Deirdre Dragovich

Combating desertification in Iran over the last 50 years: an overview of changing approaches.

Desertification in Iran was recognized between the 1930s and 1960s. This paper traces Irans attempts to reclaim desertified areas, evaluates the anti-desertification approaches adopted, and identifies continuing challenges. Iran has areas vulnerable to desertification due to extensive areas of drylands and increasing population pressure on land and water resources. Over-grazing of rangelands is a particular problem. Initially desertification was combated mainly at the local level and involved dune stabilization measures, especially the use of oil mulch, re-vegetation and windbreaks. Insufficient technical planning in the early years has led to changed approaches to plant densities and species diversity in plantations, and increased on-going management of existing plantations. Since the late 1980s forage and crop production has increased in areas where runoff control techniques are practiced. The social and economic aspects of anti-desertification programs have assisted in poverty reduction by providing off-season employment in rural areas. In 2004 a national plan to combat desertification was ratified and this placed an emphasis on community participation. Continuing challenges include managing existing desertified areas as well as taking into account potential future problems associated with rapidly depleting groundwater supplies and a predicted reduction in the plant growth period accompanying climate change.

Impact of tourists on carbon dioxide levels at Jenolan Caves, Australia: an examination of microclimatic constraints on tourist cave management.

Carbon dioxide levels and visitor numbers were monitored at Jenolan Caves in Australia. Concentrations of carbon dioxide increased with the presence of tourists. In apparently well-ventilated sections of the cave system, carbon dioxide rose from pre-tour levels of 400 ppm to a daily maximum of 1000 ppm: in a less well ventilated cave, levels increased from 400 ppm to 1500 ppm. Carbon dioxide returned to pre-tour levels (±100 ppm) overnight when no tours were conducted. Peak daily carbon dioxide concentrations in two monitored caves were closely related to visitor numbers (r = 0.86 and 0.94). The highest carbon dioxide level recorded was 1500 ppm. below the limestone corrosion threshold of 2400 ppm and well below the human safety limit of 5000 ppm. Carbon dioxide concentrations in monitored caves do not provide a constraint on management options at current levels of show cave visitation.

Using GIS-based continuous methods for assessing agricultural land-use potential in sloping areas

The dynamic nature of land qualities both in space and in time suggests that, whatever the stages of the development of an area, it is always crucial to assess land qualities in terms of their potential and suitability for specific kinds of land use on a sustainable basis. In this paper we demonstrate an integrated method of biophysical land-suitability assessment, which combines two basic land-evaluation principles: allowing trade-offs among evaluation criteria, and a limiting condition approach. Decision criteria consist mainly of biophysical parameters, based on internal and external groups of land properties. Internal variables include various physical and chemical characteristics of soils, whereas external variables are those of topographic attributes. A fuzzy set methodology was employed to calculate values of a membership function, MF (0 ⩽ MF ⩽ 1.0), of each land variable. These fuzzy membership values were then combined to produce land-suitability indices, LSIs (0 ⩽ LSIs ⩽ 1.0), which can be used to assess the potential of land for a nominated land-use type. The analysis procedure implements a convex combination, which permits trade-offs between criteria of the same group, and a multiplicative function, which takes no account of compensation between groups (internal and external variables). A limiting condition approach is also incorporated in this system to resolve shortcomings found when using a convex combination technique alone. The results show that LSIs are consistent with categorical classes generated from applying the well-established method based on the Food and Agriculture Organisation framework for land evaluation. However, the LSIs, as derived from a cell-by-cell operation, produce more detailed subdivisions of land in terms of their potential for a given purpose. The main advantages of using this model include: (1) it minimises subjectivity in the evaluation procedure; (2) it takes into account the combined effects of the factors considered, while preserving information on biophysical constraints for a given purpose; and (3) it is amenable to further computer-based applications, especially for use in geographical information systems.

Interpretation of Rock Varnish in Australia: case studies from the arid zone

SUMMARY Rock varnish has a long history of study in Australia. Although Australian varnishes have biological, chemical and morphological similarities to varnishes in other continents, rock varnishes in arid Australia tend to be less stable than in other drylands. Still, with careful sampling, radiocarbon and cation‐ratio dating of rock varnish has been used to constrain the age of Henbury Meteor Craters, Northern Territory, and rock engravings in South Australia and New South Wales, as well as to assess the geomorphic surface stability of Ayers Rock, Northern Territory, and the slopes of Pepuarta Bluff in the Olary Province of South Australia.

Marble weathering in an industrial environment, eastern Australia

Qualitative evidence from monuments and buildings in industrialized countries indicates that rates of stone deterioration rise in the presence of urban and industrial pollutants. Measurements presented here on surface reduction of marble tombstones show that mean weathering rates have increased over the period 1885 to 1955. Weathering rates were lower before the establishment of sulfur dioxide-emitting plants. Marble weathering involved solution etching along grain boundaries and within individual grains, and proceeded by surface roughening and dislodgement of grains with little apparent accumulation of gypsum. Absolute surface reduction of marble was less than that recorded in industrial environments in Europe and North America.

Measuring stone weathering in cities: Surface reduction on marble monuments

The purpose of this study was to establish whether measurements of stone weathering recorded by different observers could be aggregated into a single data base for evaluating pollution effects on calcareous building stone. Apparent differences in recorded weathering rates on marble tombstones were here found to be partly a result of lettering size measured, measuring devices used, and individual observers.

Forest management policies and oil wealth in Iran over the last century: A review

Deforestation is a problem in many developing countries. In Iran, the introduction of forestry management policies in the twentieth century coincided with a period of severe depletion in forest cover. This over‐utilization resulted from tree cutting for road construction, the establishment of sawmills and match factories, and in particular, the growing demand for charcoal and fuelwood for a rapidly increasing population. The formal forestry management policies initiated in the early 1900s were inadequately enforced, leading to continuing loss of forests through largely unregulated exploitation. Despite the discovery of oil in 1908 and natural gas in 1937, gas pipeline construction for domestic consumption was slow, kerosene was only gradually substituted for wood, charcoal consumption only fell steeply after 1960, and the established forest cover decreased sharply between 1970 and 1990. In 1991, the first of the post‐Revolution national Five Year Development Plans commenced and environmental protection was allocated significant budgetary support. The Five Year Plans implemented substantial reductions in livestock grazing in forests and encouraged reforestation, which partly offset the continuing forest removal. Using estimates based on fuelwood consumption in Brazil and USA, the forested area in Iran in 1850 would have disappeared by 2000 without the Government intervention which provided widespread access to fossil fuels. This energy‐source shift decreased local pressure on the dwindling forest resources and was reinforced by Government policies to conserve and extend forests.

Vegetation morphologic and aerodynamic characteristics reduce aeolian erosion

AbsractVegetation cover is crucial to controlling aeolian erosion but highly efficient vegetation is critical. How this efficiency is influenced by vegetation response to airflow is not clear. Here we evaluate the responses of Cosmos bipinnatus and Ligustrum lucidum Ait to a range of wind speeds in a wind tunnel. For both species, we calculate shelter effect and sand flux. We show that plant effectiveness in reducing wind speed and sediment transport is linked to their aerodynamic response to airflow which results from their morphology. We demonstrate that in low-density cover the flow-response and resistance of individuals is most critical in the optimal effectiveness of a canopy. Our wind tunnel experiment suggests that vegetation morphology and structure must be priority parameters in facilitating aeolian erosion control.

Environmental assessment of erosion following prescribed burning in the Mount Lofty Ranges, Australia

Erosion following fire has the potential to affect water quality, alter soil profiles and detrimentally affect human infrastructure. There is a clear need for environmental assessments to have regard for erosion concerns from prescribed burning. This study focussed on 10 prescribed burns conducted in the Southern Mount Lofty Ranges. Generalised additive modelling was used to determine the main significant environmental variables influencing the presence of sediment movement at 505 field-assessed sites. Sediment movement after the 10 prescribed burns was minor. Fire severity was a highly significant environmental determinant for the presence of sediment movement after prescribed burning. To predict erosion concerns, a suite of environmental variables is more reliable than focusing solely on slope steepness, as occurred before this study. These results indicate that erosion assessments need to consider a range of environmental variables to assess potential erosion and that land managers and scientists need to incorporate spatial sampling designs into erosion assessments.

Using Remote Sensing and GIS for Assessing and Mapping Land Use and Land Qualities in the Hawkesbury‐Nepean River Catchment, Australia

Abstract A methodological framework of land resource assessment, based on integrated biophysical information of the land in GIS and remote sensing is presented. The model developed uses two primary sub‐models (modules): remote sensing based land use classification, and land suitability assessment. The first module uses Landsat 7 ETM+ images to produce a land use/land cover map of the study area. A site‐specific framework was developed for use in thematic information extraction involving the use of visual analysis, spectral‐based (automated) procedures, and ancillary information. The second sub‐model implements a fuzzy set methodology, and uses soil landscape data sets and a Digital Elevation Model as evaluation criteria. The databases used were all georeferenced and standardised in a GIS format, enabling spatial analyses for possible pairings of data sets to be performed in order to derive new information sub‐sets. A test case is presented to map the spatial distribution of runoff Curve Number (CN) using soil landscape data, which were also used for land suitability evaluation, along with existing land use/land cover information. The strategies and analytical procedures developed in this research may be useful in other areas, particularly in projects related to mapping biophysical resources for sustainable land use planning and management.