Some aspects of tree-grass dynamics in Queensland's grazing lands

This review examines the interactions between grasses and trees that are relevant to Queensland's grazing lands. Soils and climate determine the potential amount of woody vegetation within an area and clearing, fire and grazing management can modify that potential. In general, the presence of non-leguminous trees reduces the potential grass production beneath their canopy and within woodland patches. Some non-native leguminous trees (e.g. Indian siris, Albizia lebbeck) enhance production of grasses beneath their canopies, whereas the widespread native leguminous trees, mulga (Acacia aneura) and brigalow (A. harpophylla) have not been reported to enhance grass production in the same way. At the patch scale, pasture production beneath woodlands with moderate to high tree basal areas is generally less than in open patches under the same soil and climatic conditions. At a landscape level, tree density, rainfall amount and distribution, and soil type modify pasture production within forest/woodland/shrubland systems. Grasses can reduce tree seedling survival but have little impact on mature woody plants, apart from providing fuel to carry a fire. Modelling studies have been used to examine some aspects of tree-grass production. Firstly, the relationship between grass production and an increasing amount of trees can vary from linear decrease, to exponential decrease to initial stimulation followed by a decrease, depending solely on the relative strengths of stimulatory and competitive effects of trees on grasses. Secondly, simulated pasture production within woodlands shows that the pasture production may be up to 50% higher in paddocks that have high variability in the distribution of those trees compared with areas where trees are uniformly distributed. This is due to the non-linear (negative exponential) relationship between pasture production and tree density that is commonly observed within Queensland. Lastly, simulation studies show that total aboveground production (trees and pasture) of mulga woodland increases as the number of trees per hectare increases. The pasture production response to tree clearing or tree planting depends on tree species, rainfall, soil type, climatic history and post-clearing management including fire and grazing, and will change with time since clearing. The greatest relative increase in pasture production following the removal of woody vegetation occurs: when the initial tree basal area is highest; where rainfall is evenly distributed though the year and on fertile soils with a low water holding capacity

Development of design allowable data for Celion 6000/LARC-160, graphite/polyimide composite laminates

A design allowables test program was conducted on Celion 6000/LARC-160 graphite polyimide composite to establish material performance over a 116 K (-250 F) to 589 K (600 F) temperature range. Tension, compression, in-plane shear and short beam shear properties were determined for uniaxial, quasi-isotropic and + or - 45 deg laminates. Effects of thermal aging and moisture saturation on mechanical properties were also evaluated. Celion 6000/LARC-160 graphite/polyimide can be considered an acceptable material system for structural applications to 589 K (600 F)

Investigating the impact of removing rabbit harbour on animal and vegetation dynamics Cottonvale Project Report 2007-2013

The field study reported here documented differences between sites that were either side of the Darling Downs Moreton Rabbit Board fence: one side had a long history of rabbit exclusion with few rabbits present whereas the other side had higher rabbit numbers over time. There were marked differences in the flora and fauna on either side of the fence, particularly rabbit abundance and pasture biomass. This difference reflected the long period of separation of the two areas by the DDMRB fence with differences in rabbit abundance as well as possible differences in general grazing management. The control of rabbit numbers on the infested side of the fence did not improve pasture condition to a state similar to that in the rabbit free area during the relatively short period of this study. Recent reviews and simulation studies of the pasture response to changes in grazing management (including changing in grazing pressure) have shown that pastures may takes many years to respond to even quite large reductions in grazing pressure (Hunt et al. 2014, Scanlan et al. 2014). Any positive impact of reduced rabbit density on the infested side will require a much longer time frame for any measureable improvement could be recorded and will depend on the general grazing management of the area. Small sample size precluded conclusively comparing rabbit survival on either side of the fence. This needs further investigation, particularly the effects on rabbit survival of those harbouring above ground compared with those living in warren systems. Similarly, reproductive output and recruitment appeared better where warrens were available, but this needs further testing in this environment with more data before more definitive conclusions can be made

Unexpected evolutionary proximity of eukaryotic and cyanobacterial enzymes responsible for biosynthesis of retinoic acid and its oxidation

Biosynthesis of retinoic acid from retinaldehyde (retinal) is catalysed by an aldehyde dehydrogenase (ALDH) and its oxidation by cytochrome P450 enzymes (CYPs). Herein we show by phylogenetic analysis that the ALDHs and CYPs in the retinoic acid pathway in animals are much closer in evolutionary terms to cyanobacterial orthologs than would be expected from the standard models of evolution

Chips Of The Old Block : Ballad

https://digitalcommons.library.umaine.edu/mmb-vp/3090/thumbnail.jp

Pasture Composition Influences Soil Erosion in Eucalyptus woodlands of Northern Queensland

Runoff and soil loss in grazed Eucalyptus woodlands of north Queensland were monitored over a 5-year period. As ground cover increased, runoff and soil loss decreased. When cover exceeded 50%, runoff and erosion were small. Ground cover was a function of standing dry mailer which decreased as tree cover and stocking rate increased and differed between pasture types. Simulated soil losses from these woodlands was \u3c10-2800 kg/ha/year, and runoff was 5- 16 mm/year. Annual soil losses (simulated) were proportional to the square of the annual simulated runoff

Teaching As We Are Taught: A Model for Whole Language Inservice

We acknowledge the truth of this criticism. As teacher educators we are well aware that how we teach is not always compatible with what we teach. While this reality is often a concern to us in our work with preservice teachers, it struck us as especially important because we had been asked to teach an off-campus, whole language inservice course. Teaching whole language demanded that our methodology complement the course content. Because of this, we organized the class in concert with characteristics of a whole language environment: time, ownership, process, conferences, and resources (Butler and Turbill, 1984). Implementing these elements provided many challenges both for the students in the course and for us. The story that follows is our view of how these characteristics affected our students\u27 experiences and our own

Modified Occupational Questionnaire (MOQ)

The Modified Occupational Questionnaire is a yesterday time diary / time use assessment designed to collect information about meaningful use of time. It can be used for research and clinical applications

Production V Conservation: A Policy Dilemma in the Tree Clearing Debate in Queensland, Australia

A process for developing policy for tree clearing that meets the competing goals of conservation and production has been followed. There were two levels at which policy was developed. An overall Statewide policy outlined general targets to meet commitments of the Queensland Government. Local guidelines were developed by a large number of groups containing representatives of government and interested conservation movement and industry representatives. The policy and the local guidelines are an important part of the process used to assess applications for permits to clear woody vegetation

Sustainable management for rangelands in a variable climate: evidence and insights from northern Australia

Inter-annual rainfall variability is a major challenge to sustainable and productive grazing management on rangelands. In Australia, rainfall variability is particularly pronounced and failure to manage appropriately leads to major economic loss and environmental degradation. Recommended strategies to manage sustainably include stocking at long-term carrying capacity (LTCC) or varying stock numbers with forage availability. These strategies are conceptually simple but difficult to implement, given the scale and spatial heterogeneity of grazing properties and the uncertainty of the climate. This paper presents learnings and insights from northern Australia gained from research and modelling on managing for rainfall variability. A method to objectively estimate LTCC in large, heterogeneous paddocks is discussed, and guidelines and tools to tactically adjust stocking rates are presented. The possible use of seasonal climate forecasts (SCF) in management is also considered. Results from a 13-year grazing trial in Queensland show that constant stocking at LTCC was far more profitable and largely maintained land condition compared with heavy stocking (HSR). Variable stocking (VAR) with or without the use of SCF was marginally more profitable, but income variability was greater and land condition poorer than constant stocking at LTCC. Two commercial scale trials in the Northern Territory with breeder cows highlighted the practical difficulties of variable stocking and provided evidence that heavier pasture utilisation rates depress reproductive performance. Simulation modelling across a range of regions in northern Australia also showed a decline in resource condition and profitability under heavy stocking rates. Modelling further suggested that the relative value of variable v. constant stocking depends on stocking rate and land condition. Importantly, variable stocking may possibly allow slightly higher stocking rates without pasture degradation. Enterprise-level simulations run for breeder herds nevertheless show that poor economic performance can occur under constant stocking and even under variable stocking in some circumstances. Modelling and research results both suggest that a form of constrained flexible stocking should be applied to manage for climate variability. Active adaptive management and research will be required as future climate changes make managing for rainfall variability increasingly challenging