Predicting sheetwash and rill erosion over the Australian continent

Soil erosion is a major environmental issue in Australia. It reduces land productivity and has off-site effects of decreased water quality. Broad-scale spatially distributed soil erosion estimation is essential for prioritising erosion control programs and as a component of broader assessments of natural resource condition. This paper describes spatial modelling methods and results that predict sheetwash and rill erosion over the Australian continent using the revised universal soil loss equation (RUSLE) and spatial data layers for each of the contributing environmental factors. The RUSLE has been used before in this way but here we advance the quality of estimation. We use time series of remote sensing imagery and daily rainfall to incorporate the effects of seasonally varying cover and rainfall intensity, and use new digital maps of soil and terrain properties. The results are compared with a compilation of Australian erosion plot data, revealing an acceptable consistency between predictions and observations. The modelling results show that: (1) the northern part of Australia has greater erosion potential than the south; (2) erosion potential differs significantly between summer and winter; (3) the average erosion rate is 4.1 t/ha. year over the continent and about 2.9 x 10(9) tonnes of soil is moved annually which represents 3.9% of global soil erosion from 5% of world land area; and (4) the erosion rate has increased from 4 to 33 times on average for agricultural lands compared with most natural vegetated lands.

Mental health and socio-economic variations in Australian suicide

This paper investigates the relationship between suicide rates and prevalence of mental disorder and suicide attempts, across socio-economic status (SES) groups based on area of residence. Australian suicide data (1996-1998) were analysed in conjunction with area-based prevalences of mental disorder derived from the National Survey of Mental Health and Well-Being (1997). Poisson regression models of suicide risk included age, quintile of area-based SES, urban-rural residence, and country of birth (COB), with males and females analysed separately. Analysis focussed on the association between suicide and prevalences of (ICD-10) affective disorders, anxiety disorders, substance use disorders and suicide attempts by SES group. Prevalences of other psychiatric symptomatology, substance use problems, health service utilisation, stressful life-events and personality were also investigated. Significant increasing gradients were evident from high to low SES groups for prevalences of affective disorders, anxiety disorders (females only), and substance use disorders (males only); sub-threshold drug and alcohol problems and depression; and suicide attempts and suicide (males only). Prevalences of mental disorder, other sub-threshold mental health items and suicide attempts were significantly associated with suicide, but in most cases associations were reduced in magnitude and became statistically non-significant after adjustment for COB, urban-rural residence, and SES. For male suicide the relative risk (RR) in the lowest SES group compared to the highest was 1.40 (95% CI 1.29-1.52, p < 0.001) for all ages, and 1.46 (95% CI 1.27-1.67, p < 0.001) for male youth (20-34 years). This relationship was not substantially modified in males when regression models included prevalences of affective disorders, and other selected mental health variables and demographic factors. From a population perspective, SES remained significantly associated with suicide after controlling for the prevalence of mental disorders and other psychiatric symptomatology. Mental conditions and previous suicidal behaviour may play an intermediary role between SES and suicide, but this study suggests that an independent relationship between suicide and SES also exists. (c) 2005 Elsevier Ltd. All rights reserved.

Gender, marital status, farm size and other factors influencing the extent of cash cropping in Kenya: A case study

This article examines the effects of commercialisation of agriculture on land use and work patterns by means of a case study in the Nyeri district in Kenya. The study uses cross sectional data collected from small-scale farmers in this district. We find that good quality land is allocated to non-food cash crops, which may lead to a reduction in non-cash food crops and expose some households to greater risks of possible famine. Also the proportion of land allocated to food crops declines as the farm size increases while the proportion of land allocated to non-food cash crops rises as the size of farm increases. Cash crops are also not bringing in as much revenue commensurate with the amount of land allocated to them. With growing commercialisation, women still work more hours than men. They not only work on non-cash food crops but also on cash crops including non-food cash crops. Evidence indicates that women living with husbands work longer hours than those married but living alone, and also longer than the unmarried women. Married women seem to lose their decision-making ability with growth of commercialisation, as husbands make most decisions to do with cash crops. Furthermore husbands appropriate family cash income. Husbands are less likely to use such income for the welfare of the family compared to wives due to different expenditure patterns. Married women in Kenya also have little or no power to change the way land is allocated between food and non-food cash crops. Due to deteriorating terms of trade for non-food cash crops, men have started cultivation of food cash crops with the potential of crowding out women. It is found that both the area of non-cash crops tends to rise with farm size but also the proportion of the farm area cash cropped rises in Central Kenya.

Marital status, farm size and other influences on the extent of cash cropping in Kenya: A household case study

This article examines the effects of marital status, farm size and other factors on the extent of cash cropping (and allocation of land use) by means of a case study in the Nyeri district in Kenya. It was found that married women are involved in the production of a relatively greater amount of output of cash crops than unmarried women since husbands prefer to have more land under cash crops than food crops. Farmers with better quality land allocate a high proportion of it to non-food cash crops, which may expose some households to greater risks of possible famine. The proportion of land allocated to food crops declines as the farm size increases while the proportion of land allocated to non-food cash crops rises as the size of farm increases. Age is also inversely associated with subsistence. Education, though inversely associated with subsistence farming does not appear to be statistically very significant as an influence on the composition of land use and composition of farm output. With growing commercialisation, married women work more hours than unmarried ones, working not only on non-cash food crops but also on non-food cash crops. Married women seem to lose their decision-making ability with growth of agricultural commercialisation, as husbands make most decisions to do with cash crops. Married women in Kenya also have little or no power to change the way land is allocated between food and non-food cash crops.

Resource entitlements of indigenous minorities, their poverty and conservation of nature: Status of Australian Aborigines, comparisons with India's tribals, theory and changing policies globally

Considers the relevance of A.K. Sen’s theory of entitlements to the situation facing indigenous tribal people, its relationship to institutionalism, and to theories of property rights. Changing world views about the resource entitlements that should be given to local communities are outlined concentrating on the views expressed by the World Conservation Union (IUCN). These changing views have relevance for the resource entitlements of indigenous tribal communities and are reflected in differences in the policy approaches inherent in the Convention on International Trade in Endangered Species (CITES) and the more recent Convention on Biological Diversity. The latter embodies the view that provision of greater resource entitlements to local communities can provide economic incentives for nature conservation. There is a case for Indigenous Australians to be given greater rights to market the natural produce from their lands. Despite progress with land rights, they are not entitled to market much of the natural produce from their land. The socioeconomic status of Australian Aborigines is outlined. Their standard of living and their life expectancy are low by world standards and in comparison to other Australians. This is partly a result of historical events that have restricted their rights. These events are outlined briefly. Views differ about the appropriate development paths for Indigenous Australians and these are assessed. Concern on environmental and economic grounds is expressed about the view that the economic development of Australian Aboriginal communities would be accelerated by replacing their communal land titles by private land titles and encouraging Western-style agriculture and commercial development of their lands. Some comparisons are also made with the situation of India’s Tribals.

The filter system for tertiary treatment of sewage effluent by land application - its performance in a subtropical environment

FILTER is an innovative, CSIRO developed system for treating effluent using high rate land application and subsequent effluent recapture via a closely spaced, subsurface drainage network. We report on the summer performance of a FILTER system established in a subtropical environment on a relatively impermeable swelling clay soil underlain by a deep regional water table. Using secondary treated sewage effluent, the FILTER system produced effluent of tertiary nutrient standards (less than or equal to5 mg/L TN; less than or equal to1 mg/L TP), with salinity levels suitable for subsequent irrigation reuse (EC less than or equal to2.5 dS/m). Removal of faecal coliforms was considerably less effective. The hydraulic loading rate achieved was about two and a half times larger than conventional irrigation demand, but this was associated with high deep percolation losses (e 3 mm/day). Comparisons are made with the original FILTER system developed and tested by Jayawardane et al. in temperate Australia. Suggestions are made for modifications to, and further testing of FILTER in a subtropical environment.

The natural history of Hendra and Nipah viruses

Pteropid bats (flying foxes), species of which are the probable natural host of both Hendra and Nipah viruses, occur in overlapping populations from India to Australia. Ecological changes associated with land use and with animal husbandry practices appear most likely to be associated with the emergence of these two agents. (C) 2001 Editions scientifiques et medicales Elsevier SAS.

A multi-purpose rainfall simulator for field infiltration and erosion studies

This paper describes a rainfall simulator developed for field and laboratory studies that gives great flexibility in plot size covered, that is highly portable and able to be used on steep slopes, and that is economical in its water use. The simulator uses Veejet 80100 nozzles mounted on a manifold, with the nozzles controlled to sweep to and from across a plot width of 1.5 m. Effective rainfall intensity is controlled by the frequency with which the nozzles sweep. Spatial uniformity of rainfall on the plots is high, with coefficients of variation (CV) on the body of the plot being 8-10%. Use of the simulator for erosion and infiltration measurements is discussed.

Nutrient dynamics in Queensland savannas: Implications for the sustainability of land clearing for pasture production

Eucalyptus savannas on low nutrient soils are being extensively cleared in Queensland. In this paper we provide background information relevant to understanding nutrient (particularly nitrogen) dynamics in sub/tropical savanna, and review the available evidence relevant to understanding the potential impact of clearing Eucalyptus savanna on nutrient relations. The limited evidence presently available can be used to argue for the extreme positions that: (i) woody vegetation competes with grasses Cor resources. and tree/shrub clearing improves pasture production, (ii) woody vegetation benefits pasture production. At present, the lack of fundamental knowledge about Australian savanna nutrient relations makes accurate predictions about medium- and long-term effects of clearing on nutrient relations in low nutrient savannas difficult. The future of cleared savannas will differ if herbaceous species maintain all functions that woody vegetation has previously held, or if woody species have functions distinct from those of herbaceous vegetation. Research suggests that savanna soils are susceptible to nitrate leaching, and that trees improve the nutrient status of savanna soils in some situations. The nitrogen capital of cleared savanna is at risk if mobile ions are not captured efficiently by the vegetation. and nitrogen input via N-2 fixation from vegetation and microbiotic crusts is reduced. In order to predict clearing effects on savanna nutrient relations, research should be directed to answering (i) how open or closed nutrient cycles are in natural and cleared savanna, (ii) which functions are performed by savanna constituents such as woody and herbaceous vegetation, native and exotic plant species. termites, and microbiotic 7 crusts in relation to nutrient cycles. In the absence of detailed knowledge about savanna functioning, clearing carries the risk of promoting continuous nutrient depiction.

Urbanization, population transition, and growth

This paper analyzes a dual economy consisting of urban market areas and less developed rural areas with or without local markets. Urban areas have better opportunities for earnings and education than rural areas. Rural families choose whether to move to urban areas at costs that differ from location to location. As per capita output grows relative to the moving cost, urbanization proceeds, leading to lower fertility, more investments in human and physical capital per child relative to output per worker, and faster economic growth. These impacts are stronger if rural areas have no access to markets.