Ecosystem Sciences

To date, there have been few attempts to model the dispersal of invasive weeds in rainforests to create predictive simulation models for their management. This may be partly due to the difficulty of describing the movement of vertebrate seed dispersers which are responsible for dispersal of most rainforest plant species, and partly due to a lack of baseline data on invasive species.

Biological invasions are a key threat to natural ecosystems and consequently a major focus of ecological research. Even though it is dispersal processes that result in the movement of invasive populations through landscapes, dispersal ecology has played a relatively minor role in invasion ecology research. This is particularly true for vertebrate-dispersed plants. To encourage thinking around these issues and a greater involvement of dispersal ecologists in invasion research, we review contributions made to invasion ecology by dispersal ecology and highlight opportunities that the study of biological invasions offers for improving our understanding of dispersal processes. We suggest that by working in the context of invasions dispersal ecologists are not only able to contribute to the development of process-based management but also gain new opportunities for developing and testing predictions in their field. Because biological invasions are perturbations of natural systems they provide excellent opportunities for both natural and manipulative experimentation with potential for a range of forms of replication. Significantly, the need to develop a predictive understanding of population-level patterns of spread in order to manage invasives demands a shift away from studying individual vectors to developing predictions that integrate across all vectors and processes in the dispersal loop. This is a significant development for dispersal ecology and is a major opportunity for dispersal ecologists to contribute to a current environmental issue.

By direct comparison between experiment and theory with no adjustable parameters, we show how the classical fluctuations on a multistate atom laser beam increase with increasing flux. The fluctuations are inherent to state changing out coupling, rf, Raman, or otherwise and are likely to be present in all atom lasers, pulsed or continuous, that employ such out coupling. If not removed or avoided, these classical fluctuations will prevent shot noise limited measurement employing atom lasers of this kind.

The study develops a spatio-temporal model of hedonic pricing that explicitly separates the land and the structure components of property prices. This is illustrated with a dataset for Brisbane, Australia, constructed by combining commercial real estate, local government databases and GIS-based spatial analyzes. The land component of prices has increased from 42% in 2000 to 66% in 2010. This has implications for a broad range of planning and policy issues, including property tax rates, town planning, and options for climate adaptations.

The properties of a relativistic plasma dispersion function (RPDF) for an intrinsically extremely relativist, strongly magnetized, one-dimensional, electron-positron plasma are discussed in detail. For a plasma with a mean Lorentz factor fγg 1 in its rest frame, the RPDF has a large peak fγg at a phase speed a fraction of order 1\fγg below the speed of light, and the asymptotic value (infinite phase speed) is fγ −$ g " 1\fγg. These features are not particularly sensitive to the choice of distribution function. The RPDF is used to discuss the properties of waves in such plasmas. Particular points discussed are the implications of the RPDF for the maximum frequency for parallel Langmuir waves, and for the reconnection between the Langmuir mode and the Alfve! n mode.

By direct comparison between experiment and theory with no adjustable parameters, we show how the classical fluctuations on a multistate atom laser beam increase with increasing flux. The fluctuations are inherent to state changing out coupling, rf, Raman, or otherwise and are likely to be present in all atom lasers, pulsed or continuous, that employ such out coupling. If not removed or avoided, these classical fluctuations will prevent shot noise limited measurement employing atom lasers of this kind.

Miconia calvescens (Melastomataceae) is a serious invader in the tropical Pacific, including the Hawaiian and Tahitian Islands, and currently poses a major threat to native biodiversity in the Wet Tropics of Australia. The species is fleshy-fruited, smallseeded and shade tolerant, and thus has the potential to be dispersed widely and recruit in relatively intact rainforest habitats, displacing native species. Understanding and predicting the rate of spread is critical for the design and implementation of effective management actions. We used an individual-based model incorporating a dispersal function derived from dispersal curves for similar berry-fruited native species, and life-history parameters of fecundity and mortality to predict the spatial structure of a Miconia population after a 30 year time period. We compared the modelled population spatial structure to that of an actual infestation in the rainforests of north Queensland. Our goal was to assess how well the model predicts actual dispersion and to identify potential barriers and conduits to seed movement and seedling establishment. The model overpredicts overall population size and the spatial extent of the actual infestation, predicting individuals to occur at a maximum 1,750 m from the source compared with the maximum distance of any detected individual in the actual infestation of 1,191 m. We identify several characteristic features of managed invasive populations that make comparisons between modelled outcomes and actual infestations difficult. Our results suggest that the model's ability to predict both spatial structure and spread of the population will be improved by incorporating a spatially explicit element, with dispersal and recruitment probabilities that reflect the relative suitability of different parts of the landscape for these processes.

We describe the construction and operation of an external cavity diode laser in which the diode is cooled to −45 • C. This technique allows us to pull the wavelength of a nominally 782 nm diode to operate at 766.7 nm, a change of over 15 nm. The important aspects of our design are its ease and low cost as compared to other designs of changing the operating wavelength of laser diodes. We provide background information on thermal design with multiple TECs so the reader can extend this example for use in their own applications.

In this paper, we present the first data from a new double MOT Bose-Einstein condensation (BEC) experiment. To assist new groups in their pursuit of BEC, we present a typical series of absorption images over an evaporative cooling ramp when BEC is reached, and compare this with a second series where the machine fails to reach condensation. All pictures in both series are presented on the same scale allowing the trend in the elastic collision rate as evaporation proceeds to be assessed simply by looking at the pictures. This is a powerful and simple diagnostic that is easily applied in the laboratory when characterizing and trouble shooting a new machine.

We present a novel technique to lock the frequency of the trapping laser of a magneto-optic trap (MOT) using a signal generated from the ultracold atoms in the MOT itself. This technique utilizes the large number of very cold, slowmoving atoms in the MOT to generate a signal free of Doppler-broadening. A system analogous to Pound-Drever-Hall locking allows an error signal to be generated on resonance without significantly perturbing the MOT. We have successfully stabilized the frequency of the main trapping laser of a 87 Rb MOT using this technique to generate a selflocked MOT.

Atom lasers have been demonstrated in both pulsed and semi-continuous modes. The dynamics of these devices is predicted to be dramatically different to the optical laser due to fundamental differences between the two types of boson fields; however to date it is the similarities that have been emphasized. Here we show how the atom laser dynamics are strongly affected by coupling of the output beam back to the condensate.

For thirty years I worked with my father, twenty-five of those as a wheat-sheep farmer at Coonalpyn in South Australia. My father is a fourth generation farmer. His greatgrandfather migrated from Germany with the Lutheran migrations of 1853 and settled in the Barossa Valley before moving on to the farmland of Horsham, Victoria, where my father began his life and his career as a farmer.

EXECUTIVE SUMMARY The Grain and Graze 2 program (2010-2014), supported by the Grains Research and Development Corporation and “Caring for our Country”, has a chief aim to benefit the profitability and natural resource outcomes of mixed crop-livestock farmers across Australia, using a regionally-based and nationally-coordinated approach. In order to justify investment in R, D and E activities a structured and quantifiable approach was developed to assist with program planning.

1. ABSTRACT This paper presents findings from a series of personal interviews undertaken with eleven irrigators from the Loxton district of South Australia as part of a larger study to identify farmers' options for adaptation to climate-related changes. Before they are able to adapt to climate change, farmers need to understand what climate-related risks exist, and then be aware of their adaptation options.

Executive Summary Farmers are being asked to respond to a number of economic, environmental and social changes simultaneously. Yet too little is understood about the factors that shape farmer's decisionmaking processes and their farming practices. Policy instruments that seek to make farms more productive or more environmentally sustainable typically seek to change farmer behaviour by appealing only, or primarily, to their economic well-being.

Abstract A wealth of evidence exists about the adoption of new practices and technologies in agriculture but there does not appear to have been any attempt to simplify this vast body of research knowledge into a model to make quantitative predictions across a broad range of contexts. This is despite increasing demand from research, development and extension agencies for estimates of likely extent of adoption and the likely timeframes for project impacts.

We investigated ant species richness, interspecific behavioral interactions, and community composition in adjacent forested and open habitat plots in two forest types of the northeastern United States: 1) the more common hemlock-White Pine forest studied at Harvard Forest Long Term Ecological Research Station in central Massachusetts, and 2) the rare Pitch Pine barrens of Myles Standish State Forest in southeastern Massachusetts, which also provide habitat for multiple rare and endangered species. Overall, we found that species richness, behavioral interactions, and ecological traits vary between forested and adjacent open habitat plots. The number of species is five times higher per plot in the hemlock-White Pine open habitat (compared to forest habitat), but this pattern (i.e., higher species richness in open vs. forested plots) is not observed in the Pitch Pine barren site. Non-metric multidimensional scaling analyses suggest that community composition is significantly different between forest and open plots at both sites. However, community composition in open plots at both sites did not significantly differ from each other. We show that behaviorally dominant and submissive species mostly occur in open plots while neutrally interacting species are more restricted to forested plots, suggesting that interspecific competitive dynamics may be contributing to the community assembly patterns observed in open habitats. Our findings suggest that conservation and management for both open and