Seit Beginn des Ackerbaus hat sich eine an die Kulturarten angepasste Ackerbegleitflora und -fauna entwickelt. Intensivierungsprozesse der landwirtschaftlichen Produktion führten in den letzten Jahrzehnten zu einer stetig voranschreitenden Umstrukturierung vieler Agrarlandschaften und einer Abnahme der Habitatdiversität. Diese Entwicklung war verbunden mit einem dramatischen Verlust der Artenvielfalt und einem drastischen Rückgang der Populationsgrößen von Segetalarten. Eine Reihe von Studien zeigt aber, dass eine artenreiche Segetalflora eine entscheidende Rolle bei der Erhaltung der Funktionsfähigkeit von Agrar-Ökosystemen spielt, z.B. durch Förderung höherer trophischer Ebenen oder durch die Bereitstellung von Ökosystemdienstleistungen. Die vorliegende Arbeit untersucht die Auswirkungen der ackerbaulichen Intensivierung auf die Segetalvegetation in Mitteldeutschland sowohl auf Landschafts- als auch auf Populationsebene. Die Ergebnisse dieser Untersuchungen wurden zur Evaluierung bestehender Projekte zur Förderung der Segetalflora genutzt und liefern eine Grundlage für zukünftige Schutzstrategien. Die Ergebnisse der Untersuchungen zeigen eine dramatische Verarmung der Segetalvegetation auf allen wichtigen Hierarchiestufen. Auf europäischer Ebene konnte für alle europäischen Länder nachgewiesen werden, dass ein höherer Weizenertrag auch mit einer erhöhten Zahl gefährdeter Segetalarten einhergeht. So hatte jede zusätzlich produzierte Tonne Weizen/ha eine Gefährdung von etwa zehn weiteren Segetalarten Ländern zur Folge. Dabei scheinen die an bestimmte Kulturarten angepassten Spezialisten am stärksten vom Aussterben bedroht zu sein. Die Untersuchungen belegen, dass der verstärkte Einsatz von Herbiziden in den EU-Mitgliedstaaten in Mittel-und Nord-Westeuropa zu einer Selektion ausgewählter Segetalarten geführt hat, die an die heutigen nivellierten Standortbedingungen angepasst ist. Auf Gesellschaftsniveau, zeigen unsere Untersuchungen deutlich, dass die Intensivierung der Nutzung von Agrar-Ökosystemen zu massiven Verschiebungen in der Zusammensetzung von Segetalgesellschaften geführt hat. In den 1950er/60er Jahren konnte die Mehrzahl der Vegetationsaufnahmen noch auf Assoziationsebene zugeordnet werden, während sich aktuelle Vegetationserhebungen oft nur noch auf der Ebene höherer Syntaxa wie Verband, Ordnung, Klasse oder als floristisch stark verarmte Fragment-Gesellschaften einstufen ließen. In diesem Zusammenhang kann in den letzten fünf Jahrzehnten auch eine Verringerung des regionalen Artenpools um 23 %, ein dramatischer Artenverlust auf Plot-Ebene (mittlerer Verlust von 17 Arten pro Aufnahme) sowie stark zurückgehende Populationsgrößen kennzeichnender Arten belegt werden. Die Ergebnisse verdeutlichen auch, dass die Intensität der Veränderungen in der Vegetationszusammensetzung zwischen den unterschiedlichen Böden variierte, wobei sandige Standorte weniger stark betroffen waren. Des Weiteren hat sich der mittlere Deckungsgrad der Segetalarten drastisch auf ein Zehntel des früheren Wertes reduziert, wohingegen der Deckungsgrad der Kulturpflanzen anstieg und die Kulturpflanzenvielfalt abnahm. Archäophyten, Neophyten und die meisten Grasartigen zeigten zum Teil starke Frequenzverluste ähnlich denen von einheimischen krautigen Pflanzen, aber nur geringe Veränderungen in ihrem Anteil an der Gesamtdeckung der Segetalarten. Der beobachtete Anstieg der „Ellenberg-Zeigerwerte“ für Stickstoff und Bodenreaktion deutet darauf hin, dass die höhere Düngergaben in Kombination mit der heute üblichen Anwendung von Herbiziden und den sehr dicht stehenden Kulturpflanzenbeständen als Hauptursachen für Veränderungen in der Segetalvegetation angesehen werden können. Der beobachtete Trend einer Vereinheitlichung der Gesellschaftstrukturen von Segetalarten, bei der Spezialisten und diagnostisch wichtige Arten zurückgehen und die Anzahl und Abundanz der Generalisten zunimmt, spiegelt die Vereinheitlichung von Anbausystemen und der Optimierung des Nährstoffangebotes in den letzten Jahrzehnten wider. Der beobachtete Rückgang der Populationsgröße, insbesondere bei selten gewordenen Arten mit geringer Populationsgröße (Adonis aestivalis L. und Consolida regalis S.F. Gray), wirkten sich auf die genetische Vielfalt dieser Populationen aus. Da die genetische Struktur zwischen den Arten und Populationen variiert, ist in diesem Zusammenhang auch die Komplexität der Landschaftsstruktur entscheidend. Anders als erwartet war die genetische Diversität innerhalb einzelner Populationen in weniger stark strukturierten Landschaften wesentlich höher als innerhalb von Populationen in strukturreichen Landschaften. Populationen aus strukturreichen Landschaften unterschieden sich genetisch zudem stärker voneinander als Populationen strukturärmerer Landschaften. Darüber hinaus wurde bei der fremdbefruchtenden C. regalis eine höhere Diversität innerhalb der Populationen festgestellt, während die selbstbefruchtende A. aestivalis eine geringere Diversität innerhalb der Populationen aufwies. Allerdings zeigten weder A. aestivalis noch C. regalis eine signifikante „Isolation-by-Distance“ unabhängig von der Landschaftsstruktur. Zusammenfassend zeigt die vorliegende Arbeit, dass auf allen Hierarchiestufen von der kontinentalen Ebene, über die Phytocoenosen bis hin zu Populationen einzelner Arten starke Veränderungen in den Segetalgesellschaften stattgefunden haben. Um das nationale Ziel der Erhöhung der Populationsgrößen der Mehrzahl der Arten in landwirtschaftlich genutzten Ökosystemen bis 2015 zu erreichen, sind neue, effektive und innovative Maßnahmen dringend erforderlich. Um den fortwährenden Biodiversitätsverlust in der Agrarlandschaft entgegenzuwirken ist vor allem eine entsprechende Ausgestaltung der Gemeinsamen Europäischen Agrarpolitik (GAP) für die Förderperiode 2014-2020 von zentraler Bedeutung.

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

The local extinction of habitat patches and dispersal between the patches are important processes structuring animal populations in heterogeneous environments. Understanding these two processes is crucial for the conservation of wildlife populations in landscapes impacted by human land-use. Approximately 50% of the subtropical rainforest in South East Queensland, Australia has been lost to deforestation over the last 100 years. While large areas of rainforest are reserved, little is known about the distribution and population status of rainforest birds within smaller remnants in the region. The overall research problem for this thesis was to understand how deforestation and fragmentation of subtropical rainforest affects the occurrence of rainforest birds and the effective dispersal of a rainforest-restricted species, the logrunner (Orthonyx temminckii). Understanding why some bird species are lost from habitat patches while others remain will lead to improved conservation of extinction prone species in fragmented landscapes. Although the mechanisms underlying local extinctions are well established in temperate systems, the relative importance of local and regional processes on species occurrence in subtropical and tropical rainforests is poorly understood. Chapter 2 investigated the relative effects of life history and scale of habitat modification on avian site occupancy using observational data collected at 46 rainforest sites in South East Queensland. A probabilistic model for the joint site occupancy of 29 bird species was used to evaluate hypotheses for the effects of avian life history traits on the occurrence of multiple species. The single-species occurrence models incorporated habitat effects on detection, which may be especially important in rainforests because dense vegetation and idiosyncratic occurrence of species can interfere with sampling. Occupancy rates for each species were modelled to determine the relative influence of process operating at the stand, landscape and patch scales. The life history analysis indicated taxonomic Family, body mass, migratory strategy and feeding strata had large effects on avian site occupancy, whereas abundance traits such as mean density and extent of occurrence showed little predictive ability. After accounting for correlated extinction risk attributed to life history, the degradation of stand structure at the local scale was more important for species richness than habitat modification at landscape or patch scales. While individual species showed various responses to the different scales of habitat modification, the distribution of many species was limited by vegetation structure at the landscape scale. Maintaining stand basal area and restoring degraded rainforests at the local scale will increase the probability of occupancy for members of the rainforest bird community. However, revegetation and retention of forest cover at the landscape scale may be necessary for the successful colonisation of many species. Chapter 3 introduced a predictive hypothesis-driven approach for quantifying the relative contribution of historic and contemporary processes to genetic connectivity. Current analytic frameworks in population genetics have difficulty evaluating meaningful hypotheses about spatial processes in dynamic landscapes. Confronting genetic data with models of historic and contemporary landscapes allowed the identification of dispersal processes operating in naturally heterogeneous and human-altered systems. Two measures of indirect gene flow were estimated from microsatellite polymorphism among 11 logrunner populations. Of particular interest was how much information in the genetic data was attributable to processes occurring in a reconstructed historic landscape and a contemporary human-modified landscape. A linear mixed model was used to estimate appropriate sampling variance from non-independent data and information-theoretic model selection provided strength of evidence for alternate hypotheses. The historic and contemporary landscapes explained an equal proportion of variation in genetic differentiation and there was considerable evidence for a temporal shift in dispersal pattern. Migration rates estimated from genealogical information were primarily influenced by contemporary landscape change. Landscape heterogeneity appeared to facilitate gene flow prior to European settlement, but contemporary deforestation is rapidly becoming the most important barrier to logrunner dispersal. Understanding asymmetric dispersal is becoming an important consideration for the conservation metapopulations. Populations acting as net exporters of dispersing animals may be able to rescue local populations from extinction and allow metapopulations to persist in degraded landscapes impacted by habitat loss. In Chapter 4, I estimated bidirectional migration rates from genetic data to infer dispersal among 11 logrunner populations. The first question posed was, does logrunner dispersal correspond to the source-sink or balanced model of dispersal? The second question involved determining the strength of evidence for two hypotheses about how landscape structure has affected asymmetric dispersal. Hypothesis one proposed that asymmetric dispersal was primarily influenced by naturally occurring habitat heterogeneity. Hypothesis two asserted that asymmetric dispersal was predominantly influenced by anthropogenic landscape change. The data were confronted with the alternate hypotheses using linear mixed models and landscape covariates extracted from digital maps. The results showed the direction of asymmetric dispersal was consistent with source-sink population structure. I also discovered that the asymmetry in dispersal was influenced more by anthropogenic landscape change than by naturally occurring habitat heterogeneity. Intact landscapes were net exporters of dispersing logrunners while landscapes heavily impacted by rainforest clearing were net importers of individuals. Elevated immigration rates into landscapes impacted by rainforest clearing appeared to arrest population declines in accordance with the rescue effect. The primary conclusion emerging from the study of patch occupancy and dispersal was that logrunner populations in South East Queensland conformed to a mainland-island metapopulation. Asymmetric dispersal from the largest expanse of upland rainforest appeared to prevent fragmented rainforests in close proximity from going locally extinct. While the distribution of logrunners was limited by the spatial configuration of rainforest patches, other rainforest birds exhibited variable responses to scale of habitat modification. The most consistent pattern was several species dropping-out of the community in degraded stands affected by selective timber harvest. Deforestation at the landscape scale also played a role in the extremely low patch occupancy rates of Albert’s lyrebirds (Menura alberti) and green catbirds (Ailuroedus crassirostris).

Made available in DSpace on 2015-03-26T13:30:54Z (GMT). No. of bitstreams: 1 texto completo.pdf: 977653 bytes, checksum: 9245342bfb1b1d3396ff9464707b4a33 (MD5) Previous issue date: 2006-07-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Amazon region has the largest drainage basin of the world, which is constituted by a diversity of waterbodies, and almost all of them are resulting from the junction of small streams ( igarapés ) that drain the forest. The igarapés present acid, nutrient-poor waters, and their food chains are dependent on allochthonous materials provided by the forest that fall into the igarapé, as pollen, flowers, fruits, leaves, branches, insects and spiders. In spite of that, the Terra-Firme system in the Amazon is recognized as the ecosystem of higher species diversity on the planet. This work aimed to describe the distribution and the beta diversity pattern of the species comprising the Odonata communities present in the Adolfo Ducke Forest Reserve river basins. It also objectives to provide information about determining factors of the fauna similarity among sites, in order to select viable units for Odonata conservation. Samples were carried out in 24 igarapés (eleven of 1st, eight of 2nd and five of 3rd order) distributed in four river basins, and in each basin it was conducted samples in six igarapés. The samples constituted on visual counting of adult individuals of Odonata present in 100 meters along each waterbody, divided into 20 stretches of 5 meters. The sampling time constituted of one hour duration on average. The total fauna of Odonata founded in the Ducke Reserve was of 17 species observed and 23 (± 4,77) estimated. The cluster analysis of the abiotic data demonstrated high similarity among the igarapés. The microdrainage basins were compared in relation to species richness and they were similar statistically, and the same result was also obtained for beta diversity. The low value of beta diversity index demonstrated high fauna similarity among the igarapés. The relationship of beta diversity between the environmental data and the distance among the igarapés was highly non-significant. The low values of beta diversity index may be attributed to the high similarity of the environment, which presented small variation in the abiotic data, and also to the distance scale of this study, which may be small enough to not represent a barrier to Odonata dispersion. Another factor that may have contributed to these values is the occurrence of a long period of environmental stability in the Amazon that allowed the species distribution in the environment, even those with low dispersion capacity. The basic environmental variables (channel width and depth) were related to species richness increase. These results are important to species conservation, and indicate the necessity of including intermediate-size streams, with higher variation in depth and channel width, to be used as one selection criteria in the choice of environmental protection areas. / A região Amazônica possui a maior bacia de drenagem do mundo, formada por uma diversidade de corpos d água, quase todos resultantes da junção de pequenos igarapés que drenam a floresta. As águas dos igarapés em geral são ácidas, pobres em nutrientes e as cadeias alimentares são dependentes de materiais alóctones, como pólen, flores, frutos, folhas, galhos, insetos e aranhas provenientes da floresta que caem sobre o igarapé. Apesar disso, o sistema de Terra-Firme na Amazônia é reconhecido como o ecossistema de maior diversidade de espécies do planeta. Este trabalho visou conhecer a distribuição e o padrão de diversidade beta das espécies que compõem as comunidades de Odonata presentes nas bacias hidrográficas existentes na Reserva Florestal Adolfo Ducke, bem como promover informações dos fatores que determinam o padrão de similaridade de composição de fauna entre locais, visando a escolha de unidades viáveis para a conservação de Odonata. Para isso, foram realizadas coletas em 24 igarapés (onze de 1a ordem, oito de 2a e cinco de 3a) distribuídos em quatro bacias, sendo que em cada bacia de drenagem foram feitas coletas em seis igarapés. As amostragens consistiram na contagem visual do número de indivíduos adultos de cada espécie de Odonata presentes em 100 metros de margem dos corpos d água, de cada área, divididos em 20 segmentos de cinco metros. O tempo médio em cada ponto de amostragem foi de uma hora. A fauna total de Odonata encontrada na Reserva Ducke foi de 17 espécies observadas e 23 (± 4,77) estimadas. A análise de agrupamento com os dados abióticos demonstrou uma grande semelhança entre os igarapés. As microbacias foram comparadas usando a riqueza de espécies, sendo estatisticamente semelhantes. Resultado parecido foi encontrado para a diversidade beta. O índice de diversidade beta foi baixo, demonstrando uma alta similaridade de fauna entre os Igarapés. As relações da diversidade beta com os dados ambientais e com a distância entre os igarapés não foram significativas. Os baixos valores de diversidade beta obtidos podem ser devido à alta similaridade dos ambientes, com pouca variação dos dados abióticos e também porque a escala de distância usada no estudo pode ter sido pequena, não representando uma barreira para a dispersão de Odonata. Outro fator que pode ter contribuído é a ocorrência de um longo período de estabilidade ambiental na Amazônia, possibilitando a distribuição das espécies no ambiente, até mesmo para aquelas espécies com baixa capacidade de dispersão. As características das variáveis ambientais básicas (profundidade e largura do igarapé) foram relacionadas com o aumento da riqueza de espécies. Esses resultados são importantes para a conservação das espécies, apontando para a necessidade de incluir riachos intermediários, com maior variação na profundidade e largura, para serem usados como critério de seleção na escolha de áreas para proteção ambiental.