The thesis focuses on the study of arboreal ant communities in a highly diverse tropical rainforest in Papua New Guinea. In the first study of its kind, whole patches of forest were sampled extensively for ants foraging and nesting in tree trunks and canopies. An extraordinary amount of material collected from 684 felled trees and 260 bait stations in plots of primary and secondary forest was used to study the mechanisms structuring the diversity and species coexistence of this ecologically important insect group at the local scale. The first chapter addresses the question "Why are ant communities more species rich in primary than in secondary forests?" and explores the main environmental traits that influence their diversity in tropical trees. The second chapter compares the community diversity and composition and nesting preferences of ant species between both forest types. The final third chapter introduces a novel method, involving large-scale manipulation of ant communities that could serve as a template for future studies focused on complex tropical food-webs of canopy arthropods and plants. In summary, the results of the thesis highlight the importance of primary vegetation in conserving the diversity of native ant communities and the relevance of nesting microhabitats and their turnover between trees, rather than tree taxonomic diversity, for sustaining the diverse arboreal fauna in tropical forests.

How do gender separation and the transition to wind pollination happen in temperate trees? What does the reproductive ecology in the crowns of temperate forest trees look like? These connected questions intrigued researchers before and since Darwin but it is only in the last years that a direct study of the latter question has been enabled. A research crane was used to study the flowering ecology of Fraxinus excelsior, Acer platanoides, Acer pseudoplatanus and Tilia cordata in Leipzig’s floodplain forest. These species originate from hermaphrodite insect pollinated plant families and exhibit different grades of gender separation and different stages between insect and wind pollination. As they are typical elements of temperate deciduous forests, an ecological comparison of their flowering ecology may shed new light on the evolution of gender separation and wind pollination in this habitat. Using the crane, gender distribution, flowering phenology in relation to microclimate, pollination levels (including pollen tubes in the styles) and fruit set were studied in ca. 200 trees over 2-4 years. Main results are a new appreciation of the sexual system of Fraxinus excelsior as dioecy, of Tilia cordata as andromonoecy and a detailed description of the intricacies of the heterodichogamous sexual system of Acer pseudoplatanus. Several flowering phenological patterns are described in Fraxinus excelsior and Acer platanoides in relation to microclimate in early spring. The role of small arthropods is underlined as gall mites may play a role in gender specialisation in Fraxinus excelsior, gall midges are related to maleness in T. cordata and thrips are probably the pollinators of Acer pseudoplatanus in the stand. Thrips pollination is suggested to be a possible stepping-stone between insect pollination and wind pollination, which may drive the transition in Acer pseudoplatanus and possibly in intensively flowering dominant species in other habitats. The study presents the complexity of the reproductive systems and the strong interdependencies among their elements.

Woodlands constitute the subsistence base of the majority of people in the Sudano-Sahelian zone (SSZ), but low availability of in situ data on vegetation structure and composition hampers research and monitoring. This thesis explores the utility of remote sensing for mapping and analysing vegetation, primarily trees, in the SSZ. A comprehensive literature review was first conducted to describe how the application of remote sensing has developed in the SSZ between 1975 and 2014, and to identify important research gaps. Based on the gaps identified in the literature review, the capabilities of two new satellite systems (WorldView-2 and Landsat 8) for mapping woodland structure and composition were tested in an area in central Burkina Faso. The results shows that WorldView-2 represents a useful data source for mapping individual trees: 85.4% of the reference trees were detected in the WorldView-2 data and tree crown area was estimate with an average error of 45.6%. In addition, WorldView-2 data produced high classification accuracies for five locally important tree species. The highest overall classification accuracy (82.4%) was produced using multi-temporal WorldView-2 data. Landsat 8 data proved more suitable for mapping tree canopy cover as compared to aboveground biomass in the woodland landscape. Tree canopy cover and aboveground biomass was predicted with 41% and 66% root mean square error, respectively, at pixel level. This thesis demonstrates the potential of easily accessible data from two satellite systems for mapping important tree attributes in woodland areas, and discusses how the usefulness of remote sensing for analyzing vegetation can be further enhanced in the SSZ. / Merparten av befolkningen i Sudano-Sahel zonen (SSZ) är beroende av naturresurser och ekosystemtjänster från woodlands (öppen torrskog) för att säkra sin försörjning. Tillgången av fältmätningar av vegetationens struktur och sammansättning är mycket låg i detta område, vilket utgör ett problem för forskning och miljöövervakning. Denna avhandling undersöker nyttan av fjärranalys för att kartlägga och analysera vegetation, främst träd, i SSZ. En omfattande litteraturöversikt genomfördes först för att undersöka hur tillämpningen av fjärranalys har utvecklats i SSZ mellan 1975 och 2014, samt att identifiera viktiga forskningsluckor. Några av de luckor som konstaterades i litteraturgenomgången låg till grund för de följande studierna där två nya satellitsystem (Worldview-2 och Landsat 8) utvärderades för deras användbarhet att kartlägga trädtäckets struktur och artsammansättning i ett woodland-område i centrala Burkina Faso. Resultaten visar att Worldview-2 är en värdefull datakälla för kartering av enskilda träd: 85.4% av referensträden detekterades och trädkronornas storlek uppskattades med ett medelfel av 45.6%. Worldview-2-data producerade även hög klassificeringsnoggrannhet för de fem lokalt viktigaste trädslagen. Den högsta noggrannheten (82.4%) uppnåddes med multi-temporal Worldview-2-data. Landsat 8 data visade sig mer lämpade för kartering av krontäcke, jämfört med biomassa. Medelfelet för karteringen var 41% för krontäcke och 66% för biomassa, på pixelnivå. Avhandlingen visar att lättillgängliga data från två satellitsystem är användbara för kartläggning av viktiga trädattribut i woodlands, samt diskuterar hur nyttan av fjärranalys för vegetationsanalys kan ökas ytterligare i SSZ.

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Indiana University-Purdue University Indianapolis (IUPUI) / Underground septic systems thrive or fail based on the relationship with their local environment. This paper explores ways environmental variables such as soil type, tree roots, degree of slope, and impervious surfaces affect on-site wastewater treatment systems. It also discusses the effects each of these variables may have on a septic system, and the resulting impact a compromised system may have on the surrounding environment. This research focuses on an approximately 20 square mile area of central Washington Township in Marion County, Indiana. This area of central Indiana contains a large septic system owning population in a sampling of different environments such as wooded areas, hilly areas, and a variety of different soil types.