Contenu du sommaire : Connaissance de la friche

ABSTRACT : Although it appears indusputable that wastelands are increasing, agricultural censuses show that apart from their geographical stability (concentration in the south of France), there is a surprising trend towards their reduction. In some cases this paradox can be explained by changes in land classification between neighbouring categories (productive or non-productive moors and grazing land ; fallow areas ; woods and forest owned by farmesr), but basically it reflects the fact that abandoned areas not belonging to a holding are nor recorded in agricultural statistics.

In areas with a fragile economic base, rural wastelands have never been more than an indicator of more important spatial changes : the concept of rural fragility refers both to inherited situations (demographic decline, economic difficulties, spatial and landscape changes) and to current changes, with the human factor being a decisive element. In order to assess this notion of fragility and its different thresholds, degrees of developent and maner of operation, it is necessary to undertake a detailed study using various quantitative and qualitative variables. The diversity of the Rhône-Alpes region makes it particularly suitable for such research.

Given the restrictive connotation attached to the word wasteland, the term uncultivated land is prefered. If such a feature appears as a constant feature of the landscape, the logic of its development has varied over the centuries. II the present context it results from the interaction of numerous factors, of an economic, social and natural character. In order to define a management policy for rural areas, it is essential to take such factors into account and to evaluate their importance.

Waste land, defined as an area of land that has not been cultivated for at least a year and has become overgrown, has a representation in the landscape. Its perception is highly subjective, depending on the eyes of the beholder. The author develops a method which allows account to be taken of this perception and to create a typology of waste areas. The technique of the semantic differential is tested using factor analysis. As a result a typology based on 4 criteria is proposed which, when linked to other data, offers the basis for a programme of remedial action.

Until recently biogeographers have shown little interest in the study of wastelands. However, in 1987 and 1989 twoattempts were made in the northern part of the Pays d'Auge in the department of Calvados. This work led to the development of a methodology : the concept of the geosystem has been used and adapted to the question of abandoned land. Wasteland is seen as an uncultivated area, characterised both by relatively stable inputs - superficial topographic formations, stationary bioclimates - and by variable inputs - physiognomy and flora. The future development of uncultivated areas is closely linked to man's decisions.

SUMMARY: The example of the region of western upper-Languedoc is used to examine the ambiguities which arise when fallow land is used as evidence of agricultural decline. Land abandonment is a reversible and incomplete process, but it leads to successive changes of varying degrees of rapidity in the landscape ; these produce a return to natural forest vegetation. However, other forms of use of abandoned areas (e.g. urban development, tourism or afforestation), may alos gradually remove the traces of agricultural decline. In contrast, certain areas of moorland and "garrigue" vegetation, whose stable form prevents them from being regarded as abandoned land, form an integral part of the landscape heritage.

The intensification of agriculture and the reduction in the number of farmers have led to a modified pattern of land use and the appearance of areas of waste land in the landscape. The trend is evident in the Parc du Pilât and is a cause for concern. II waste land is often synonymous with abandonment and considered unusable, it may also be seen as a positive element froman ecological and landscape point of view. In order to manage such land, it is important to undestrand its precise pattern of development and present state. A method of analysis has been developed based on land-use mapping from aerial photographs for the years 1950 and 1980.

The natural reserve of the Marais de Lavours (460 hectares), lying between the lake of Bourget and the Rhône, plays an important role in regulating water flow. It is also the site of a various rare animal species. In the past, this area was integrated into the local economy (haymaling, digging of peat), but progresively this marsh has been abandoned and then spoilt by improvement works to the Rhône. Such change has resulted in the area becoming more isolated and uniform in character. To maintain the diversity necessary to allow the survival of the area's different species, the managers of the Reserve has introduced on an experimental basis Highland cattle and horses from the Camargue. The animals appear to have acclimatised to the area with relatively little help, and their action on the environment corresponds withe expectations of the Reserv's managers. Nevertheless, longer terms problems of the "natural" management of this situation remain.

ABSTRACT : For a number of years the depopulation of the dry Pre-Alps in the department of Drôme, a medium-level mountainous region characterised by unfavourable conditions, has led to numerous development schemes ; they were implemented first on a limited scale and more recently in a more extensive and integrated way. Signs of revival can be seen such as the settlement of farmers, but much remains to be land tenure and the development of tourism.