Dissertations / Theses on the topic 'Landscape scale structure'

Floodplains are amongst the most productive and biodiverse ecosystems. The structure and functioning of floodplains is controlled by the interaction of intermittent inundation with the floodplain landscape. These interactions create highly complex and dynamic ecosystems that are difficult to study at large scales. Consequently, most research of floodplains has been conducted at small spatial and temporal scales. Inundation of floodplains can extend over many square kilometres, however, which unifies the floodplain landscape into an integrated ecosystem operating at the landscape scale. The lack of data and poor understanding of the landscape-scale structure and functioning of floodplains limits the possibility of managing floodplains sustainably as pressure for exploitation of their resources increases. This thesis quantifies the landscape-scale relationship between the frequency and patterns of inundation, the composition and structure of the landscape, and the functioning of the floodplain landscape in terms of the distribution and dynamics of plant growth vigour over an area of approximately 376,000 ha on the Lower Balonne Floodplain; highly biodiverse, semi-arid floodplain ecosystem that straddles the state border between New South Wales and Queensland approximately 500 km inland from the eastern coast of Australia. Mean annual rainfall at St.George, to the north of the study area, is approximately 400�450 mm per year, and median annual evaporation is approximately 2000 mm per year. Plants and animals on the floodplain are therefore heavily dependent upon flooding for survival. This project is based on the analysis of 13 Landsat Thematic Mapper satellite images captured over a 10-year period during which land and water resource development increased substantially. There is now concern that development activities have affected the functioning of the floodplain to the detriment of the natural environment and agricultural productivity. The impacts from these activities on the functioning of the floodplain are not yet known, however. Inundation of the Lower Balonne Floodplain was mapped using a two-part process involving a band ratio to identify deep clear water, and a change detection analysis to identify areas of shallower inundation. This analysis shows that, in contrast with most floodplains, the main flowpath of the Lower Balonne Floodplain runs along its central axis away from river channels, which flow along the floodplain�s outer edges. Inundation propagates from the centre of the floodplain out towards river channels as flood discharge volumes increase. Variations in the spatial pattern of inundated patches within the inundated extent create distinctive aquatic habitat and connectivity conditions at different flow levels. These can be described in terms of three connectivity phases: (I) Disconnected, in which isolated patches of inundation occur at low flows and river channels are hydrologically dislocated from the floodplain; (II) Interaction, where increased hydrological connectivity between inundated patches, and between the floodplain and the river channels at moderate flows, may enable significant exchange of materials, organisms and energy; and (III) Integration, in which almost the entire floodplain landscape is connected by open water during large magnitude floods. There is an abrupt transition in inundation patterns as flows increase between 60,000 ML day-1 and 65,000 ML day-1 (ARI 2 to 2.3 years) in which inundation patterns transform from being relatively disconnected into a highly integrated network of patches. These patterns may have significant consequences for the structure and functioning of the floodplain. Increases in flows across this small range may therefore mark an important ecological flow threshold on this system. Water resource development impacts have changed the relative frequency of flows on the Lower Balonne Floodplain, which will probably affect the sequence of connectivity phases over time. The most likely impact of these changes will be to create a floodplain that is drier overall than under natural flow conditions, and that has a smaller and wetter area of high inundation frequency. The relationship between inundation and the structure of the floodplain landscape was examined by comparing a landcover map showing the distribution and character of 10 landcover types to the inundation frequency maps. Landcover types were mapped from a multi-date Reference Image composite of seven images captured over a period of 10 years. The Reference Image improves landcover discrimination by at least 14% over classification of a single-date image, and has an overall accuracy between 82.5% and 85% at the landscape-scale. The Reference Image shows that the landscape of the Lower Balonne Floodplain is a highly fragmented mosaic of diverse landcover types distributed in association with inundation frequency. Stratifying the floodplain into zones of frequent and rare inundation shows that frequently inundated areas have a less fragmented but less diverse landscape structure than rarely inundated areas. Assessment of the functioning of each landcover types within the floodplain ecosystem, based on landscape pattern metric analysis, indicates that the function of landcover types also changes between inundation frequency zones. Most importantly, these changes include a transformation of the matrix landcover type, which controls the character and dynamics of the ecosystem overall, from Open Grassland to Coolibah Open Woodland in the frequently inundated zone. The landscape structure of the Lower Balonne Floodplain has been affected by development impacts, which include clearing of native vegetation, isolation of parts of the floodplain from natural inundation events by the construction of levee banks and drainage channels, and grazing impacts. Changes to the inundation regime may also affect the structure of the floodplain landscape. Over the long term, these changes are likely to create a larger area of Open Grassland and a smaller area of Coolibah Open Woodland as the zone of frequent inundation becomes smaller and wetter. To examine the functioning of the floodplain ecosystem, the inundation maps were compared to remotely sensed indexes of plant growth vigour at the landscape and landcover-type scales. The dynamics of plant growth vigour over time are influenced by factors operating at the regional, landscape and patch scales. Evaporation is the major control of growth vigour levels at the landscape scale, but each landcover type has a distinctive pattern of growth vigour dynamics that is related to its composition and location, and possibly its landscape structure. The association between the spatial distribution of plant growth vigour and inundation frequency is non-linear, with the highest growth vigour occurring where inundation occurs approximately once per year. This indicates a subsidy-stress interaction with water in which plant growth vigour is limited by soil anoxia in areas of frequent or long term inundation, and by drought stress in rarely inundated areas. A landscape-scale model of growth vigour dynamics, founded on the principles of Hierarchical Patch Dynamics and Landscape Ecology, was created from growth vigour measurements of each landcover type over time. This model was used to examine possible impacts of development activities on the functioning of the floodplain ecosystem. This model shows that the response of plant growth vigour development activities can be complex and subtle, and include a change in mean long-term growth vigour and an increased susceptibility to drought. The model also indicates that periods of high growth vigour can occur in substantially altered floodplain ecosystems. The model was also used to explore the levels of landcover change that might cause a threshold change in the functioning of the ecosystem, which may substantially alter the disturbance-response characteristics of the floodplain ecosystem. The model indicates a threshold change when the extent of Open Grassland is reduced by 30% of its extent in 1993, in which plant growth vigour response to disturbance is virtually inverted from that observed in the images. The temporal variability of plant growth vigour levels increases as the extent of Open Grassland is further reduced. This thesis makes a number of important contributions to our understanding of floodplain structure and functioning. It includes the development of new techniques suited to studying large diverse and complex landscapes at the landscape scale from satellite images, and provides quantitative data describing the links between the structure of floodplain landscapes and their functioning at the landscape scale. This work improves the understanding of floodplain ecosystems by integrating models of floodplain structure and functioning, which have been developed largely from smaller-scale studies of temperate and tropical floodplains, with landscape-scale measurements of this semi-arid system. This thesis also has implications for the Lower Balonne Floodplain by improving the level of information about this important ecosystem and providing baseline data against which the condition of the floodplain can be assessed in future.

Thesis (Ph. D.)--University of Canberra, 2004.
Title from PDF title page (viewed on July 20, 2005). Pages 185-194 lacking in digital version of thesis. Includes bibliographical references (p. 155-184).

This research is an investigation into the phrase 'intermediate landscape' and tests this concept in the re-development of the Sanya waterfront, China. The phrase is based on the 'missing link' in the current disconnection between the landscape and urban development in Sanya city. If the landscape is considered as a connection across scales and urban systems rather than an isolated system, then how can landscape affect the structure and function of urban development? The 'intermediate landscape' considers the impact of understanding landscape not as an additional layer, but as a structure that can connect the urban context at different scales while at the same time addressing its function. This project attempts to formulate strategies of 'intermediate landscape' to coordinate the transformation of developing cities.

A primary goal in ecology is to understand why localities with similar abiotic environmental conditions often exhibit differences in species composition. Previous work points to the potential importance of historical or regional processes, such as priority effects and dispersal limitation, but the ways in which landscape structure moderates the impacts of such processes remain unclear. Using spatially explicit simulations of competitive metacommunities, I investigated if spatial autocorrelation of the environment (SAE), the degree of clustering of similar environments, in the broader landscape interacted with dispersal capacity to affect the predictability of local community composition. My study employed a fully crossed factorial design of SAE (random configuration to high positive SAE), dispersal capacity (local versus global [control]), and fundamental niche scenario (niche-differentiated versus neutral [control]). I quantified community composition predictability by measuring Bray-Curtis similarity among the same localities of replicate metacommunities. The results showed that in the absence of either niche differentiation or spatially restricted dispersal, variation in SAE had no impact on the predictability of local community composition. In contrast, in the presence of both niche differentiation and spatially restricted dispersal (characteristics of many metacommunities in nature), increasingly positive SAE increased community composition predictability. This was attributed to the enhancement of landscape connectivity facilitating deterministic species-environmental sorting of differentially adapted species, which reduced the influence of stochastic community assembly processes. Thus, the results suggest that the variation in local species composition often observed among sites with similar environmental conditions could be attributed in part to differences in the spatial configuration of environmental conditions within the broader landscape. My work has potentially profound implications for basic and applied ecology. For example, the results suggest that practitioners should expect the reliability of composition-environment correlations to vary depending upon the spatial attributes of the ecosystem in question; they should be most useful as predictive tools within ecosystems characterized by strongly positive SAE. The results also yield an apparently novel and testable prediction: ecosystems characterized by high positive SAE will exhibit more repeatable community composition-environment relationships than ecosystems characterized by less clustering of similar environmental conditions in the landscape.

A presente dissertação intitulada “Modelação geográfica em processos de caracterização e avaliação da paisagem numa perspectiva transfronteiriça” tem como objectivo o desenvolvimento de metodologias e abordagens na análise da estrutura da paisagem e da sua relação com as funções ecológicas da paisagem. Explora-se o detalhe cartográfico e temático da cartografia de ocupação e uso do solo resultante da aplicação da legenda hierárquica Corine Land Cover (CLC) Nível 5 (Guiomar et al. 2009, Batista 2011), e a cartografia CLC2006, para a definição de unidades locais e regionais de paisagem. Analisa-se o comportamento das métricas de paisagem nos seus diferentes níveis de organização hierárquica: CLC N2, CLC N3, CLC N4 e CLC N5 e testam-se métodos para a utilização de métricas como classificadores de unidades de paisagem, nomeadamente testando o seu comportamento na cartografia de ocupação e uso do solo e das unidades locais e regionais de paisagem. Propõe-se a integração da componente tridimensional no cálculo das métricas de paisagem e ensaia-se a relação entre as métricas de paisagem e funções da paisagem. É também apresentado um conjunto de ensaios em torno da consistência das métricas de paisagem aplicadas em paisagens reais no Alentejo Central e zona transfronteiriça Alentejo, Centro (Portugal) e Extremadura (Espanha). Dos resultados obtidos ressaltam as vantagens das novas abordagens na avaliação das características estruturais e funcionais da paisagem independentemente da área e escala de observação; ABSTRACT: This thesis entitled "Geographical modelling for characterization and assessment of landscape in a crossborder perspective" aims to develop methodologies and approaches to analyse landscape structure and its relation to landscape ecological functions. It explores the cartographic and thematic detail of the land cover and land use maps resulting from the Corine Land Cover Level 5 (Guiomar et al. 2009, Batista 2011) and the CLC2006 maps, for the definition of local and regional landscape units (LLUs). It is analysed the behavior of landscape metrics at different thematic scales of CLC maps: CLC N2, CLC N3, CLC N4 and CLC N5 and methods for using metrics as landscape unit’s classifiers are developed, namely by testing the behavior of landscape metrics with land use and LLU maps. It is proposed to include the 3D component in landscape metrics calculation and it is tested the relations between landscape metrics and landscape functions. Several tests conducted in order to evaluate the consistency of landscape metrics applied to real landscapes in Central Alentejo and in the border area of Alentejo and Extremadura (Spain) are presented. The main results showed the advantages of the new methodology for evaluating landscape structural and functional characteristics, independently of the observation area or scale.

Abstract :The main goal of this stud y was to quantify the effect s of landscape structure on the abundance of Ruby-throate d Hummingbird s (Archilochus colubris) in forest patches and this, while accounting for its indirect effects on open flower community an d the occurrence of Yellow-bellied Sapsucker s (Sphympicus varius), a potential commensal of hummingbirds. We sampled 40 forest patches (0. 5 to >10 0 ha ) where we had installed 2 nectar feeders (forest edge and 40 m within forest ) during 2 breeding season s (2006 and 2007) . We visited forest patches weekly and recorded the number of hummingbirds detected within 10 m of feeders during 10 min. Mean daily artificial nectar consumption by hummingbirds, as well as their relative total abundance an d the respective relative abundance of adult males and females, were all affected by forest cover. Except for the relative total abundance, this effect of forest cover depended upon the size of forest patches. Nectar consumption and abundance generally peaked in forest patches of intermediate size found in landscapes characterized by intermediate forest cover. Mea n daily artificial nectar consumption and the relative total abundance, a s well as that of males, were higher at feeders located on the forest edge compared to 40 m inside forest patches. Regarding indirect landscape effects, landscape structure influenced the structure of open flower communities surrounding feeders, which in turn, affected the relative total abundance of hummingbirds, a s well as that of adult males. On the other hand, we failed to find strong evidence that landscape structure affected the occurrence of Yellow-bellied Sapsuckers or that the latter influenced Ruby-throated Hummingbird abundance patterns. These results support the idea that landscape structure may affect the abundance pattern of a species directly as well as through mechanisms which are themselves dependent upon the composition and configuration of landscapes //Résumé : La structure des paysages peut influencer l'écologie d'une espèce directement, en contraignant ses mouvements, par exemple, de même qu'indirectement en affectant, entre autres, l'abondance de ses proies ou prédateurs. Quoique plusieurs études aient tenté de quantifier l'influence de la structure du paysage sur les patrons d'abondance, rares sont celles qui ont mesuré simultanément les effets directs et indirects du paysage. L'objectif de ce mémoire consiste à modéliser simultanément les effets directs de la structure du paysage sur l'abondance relative du Colibri à gorge rubis ( Archilochus colubris ) et sa consommation de nectar artificiel ainsi que les effets indirects par lesquels le paysage peut aussi agir tels la disponibilité en ressources alimentaires (communautés floristiques) et la relation interspécifique de commensalisme avec le Pic maculé ( Sphyrapicus varius ). Pour ce faire, j'ai échantillonné 40 îlots forestiers (0,5 à >100 ha) dans la région de l'Estrie (Québec, Canada). À chacun d'eux, j'ai installé deux abreuvoirs (en bordure et 40 m à l'intérieur) durant les étés 2006 et 2007 et ont été visités de façon hebdomadaire. J'ai détecté une relation quadratique du couvert forestier dans le paysage avec l'abondance totale relative, celle des mâles et des femelles ainsi que pour la consommation quotidienne moyenne. Ces effets varient en fonction de la taille d'îlot sauf pour l'abondance relative totale. Les valeurs maximales se situent à des niveaux intermédiaires de couvert forestier et de taille d'îlots. Certaines caractéristiques mesurées étaient à l'échelle locale comme la position de l'abreuvoir dans l'îlot forestier ou la structure de la végétation. J'ai détecté un effet de bordure pour toutes les variables sauf l'abondance des femelles. L'indice de structure de végétation n'avait d'influence que sur l'abondance des mâles. Concernant les effets indirects, l'ensemble des variables du paysage explique 69,61% de l'indice de communauté floristique et ce dernier a un effet significatif sur l'abondance totale et l'abondance des colibris mâles. Pour la relation avec le pic, les variables du paysage mesurées n'ont pas permis de détecter un effet. De plus, bien qu'étant une variable non significative, les modèles incluant la présence du Pic maculé étaient généralement parmi les plus performants. L'ensemble de ces résultats soutient l'importance de combiner l'écologie du paysage et l'écologie comportementale dans les mêmes modèles afin de tenir compte non seulement des effets directs mais aussi des effets indirects du paysage //

Mestrado em Biologia Aplicada - Ecologia, Biodiversidade e Gestão de Ecossistemas
The conversion of natural environments into agricultural land has profound effects on the composition of the landscape, often resulting in a mosaic of crop fields, pastures and remnant patches of natural vegetation. It is thought that an increase in structural complexity of a habitat mosaic may improve the availability of ecological niches for animals, potentially increasing species diversity. Bats are highly vagile, and many species require the use of distinct habitats to fulfil their daily and seasonal needs. However, their distribution throughout a landscape may reflect a response to landscape structure and spatial and seasonal dynamics of resource distribution, as well as preferences for some habitats relative to others, determined by species eco-morphological traits. Therefore, the way bats select a habitat is an aggregative response to both landscape and local features. We investigated the spatial and seasonal patterns of bat diversity and activity within a heterogeneous landscape in Portugal, constituted by a mosaic of natural, semi-natural and human-altered terrestrial, freshwater and brackish habitats. Furthermore, we investigated which landscape features determine those patterns, across four distinct focal scales. We sampled bats acoustically, while simultaneously sampling insects with light traps, across 24 sampling sites representative of the main habitat types that shape the landscape. We found bat assemblages of the different habitats to be relatively similar, and that bat activity hardly differed among them. However, we found seasonal variation in bat activity within habitats. Additionally, our results revealed both scale- and guild-dependent responses of bats to landscape and local features. Overall, our results suggest that bats exploit all habitats of this heterogeneous area, and that the mosaic landscape provides them several opportunities, which results in strong seasonal and spatial dynamics. On the other hand, we found these dynamics to be influenced by broad-scale landscape features, as well as by weather conditions, and local resource availability and distribution. Lastly, our results indicate that forest and Bocage habitats are potential keystone structures for bats within this heterogeneous landscape.
A conversão de ambientes naturais em terrenos agrícolas tem efeitos profundos na composição da paisagem, frequentemente resultando em mosaicos de campos de cultivo, pastagens e restantes fragmentos de vegetação natural. Pensa-se que um aumento na complexidade estrutural de um mosaico de habitats pode favorecer a disponibilidade de nichos ecológicos para os animais, potencialmente aumentando a diversidade de espécies. Os morcegos são muito móveis, e muitas espécies requerem o uso de diferentes habitats de forma a cumprir as suas necessidades diárias e sazonais. No entanto, a sua distribuição ao longo de uma paisagem pode refletir uma resposta à estrutura da mesma, e às dinâmicas de distribuição espacial e temporal dos recursos, assim como refletir as preferências de alguns habitats em detrimento de outros, determinadas pelas características eco-morfológicas da espécie. Desta forma, a seleção de habitat por parte dos morcegos é uma resposta conjunta a características locais e de paisagem. Neste estudo foram investigados os padrões espaciais e sazonais de atividade e diversidade de morcegos numa paisagem heterogénea em Portugal, constituída por um mosaico de habitats naturais, semi-naturais e alterados pelo Homem, tanto em ambientes terrestres, como sob a influência de água-doce ou salobra. Além disso, foram investigadas quais as características da paisagem que determinam esses padrões, ao longo de quatro escalas focais distintas. A amostragem de morcegos foi feita acusticamente, enquanto em simultâneo se amostraram insetos usando armadilhas de luz, em 24 pontos representativos dos principais tipos de habitat que caracterizam a paisagem. Foi descoberto que as assemblages de morcegos dos diferentes habitats eram relativamente semelhantes entre si, e que a atividade de morcegos praticamente não diferia entre habitats. No entanto, verificou-se a existência de uma forte variação sazonal dos níveis de atividade de morcegos nos vários habitats. Além do mais, os resultados obtidos revelaram que a resposta dada pelos morcegos às características locais e de paisagem é dependente da escala e da guild. De uma forma geral, os resultados obtidos sugerem que os morcegos exploram todos os habitats que constituem esta paisagem heterogénea, e que o mosaico de habitats lhes fornece diversas oportunidades, o que resulta em fortes dinâmicas espaciais e sazonais. Por outro lado, foi descoberto que estas dinâmicas são influenciadas por características da paisagem a uma larga escala, assim como por condições meteorológicas, e pela disponibilidade e distribuição locais de recursos. Por último, os resultados indicam que as zonas florestais e o Bocage são potencialmente os habitats mais importantes para os morcegos nesta paisagem heterogénea.

La diversité des systèmes de culture et des variétés joue un rôle important dans la capacité des agricultures familiales à résister aux chocs socio-économiques et environnementaux. Pour une meilleure conservation, cette diversité agricole doit d’être caractérisée et suivie dans l’espace et le temps. Tandis qu’ils étaient dominés par des éléments sur le prix, les surfaces et les productions jusqu’à récemment, les systèmes de suivi agricole commencent à intégrer les questions de diversité. Alors que jusqu’à la fin des années 1990 elle était considérée comme un facteur limitant dans l’amélioration de la productivité des systèmes d’exploitations dans le processus de sélection variétale. Or dans une situation d’incertitude pluviométrique, pour réduire le risque de cet aléa, les agriculteurs ont recours à plusieurs espèces et variétés pour survivre et produire au travers de tous les aléas rencontrés. La stratégie paysanne consiste à cultiver à la fois plusieurs variétés présentant diverses caractéristiques agronomiques (précocité, rendement, résistance aux pathologies, aux parasites, à la sécheresse, etc.) et culinaires dans un même champ ou dans des champs différents. Cette stratégie permet aux paysans de cultiver les variétés s’adaptant le mieux aux conditions pédologiques de leurs champs et répondant à la fois à leurs divers besoins.C’est dans ce contexte que se situe la présente thèse qui vise principalement à analyser la structuration spatiale de l’agrobiodiversité dans la zone cotonnière. Pour atteindre cet objectif, plusieurs méthodes et approches ont été utilisées. L’approche adoptée combine l’analyse numérique d’images satellitaires et l’utilisation de données issues d’enquêtes de terrain. L’analyse de ces données s’appuie sur la distribution spatiale de la biodiversité et sa corrélation avec les pratiques et les conditions agro-écologiques, les résultats et les performances agronomiques.Les principaux résultats issus de l’analyse des données de l’étude sont :a) On observe une grande hétérogénéité et une diversité des paysages dans la zone cotonnière du Mali-Sud avec au total, onze (11) unités de paysages ;b) On constate une grande diversité au niveau spécifique et des systèmes de culture. Les valeurs moyennes de l’indicateur de diversités spécifiques les plus sont enregistrées dans les villages où la moyenne pluviométrique est comprise entre 700 à 1000 mm d’eau suivis par des villages de moins de 700 mm ;c) L’indicateur de pression spécifique montrant une répartition géographique des pressions des différentes espèces culturales. En effet dans les villages où le coton est en tête de rotation, il exerce une forte pression sur les autres espèces. Dans ces villages, la surface en coton est beaucoup plus importante que celle des autres espèces ;d) Le rendement fait constater que la plupart des villages ont des moyens de coton au-dessus de la moyenne nationale en 2015. En analysant son évolution entre 2013 et 2015, on constate une baisse de rendement dans la plupart des villages même si cette baisse est très souvent en dent de scie avec des hausses en 2013 et 2014.e) L’indicateur de stabilité du rendement montrant que les rendements sont stables avec toutes les espèces sauf le maïs.f) Ces résultats ouvrent la voie à une plus grande contribution de la géographie dans l’analyse agronomique
The diversity of cropping systems and varieties plays an important role in the ability of family farms to withstand socio-economic and environmental shocks. For better conservation, this agricultural diversity needs to be characterized and monitored in space and time. While they were dominated by elements of price, area and production until recently, agricultural monitoring systems are beginning to integrate diversity issues. The diversity of cropping systems and varieties plays an important role in the ability of family farms to resist socio-economic and environmental shocks, whereas until the end of the 1990s it was considered as a limiting factor in improving the productivity of farming systems in varietal selection processes. In a situation of uncertain rainfall, to reduce the risk of this hazard, farmers use several species and varieties to survive and produce through all the hazards encountered. The peasant strategy consists in cultivating several varieties with different agronomic characteristics (early maturity, yield, resistance to diseases, parasites and drought, etc.) and culinary in the same field or in different fields. This strategy allows farmers to cultivate the varieties best suited to the soil conditions of their fields and to meet their diverse needs.It is in this context that this thesis focuses on the spatial structuring of agrobiodiversity in the cotton zone. To achieve this objective, several methods and approaches have been used. The approach adopted combines the digital analysis of satellite imagery and the use of data from field surveys. The analysis of these data is based on the spatial distribution of biodiversity and its correlation with agro-ecological practices and conditions, agronomic performance and performance.The main results from the analysis of the study data are:a) There is a great heterogeneity and diversity of landscapes in the cotton zone of Mali-Sud with a total of eleven (11) landscape units;b) There is great diversity at the specific level and in cropping systems. The mean values of the most specific indicator of diversity are recorded in villages where the mean rainfall is between 700 and 1000 mm of water followed by villages of less than 700 mm;c) The specific pressure indicator shows a geographical distribution of the pressures of the different crop species. Indeed, in villages where cotton is at the head of rotation, it exerts strong pressure on other species. In these villages, the cotton area is much larger than for the other species;d) For yield, most villages have average yields of cotton above the national average in 2015. Analyzing its evolution between 2013 and 2015, there is a decline in yield in most villages if this decline is very often sawtooth with increases in 2013 and 2014.e) The yield stability indicator shows that yields are stable with all species except maize.These results open the way for a greater contribution of geography in agronomic analysis

Fatores que influenciam a comunidade de morcegos em vinhas: o papel das caraterísticas da paisagem, estruturas naturais e gestão As vinhas são um sistema agrícola muito representado na Europa. Essas áreas apresentam baixos níveis de biodiversidade devido à simplificação da paisagem e ao elevado uso de pesticidas, o que reduz a disponibilidade de insetos e as torna pouco atrativas para morcegos. Nós investigámos o efeito da gestão, do tipo de uso do solo e das estruturas naturais na atividade e riqueza de morcegos em vinhas a duas escalas espaciais: 500 m (escala de vinha) e 1500 m (escala de paisagem). Os resultados demonstraram que as estruturas e os habitats naturais foram mais importantes para os morcegos do que a gestão da vinha. Nós sugerimos que as prioridades de conservação devem ser criar ou manter vegetação ripária e áreas de montado. Essas estruturas naturais são uma componente chave na gestão para promover o uso das vinhas por morcegos, aumentando o seu potencial como reguladores de pragas agrícolas; ABSTRACT: Vineyards are one of most represented agricultural systems in European landscape. These areas can present low biodiversity levels due to simplification of landscape and the high input of pesticides, which reduce insect availability and makes them unattractive for bats. We assessed the effect of farming management, land use type and natural structures on bat activity and species richness in vineyards at two spatial scales: 500 m (vineyard scale) and 1500 m (landscape scale). Our results demonstrate that natural structures and habitats were more important to the bat community than vineyard management. We suggest that conservation priorities should be to create or maintain riparian vegetation – near streams or small dams - and areas of “montados”. These natural structures are important for bat populations within or near vineyards, and a key component of agricultural management to promote bat use of vineyards, enhancing their role as pest regulators.

Understanding how mountain landscapes respond to variations in tectonic forcing over a range of temporal scales in active mountain belts remains as a prominent challenge in tectonic and geomorphological studies. Although a number of empirical and numerical studies have examined this problem, many of them were complicated by issues of scale and climatic variability. More specifically, the relative efficiencies of fluvial and glacial erosion, which are presumably controlled by climate, are difficult to unravel. The Teton Range in Wyoming, which results from motion on the crustal-scale Teton fault, is an ideal natural laboratory for addressing this challenge as the tectonic uplift boundary condition and the variation of uplift along strike is well-documented by previous studies and due to its relatively small size, climate can be reasonably expected to vary consistently along strike. Here, we present the results from a study that examines how the Teton landscape responds across the longest (106-7 yrs) and shortest (102-4 yrs) temporal scales. Long-term canyon incision rates determined from apatite (U-Th)/He (AHe) analysis of major drainages are highest (0.24 mm yr-1) where measured uplift rates and duration are highest (near Mount Moran), leading us to propose that tectonic forcing operates as the first order control on long-term Teton erosion. Short-term denudation rates, which are derived by determining sediment volumes in Moran Bay that are deposited in catchments generated during the most recent glacial interval (Pinedale, ~15.5 ka), are 0.00303 – 0.4672 mm yr-1. We compare these rates to previous work, which found that high rock fall rates (1.13-1.14 mm yr-1) deposit large talus volumes in Avalanche and Moran Canyons. Despite their magnitude, such high rates of mass wasting are not sustained over long periods of time, as measured lake sediment volumes (0.007 km3) are. We conclude that the Tetons are transport limited during the interglacial and large volumes of canyon sediment generated during this time cannot be moved absent the advance of valley glaciers. That is, fluvial systems in small mountain systems are substantially less effective than glaciers in denuding mountain topography.

The genetic diversity and genetic structure of populations, and the processes shaping gene flow within and between populations, are influenced by the landscapes they occur within. Within terrestrial landscapes, rivers and their riparian habitat are among the most dynamic, diverse and complex of landscapes and their linear structure appears as an interlinking feature across large landscapes. This thesis took a landscape genetics approach to examine the influence of river landscape features on Alnus glutinosa populations, a widespread keystone tree species of European riparian ecosystems. By accounting for the differing dispersal mechanisms of A. glutinosa (wind and water), landscape effects on seed- and pollen-mediated gene flow, genetic diversity, demographic and genetic structure were identified at different spatial scales of a large UK river catchment. Widespread gene flow within and between A. glutinosa populations was identified with no apparent limitation of wind-mediated pollen dispersal. Hydrochorous dispersal of seed between populations was evident, and found to increase genetic connectivity between riparian populations; however an isolation by distance effect was identified between populations located further apart from each other. No pattern of genetic diversity was found, with high levels of genetic diversity identified at all spatial and temporal scales. At the river-catchment scale no genetic clustering was observed, either within or between the six rivers studied. Demographic structuring within A. glutinosa populations was evident, and correlated with distance from the main river channel. Interactions between seed dispersal, hydrological disturbance, colonisation, and historical influences are discussed in relation to fine-scale spatial genetic structure between A. glutinosa sapling and adult generations. Central to the landscape genetics approach taken in this thesis was the incorporation of key A. glutinosa life history attributes. By incorporating gene flow analyses, species ecology and landscape features, the research presented here furthers our understanding of riverine landscape influences on their riparian populations at different spatial scales and can be used to inform management principles.

A major challenge in agroecosystems is how to manage the systems so that it reduces crop pests and enhances natural pest control. This thesis investigates patterns of crop pests and top-down effects of birds and arthropod predators in relation to land-use composition across spatial scales. In paper (I) I examined the crop distribution and land-use types in relation to the crop raiding patterns in 15 transectsin sites close to and far from forests along with a questionnaire survey at household level. I found severe crop raiding close to forests, but it had no impact on crop composition growing between the two sites. In paper (II) I examined the effect of forest and tree cover, at local and landscape scales, on the abundance of arthropod predators by collecting specimens from 40 home gardens. My result showed higher abundance of arthropod predators when either the home garden or the surroundings had a high tree-cover, compared to when tree-cover at both scales was similarly either high or low. In paper (III) I investigated the effect of excluding birds and arthropod predators on leaf damage on rape seed in 26 home gardens. I found stronger top-down impacts from arthropod predators on crop pests in tree-poor gardens than in tree-rich gardens. There was no effect of birds. In paper (IV) I explored the effect of landscape complexity on bird and arthropod predation using plasticine caterpillars in 36 home gardens across landscapes. The rate of arthropod predation on caterpillars was higher in simple than in complex landscapes. The rate of bird predation did not vary between complex and simple landscapes. In simple landscapes, arthropod predation was higher than that of birds. The overall results suggest that simplified gardens/landscapes still have enough habitat heterogeneity to support arthropod predators for the significant top-down controlling effect on crop pests. However, I did not find clear effect of complexityon the top-down effect of birds.

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 1: Manuscript; Paper 3: Manuscript; Paper 4: Manuscript

The major human activities that have transformed the Earth include agriculture and urbanization. The present study was conducted to contribute to a description of the effect on birds of urbanization and agriculture in an Indian region. Terrestrial bird assemblages were censused along a five-stage urbanisation gradient between January and April 2010-2013 near the city of Amravati, on the Deccan Plateau, Central India. Altogether, 89 species of birds were recorded, with the highest species richness in the rural areas (67 species) and lowest in the urban stage (29 species). The assemblages were significantly nested in all the five stages. Maximum cumulative species abundance (12 399 individuals over four years) was found in the urban stage, and was due to the constant presence of large groups of Rose-ringed Parakeets (Psittacula krameri). The lowest bird abundance was found in the industrial zone (4837 in total), where there was also a nearly two-fold decrease from 2010 to 2013. Thirty-six species demonstrated significant variation in their densities at least in one stage and between at least two months (p<0.05). Densities of 13.9% (n=5) of those species varied significantly in two stages, that of Copsychus saularis in three stages, and of Phoenicurus ochruros, in all five stages. Urban, suburban, periurban and forest stages were characterised by relatively stable species densities (significant changes observed only for 17.2% (n=5), 17.1% (n=6), 12.9% (n=7), and 17.8% (n=16) species, respectively). The additive diversity partitioning indicated that of the overall diversity (gamma-diversity), alpha diversity (within transects located within one stage) contributed 50.1% to the total diversity, and the controbution of within-stage variability was small (2.7%). Additionally, censuses on cultivated fields were taken. In two areas under mixed cropping systems, 53 bird species were identified in the two years period between June and December, 2011 and 2012. Out of the 53 detected species, only 14 were common (recorded at ≥50% of visits). Twenty-one species were recorded at Zadgaon in crops of tur (Cajanus cajan), cotton (Gossypium arboreum) and soybean (Glycine max). Nineteen species were recorded at Bhankhed in jawar (Sorghum bicolor), cotton and mung bean (Phaseolus aureus). At Zadgaon, territorial activity was observed in four species: the House Sparrow (Passer domesticus), Jungle Babbler (Turdoides striata), Yellow-eyed Babbler (Chrysomma sinense) and Red-wattled Lapwing (Vanellus indicus). The study indicated that four bird species were found under high risk, thirteen species at medium risk and eight species at low risk due to pesticide applications in croplands. The extent of crop damage in fields of groundnut, pearl millet, peas, sorghum, and sunflower was assessed by doing actual field censuses. The sustainable solution for reducing crop damage is a need for the farmers and such techniques will help to avoid direct or indirect effects of use of lethal bird control techniques on bird species diversity.

QC 20141022

Mesoscopic spin systems can be designed and fabricated using modern nano-fabrication techniques. These systems can contain large numbers of patterned ferromagnetic elements, for which the shape will generally determine their effective mesospin dimensionality. The lateral arrangement of these mesospins can be further used to tune the interactions between them. With an appropriate choice of material, it is possible to define a temperature range where thermal fluctuations of these mesospins are experimentally accessible. To actively define this range, we use δ-doped Palladium, a three-layer system of Palladium—Iron—Palladium, for which the Curie-temperature scales with the Iron layer thickness. The patterned mesoscopic elements used in this work have a stadium-like shape that promotes a single magnetic domain state, thus making these islands behave as one-dimensional Ising-like mesospins that can be observed using magnetic imaging techniques. We investigate the impact on the magnetic order resulting from modifications of the square spin ice geometry. By adding, removing and merging elements in the square artificial spin ice architecture, energy-landscape variations can be realized. Firstly, an added interaction modifier is used to equilibrate the interactions between the mesospins at the vertex level, which can restore the degenerate ground state of the square spin ice model. Secondly, the removal of elements can lead to topologically frustrated spin systems, as not all building blocks can simultaneously be in their lowest energy state. Furthermore, the merging results in multiple element sizes in the mesospin system. As the magnetization reversal barrier is dependent on the element size, these mesospin systems have different energy barriers. The thermal ordering process in such a system differs from a single-size element system with its unique energy barrier. Using reciprocal space analysis tools like the magnetic spin structure factor we show that systems with multiple element sizes achieve a higher short-range order then their single-size element references. The magnetic order in mesoscopic spin systems could successfully be tailored by modifications of the lattice geometry.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.
Source: Dissertation Abstracts International, Volume: 67-11, Section: A, page: 4356. Adviser: Zsuzsa Gille. Includes bibliographical references (leaves 190-208) Available on microfilm from Pro Quest Information and Learning.

Road expansion and increased traffic likely exacerbates barriers to amphibian migration and dispersal. Within British Columbia’s south Okanagan valley there is particular concern that the COSEWIC-listed blotched tiger salamander (Ambystoma mavortium melanostictum) and Great Basin spadefoot (Spea intermontana) are vulnerable to road effects in their annual movements from upland overwintering habitat to lowland breeding areas. My study utilizes a before after control impact approach to assess amphibian movement and population threats across this highway-bisected landscape. Throughout the spring and summer of 2010-2012, fifty two kilometers of roadways (31 km of highway, 21 km of paved backroad) were repeatedly surveyed from the Canada-USA border to north of Oliver, BC; surveys were carried out utilising vehicles and on foot. Along Highway 97, a three kilometer four-lane highway expansion project was constructed through 2010 and open to traffic use in 2011. Adjacent to a floodplain, survey effort was focused throughout this transect for informed roadkill mitigation structure placement and ongoing ecopassage effectiveness monitoring. Automated camera trap monitoring of culverts within highly concentrated amphibian road hotspots during spring and summer 2011 (three culverts) and 2012 (two culverts) resulted in over eight hundred amphibian culvert events observed. Two sample Wilcoxon tests revealed differences between years in amphibian occurrence between 2010 and 2012 (W = 4679.5, p= 0.02), and mortalities among transect areas, with the largest differences between years within the Osoyoos passing lanes transect. Amphibian mortalities within the passing lanes transect were significantly reduced with the implementation of mitigation structures (x̅2010= 13.2 ± 32.5, x̅2011= 4.7 ± 12.8, x̅2012= 2.3 ± 7.3; 2010 vs. 2012: W= 1535.5, p< 0.001). Roadkill mitigation structures proved effective in observed amphibian occurrence of the entire passing lanes stretch as well as at distances 100 m and 200 m from observed culverts. Double fenced areas resulted in a 94% reduction in amphibian road occurrence. Five species of amphibians were observed over the three survey years (4051 road incidences over 657 survey hours): Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas), long-toed salamander (Ambystoma macrodactylum) plus blotched tiger salamander and Great Basin spadefoot. This study aims to provide a better understanding of amphibian hotspots on roadways and ecopassage use within the south Okanagan. It may act as a catalyst to further wildlife-vehicle interaction studies with improved mitigation solutions for amphibian roadway fatalities.

碩士
國立臺灣大學
園藝學研究所
97
Scale is a very important concept in the area of ecology science, with different research objectives and subjects to select the appropriate scale. Taiwan is a relatively small country with high landscape heterogeneity and high fragmentation. It is necessary to find a suitable scale to study the ecological phenomena for such a place. Based on the theory of landscape structure and hierarchy theory, this study discusses the relationship between species diversity and landscape structures in cross-scale. The study site, Miaoli Sanwan township, is situated in a traditional rural landscape of Taiwan. The spatial information is calculated at different extents and grids of scale with eCognotion 4.0, ArcGis 9.2, and Fragstats3.2. In this study, birds and butterflies are taken as representative species of different ecology statuses. First, this study tries to find the core-scale of birds and butterflies that reflect significantly the changes of landscape structures. It is followed by a discussion of the relationship between the biodiversity and landscape structures at different scales, specifically for birds and butterflies. This finding shows that the core-scale of birds and butterflies are different, and the difference of core-scale reflects the differences in ecological characteristics. The core-scale of birds represents the concept of home range and that of butterflies reflects the flying distance. A home range reflects the life history of a bird: its defensive zone, the eating area, and the food density of the place. The flying distance of butterflies represents their daily needs and their migration to new habitats. The results suggest that to preservation of the woodland and farmland areas requires biodiversity and that the relationships between landscape structures and species are different. This study suggests that different species have different ecological processes that dominate at different scales. Cross-scale research can contribute to the understanding of the landscape integrity of the ecosystem. And in the landscape planning applications, we need to address different strategies and approaches for habitat construction in response to the changes of scale.

Sound understanding of the influence of scale and context on ecological patternprocess relationships is lacking in many systems. The hierarchical patch dynamics paradigm (HPDP) provides a framework for addressing spatio-temporal heterogeneity, but the range of systems in which, and scales at which, its principles apply are largely unknown. Furthermore, it does not explicitly account for the influence of spatial context. Recent developments in remote sensing science show potential for bridging this gap by enabling the exploration of landscape heterogeneity at multiple scales and across a wide range of systems and contexts, but the ecological application of these new techniques is lagging. The savanna riparian landscapes of the northern Kruger Park, South Africa, provided a unique platform in which to explore the influence of spatial context, and to test the pattern-process-scale and metastability principles of the HPDP, to further its potential as a unifying framework in landscape ecology. LiDAR and high-resolution aerial imagery were integrated through object-based image analysis to create spatial representations of woody structure (canopy height, canopy cover, canopy height diversity and canopy cover diversity) across a portion of the savanna landscape (60 000ha). Temporal change in woody cover and heterogeneity (number and size of woody patches) was assessed from a historical aerial photography record, that spanned 59 years from 1942 to 2001. Spatial relationships between environmental variables and patterns of woody structure and dynamics were tested at broad (100ha), medium (10ha) and fine-scales (1ha) through canonical correspondence analysis (CCA). The relative contribution of different categories of environmental variables, to the total explained variation in woody structure, was assessed at each scale through partial canonical correspondence analysis (PCCA). Spatial variation in environmental variables, and the influence of spatial context on woody structure-environment relationships, was explicitly tested through geographically weighted regression (GWR). LiDAR results provided an unprecedented basis from which to explore spatial patterns of woody structure in an African savanna. Standard approaches to generating normalized canopy models (nCM) from LiDAR suffered interpolation artifacts in the heterogeneous landscape, but an object-based image analysis technique was developed to overcome this shortfall. The fusion of LiDAR with aerial imagery greatly enhanced the structural description of the landscape, and the accuracy of canopy height estimates varied between different vegetation patch types. Woody structure and dynamics displayed distinct spatial trends across the landscape with high diversity and variability occurring in the alluvial riparian zones. Woody canopy height, canopy cover and cover dynamics exhibited scale variance in their relationship with environmental variables, but woody structural diversityenvironment relationships were scale invariant across the analysis patch hierarchy. These findings from different woody attributes both support and contradict the pattern-process-scale principle of the HPDP, which hypothesizes that ecological processes shift with scale, but that spatial variance measures exhibit stepwise patterns of change with scale, along a patch hierarchy. Percentage woody cover was stable over time across the landscape, despite high variability at smaller scales. However the metastability principle cannot be considered generally applicable in this system, as a broader view of the woody component revealed a marked decline in woody heterogeneity over time. Although losses of woody cover on the diverse alluvial substrates were countered by increases of cover in the uplands, analysis of current woody structure in the context of historical change revealed that the increases took place in the form of shrub encroachment and not the replacement of tall trees. The vertical structure of woody vegetation, and therefore both the biodiversity and ecological functioning of the system, has changed over time across the landscape. The metastability principle of theHPDP may not be applicable in spatially heterogeneous systems, where ecological processes act differentially across the landscape, but may apply within specific patch types at certain temporal scales. Spatially localized analysis models revealed significant spatial non-stationarity in the majority of processes correlated with woody structure, and showed that both the magnitude and direction of woody structure-environment relationships varied in different spatial contexts across the landscape. These results have fundamental implications for the manner in which both science and conservation measures are conducted in heterogeneous systems. Global analysis models, that assume stationarity, are widely accepted and employed in ecological research but may greatly misrepresent ecological relationships that are context-dependent. These findings question the level of system understanding that field studies can provide, by revealing the dangers of inferring patterns and relationships from measurements of limited spatial representation. Leveraging the latest remote sensing technologies, that provide large-extent but fine-grain coverage, in a scaled and context conscious manner, will enhance ecological understanding by spatially quantifying the full spectrum of system heterogeneity. The heterogeneous patterns, scaled relationships and context-dependent patterns identified in this study are challenging from both ecological research and biodiversity conservation points of view. Traditional approaches to science and conservation are ill equipped to address these issues. The HPDP provides an excellent conceptual construct for meeting such challenges, but the influence of spatial context needs to be more explicitly incorporated within the framework. A catchment-based hierarchy is suggested for guiding future research and conservation efforts in heterogeneous landscapes, where context-dependency of ecological processes may be the norm.

Heterogenität von Umweltbedingungen gilt als einer der wichtigsten Faktoren für die Verteilung von Artenreichtum weltweit. Laut der Habitatheterogenität-Hypothese bieten räumlich heterogenere Gebiete eine höhere Vielfalt an Umweltparametern und weisen mehr Refugien und Möglichkeiten zur Isolation und Radiation auf. Dadurch begünstigen sie Koexistenz, Persistenz und Diversifikation von Arten. Die Erforschung potentieller positiver Effekte von Heterogenität auf Artenreichtum fasziniert Ökologen und Evolutionsbiologen seit Jahrzehnten. Dementsprechend existieren zahlreiche Studien über die Beziehung zwischen Heterogenität und dem Artenreichum verschiedener Taxa unter unterschiedlichsten ökologischen Gegebenheiten. Heterogenität kann sich auf biotische und abiotische Bedingungen beziehen und wurde daher mittels vieler verschiedener Maße quantifiziert. Diese finden zudem auf sehr unterschiedlichen Skalen Anwendung, die von der Architektur einer einzelnen Pflanze über Landschaftsstruktur bis hin zu topographischem Relief reichen. Die Vielfalt der Maße sowie eine oft unbestimmte und inkonsistente Terminologie, die in der Forschung zu Heterogenität-Artenreichtums-Beziehungen verwendet wird, erschweren das Verständnis, den Vergleich und die Synthese der entsprechenden Studien. Desweiteren gibt es große Unterschiede in der Form und Stärke der Beziehungen: während viele Studien einen positiven Zusammenhang zwischen Heterogenität und Artenreichtum nachwiesen, sind auch negative, unimodale und nicht signifikante Zusammenhänge bekannt. Deshalb existiert bisher kein eindeutiger Konsens bezüglich der generellen Heterogenität-Artenreichtums-Beziehung. Im Rahmen der vorliegenden Dissertation fertige ich ein systematisches Literaturreview an, mit dem ich einen Überblick über die verwendeten Maße und Begriffe gebe, die bisher in der Forschung zu Heterogenität-Artenreichtums-Beziehungen Anwendung fanden. Basierend auf 192 Studien identifiziere ich 165 verschiedene Heterogenitätsmaße, die ich bezüglich ihrer Themenfelder und Berechnungsmethoden klassifiziere. Es werden fünf Themenfelder unterschieden, nämlich Landbedeckung und Vegetation als biotische Komponenten, und Klima, Boden und Topographie als abiotische Komponenten von Heterogenität. Desweiteren identifiziere ich achtzehn verschiedene Berechnungsmethoden, wie z.B. Anzahl, Standardabweichung und Variationskoeffizient. Die Höhenspannweite in einem Gebiet erweist sich als das häufigste Heterogenitätsmaß in der Literatur, wohingegen Maße von klimatischer Heterogenität und Bodenheterogenität unterrepräsentiert sind. Weiterhin stelle ich ein deutliches räumliches und taxonomisches Ungleichgewicht in der Forschung fest, wobei ein Großteil der Studien den Einfluss von Heterogenität in der Paläarktis untersucht und sich auf den Artenreichtum von Vertebraten oder Pflanzen konzentriert. Ich kompiliere über 100 verschiedene Begriffe für Heterogenität, wie z.B. Habitatdiversität oder Habitatheterogenität, und weise auf mangelhafte und teilweise sogar widersprüchliche Definitionen hin. Solche Unklarheiten erschweren das Verständnis der Begriffe und Studien, weshalb ich für eindeutige Terminologie plädiere und mich gegen die Verwendung von Synonymen ausspreche. Desweiteren gebe ich einen Überblick über mögliche Mechanismen, die als Grundlage von positiven Zusammenhängen zwischen Heterogenität und Artenreichtum in der Literatur diskutiert werden. Insgesamt identifiziere ich sieben Hauptmechanismen, die mit der Förderung von Koexistenz, Persistenz und Diversifikation von Arten zusammenhängen. Diese Mechanismen stelle ich in Beziehung zu den Themenfeldern der Heterogenitätsmaße, den Taxa und den räumlichen Skalen, die in den jeweiligen Studien behandelt werden. Basierend auf dem gleichen Datensatz von 192 Studien und 1148 Datenpunkten führe ich anschließend eine Meta-Analyse durch, um die generelle Richtung und Stärke des Zusammenhangs zwischen Heterogenität und dem Artenreichtum terrestrischer Pflanzen und Tiere zu untersuchen. Hierbei weise ich quantitativ nach, dass der Zusammenhang von der Landschaftsebene bis zur globalen Skala über Taxa, Habitattypen und räumliche Skalen hinweg generell positiv ist. Während kein signifikanter Unterschied in der Effektgröße zwischen biotischer und abiotischer Heterogenität besteht, weisen Vegetations- und topographische Heterogenität signifikant stärkere Assoziationen mit Artenreichtum auf als klimatische Heterogenität. Durch gemischte Meta-Regressionen identifiziere ich weiterhin Studieneigenschaften, die die Stärke des Zusammenhangs zwischen Heterogenität und Artenreichtum beeinflussen. Räumliche Skalen, insbesondere Flächenkonstanz, räumliche Auflösung und Ausdehnung, stellen sich als besonders wichtige Einflussgrößen für die untersuchte Beziehung zwischen Artenreichtum und auf Landbedeckung und Höhe basierenden Heterogenitätsmaßen heraus. Ausgehend von den Ergebnissen des Literaturreviews untersuche ich schließlich die Ähnlichkeit zwischen einer Reihe von Heterogenitätsmaßen sowie deren differentiellen Einfluss auf den globalen Artenreichtum terrestrischer Säugetiere. Ich berechne systematisch 51 verschiedene Heterogenitätsmaße auf globaler Ebene, die alle fünf Themenfelder von Heterogenität abdecken und neun verschiedene Berechnungsmethoden beinhalten. Ich zeige, dass manche dieser Maße sich deutlich voneinander abheben, während andere stärker kollinear und zum Teil redundant sind. Ich stelle Ähnlichkeiten und Unterschiede zwischen verschiedenen Regionen in Bezug auf räumliche Muster einzelner Heterogenitätsmaße sowie einen multidimensionalen Heterogenitätsraum heraus, der auf einer Hauptkomponentenanalyse beruht. Außerdem untersuche ich den Zusammenhang zwischen jedem einzelnen Heterogenitätsmaß und dem Säugetierreichtum in einfachen und multiplen Regressionsmodellen, welche zusätzlich den Einfluss von Klima, biogeographischer Region und menschlichem Einfluss berücksichtigen. Mit Hilfe von bedingten Inferenzbäumen analysiere ich den Einfluss der verschiedenen Themenfelder und Berechnungsmethoden der Heterogenitätsmaße auf die Modellgüte über drei räumliche Auflösungen hinweg. Die Wahl der Themenfelder stellt sich dabei als wichtigster Einflussfaktor heraus, wobei sich Maße klimatischer und topographischer Heterogenität besonders positiv auf die Modellgüte auswirken. Desweiteren zeichnen sich Modelle mit Anzahl- oder Spannweitemaßen ebenfalls durch hohe Modellgüte aus, wohingegen der Variationskoeffizient und ein Geländeschroffheitsindex mit relativ geringer Modellgüte zusammenhängen. Insgesamt betonen meine Ergebnisse die hohe Bedeutung methodischer Entscheidungen auf die Ergebnisse von Heterogenität-Artenreichtums-Studien. Dies wiederum dokumentiert wie wichtig es ist, sinnvolle, taxon- und skalenabhängige Heterogenitätsmaße zu verwenden, die dem jeweiligen Untersuchungssystem und dem zu untersuchenden Mechanismus entsprechen. Diese Dissertation stellt die bisher umfangreichste Untersuchung der Quantifizierung und Terminologie von Heterogenität über Themenfelder und verschiedene taxonomische Gruppen hinweg dar. Sie belegt erstmals einen generell positiven Zusammenhang zwischen biotischer und abiotischer Heterogenität und dem Artenreichtum terrestrischer Pflanzen und Tiere auf relativ großen räumlichen Skalen. Meine Forschung demonstriert deutlich die enorme Komplexität von Heterogenität als Thema und Forschungsgebiet. Trotz der beachtlichen Fortschritte, die durch diese Arbeit in der Erforschung von Heterogenität-Artenreichtums-Beziehungen gemacht wurden, gilt es noch zahlreiche offene Fragen zu beantworten. Die vorliegende Dissertation soll eine solide Basis schaffen, um diese Herausforderung in Zukunft anzugehen.