Inventories and significance of the genetic resources of an African mahogany species (Khaya senegalensis (Desr.) A. Juss.) assembled and further developed in Australia.

The forest tree species Khaya senegalensis (Desr.) A. Juss. occurs in a belt across 20 African countries from Senegal-Guinea to Sudan-Uganda where it is a highly important resource. However, it is listed as Vulnerable (IUCN 2015-3). Since introduction in northern Australia around 1959, the species has been planted widely, yielding high-value products. The total area of plantations of the species in Australia exceeds 15,000 ha, mostly planted in the Northern Territory since 2006, and includes substantial areas across 60-70 woodlots and industrial plantations established in north-eastern Queensland since the early-1990s and during 2005-2007 respectively. Collaborative conservation and tree improvement by governments began in the Northern Territory and Queensland in 2001 based on provenance and other trials of the 1960s-1970s. This work has developed a broad base of germplasm in clonal seed orchards, hedge gardens and trials (clone and progeny). Several of the trials were established collaboratively on private land. Since the mid-2000s, commercial growers have introduced large numbers of provenance-bulk and individual-tree seedlots to establish industrial plantations and trials, several of the latter in collaboration with the Queensland Government. Provenance bulks (>140) and families (>400) from 17 African countries are established in Australia, considered the largest genetic base of the species in a single country outside Africa. Recently the annual rate of industrial planting of the species in Australia has declined, and R&D has been suspended by governments and reduced by the private sector. However, new commercial plantings in the Northern Territory and Queensland are proposed. In domesticating a species, the strategic importance of a broad genetic base is well known. The wide range of first- and advanced-generation germplasm of the species established in northern Australia and documented in this paper provides a sound basis for further domestication and industrial plantation and woodlot expansion, when investment conditions are favourabl

Measurement of the distributed-Brillouin-gain spectrum in optical fibers by using a single laser source

Brillouin-gain-spectrum measurement along an optical fiber has recently gained a lot of interest owing to its potential for strain monitoring in installed cables and for distributed temperature sensing. We present a method that has the following advantages: (1) few optical elements are required, (2) a single laser source is used, and (3) a single fiber end is accessed. A schematic diagram of the experimental setup is shown. The operation of this setup relies on two features. First, the pump and probe signals are pulses that both propagate back and forth through the fiber by using a reflection at the far end. The second and more important feature is the use of a guided-wave intensity modulator for pulsing the laser light to form the pump signal and for generating the probe signa

Corymbia species and hybrids: a solution to Queensland hardwood plantations

Hardwood plantations are relatively new in northern Australia. Of the species available, the spotted gums are the most important commercial hardwood plantation taxon for high quality timber in the humid and sub-humid zones of Queensland and northern New South Wales. The domestication and genetic improvement of the spotted gums (Corymbia citriodora subsp. citriodora (CCC), C. citriodora subsp. variegata (CCV) and C. henryi (CH) however only commenced in Queensland in 1997. Since then seed orchards and progeny trials have been established for all three species. One major failing of these species is all provenances are somewhat susceptible (Dickinson et al 2004) to the fungal disease, Ramularia Shoot Blight caused by Quambalaria pitereka (Simpson 2000). In amenity plantings and wind breaks of C. torelliana, hybrids with the spotted gum species were noticed that had great vigour, good form and resistance to Ramularia Shoot Blight. As a consequence a breeding program has been initiated in Queensland, to hybridise the spotted gum species with C. torelliana (CT). This paper reports on the genetic base of each species and presents preliminary result on the performance of these species and hybrids in trials

Techniques for bandwidth measurements of optical guided-wave modulators

High-speed optical guided-wave switches and modulators are promising components for present and future applications in lightwave communication and measurement systems, or more generally for optical signal processing purposes. Integrated electro-optic modulators with bandwidth extending over a few gigahertz and low drive voltages are now commercially available. Due to their potential applications, bandwidth characterization is an important feature of the metrology of these devices and is often limited by the finite response time of the detection system. In this paper the bandwidth limitations of the electro-optic modulators are discussed and the authors report two techniques for bandwidth measurements, which have the significant advantage of using only low-frequency detection. This was made possible by processing the lightwave directly, using either a sampling technique with a narrow optical pulse as a probe signal or a direct optical spectrum analysis of the modulated signal

Fast measurement of local PMD with high spatial resolution using stimulated Brillouin scattering

Local beat length with a 21.5cm spatial resolution is measured in one second along a single mode fibre using the polarisation dependence of stimulated Brillouin scattering, in a non-destructive and simple way

Simple distributed fiber sensor based on Brillouin gain spectrum analysis

A novel configuration of a distributed fiber sensor by Brillouin gain analysis has been developed for temperature and strain monitoring. It uses a single laser source, and the required light signals are all generated with an electro-optic modulator, resulting in high stability and excellent reliability of the measuring setup. Measurement of the induced strain in a wound fiber is presented as a demonstration of the system performanc