Degradation Of Arid Lands Research Articles

The cost of mitigation strategies for agricultural adaptation to global change

Land recovery and the improvement of lands affected by desertification for agricultural use, is achieved when a sustained recovery of agricultural productivity over time is obtained. In the areas affected by desertification and drought, it is common that the ecosystems do not have enough funding for water management and irrigation. This situation leads to an inadequate assessment of the environmental goods and services in arid zones. As a result we have a misuse of these dry lands. Many countries are implementing policies and making investments and efforts to mitigate arid land degradation and desertification through the National Action Programs (NAP). However, for the long term planning of mitigation and adaptation strategies, it is necessary to know the cost of recovery and land improvement in certain areas in order to forecast the budgets. This is the main objective of this paper in order to combat desertification and drought in central northern Chile. We have calculated a recovery cost per hectare by region and for each of the agriculture, livestock and forestry (ALF) promotion agencies. The results indicate that the cost of land reclamation in the northern regions is much higher than in the southern regions of this studied area. The cost is especially high for Region II, where investment per hectare is almost to 3000 US$ per hectare. At the other extreme is the Region VII, in the south of the studied area where the investment required per hectare barely reaches 500 US$. The contribution of the promotion agencies to the total cost also varied among regions and agencies. We discuss the results within a context of recovery cost per hectare depending on the different environmental characteristics and agricultural development of each of the studied regions.

Assigning life-history traits to plant species to better qualify arid land degradation in Presaharian Tunisia

Apart from a decrease in total perennial plant cover, degradation of North-African arid lands is not easy to qualify. Yet, simple and comprehensive yardsticks are necessary to assess degradation. We assigned components of competitive ability (C), stress tolerance (S) and ruderality (R) to 15 common perennials of Presaharian Tunisia. We used for that purpose phyto-ecological studies, data about life-form, grazing value and demography and circumstantial data. Assigning CRS-strategies to these species improves understanding of vegetation change under increased anthropic influence, helps to conceive experiments to confirm underlying hypotheses and sheds another light on the controversy about restoring arid lands.

Man-Made Deserts: Desertization Processes and Threats

Desertization is defined as the irreversible extension of desert land forms and landscapes to areas where they did not occur in a recent past. Such extension does not result from a would-be increasing aridity as there is no evidence of any global long-term trends in rainfall in arid lands since the period of instrumental record (ca. 150 years). The 0.5° C of global temperature increase over the past 100 years remains well within the range of historical fluctuations. The creation of man-made deserts is actually the result of long-lasting mismanagement of natural resources under the pressure of excessive human and livestock populations. Such land abuse may drive ecosystems beyond their resilience potential for recovery. The causes and mechanisms of arid land degradation pertain to direct and indirect activities, processes, and phenomena, which are not necessarily linked to aridity or drought. Causes, severity, and extent of desertization are quantified from various sources. The potential for biological recovery is analyzed and the ways and means to achieve rehabilitation assessed. The conclusion addresses the issue of the future of desertization under the additional threat of an increased aridity that might occur assuming a possible global temperature increase of the planet, triggered by atmospheric pollution. It tries to quantify the possible increase of aridity under various scenarios.

A conceptual approach for evaluating the storage and release of contaminants derived from process based land degradation studies: an example from the Guadalentı́n basin, Southeast Spain

The implications for land use change for the storage and release of contaminants in the Guadalentı́n catchment in SE Spain are considered. As part of a large project examining the impact of land use and climate change on arid land degradation, information has been collected on how soil properties, hydrology and vegetation are evolving on abandoned land. This information was used to characterise land degradation response units in two areas, one on slates the other on marls and limestone. The way in which changes and degradation processes on the different land units influence the ability of the land units to retain contaminants, as well as the risk of these being transported by erosion, was evaluated. It was concluded that in the slate area, the only areas of risk are in the valley bottom flood plains. Chemicals may be transported here by subsurface flow from the slopes. In the limestone and marl area there is a more general risk because of the high erodibility of the soil and because abandoned areas do not revegetate quickly following abandonment. Water from these overland flow producing areas may erode agricultural fields which are situated at the lowest position in the landscape. In the marl and limestone area, a comparison was made for the situation in 1957 and 1993. The situation today is different from 1957 because of larger field sizes and changed land-use. In both the old and current landscapes, there were significant stores of sediment in the agricultural areas that form potential sediment and contaminant sources.

Policy roots of land degradation in the arid region of the United States: An overview

The roots of land degradation in the arid region of the United States are set firmly in the era of open range conditions that led to the depletion of rangeland resources in the late 19th and early 20th centuries. Upon closure of the open range and establishment of the U.S. Forest Service and the Bureau of Land Management, public lands in the arid region were protected from the classic tragedy of the commons. Private lands, in turn, fell under the stewardship guidance of such organizations as the Soil Conservation Service, the Agricultural Stabilization and Conservation Service, and the Cooperative Extension Service. Despite these institutional protections, arid land degradation continues at an ecologically and socially unacceptable rate. The most likely explanation for this degradation resides in the institutions and public policies that shape and control livestock grazing. Flaws and disincentives endemic to the grazing permit system have encouraged destructive grazing. Federal subsidies to public- and private-land ranchers have encouraged rangeland stocking rates in excess of carrying capacity on economically and ecologically marginal lands and consistently favored unsound land management practices over superior ones. Policy-generated distortions of market forces have lead to unanticipated and environmentally undesirable land use outcomes. Land management, technical support, and educational institutions have also inadvertently contributed to land degradation in the arid region. Reversing the trend of land degradation in an advanced country like the United States demands that we understand the role of public policy in land use outcomes and that we structure future public policies in accordance with the lessons of recent history.