Mediterranean desertification and land use. Project 2: target areas

The Decision Support System was developed initially for the Agri river basin in southern Italy but its flexible design enables it to be applied to other Mediterranean basins also. It provides a means of investigating, in a predictive manner, the interaction of complex physical and socioeconomic systems and their impact on the development of desertification at the basin scale. Specifically it can contribute in a formal scientific manner to the making of decisions concerned with land management in areas affected by desertification. Two particular issues which the System can address are ' the desertification consequences of specified climate scenarios, within a context of fixed agricultural policy (especially crop subsidies); and the sustainability of a specified land use or agricultural policy for a given climate scenario. Considerable emphasis is placed on ensuring relevance to desertification issues and user friendliness.

The main work consisted of the evaluation of the vegetations response to the climactic condition in a semi-arid area in order to study the resistance of the vegetation cover to the desertification process and drought periods. The work was carried out using the remotely sensed imagery jointly with the climactic data derived from the meteorological stations in the study area in the period of 1990-1998. An improved vegetation map was performed in MEDALUS II project and used as a basic map for the natural vegetation cover. The studied natural vegetation classes included seasonal grasses, disperse material, Rosmarinus, Stipa and pine forests. The vegetation response was studied by the NDVI derived from the geometrically corrected and atmospherically normalized multitemporal Landsat TM imagery. On the other hand, for the comparison of the spectral data (NDVI), precipitation images were generated from the field stations records in the same resolution of the Landsat TM imagery (30m) and accordingly the accumulated precipitation over each natural class was calculated from the hot summers (mainly August) till the date of the image acquisition. The study shows a severe drought period in 1994 (less than 150 mm) and previous wet year in 1990. The mechanism of the water use of each natural vegetation cover was evaluated from the study and the interpretation of the relationship between the vegetation response and the accumulated precipitation, and finally a vegetation resistance factor was developed for each natural vegetation type. The results also includes the construction of new vegetation index known as GESAVI (Generalized Soil Adjusted Vegetation Index) for the study of the vegetation dynamics. The new vegetation index is under improvement and validation.

Within the work carried out in MEDALUS project a database was created, which contains data on soil, soil erosion, vegetation and climate, management of a target area in Greece ( LESVOS). LESVOS database contains data on maps (scale 1:50 000) for the following: (a) soils such as texture, drainage, slope, rock fragment content, soil depth, classification, (b) vegetation such as vegetation cover, species composition (c) climate including basic climate data for three different climatic zones occurring in the island, (d) land management such as intensity of land use, policy enforcement, and (e) historical evolution of land use (3000 years). The database can be used for control and prediction of desertification through modelling development.

The given manual is a tool which can be used for desertification studies. It includes the following: (a) a series of key indicators or parameters which can be used in defining environmentally sensitive areas to desertification (ESAS) scales of 1:10 000 to 1:100 000, (b) regional indicators for defining ESAS, (c) a methodology and the data basis required for mapping ESAS, (d) application of the proposed methodology in three Mediterranean regions. The key indicators for defining ESAs to desertification, which can be used at regional or national level, can be divided into four broad categories defining the qualities of soil, climate, vegetation and management. The approach includes parameters, which can be easily found in existing soil, vegetation and climate reports. The developed methodology has proved as a valuable tool for land use planners at local, regional, national or European level for mapping ESAs to desertification and defining the appropriate measurements for land protection from desertification.

One of the most important end-products of MEDALUS III has been the definition of an Environmentally Sensitive Areas Identification System (ESAIS) to assess land degradation and desertification risk, based on a set of land parameters and indicators (from soil properties, morphology, vegetation cover, land use, soil erosion, fire risk, climate to management practices and environmental protection), that reflect the current state of the environment (adopting a land quality approach), present degradation levels related to desertification and the type, degree and intensity of management practices, policy enforcement and environmental protection, in target areas. By cross relating the different thermatic layers, a final ESA map was produced for the target area, representing distinctive types of ESA`s ranked by its environmental degradation conditions and management quality, from "critical" areas to "not affected" areas. The application of the ESAIS methodology for the Alentejo target area - Mertola Municipality has given rather satisfactory and important results, providing a good integrated assessment of desertification in Mertola and with possible upscaling to the broader Alentejo region.

The result is four new methods for soil preparation and (4)Mediterranean species plantation for the restoration of degraded Mediterranean vegetation as result of fires or over-exploitation in semi-add environments where the process of desertification is active. The methods consist in the cost efficient soil preparation by machinery and subsequent plantation. Water harvesting is and benefit contributing to the prevention of flash floods frequent in the area. It is aimed to the national and local agencies and private and public companies as well as ONG's involved in the application of desertification mitigation actions directly in the field

The research activity undertaken during the Medalus 111 research program involved the identification of most representative indicator that could be extrapolated among the key desertification indicators in order to combat the desertification phenomena. Organic matter content was identified evaluating different areas having diverse soil nature, exposure., pluviometric trend, slope. texture, and other physical, chemical and biological characteristics. Organic matter content was evaluated and correlated to the microbiological activity in the soil. In fact. there was a strict relationship between organic matter content in the soil and the density of soil microbial actiN,ih,. MorcoN,er. different cover crops gave diverse respiratory values of the microbial flora. An interesting example is the fact that a terrain with forest vegetation cover having a high organic matter content showed very low respiratory activity,. Otherwise, strongly degraded areas with little vegetation cover and scarce organic matter content illustrated a N,en, high respiration rate ready to stop as soon as the organic matter contents fails below 0.5-0. 1. These cases depict advanced desertification phenomena that cannot be recuperated simply adding organic matter to the soil. Therefore. the desertification process becomes irreversible and the terrain is in coma.

A procedure was developed and applied that enables the potential response of areas to desertification drivers to be assessed from "functional performance indicators". This was achieved for areas where desertification was related mainly to grazing or land use charge. The procedure is based on hierarchy theory, the notion of desertification response unit and on the concepts of soil and ecological function. It can be applied in almost all situations, provided that the functional indicators have been underpinned with models and field data to examine the spatial and temporal sensitivities to desertification. Moreover, the loss of economic and environmental functions resulting from soil degradation or land use change can be evaluated in terms of actual financial or cultural losses. The functional desertification indicators can be used for comparing regions that are quite different and form a bridge between biophysicial and socio-economic research methodologies. The indicators are also indicators of environmental health and soil quality and as such are of potential practical use to anyone interested in evaluating in a non-arbitrary way, the condition of the land for various objectives and for assessing risk.

Hilly areas under cultivation are protected from soil erosion by the construction of terraces. This conservation management requires high labour cost to maintain the terraces. The collapse of these terraces results in an immediate wash out of the soil protected into the terraces with a consequent increased rate of land degradation. The obtained results provide a methodology to predict the stability of terraces. The methodology relate the stability of terraces to land characteristics such as slope gradient, soil type, stone composition and management practice. Taking into account that the maintenance of terraces is absolutely necessary for hilly land protection, terraced areas can be classified in categories based on the priority for maintenance. This methodology can be applied in order to map and classify terracing land according to their stability of terrace and consequently to the priority for maintenance. This information is very valuable to local or national level and can be used by farmer's unions, local authorities, environmental agencies in order to influence policies for terrace maintenance and hilly land protection.

In order to adequately manage the land and its resources systems which allow us to identify and understand the factors that combine and accelerate land degradation need to be developed. The system being developed can be used to isolate current degradation phenomena. To do this, cross analysis techniques can be applied to the data held in information layers. The information in these layers comes from a variety of sources - some based on preexisting themes, some based on combinations of these themes, and some created ex-tiovo from other analyses. It must be emphasized that the main reason for this Environmental Sensitivity evaluation Model is to define a reference framework to be used in analyzing various situations within the Mediterranean Environment under the following operational constraints. - the system, must be reasonably simple to establish, robust in operation, and widely applicable; - the selection of the information layers is made, not only on the basis of their actual information content (i.e. their relationship with the phenomena under study), but also as a function of our ability to obtain and update the data with ease and economy. - the system must be adaptable and accommodate the development and refinement of the existing information content and the addition of new information.

It was collected extensive database of physical and socioeconomic aspects of Guadalentin basin, a semiarid area located in Region of Murcia, SE Spain. This includes both present and past data, and most of them are geo-referenced at different spatial resolutions and implemented on a GIS, and standard database formats. This database is used for the study of degradation processes in the area taking into account biophysical and socioeconomic processes. Therefore, database is not an isolated product but it incorporates a set of analysis of landscape evolution, relationship between exploitation of land and degradation processes, methods for assessing marginality of lands, risk of erosion, etc. All of these analysis are used for land planning and management.

Planning of desertification mitigation or land reclamation require instruments to carry out objective, fast and low cost assessments of land degradation status at adequate scales. This result is a new procedure to fulfil this goal. It is based on determining the deviation between actual and potential vegetation in terms of site water balance. Frequency and spatial pattern of the assessment errors are provided. In its present version, the procedure is adapted to work in marginal areas, forests and rangelands, and can be used with widely available data, in particular, remotely sensed imagery, digital elevation models and climate records.

Soil samples under five shrub species was examined for microbial activity distribution between bacteria and fungi during the dry season. Bacteria show a uniform response while fungi differentiate depending on the shrub species from which the sample is derived.

Exploitable results

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