Dehesa Agroforestry-stockbreeding Systems.

The application of the hot spot detection procedure points at the province of Caceres as affected by current desertification risk. Stock breeding is the main land use change in Caceres, suggesting that the underlying land use system is the ‘dehesa’.

The Spanish term ‘dehesa’ designates a particular type of landscape and land use which is widespread over shallow, acidic and nutrient poor soils of rolling topography in the Western sector of the Iberian plateau. Its climate is semi-arid, with a strong contrast between cold-humid and hot-dry seasons. Vegetation is structured in an upper layer of scattered evergreen trees and a ground layer of grassland. In degraded or poorly managed dehesas, a shrub layer often appears. The land use system is complex and integrates agroforestry and stock breeding (sheep, beef and pigs).

The ‘dehesa’ is an extensive land use system that takes profit from marginal lands with enterprises that manage large areas with low income per unit area. There is a general agreement in that traditional ‘dehesas’ are very efficient in maintaining spatial heterogeneity and preserving ecological diversity and landscape functions (Gomez Gutierrez 1992, Montero et al 1997).

However, survival of traditional ‘dehesa’ in the current and future economic environment faces to several difficulties. One of the most serious is the small size of circulating capital in relation to the fixed one. Because of this, profitability depends more on land added value than on its production and cash availability is often very low  (Campos Palacin & Abad 1987). As a consequence, landowners are little interested in sustainable management and conservation of their resources (Montero et al 1997).

In such circumstances, the immediate and dramatic effects of policy stimuli on livestock are easy to be predicted. All provinces which have large ‘dehesa’ surfaces show significant livestock increases. Landowners overstock their holdings above carrying capacity by supplying feed from outside.

There is still few information about the effects of such behaviour on vegetation. Similar conditions on the Algerian steppes lead to grassland degradation because animals look for cellulose (Aidoud et al 1998). The hydrological and erosional implications are better reported. It has been shown that soil compaction by trampling diminishes infiltration and increases quick runoff and soil erosion (Schnabel 1997). This effect is particularly conspicuous after drought periods, in bottom lands where stock concentrates.

The desertification risk which has been detected in Caceres is a focus that may be spread over 30 000 km2 of ‘dehesas’ that extent along a North-South zone in the provinces of Salamanca , Caceres , Badajoz , Sevilla , and Cadiz . Such landscapes hold large ecological value but they are managed with land use systems poorly adapted to the prevailing socio-economic conditions, and are strongly affected by policy regulations little concerned with them.