An economic analysis of revegetation for dryland salinity control on the Lower Eyre Peninsula in South Australia

Dryland salinity is a major natural resource management problem imposing large economic and environmental costs in many countries throughout the world. The major cause of dryland salinity is the replacement of perennial native vegetation with annual crops and pastures. This results in greater amounts of water entering a groundwater system, watertable rise and the concentration of naturally occurring salts near the soil surface. Many consider that the best long‐term solution is the re‐establishment of high water use perennial vegetation through production systems such as agroforestry. This paper presents a benefit–cost analysis (BCA) of revegetation to control dryland salinity over a 20‐year period in South Australia. The results of the BCA indicate that market costs are likely to exceed market benefits for broad‐scale revegetation programmes. These results are driven by hydrogeological studies, which indicate that as much as 50 per cent of a ‘problem‐type’ catchment needs to be revegetated to save only 3 per cent of land from being salt affected. The conclusion is that revegetation programmes need to be highly targeted to areas of a catchment with large potential to control salinity, land that has minimal value for other uses and regions with high infrastructure and ecological value. Copyright © 2002 John Wiley & Sons, Ltd.     

Abandonment of traditional terraced landscape: A change detection approach (a case study in Costa Viola,Calabria, Italy)

This paper presents the results of a change‐detection study of the historical agricultural terraced landscape in “Costa Viola” (Calabria, South Italy). During the last century, because of the loss of economic competitiveness, it has undergone progressive abandonment, followed by landscape degradation. Taking into consideration the very steep slopes of Costa Viola and the need to analyse with high precision the historical evolution of the terraced landscape, research methods were implemented coupling advanced geomatic techniques with in situ detailed surveys. Based on historical aerial photographs, orthophotos, and numeric cartography, we analysed the land use/land cover change in the period 1955–2014 using photogrammetric and geoprocessing techniques, focusing particularly on trajectories in agricultural terraces. Area covered by active terraces decreased dramatically between 1955 and 2014, from 813.25 to 118.79 ha (−85.4%). The implemented spatial database was built in a free open‐source software taking into consideration spatial accuracies and completeness. Spatial comparison among land use/land cover maps was carried out using a postclassification comparison technique that can provide complete cross‐tabulation matrices. These data were compared with socio‐economic statistics concerning demography and trends of farms with vineyards. The evolutionary dynamics of the active agricultural terraces were also analysed trough the definition of 6 types of spatio‐temporal patterns recognised in the analysed period. These methods allowed to highlight the ongoing dynamics of abandonment of agricultural terraces in relation to their main causes and effects. Although tailored for the specific case study, they can be applied to many other terraced agricultural landscapes presenting similar characteristics and problems.     

Recognition and characterisation of the aeolian component in soils in the Girilambone Region,north western New South Wales,Australia

Characterisation of aeolian material in the Girilambone Region of New South Wales (600 km NW of Sydney), using particle size analysis, mineralogy, geochemistry and micromorphological analysis, shows that it consists of spheroidal, highly abraded 70 μm quartz grains. Although relatively pure aeolian accessions are found on top of Tertiary leucitite flows, the aeolian material is generally admixed with residual and transported soil to a depth of 0.3 m throughout the region. This study has established a set of criteria for identifying the aeolian contribution to soils in the Girilambone region of north western New South Wales where it is difficult to distinguish. These include: a characteristic particle size of 70 μm of the quartz grains; highly abraded and spherical morphology; presence of thin clay coats on well-rounded grains; and gradational patterns in particle size distribution, mineralogy and geochemistry through the soil profile. These types of soils, with a high content of silt and fine sand, do not readily form aggregates, particularly where they have low organic content. To improve the sustainability of cropping and pastoral activities on these soils, their management should aim to maintain or increase structural stability, for example by addition of organic material. Mineral exploration procedures should avoid the diluting aeolian component by sampling the > 150 μm fraction from surficial soils or material from below 0.3 m.     

Capacity of fatty acid profiles and substrate utilization patterns to describe differences in soil microbial communities associated with increased salinity or alkalinity at three locations in South Australia

 Fatty acid methyl ester (FAME) profiles, together with Biolog substrate utilization patterns, were used in conjunction with measurements of other soil chemical and microbiological properties to describe differences in soil microbial communities induced by increased salinity and alkalinity in grass/legume pastures at three sites in SE South Australia. Total ester-linked FAMEs (EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs), were also compared for their ability to detect differences between the soil microbial communities. The level of salinity and alkalinity in affected areas of the pastures showed seasonal variation, being greater in summer than in winter. At the time of sampling for the chemical and microbiological measurements (winter) only the affected soil at site 1 was significantly saline. The affected soils at all three sites had lower organic C and total N concentrations than the corresponding non-affected soils. At site 1 microbial biomass, CO₂-C respiration and the rate of cellulose decomposition was also lower in the affected soil compared to the non-affected soil. Biomarker fatty acids present in both the EL- and PL-FAME profiles indicated a lower ratio of fungal to bacterial fatty acids in the saline affected soil at site 1. Analysis of Biolog substrate utilization patterns indicated that the bacterial community in the affected soil at site 1 utilized fewer carbon substrates and had lower functional diversity than the corresponding community in the non-affected soil. In contrast, increased alkalinity, of major importance at sites 2 and 3, had no effect on microbial biomass, the rate of cellulose decomposition or functional diversity but was associated with significant differences in the relative amounts of several fatty acids in the PL-FAME profiles indicative of a shift towards a bacterial dominated community. Despite differences in the number and relative amounts of fatty acids detected, principal component analysis of the EL- and PL-FAME profiles were equally capable of separating the affected and non-affected soils at all three sites. Redundancy analysis of the FAME data showed that organic C, microbial biomass, electrical conductivity and bicarbonate-extractable P were significantly correlated with variation in the EL-FAME profiles, whereas pH, electrical conductivity, NH₄-N, CO₂-C respiration and the microbial quotient were significantly correlated with variation in the PL-FAME profiles. Redundancy analysis of the Biolog data indicated that cation exchange capacity and bicarbonate-extractable K were significantly correlated with the variation in Biolog substrate utilization patterns. Received: 8 March 2000     

Distribution patterns and conservation status of four bustard species (Family Otididae) in a montane grassland of South Africa

The abundance and distribution patterns of four threatened species of bustards (Eupodotis caerulescens, E. barrowii, E. melanogaster and Neotis denhami) in 3200 km² of montane grasslands in the Wakkerstroom district, South Africa were characterised and related to altitude, topography and land use. During 2001 and 2002, 61 car-driven transects (544 km in total) were carried out to count bustards at the onset of the breeding season. The spatial patterns of land use and bustard occurrence along transects were characterised using geostatistics. The influence of explanatory variables on each species occurrence was assessed using logistic regression. There were inter-specific differences in distribution, with E. caerulescens occurring at higher altitudes than the other species. These differences were partly explained by different habitat preferences. Population estimates for the study area were ≈1400 E. caerulescens, 150 E. barrowii and 30 male E. melanogaster. The main threats for the bustard populations in the region are commercial afforestations (mainly for N. denhami) and agricultural intensification (mainly for E. barrowii and E. melanogaster). The results of this study can be used as a baseline situation against which future monitoring could be compared. The used method proved to be effective for characterising occurrence patterns and censusing bustard populations in relatively large areas, as well as describing large-scale habitat patterns.     

Response of travelling bottlenose dolphins (Tursiops aduncus) to experimental approaches by a powerboat in Jervis Bay, New South Wales, Australia

Powerboats are potentially a significant source of disturbance to coastal cetaceans. Information is scarce, however, on the nature of interactions between powerboats and dolphins, particularly when both surface and acoustic behaviour are combined. The surface behaviour and acoustic response of travelling dolphins to approaches by a powerboat were assessed by a series of experimental trials between November 2001 and November 2003 in Jervis Bay, New South Wales, Australia. Dolphin behaviour was monitored continuously from an independent research boat before, during and after a powerboat approached (n = 12). Treatments were interspersed with control observations (n = 12). Changes in surface behaviour indicated differences between the treatment and control periods (z = 2.24, p = 0.025), with dolphins tending to alter their surface behaviour when exposed to the powerboat approach. Analysis also revealed a change in the direction of travel by dolphin groups when approached (z = 3.22, p = 0.001). Changes in surface behaviour occurred at vessel approach distances outside the minimum approach distance of 30 m for recreational and commercial vessels, as proposed by the New South Wales National Parks and Wildlife Service. In contrast, there were no changes in dolphin whistle rates (F_3,12 = 0.74, p = 0.54) or the duration of echolocation click bouts (F_3,12 = 0.76, p = 0.59) when approached. These findings indicate that powerboats do affect the surface behaviour and direction of travelling inshore bottlenose dolphins in Jervis Bay; however it appears that this impact is not reflected in their acoustic behaviour.     

Assessing the impacts of roads in peri-urban reserves: Road-based fatalities and road usage by wildlife in the Royal National Park, New South Wales, Australia

For protected reserves set aside for conservation, the impact of roads and traffic on wildlife can be severe, particularly for those in the peri-urban environment. Often reserves possess many sealed roads that have regular traffic from tourists and local residents. As managerial bodies struggle to control the wide variety of threats to the fauna within these reserves, the loss of life on roads only compounds the precarious nature of wildlife survival in these disturbed environments. As a first step to addressing this concern in Australia, this study quantifies the fatalities of wildlife killed on roads within the Royal National Park in New South Wales, and estimates those wildlife species using roadside habitat in order to identify species susceptible to collisions. Modelling of fatality data indicated that mammals were most likely to be killed where forage was abundant on the roadside verge and where there was plenty of protective cover, while birds were most likely to be killed when the height of roadside vegetation was low. A number of collision hotspots were identified along the surveyed road that should be the target of mitigation efforts. The average speed of vehicles travelling within the park peaked at night. This is of particular concern as activity by Australian mammals tends to be greatest at night. The findings indicate that roads in peri-urban reserves have the potential to alter the movement of animals and impact on their populations through loss of life.     

Urban Waste Management and Potential Agricultural Use in South American Developing Countries: A Case Study of Chimborazo Region (Ecuador)

In South America, a high percentage of urban waste streams are not well managed, implying associated health and environmental risks. In Ecuador, around 2.7 million tons of municipal solid wastes (MSW) are generated annually, with 80 percent located in urban areas. Correct management and hygienic and ecological issues from these increased quantities of waste is the responsibility of municipalities that must provide sewerage, wastewater treatment, and solid waste management, according to the Constitution of the Republic (Art 264). With only seven licensed landfill areas out of thirty-one in total (66 percent mechanized and 34 percent manually sorted), a sustainable waste management model must be developed to reduce environmental hazards and also to obtain new bioproducts such as compost or fertilizers. Agricultural utilization of MSW compost is the most cost-effective management option compared to traditional means such as landfilling or incineration, and this option also enables the recycling of potential plant nutrients. In this work, the problem we addressed was to obtain analytical information about representative MSW samples from different origins and locations within the Chimborazo region in order to establish its potential for composting. In the studied MSW samples (which included sludge from aerobic wastewater treatment plants), high nutrient contents and low concentrations of heavy metals were observed, showing great potential to develop high-quality compost. In addition, improvement of separate collections of food market and/or municipal gardening wastes can provide specific clean waste streams of degradable materials to be managed separately from not separately collected MSW.