Desert regions are increasingly being put into use for a variety of purposes. The California Desert may be subjected to a number of energy technologies—particularly those related to harnessing solar energy—in the near future. In conjunction with past or other current disturbances, the fragmentation and pollution impacts of energy development could pose serious threats to the desert's fragile ecosystems.

Land-intensive energy technologies, such as solar receivers and biomass crops, will mainly result in changes that disrupt natural habitats. If all feasible energy schemes came to fruition, we estimate that one-half of the California Desert's area would be devoted to energy production. Even for much lower estimates of energy development, most of the Desert's natural habitat would be fragmented in park areas. Based upon island geographic principles and conservation biology, loss of species would be inevitable. Some species are already threatened with extinction.

Research is required to determine ways in which the Desert's natural resources—solitude, scenic vistas, wildlife, and insolation—can best be used to meet energy, recreation, and conservation, needs. In particular, research is required to estimate how successive small habitat losses would stress desert ecosystems.

To date, the principal constraint upon the implementation of a dust monitoring programme for desertification control in West Africa, is our limited knowledge of the dust processes to be monitored. A review of the state of dust research in Africa and over the Atlantic reveals a strong imbalance in favour of the latter, and resolves some misconceptions concerning dust source-areas and the relative importance of winter and summer dust. The results of Atlantic Ocean dust research are here brought together with the recent results of Harmattan dust research in Nigeria to demonstrate, at least tentatively, that the Harmattan and winter dust comprise a contiguous aeolian process system referred to as the Harmattan aeolian system.

The Harmattan aeolian system is used here as a conceptual framework for the dust monitoring programme. Three dust process-zones are identified, within which three basic aeolian processes operate: dust entrainment (primary and secondary), dust transport, and dust deposition (primary and secondary). Within each dust process-zone, standardized dust collection, measurement, and analysis techniques, are proposed for a network of monitoring sites. Entrainment and transport can be measured — directly using aerosol pump-samplers and indirectly by relating dust-aerosol concentration to solar radiation and visibility. The indirect approach has the advantage that it opens up a large body of historical data on dust and, therefore, desertification. Deposition can be measured using dust-traps. The importance of such aspects as site characteristics, measurement period, and laboratory methods, are also discussed. Finally, a minimal administrative structure is suggested, allowing for the possibility of UNEP or other major support.

The formation of quasi-tubular voids in the subsoil, known as ‘piping’, is an important form of subsoil erosion that arises when substantial volumes of subsurface lateral throughflow pass through dispersible subsoils. Amongst the environmental factors that favour the development of piping are high contents of expansible clay minerals, a severe dry season, and convexities in the slope profile. The first two of these are characteristic of considerable areas in Central Tunisia.

In addition to natural slope-convexities, further topographic loci for pipe initiation and development are provided by the artificial convexities introduced into the slope profile by the construction of conservation banks. The earthworks are designed as protection against surface erosion processes, which prevail for most of the year in this part of Tunisia. However, it appears that the banking is particularly vulnerable to piping, which is causing considerable disruption. Australian experience indicates that banking should be used very sparingly on soils which are at all prone to piping, and that care is needed in both the alignment and construction of such banks as are deemed unavoidable.

Experimental trampling was carried out in recently-burned and unburned areas of a dry sclerophyll forest. Percentage cover was greatly reduced by burning and trampling. Plant numbers were relatively unaffected by burning, and trampling had approximately the same effect on plant numbers in recently-burned and unburned areas.

The reduction of cover and plant numbers to 50% of their original value by fewer than 16 passages was near to that predicted on the basis of the low primary productivity of the ground-flora, and suggests that this type of vegetation is quite vulnerable to trampling.

The love for ancient desert sport, dwindling of the population of Houbara Bustard (Chlamydotis undulata) in the traditional hunting grounds of the Gulf States, Middle East, and North Africa, and also in some accessible parts of Pakistan through hectic mechanized hunting, has attracted the now-rich Arab falconers to strike at the populations wintering in relatively inaccessible areas of Baluchistan during the last 5–10 years. The present paper is the first known attempt at analysing the multidirectional effects of falconry in that last area, and depends upon the information collected during the Author's tours of different areas of Baluchistan and through information collected from various agencies.

The falconry that is now being done in the wintering grounds of the Houbara Bustard in Baluchistan is liable to have a very severe impact on the birds' population as the summering population is packed in some 1/8th of its summering grounds, thus yielding a very high density of birds. The falconry activities not only constitute a direct assault on the population of the Asian Race of Houbara, with a hunting toll of 4,955 during 1984–85 (a progressive increase from 418 during 1981–82 as reported but in reality expected to be much higher). There is also a significant effect on the population of falcons, some 300–400 being used every year, though the actual toll is probably much higher, as many are lost during trapping, training, transportation, and selling. The hunting parties are also responsible for direct and/or indirect killing of associated wildlife including hares, various deer, See-see Partridges, sandgrouses, Stone Curlew, and Cream-coloured Courser, while some 200 head of antelope were taken out of their ecosystems and sold to, or wasted in the hands of, falconry parties during the 1983–84 season.

The hectic activity of the falconers in the area, and their associated men and materials, are responsible for disturbing the biological phenomena of the animal wildlife, including hormonal balance and feeding activities. The period of mating and reproduction of most of the desert animals coincides with the falconry in the area, and hence these activities result in the production of malnourished, biologically unbalanced individuals.

The indiscriminate killing of Houbara and falcons may result in unbalanced ecosystem, with the massive elimination of Houbara resulting in increases in the populations of harmful organisms lying at lower trophic levels, and decreases in the populations of organisms lying at higher trophic levels. The elimination of raptorial falcons has probably resulted in increases in the populations of rodents in the northeastern part of Baluchistan and hence increased damage to agricultural crops or water channels. The falconry also has the potential of physically destroying the habitat through crushing of the slow-growing plants, denuding the camping sites through movement of men and materials, dumping of nondegradable wastes, and woodcutting for camp fires. The movement of heavy hunting vehicles sometimes causes severe damage to small earthfilled dams that are used for storing irrigation water, slowing rapid runoff, and recharging ground-water resources.

Insect control programmes sometimes include environmental modification techniques such as diking and drainage. The impacts of such techniques are not often known or assessed. As a telling example having wide implications, we present an analysis of impacts in a small estuary which has been subjected to both diking and ditching—primarily for mosquito control.

The major impacts stem from katteklei formation. Desiccated salt-marsh sediments produce acidified leachates which result from oxidation of pyrites. Lowered pH and high (acid-mobilized) aluminium concentrations both surpass levels that are known to be toxic to aquatic fauna. Fish and invertebrate communities in the basin are impoverished, and important commercial species such as American Eels and Alewives are heavily decimated. The acid-tolerant mosquito Aedes cantator thrives, however. Thus a natural system of substantial economic and aesthetic value has been inadvertently devastated through application of unnecessarily harsh as well as, in this case, ineffective mosquito control methods. Their use should be re-evaluated for similar impacts wherever such application has been carried out or is being contemplated.

Widespread agricultural burning during the dry season in the Pacific watershed of Panama is an important ecological phenomenon. During that time over 10% of the land surface (woodlands and savannas) is burned annually, with the resulting production of large amounts of charcoal. The major portion of the charcoal remains on land, but 5% is mobilized by river runoff and winds to the sediments of the Gulf of Panama.

The aeolian transport of particulate charcoal by the north-easterly Trade Winds has been monitored by dry-deposition and aerosol paniculate collectors. During the burning-season, atmospheric charcoal concentrations in rural Panama can be similar to urban concentrations in North America or Europe. More than 60% of the charcoal aerosol mass was carried as fine particles (< 2 urn diameter), suggesting that long-range transport is possible.

Dry-deposition fluxes, which are positively correlated with the areal extent of land that is burned, are more than an order of magnitude less than the charcoal fluxes to the uppermost near-shore sedimentary deposits in the Gulf of Panama. This implies that aeolian transport is not the principal mechanism of charcoal mobilization to these sediments. The extremely high runoff per unit area in the Gulf of Panama watershed is probably responsible for the predominance of continental runoff as the charcoal transport mechanism in the region.

Being relatively indestructible, charcoal can also be used as a tracer for past burning activities. Sediment box-cores have been recovered from the Gulf of Panama, and Pb-210 geochronologies were utilized to determine sedimentation rates. The charcoal particles were isolated by chemical methods and their fluxes, size-distributions, and morphologies, were analysed. The relative uniformity of these measurements in the marine sediment geochronologies indicates stability of burning patterns in central Panama during the last two centuries.

Environmental law is an important tool for environmental management. A review of the environmental legislation existing in developing countries presents a very diverse picture. Generally speaking, the Asian countries have for the most part well-established and often highly-developed legal systems, which, when necessary, can assimilate new legal mechanisms and legislation for environmental management without undue turbulence. In contrast, the African countries have not on the whole made environmental protection a part of the fundamental laws that exist at present.

Poor effectiveness of environmental legislation in developing countries should be a matter of very serious concern. Such poor effectiveness is primarily due to two major problems: a piecemeal, unsystematic legal approach to environmental management, and the lack of effective implementation of existing environmental legislation—irrespective of how good it may be to deal with the overall problem.