Suchergebnisse

At the time of European entry, 18 species of rodent occurred in the arid zone
of the Northern Territory, including two endemic species,
Zyzomys pedunculatus and
Pseudomys johnsoni. The tally is somewhat inflated, as
the arid Northern Territory is on the margins of the distribution for seven of
these species.
The historical record for this fauna is generally reasonably good, due to
important collections around the end of the nineteenth century, some landmark
studies (notably by H.H. Finlayson) earlier this century, documentation of
Aboriginal knowledge, and the recent discovery and analysis of fossil and
sub-fossil deposits. Notwithstanding this good historical baseline, recent
research has added three native species to the fauna, and re-discovered one
species, Z. pedunculatus, earlier feared extinct.
Over the last 200 years, four species
(Leporillus apicalis,
Notomys amplus, N. longicaudatus
and Pseudomys fieldi) have disappeared, and a further
five species (N. cervinus,
N. fuscus, P. australis,
Rattus tunneyi and
Z. pedunculatus) have declined considerably, with
several of these perhaps no longer present in the area. The decline in this
rodent fauna is matched, or indeed surpassed, by declines in the arid-zone
bandicoots, small macropods and large dasyurids. But notably the small
dasyurids have generally suffered few declines. There has been differential
decline within the rodent fauna, with declines mainly affecting larger
species, species with the most idiosyncratic diets, and species occurring
mainly in tussock grasslands and gibber plains.
The main conservation and management actions required to safeguard what is
left of this fauna are carefully targetted studies examining the effect of
threatening processes, complemented by landscape-wide amelioration of these
threats. Additional autecological studies are also needed for some species,
and some exceptionally poorly known areas should be surveyed. Current work
examining the distribution, ecology and management requirements of the
endangered Z. pedunculatus is a major priority.

Semi-arid areas are, due to their climatic setting, characterized by small water resources. An increasing water demand as a consequence of population growth and economic development as well as a decreasing water availability in the course of possible climate change may aggravate water scarcity in future, which often exists already for present-day conditions in these areas. Understanding the mechanisms and feedbacks of complex natural and human systems, together with the quantitative assessment of future changes in volume, timing and quality of water resources are a prerequisite for the development of sustainable measures of water management to enhance the adaptive capacity of these regions. For this task, dynamic integrated models, containing a hydrological model as one component, are indispensable tools. The main objective of this study is to develop a hydrological model for the quantification of water availability in view of environmental change over a large geographic domain of semi-arid environments. The study area is the Federal State of Ceará (150 000 km2) in the semi-arid north-east of Brazil. Mean annual precipitation in this area is 850 mm, falling in a rainy season with duration of about five months. Being mainly characterized by crystalline bedrock and shallow soils, surface water provides the largest part of the water supply. The area has recurrently been affected by droughts which caused serious economic losses and social impacts like migration from the rural regions. The hydrological model Wasa (Model of Water Availability in Semi-Arid Environments) developed in this study is a deterministic, spatially distributed model being composed of conceptual, process-based approaches. Water availability (river discharge, storage volumes in reservoirs, soil moisture) is determined with daily resolution. Sub-basins, grid cells or administrative units (municipalities) can be chosen as spatial target units. The administrative units enable the coupling of Wasa in the framework of an integrated model which contains modules that do not work on the basis of natural spatial units. The target units mentioned above are disaggregated in Wasa into smaller modelling units within a new multi-scale, hierarchical approach. The landscape units defined in this scheme capture in particular the effect of structured variability of terrain, soil and vegetation characteristics along toposequences on soil moisture and runoff generation. Lateral hydrological processes at the hillslope scale, as reinfiltration of surface runoff, being of particular importance in semi-arid environments, can thus be represented also within the large-scale model in a simplified form. Depending on the resolution of available data, small-scale variability is not represented explicitly with geographic reference in Wasa, but by the distribution of sub-scale units and by statistical transition frequencies for lateral fluxes between these units. Further model components of Wasa which respect specific features of semi-arid hydrology are: (1) A two-layer model for evapotranspiration comprises energy transfer at the soil surface (including soil evaporation), which is of importance in view of the mainly sparse vegetation cover. Additionally, vegetation parameters are differentiated in space and time in dependence on the occurrence of the rainy season. (2) The infiltration module represents in particular infiltration-excess surface runoff as the dominant runoff component. (3) For the aggregate description of the water balance of reservoirs that cannot be represented explicitly in the model, a storage approach respecting different reservoirs size classes and their interaction via the river network is applied. (4) A model for the quantification of water withdrawal by water use in different sectors is coupled to Wasa. (5) A cascade model for the temporal disaggregation of precipitation time series, adapted to the specific characteristics of tropical convective rainfall, is applied for the generating rainfall time series of higher temporal resolution. All model parameters of Wasa can be derived from physiographic information of the study area. Thus, model calibration is primarily not required. Model applications of Wasa for historical time series generally results in a good model performance when comparing the simulation results of river discharge and reservoir storage volumes with observed data for river basins of various sizes. The mean water balance as well as the high interannual and intra-annual variability is reasonably represented by the model. Limitations of the modelling concept are most markedly seen for sub-basins with a runoff component from deep groundwater bodies of which the dynamics cannot be satisfactorily represented without calibration. Further results of model applications are: (1) Lateral processes of redistribution of runoff and soil moisture at the hillslope scale, in particular reinfiltration of surface runoff, lead to markedly smaller discharge volumes at the basin scale than the simple sum of runoff of the individual sub-areas. Thus, these processes are to be captured also in large-scale models. The different relevance of these processes for different conditions is demonstrated by a larger percentage decrease of discharge volumes in dry as compared to wet years. (2) Precipitation characteristics have a major impact on the hydrological response of semi-arid environments. In particular, underestimated rainfall intensities in the rainfall input due to the rough temporal resolution of the model and due to interpolation effects and, consequently, underestimated runoff volumes have to be compensated in the model. A scaling factor in the infiltration module or the use of disaggregated hourly rainfall data show good results in this respect. The simulation results of Wasa are characterized by large uncertainties. These are, on the one hand, due to uncertainties of the model structure to adequately represent the relevant hydrological processes. On the other hand, they are due to uncertainties of input data and parameters particularly in view of the low data availability. Of major importance is: (1) The uncertainty of rainfall data with regard to their spatial and temporal pattern has, due to the strong non-linear hydrological response, a large impact on the simulation results. (2) The uncertainty of soil parameters is in general of larger importance on model uncertainty than uncertainty of vegetation or topographic parameters. (3) The effect of uncertainty of individual model components or parameters is usually different for years with rainfall volumes being above or below the average, because individual hydrological processes are of different relevance in both cases. Thus, the uncertainty of individual model components or parameters is of different importance for the uncertainty of scenario simulations with increasing or decreasing precipitation trends. (4) The most important factor of uncertainty for scenarios of water availability in the study area is the uncertainty in the results of global climate models on which the regional climate scenarios are based. Both a marked increase or a decrease in precipitation can be assumed for the given data. Results of model simulations for climate scenarios until the year 2050 show that a possible future change in precipitation volumes causes a larger percentage change in runoff volumes by a factor of two to three. In the case of a decreasing precipitation trend, the efficiency of new reservoirs for securing water availability tends to decrease in the study area because of the interaction of the large number of reservoirs in retaining the overall decreasing runoff volumes. ; Semiaride Gebiete sind auf Grund der klimatischen Bedingungen durch geringe Wasserressourcen gekennzeichnet. Ein zukünftig steigender Wasserbedarf in Folge von Bevölkerungswachstum und ökonomischer Entwicklung sowie eine geringere Wasserverfügbarkeit durch mögliche Klimaänderungen können dort zu einer Verschärfung der vielfach schon heute auftretenden Wasserknappheit führen. Das Verständnis der Mechanismen und Wechselwirkungen des komplexen Systems von Mensch und Umwelt sowie die quantitative Bestimmung zukünftiger Veränderungen in der Menge, der zeitlichen Verteilung und der Qualität von Wasserressourcen sind eine grundlegende Voraussetzung für die Entwicklung von nachhaltigen Maßnahmen des Wassermanagements mit dem Ziel einer höheren Anpassungsfähigkeit dieser Regionen gegenüber künftigen Änderungen. Hierzu sind dynamische integrierte Modelle unerlässlich, die als eine Komponente ein hydrologisches Modell beinhalten. Vorrangiges Ziel dieser Arbeit ist daher die Erstellung eines hydrologischen Modells zur großräumigen Bestimmung der Wasserverfügbarkeit unter sich ändernden Umweltbedingungen in semiariden Gebieten. Als Untersuchungsraum dient der im semiariden tropischen Nordosten Brasiliens gelegene Bundestaat Ceará (150 000 km2). Die mittleren Jahresniederschläge in diesem Gebiet liegen bei 850 mm innerhalb einer etwa fünfmonatigen Regenzeit. Mit vorwiegend kristallinem Grundgebirge und geringmächtigen Böden stellt Oberflächenwasser den größten Teil der Wasserversorgung bereit. Die Region war wiederholt von Dürren betroffen, die zu schweren ökonomischen Schäden und sozialen Folgen wie Migration aus den ländlichen Gebieten geführt haben. Das hier entwickelte hydrologische Modell Wasa (Model of Water Availability in Semi-Arid Environments) ist ein deterministisches, flächendifferenziertes Modell, das aus konzeptionellen, prozess-basierten Ansätzen aufgebaut ist. Die Wasserverfügbarkeit (Abfluss im Gewässernetz, Speicherung in Stauseen, Bodenfeuchte) wird mit täglicher Auflösung bestimmt. Als räumliche Zieleinheiten können Teileinzugsgebiete, Rasterzellen oder administrative Einheiten (Gemeinden) gewählt werden. Letztere ermöglichen die Kopplung des Modells im Rahmen der integrierten Modellierung mit Modulen, die nicht auf der Basis natürlicher Raumeinheiten arbeiten. Im Rahmen eines neuen skalenübergreifenden, hierarchischen Ansatzes werden in Wasa die genannten Zieleinheiten in kleinere räumliche Modellierungseinheiten unterteilt. Die ausgewiesenen Landschaftseinheiten erfassen insbesondere die strukturierte Variabilität von Gelände-, Boden- und Vegetationseigenschaften entlang von Toposequenzen in ihrem Einfluss auf Bodenfeuchte und Abflussbildung. Laterale hydrologische Prozesse auf kleiner Skala, wie die für semiaride Bedingungen bedeutsame Wiederversickerung von Oberflächenabfluss, können somit auch in der erforderlichen großskaligen Modellanwendung vereinfacht wiedergegeben werden. In Abhängigkeit von der Auflösung der verfügbaren Daten wird in Wasa die kleinskalige Variabilität nicht räumlich explizit sondern über die Verteilung von Flächenanteilen subskaliger Einheiten und über statistische Übergangshäufigkeiten für laterale Flüsse zwischen den Einheiten berücksichtigt. Weitere Modellkomponenten von Wasa, die spezifische Bedingungen semiarider Gebiete berücksichtigen, sind: (1) Ein Zwei-Schichten-Modell zur Bestimmung der Evapotranspiration berücksichtigt auch den Energieumsatz an der Bodenoberfläche (inklusive Bodenverdunstung), der in Anbetracht der meist lichten Vegetationsbedeckung von Bedeutung ist. Die Vegetationsparameter werden zudem flächen- und zeitdifferenziert in Abhängigkeit vom Auftreten der Regenzeit modifiziert. (2) Das Infiltrationsmodul bildet insbesondere Oberflächenabfluss durch Infiltrationsüberschuss als dominierender Abflusskomponente ab. (3) Zur aggregierten Beschreibung der Wasserbilanz von im Modell nicht einzeln erfassbaren Stauseen wird ein Speichermodell unter Berücksichtigung verschiedener Größenklassen und ihrer Interaktion über das Gewässernetz eingesetzt. (4) Ein Modell zur Bestimmung der Entnahme durch Wassernutzung in verschiedenen Sektoren ist an Wasa gekoppelt. (5) Ein Kaskadenmodell zur zeitlichen Disaggregierung von Niederschlagszeitreihen, das in dieser Arbeit speziell für tropische konvektive Niederschlagseigenschaften angepasst wird, wird zur Erzeugung höher aufgelöster Niederschlagsdaten verwendet. Alle Modellparameter von Wasa können von physiographischen Gebietsinformationen abgeleitet werden, sodass eine Modellkalibrierung primär nicht erforderlich ist. Die Modellanwendung von Wasa für historische Zeitreihen ergibt im Allgemeinen eine gute Übereinstimmung der Simulationsergebnisse für Abfluss und Stauseespeichervolumen mit Beobachtungsdaten in unterschiedlich großen Einzugsgebieten. Die mittlere Wasserbilanz sowie die hohe monatliche und jährliche Variabilität wird vom Modell angemessen wiedergegeben. Die Grenzen der Anwendbarkeit des Modell-konzepts zeigen sich am deutlichsten in Teilgebieten mit Abflusskomponenten aus tieferen Grundwasserleitern, deren Dynamik ohne Kalibrierung nicht zufriedenstellend abgebildet werden kann. Die Modellanwendungen zeigen weiterhin: (1) Laterale Prozesse der Umverteilung von Bodenfeuchte und Abfluss auf der Hangskala, vor allem die Wiederversickerung von Oberflächenabfluss, führen auf der Skala von Einzugsgebieten zu deutlich kleineren Abflussvolumen als die einfache Summe der Abflüsse der Teilflächen. Diese Prozesse sollten daher auch in großskaligen Modellen abgebildet werden. Die unterschiedliche Ausprägung dieser Prozesse für unterschiedliche Bedingungen zeigt sich an Hand einer prozentual größeren Verringerung der Abflussvolumen in trockenen im Vergleich zu feuchten Jahren. (2) Die Niederschlagseigenschaften haben einen sehr großen Einfluss auf die hydrologische Reaktion in semiariden Gebieten. Insbesondere die durch die grobe zeitliche Auflösung des Modells und durch Interpolationseffekte unterschätzten Niederschlagsintensitäten in den Eingangsdaten und die daraus folgende Unterschätzung von Abflussvolumen müssen im Modell kompensiert werden. Ein Skalierungsfaktor in der Infiltrationsroutine oder die Verwendung disaggregierter stündlicher Niederschlagsdaten zeigen hier gute Ergebnisse. Die Simulationsergebnisse mit Wasa sind insgesamt durch große Unsicherheiten gekennzeichnet. Diese sind einerseits in Unsicherheiten der Modellstruktur zur adäquaten Beschreibung der relevanten hydrologischen Prozesse begründet, andererseits in Daten- und Parametersunsicherheiten in Anbetracht der geringen Datenverfügbarkeit. Von besonderer Bedeutung ist: (1) Die Unsicherheit der Niederschlagsdaten in ihrem räumlichen Muster und ihrer zeitlichen Struktur hat wegen der stark nicht-linearen hydrologischen Reaktion einen großen Einfluss auf die Simulationsergebnisse. (2) Die Unsicherheit von Bodenparametern hat im Vergleich zu Vegetationsparametern und topographischen Parametern im Allgemeinen einen größeren Einfluss auf die Modellunsicherheit. (3) Der Effekt der Unsicherheit einzelner Modellkomponenten und -parameter ist für Jahre mit unter- oder überdurchschnittlichen Niederschlagsvolumen zumeist unterschiedlich, da einzelne hydrologische Prozesse dann jeweils unterschiedlich relevant sind. Die Unsicherheit einzelner Modellkomponenten- und parameter hat somit eine unterschiedliche Bedeutung für die Unsicherheit von Szenarienrechnungen mit steigenden oder fallenden Niederschlagstrends. (4) Der bedeutendste Unsicherheitsfaktor für Szenarien der Wasserverfügbarkeit für die Untersuchungsregion ist die Unsicherheit der den regionalen Klimaszenarien zu Grunde liegenden Ergebnisse globaler Klimamodelle. Eine deutliche Zunahme oder Abnahme der Niederschläge bis 2050 kann gemäß den hier vorliegenden Daten für das Untersuchungsgebiet gleichermaßen angenommen werden. Modellsimulationen für Klimaszenarien bis zum Jahr 2050 ergeben, dass eine mögliche zukünftige Veränderung der Niederschlagsmengen zu einer prozentual zwei- bis dreifach größeren Veränderung der Abflussvolumen führt. Im Falle eines Trends von abnehmenden Niederschlagsmengen besteht in der Untersuchungsregion die Tendenz, dass auf Grund der gegenseitigen Beeinflussung der großen Zahl von Stauseen beim Rückhalt der tendenziell abnehmenden Abflussvolumen die Effizienz von neugebauten Stauseen zur Sicherung der Wasserverfügbarkeit zunehmend geringer wird.

Agricultural technology change is required in developing countries to increase the robustness to climate-related variability, feed a growing population, and create opportunities for market-oriented production. This study investigates technological change in the form of adoption of improved wheat, drought-tolerant teff, and cash crops in the semi-arid Tigray region in northern Ethiopia. We analyze three rounds of panel data collected from smallholder farms in 2005/2006, 2009/2010 and 2014/2015 with a total sample of 1269 households. Double-hurdle models are used to assess how the likelihood (first hurdle) and intensity of technology adoption (second hurdle) are affected by demographic, weather, and market factors. The results indicate that few smallholders have adopted the new crops, those that have adopted the crops only plant small shares of their land with the new crops, and that there has been only a small increase in adoption over the ten-year period. Furthermore, we find that high population density is positively associated with the adoption of improved wheat, and previous period's rainfall is positively associated with the adoption of drought-tolerant teff. The adoption of cash crops is positively associated with landholding size and access to irrigation. The policy implications of these results are that the government should increase the improved wheat diffusion efforts in less population dense areas, make sure that drought-tolerant teff seed is available and affordable after droughts, and promote irrigation infrastructure for production of cash crops.

Agricultural technology change is required in developing countries to increase the robustness to climate-related variability, feed a growing population, and create opportunities for market-oriented production. This study investigates technological change in the form of adoption of improved wheat, drought-tolerant teff, and cash crops in the semi-arid Tigray region in northern Ethiopia. We analyze three rounds of panel data collected from smallholder farms in 2005/2006, 2009/2010 and 2014/2015 with a total sample of 1269 households. Double-hurdle models are used to assess how the likelihood (first hurdle) and intensity of technology adoption (second hurdle) are affected by demographic, weather, and market factors. The results indicate that few smallholders have adopted the new crops, those that have adopted the crops only plant small shares of their land with the new crops, and that there has been only a small increase in adoption over the ten-year period. Furthermore, we find that high population density is positively associated with the adoption of improved wheat, and previous period's rainfall is positivly associated with the adoption of drought-tolerant teff. The adoption of cash crops is positively associated with landholding size and access to irrigation. The policy implications of these results are that the government should increase the improved wheat diffusion efforts in less population dense areas, make sure that drought-tolerant teff seed is available and affordable after droughts, and promote irrigation infrastructure for production of cash crops.

AbstractThis paper examines acts of land 'self-provisioning' ('siziphile' land occupations) and 'radical land restitution' (of land previously annexed from people by the local authority for a pilot grazing project) by villagers in a communal area in Lupane District in north-western Zimbabwe. Situating these occurrences within the wider and historical context of 'madiro' (freedom farming and unauthorised development of settlements) and Matabeleland land politics and semi-proletarianisation, it stresses the livelihood history of households, the disappointments with local job opportunities and destruction of urban-based livelihoods in a crumbling economy, and the accompanying crisis of communal area agriculture. It concludes that these factors provided a real threat to semi-proletarianisation. By self-provisioning of the land the overriding concern of villagers was to maintain a certain level of livelihood survival, even if it was at odds with their livelihood strategies, while they sought opportunities to maintain semi-proletarianisation.

Groundwater is a vital resource in arid and semi-arid regions, increasingly relied upon for year-round access, though lack of both study and regulation contribute to unsustainable pressures potentially contributing to a negative spiral of ecological, social and economic decline. Using field visits, interviews with locals and experts, and literature reviews, we explored a successful programme of community-based groundwater recharge in three adjacent catchments (the Arvari, Sarsa and Baghani) in semi-arid north Rajasthan, India, led by the NGO Tarun Bharat Sangh (TBS) in order to determine how successes were achieved and could be replicated. TBS-led initiatives rebuilt traditional village governance structures and participation in community-designed and maintained water harvesting structures (WHSs), which were efficient both economically and in technical design using indigenous knowledge. Enhanced seasonal groundwater recharge enabled by WHSs regenerated aquatic, farmed and natural ecosystems, underpinning a positive cycle of interdependent social and economic regeneration. Locally appropriate, integrated social and technical solutions maintaining this positive cycle have increased the quality of ecosystems and the wellbeing of local people. We used the STEEP (Social, Technological, Economic, Environmental, Political) framework to stratify outcomes, exploring principles underpinning successful local and catchment-scale regeneration and drawing out lessons transferrable to similarly water-stressed regions.

Shortage of water in natural pastures led to a sharp decline in a large rabbit population in arid, northeastern
South Australia. The pastures were dry and some rabbits drank at springs and water troughs.
Further from water, rabbits climbed trees and shrubs to obtain succulent leaves and twigs. Rabbits
provided with water maintained their weight and apparently survived better than those which did not
drink. It seems unlikely that the rabbits lost weight because the water shortage reduced the amount of dry
food they could eat. In caged rabbits, water shortage limits food intake but also results in low gut fill;
whereas the wild rabbits had the normal amount of digesta in their guts. It is more likely that, as the
pastures became dry, rabbits ate woody twigs and bark which were moist enough to meet their water
requirements but contained too little digestible energy for maintenance. The water shortage apparently
arose because rabbits were numerous and had eaten out the succulent pasture plants. Normally, it takes a
long drought to reduce arid-zone plants to dry straw, and overgrazing is probably the usual cause of a
lack of adequate water for rabbits.

Rainfed cultivation in drylands, especially arid and hyper-arid lands, is often considered to play a minor role in human livelihood. Understanding the long-term development of this practice will augment knowledge of past land use strategies to inform models of land cover and climate change. Drawing upon the results of an ethnoarchaeological study, this paper presents a review of non-irrigated agricultural practices in the absence of anthropogenic water-harvesting structures, in arid and hyper-arid lands of North Africa. A proposal on how to identify the presence and extent of these practices in the past in world's drylands at large is ultimately presented. ; DU was funded by the Italian Ministry for Foreign affairs (MAE-DGSP VI). RAINDROPS has received funding from the European Union's Horizon 2020 research and innovation programme (ERC-Stg-2017) under grant agreement No 759800. Additional funding for fieldwork of AZ is from the University of Milano. This work is also part of the PAGES LandCover6k effort and the INQUA International Focus Group HoLa (Holocene Global Landuse). CL, SB and MM are members of CaSEs, an "Excellence Research Group" of the Catalan Agency for Research (AGAUR SGR-1417 and SGR-0212).

Part 1: Assessment of groundwater quality -- Chapter 1: Unveiling the Hidden Depths: A Review for Understanding and Managing Groundwater Contamination in Arid Regions -- Chapter 2: Risk Assessment of Potential Groundwater Contamination by the Agricultural Drainage Water in the Central Valley Watershed, California, USA -- Chapter 3: Impact of Bugun Reservoir on Groundwater and Soil: A Case Study from South Kazakhstan -- Chapter 4: Impact of Climate Changes on Seawater Intrusion in the Nile Delta Aquifer (Egypt) -- Chapter 5: Groundwater Quality Prediction in Upper and Middle Cheliff Plain, Algeria Using Artificial Intelligence -- Chapter 6: Evolution of Groundwater in the Cheliff and Mitidja Aquifers (North Algeria) in Qualitative and Quantitative Terms -- Chapter 7: Groundwater Pollution Sources and Its Quality in Kingdom of Saudi Arabia- State-of-the-Art -- Chapter 8: Isotopic and Chemical Composition of Egypt's Groundwater Resources -- Chapter 9: Understanding Seawater Intrusion byHydrochemical Parameters and Stable Water Isotopes along the Coastal Alluvial Aquifers of the Essaouira Basin, Morocco -- Part 2: Major global contaminants in groundwater -- Chapter 10: Geochemical Controls on Fluoride Enrichment in Groundwater of a Geologically Heterogeneous Part of Ghana: Implications for Human Health Risk Assessment -- Chapter 11: Uncovering Fluoride Contamination in Groundwater of Arid and Semi-Arid Regions: Stigma to Solutions -- Chapter 12: Nitrate Contamination in Groundwater of Arid and Semi-Arid Regions: Ecotoxicological Impacts and Management Strategies. .

The distribution of the koala (Phascolarctos cinereus) and the common brushtail possum (Trichosurus vulpecula) within the Prairie-Torrens Creek Alluvials province of the Desert Upland region of north-western Queensland was examined. The optimum habitat for each species as indicated by the occurrence of faecal pellet groups was found to be that associated with creek-lines. However, other land types were also used by each species to varying degrees. The relationship between various habitat variables and pellet group counts was investigated using Multiple regression and a Generalised linear model. Proximity to creek-bed, total basal area of trees, species richness and Acacia basal area (negative) best explained the occurrence of koalas. Proximity to creek-bed, Acacia basal area (negative), total basal area of trees, and available water (negative) best explained the occurrence of brushtail possums. In contrast to studies of arboreal species in the moist-south-eastern forests of Australia no relationship was found between foliar nutrient concentrations and the occurrence of koalas or brushtail possums. However, a significant relationship was found between leaf water concentration and the occurrence of koalas. It is suggested that water availability is the paramount factor defining preferred arboreal habitat in arid and semi-arid woodlands.