecidual e Cerrado do interior paulista. No Capítulo I, analisamos a composição e a estrutura da comunidade de aves do PEPF. Registramos 207 espécies de aves na área, entre fevereiro de 2011 e outubro de 2013, incluindo 15 ameaçadas/quase ameaçadas de extinção, 22 endêmicas de Mata Atlântica e duas endêmicas de Cerrado. Verificamos que o PEPF apresenta riqueza avifaunística similar aos grandes fragmentos da região, embora as espécies mais sensíveis e mais exigentes na exploração de recursos sejam pouco abundantes quando comparadas às espécies generalistas e em relação aos fragmentos mais conservados do entorno. No Cap. II, avaliamos a interação entre as aves frugívoras e as plantas ornitocóricas do PEPF. Houve disponibilidade de frutos atrativos ao longo de todo o ano, com pico de produtividade entre setembro e outubro, em consonância com o período pré-reprodutivo das aves e com a chegada de espécies migratórias. Embora predominem as aves generalistas que dispersam principalmente pequenas sementes de plantas de estágios iniciais da sucessão, constatamos que o PEPF apresenta uma rede de interações ave frugívora-planta bastante diversificada em comparação com outros fragmentos florestais do Estado, em função da variedade de ambientes disponíveis, da conexão com outros fragmentos do entorno e do seu tamanho médio e formato arredondado, amenizando os impactos da matriz. No Cap. III, avaliamos o potencial de poleiros para aves no incremento da chuva de sementes em um antigo pasto abandonado, dentro dos limites do PEPF. Para tanto, instalamos coletores de sementes sob poleiros naturais (árvores vivas) e artificiais, constatando que o número de sementes depositadas aumentou proporcionalmente à quantidade de estruturas de pouso dos poleiros. Os poleiros naturais também disponibilizaram outros recursos para a avifauna, como frutos, insetos e abrigo, tornando-os mais atrativos. Concluímos que os poleiros naturais e os poleiros artificiais com arquitetura mais elaborada demonstraram maior eficiência na atração das aves dispersoras e no incremento da deposição de sementes, sendo os mais recomendados para a recuperação daquela área e para projetos de restauração ecológica.
127

Mapeamento e caracterização dos fragmentos florestais da bacia do baixo rio São Francisco em Sergipe e suas implicações a para conservação de guigós (Callicebus sp.) / MAPPING AND CHARACTERIZATION OF THE FOREST FRAGMENTS DOWN RIVER BASIN IN SAN FRANCISCO AND SERGIPE IMPLICATIONS FOR CONSERVATION GUIGÓS (Callicebus SP.).

Santos Junior, Eduardo Marques 23 February 2010 (has links)
The assessment of the geographic distribution of organisms in fragmented landscapes is one of the principal approaches of Conservation Biology, due to the extensive loss of natural habitats, both in overall quantity and quality (habitat fragmentation). In the Brazilian state of Sergipe, the surviving remnants of the forested habitats of the Atlantic Forest and Caatinga biomes support an important diversity of organisms. Given this, the objective of the present study was the quantification and characterization of the forest fragments of the lower Rio São Francisco basin (LSF) in Sergipe, with regard to the size, form, and distribution of fragments from the viewpoint of the conservation of local populations of titi monkeys (Callicebus sp.). This assessment was based on geoprocessing techniques, which were used to map the study area using the programs SPRING 5.1.4 and ENVI 4.3 for the analysis of satellite images in order to estimate the number of fragments within the study area and their characteristics (size, shape, perimeter). A total of 5453 fragments were identified in the LSF, with a total area of 73,850.70 hectares, approximately 10.9% of the 679,210.30 ha of the study area. The program Patch Analyst 4 defined mean fragment size as 13.54±72.14 ha, although only 560 fragments were larger than 20 hectares. The mean and weighted shapes indices (MSI = 2.55 and AWMSI = 3.68) indicated a tendency towards highly irregular fragment shapes (ideal value = 1 for both indices) characterized by a high proportion of edge habitat. Titi monkey populations were surveyed at 67 sites using the playback technique. A total of 15 populations were identified, 13 at new localities. These populations are concentrated in three sub-basins of the LSF those of the Betume, Capivara, and Curituba rivers. The total area occupied by titis was 2,660.10 ha, with occupied fragments varying in size from 2.63 to 1,069.0 hectares. By logistic regression analysis was performed as the program Spatial Analysis in Macroecology (SAM) was able to verify that the features of the landscape and the position does not determine the presence / absence of outriggers in these fragments (p = 0.4962 > 0.05). These findings are extremely important for the long-term planning of conservation and management strategies in the study area, not only for Callicebus, but the ecosystems as a whole. / A distribuição geográfica dos organismos em paisagens fragmentadas é uma das principais abordagens da biologia da conservação devido ao quadro de perda do hábitat em quantidade e qualidade. Em Sergipe, os remanescentes florestais dos biomas da Mata Atlântica e da Caatinga ainda abrigam uma importante diversidade biológica. Este trabalho teve o objetivo de quantificar e caracterizar os fragmentos de floresta da bacia do baixo rio São Francisco de Sergipe (BSF) avaliando-os quanto ao tamanho, a forma e distribuição sob o ponto de vista da conservação de populações de Callicebus ssp. Foram usadas técnicas de geoprocessamento para mapear a área de estudo onde se utilizou os programas SPRING 5.1.4 e ENVI 4.3 e imagens de satélite para estimar a quantidade de fragmentos existentes na região. Foi avaliada uma área de 679.210,30 ha, da qual 10,87% (73.850,70 ha) correspondem a 5.453 fragmentos. Os resultados obtidos através dos programas Patch Analyst 4 e Fragstats 3.3 sobre a forma e tamanho destes fragmentos indica uma média de tamanho para BSF de 13,54 (±72,14). Apenas 560 fragmentos possuem mais que 20,0 ha e estes possuem formas muito irregulares conforme indicam os resultados dos índices de forma médio (MSI = 2,55) e o índice ponderado pelo tamanho da área (AWMSI= 3,68) cujos valores ideais são iguais a 1,0. Os levantamentos de guigós foram realizados com a técnica do Playback para quantificar suas populações em 67 fragmentos. Ao todo 15 populações de guigós foram identificadas, das quais 13 são novas localidades de ocorrência. As populações concentram-se em três sub-bacias: Betume, Capivara e Curituba. A área dos fragmentos com presença de guigós totalizou 2.660,10 ha e variou de 2,63 ha a 1.069,0 ha. Através da análise de regressão logística realizada como o programa Spatial Analysis in Macroecology (SAM) foi possível verificar que as características da paisagem e a posição não determinam a presença/ausência de guigós nesses fragmentos (p: 0.4962>0,05). Essas informações são extremamente importantes no planejamento de conservação de longo prazo e como subsídios para estratégias de manejo na área de estudo não somente para Callicebus sp., mas para o ecossistema como um todo.
128

Guilda de abelhas e outros visitantes de Matayba guianensis (Sapindaceae) em vegetação de cerrado

Carvalho, Ana Maria Coelho 13 February 2009 (has links)
In entomophilous plants, the most frequent flower visitors are social and solitary bees. The relationship is mutualistic, as bees benefit from pollen and nectar, and plants have their pollination performed by bees. The study of the guilds of flower-visiting bees presents as results, among others, the understanding of the guild structure and the factors that interfere with this structure. Among these, the deforestation of natural areas, as in the Cerrado , has been considered as one of the main factors. Thus, a common Cerrado plant Matayba guianensis Aubl., (Sapindaceae) was chosen, with the goal of studying the structure of the guild of flower-visiting bees in this species. Other objectives were: to investigate whether the environmental differences among three Cerrado areas would have an influence on the structure of this guild and determine the flower visitors and probable pollinators of Matayba guianensis, besides bees. Three Cerrado sites were chosen in the city of Uberlândia, Minas Gerais, Brazil: the Panga Ecological Station (EEP), with 1,011.90 a; the Palma da Babilônia Farm (FPB), with 444.79 a and the Souza Cruz (SC) Property, with 70.43 a. The areas presented environmental differences evinced by the estimates of natural vegetation in the surroundings: 52.62 % for EEP, 32.94 % for FPB and 9.73 % for SC. Bees and other insects were collected on Matayba guianensis in two consecutive flowering periods, from October to December of 2005 and 2006. Matayba guianensis presented asynchrony in its phenological stages and predominance of staminate individuals (64,7%) in comparison to the estaminate/pistilate and only pistilate individuals, and was considered a generalist species regarding its flower visitors. In the first phase, 1516 bees were collected, belonging to five families of Apoidea and to 80 species. Analyzing these, we found 30% of dominant and 46.3% of rare species. In the second phase, 562 bees, belonging to 66 species, composed of 15.2 % of dominant ones and 56.1% of rare ones, were collected. Overall, 2078 bees, pertaining to 105 species, were collected. The Apidae family stood out in terms of number of species and individuals. The most abundant species was Apis mellifera, which represented 41.9 % and 32.7% of the bees collected in the first and second phases, respectively, followed by Scaptotrigona depilis. The visitation pattern of these species is not indicative of resource sharing. The structure of the guild, with many rare species and few abundant ones, as much as the richness and abundance of the families of Apoidea, was similar to other studies conducted in the Cerrado region. The collecting of bees in a single plant species was capable of representing, at least partially, the richness of bees in the Cerrado . There was great similarity between the bee guilds in EEP and FPB. The composition of species of each guild varied more among the three areas than the richness and abundance. The comparison between the bee guilds collected in EEP in 1988/89 and 2005/2006 made the changes in abundance and composition of species evident. The proportion of natural vegetation, the location and the biology of each species, such as in the case of Melipona, are factors that influenced the structure of the bee guilds. Other flower visitors of Matayba guianensis were the Coleoptera, with 35 species, the Diptera, with 37 and wasps, with 54. Some of these species, as Ornidia obesa and Palpada sp.1, may act as pollinators. Other species are probably damaging the plant, as the phytophagous Coleoptera. Matayba guianensis is a key plant in the maintenance of guilds of bees as well as of other Cerrado insects. / Nas plantas entomófilas os visitantes florais mais freqüentes são abelhas sociais e solitárias. A relação é mutualística, com as abelhas se beneficiando do pólen e do néctar e as plantas se beneficiando da polinização realizada pelas abelhas. O estudo das guildas de abelhas visitantes de flores permite, entre outros, o entendimento da estrutura da guilda e dos fatores que interferem nessa estrutura. Dentre estes, o desflorestamento de áreas naturais, como o cerrado, tem sido apontado como um dos principais fatores. Assim, escolheu-se uma planta comum de cerrado, Matayba guianensis Aubl. (Sapindaceae), objetivando-se estudar a estrutura da guilda de abelhas visitantes e aspectos de sua biologia floral. Outros objetivos foram verificar se as diferenças ambientais entre três áreas de cerrado influenciariam na estrutura dessa guilda e determinar os visitantes florais e possíveis polinizadores de Matayba guianensis, além das abelhas. Escolheu-se três áreas de cerrado (sentido restrito), no município de Uberlândia, MG: a Estação Ecológica do Panga- EEP, com 403,85 ha; o cerrado na Fazenda Palma da Babilônia-FPB, com 180 ha e a reserva na Souza Cruz-SC, com 28,5 ha. As áreas apresentavam diferenças que foram evidenciadas pelas estimativas de vegetação natural no entorno: 52,62 % para a EEP, 32,94 % para a FPB e 9,73 % para a SC. As abelhas e outros insetos foram coletados em Matayba guianensis em duas floradas consecutivas, de outubro a dezembro de 2005 e de 2006. Essa planta apresentou assincronia em suas fases fenológicas e predominância de indivíduos estaminados (64,7%) em relação aos estaminados/pistilados e pistilados, sendo generalista quanto a seus visitantes florais. Na primeira etapa, foram coletadas 1516 abelhas, pertencentes a cinco famílias de Apoidea e a 80 espécies. Destas, 30% foram dominantes e 46,3%, espécies raras. Na segunda etapa, coletou-se 562 abelhas pertencentes a 66 espécies, com 15,2 % de espécies dominantes e 56,1% de espécies raras. No total, foram coletadas 2078 abelhas pertencentes a 110 espécies. A família Apidae sobressaiu em número de espécies e de indivíduos. A espécie mais abundante foi Apis mellifera, que representou 41,9 % e 32,7% das abelhas coletadas na primeira e segunda etapas, seguida por Scaptotrigona depilis, com 24% e 20,6%, respectivamente. As espécies mais comuns apresentaram alguns picos de atividade não coincidentes, mas não houve um padrão de partição de recursos ao longo do dia. A estrutura da guilda, com muitas espécies raras e poucas espécies abundantes, assim como a riqueza e abundância das famílias de Apoidea, mostrou-se semelhante a outros trabalhos realizados no cerrado. A coleta de abelhas em uma única espécie de planta foi capaz de representar parcialmente a riqueza de abelhas do cerrado. A similaridade entre a guilda de abelhas da EEP foi bastante semelhante à da FPB. A composição das espécies de cada guilda variou mais entre as três áreas do que a riqueza e abundância. A comparação entre as guildas de abelhas da EEP coletadas em 1988/89 e em 2005/2006 evidenciou alterações na abundância e composição das espécies. A proporção de vegetação natural, a localização e a biologia de cada espécie, como no caso de Melipona, são fatores que influenciaram na estrutura das guildas de abelhas. Outros visitantes florais de Matayba guianensis foram os coleópteros, com 35 espécies; dípteros, com 37 e vespas, com 54. Muitas destas espécies, como os dípteros Ornidia obesa e Palpada sp.1, podem atuar como polinizadores. Outras espécies devem estar prejudicando a planta, como os coleópteros fitófagos. Matayba guianensis é uma planta-chave na manutenção de guildas de abelhas e de outros insetos do cerrado. / Doutor em Ecologia e Conservação de Recursos Naturais
129

Ekologie lasicovitých šelem / Ecology of mustelids in the Central European landscape

ŠÁLEK, Martin January 2009 (has links)
Ph.D. thesis is focused on different aspects of ecology of several mustelid species in the Central European landscape. Particularly, nest predation, habitat and resting sites selection, predator-prey interactions as well as impact of fragmentation and urbanization on mustelids were described in 8 published papers or manuscripts.
130

Mamíferos terrestres de maior porte e a invasão de cães domésticos em remanescentes de uma paisagem fragmentada de Mata Atlântica: avaliação da eficiência de métodos de amostragem e da importância de múltiplos fatores sobre a distribuição das espécies / Terrestrial large mammals and invasion of domestic dogs in remnants of an Atlantic Forest fragmented landscape: evaluation of the efficiency of sampling methods and of the importance of multiple factors on species distribution.

Karina Dias Espartosa 12 March 2009 (has links)
Nessa dissertação, avaliei a eficiência e congruência de métodos para amostragem de mamíferos de maior porte e investiguei a influência de fatores múltiplos correlacionados, comuns em paisagens fragmentadas, sobre a distribuição destes animais em remanescentes de Mata Atlântica. Através de amostragens padronizadas em 24 remanescentes florestais de uma paisagem rural com 49% de remanescentes florestais no Planalto Paulista e de um delineamento pareado, no capítulo 2 comparei o desempenho e a congruência de dois métodos (pegadas em parcelas de areia e armadilhas fotográficas) e de dois tipos de isca (banana e iscas de cheiro) para a estimativa da riqueza e taxa de ocorrência de mamíferos de maior porte. Ambos os métodos se mostraram adequados para o estudo destes animais em florestas tropicais e dos fatores que afetam sua distribuição em paisagens alteradas, pois (1) registram as espécies de menor porte e noturnas, (2) podem ser padronizados entre áreas heterogêneas, (3) apresentam desempenho semelhante no registro da maioria das espécies e da riqueza de espécies, e (4) refletem de maneira similar o padrão de ocorrência das espécies entre diferentes áreas. Frente às iscas de cheiro utilizadas, a banana foi a isca mais eficiente na amostragem tanto das espécies herbívoras/frugívoras quanto das espécies onívoras, destacando a necessidade da padronização das iscas utilizadas e do uso de iscas complementares ou de iscas que atraiam uma ampla gama de animais. Usando os dados obtidos com armadilhas fotográficas, avaliei quais fatores condicionam a presença e a freqüência de ocorrência de cães domésticos (capítulo 3) e de mamíferos de maior porte (capítulo 4) nos remanescentes. Esta avaliação foi realizada através da seleção de modelos de regressão construídos com base na relação causal entre os fatores estudados - que pode ser estabelecida a partir de como usualmente se dá a expansão das atividades humanas em florestas neotropicais - e comparados através do critério de informação AIC (The Akaike Information Criterion). Para o cão doméstico, foram considerados quatro fatores: extensão de estradas, quantidade de mata e número de cães domésticos no entorno, e qualidade da vegetação. Foi observada uma forte relação positiva entre o total de residentes e o total de cães domésticos no entorno dos remanescentes. Dentro dos remanescentes, o cão doméstico foi mais registrado do que sete das 11 espécies nativas, sua ocorrência foi mais bem explicada pela quantidade de cães no entorno, e sua freqüência de ocorrência pela diminuição da quantidade de mata no entorno, o que mostra a necessidade de controle populacional desta espécie no entorno de áreas naturais e da manutenção de áreas florestadas mais extensas, menos suscetíveis a entrada deste invasor. Para os mamíferos de maior porte, os fatores considerados foram: quantidade de mata e número de residentes no entorno dos remanescentes, distância à estrada de asfalto, freqüência de ocorrência de cães domésticos nos remanescentes, e qualidade da vegetação dos remanescentes. Os resultados demonstraram que, apesar da ampla variação na resposta das espécies a estes fatores, a distância a estradas de asfalto e a freqüência de ocorrência de cães domésticos, fatores que são correlacionados a disponibilidade de habitat e não são freqüentemente considerados, determinaram a distribuição de um número maior de espécies. A comunidade de mamíferos de maior porte encontrada é simplificada, dominada por espécies generalistas e com poucos dispersores e predadores de sementes e plântulas, o que pode levar a conseqüências negativas para outras espécies e para o funcionamento e regeneração das florestas remanescentes. Estes resultados sugerem que para a conservação de uma comunidade íntegra de mamíferos de maior porte na Mata Atlântica é necessário, não apenas a manutenção de grandes contínuos de mata nativa ou de paisagens com percentual alto de matas remanescentes, mas a redução drástica das perturbações associadas à ocupação e atividades humanas. O manejo e restauração de paisagens devem considerar a proximidade entre os remanescentes florestais e estradas, principalmente as asfaltadas e de alto tráfego, e a importância de campanhas de controle populacional e vacinação de cães domésticos. / In this master thesis, I evaluated the efficiency and congruence of methods for sampling large mammals, and investigated the influence of multiple and correlated factors, common in fragmented landscapes, on the distribution of these animals in Atlantic Forest remnants. Through standardized surveys at 24 forest remnants in a rural landscape with 49% of remaining forest in the Planalto Paulista and using a paired design, in chapter 2 I compared the performance and the congruence of two methods (tracks in sand plots and camera-trapping) and of two types of baits (banana and scent lures) for estimating richness and rate of occurrence of large mammals. Both methods are suitable for studying these animals in tropical forests as well as the factors that affect their distribution in disturbed landscapes, because (1) they record medium-sized and nocturnal species, (2) can be standardized among heterogeneous sites, (3) present similar performance for recording most species and richness, (4) reflect in similar ways the pattern of species occurrence among different sites. Compared with scent lures, banana was the most efficient bait for sampling herbivores/frugivores as well as omnivores, highlighting the need to standardize baits and use complementary baits or baits that attract a wide range of animals. Using camera-trapping data, I evaluated which factors determine the presence and the frequency of occurrence of domestic dogs (chapter 3) and of large mammals (chapter 4) in remnants. This evaluation was done through the selection of regression models buit based on the causal relationship among studied factors which can be established from the way expansion of human activities usually happens in neotropical forests and compared through the AIC, The Akaike Information Criterion. For the domestic dog, four factors were considerate: extension of roads, amount of forest and number of domestic dogs in the surroundings, and vegetation quality. It was observed a strong positive relationship between the total number of residents and the total number of domestic dogs in the surroundings. Inside remnants, the domestic dog was more frequently recorded than seven of the 11 native species, its occurrence was better explained by the number of dogs in the surroundings, and its frequency of occurrence by the reduction of the amount of forest in the surroundings, which indicates the need of population control of this invasive species in the surroundings of natural areas and of the maintenance of extensive forests areas that are less susceptible to the entrance of this invasive species. For native large mammals, the considered factors were: amount of forest and number of residents in the surroundings, distance from paved roads, frequency of occurrence of domestic dogs and vegetation quality. Results suggested that, despite the large variation in the responses of species to the studied factors, distance from paved roads and frequency of occurrence of domestic dog, factors that are correlated with habitat availability and are not frequently considered, determined the distribution of a larger number of species. The large mammal community found is simplified, dominated by generalist species and with few seed and seedling dispersers and predators, which can lead to negative consequences to other species and to forest functioning and regeneration. These results suggest that for conserving a complete large mammal community at the Atlantic Forest, not only the maintenance of large tracts of continuous forest or landscapes with high percentage of remaining forest is needed, but also a drastic reduction of disturbances associated with human activities and occupation. Landscape management and restoration should consider the proximity between forest remnants and roads, especially those that are paved and present high traffic, and the importance of campaigns of domestic dog population control and vaccination.

Page generated in 0.1131 seconds