Dehesa de San Francisco (Santa Olalla de Cala)

Dehesa de San Francisco (Santa Olalla de Cala)

1. Context

The Dehesa San Francisco (516 ha) is located in Natura 2000 site Sierra de Aracena y Picos de Aroche. The owner is Fundación Monte Mediterraneo and the main activities are livestock farming (bovine, ovine and porcine) and cork production under Ecological and Forest Stewardship Council (FSC) Certification. Secondary activities in the farm are rural tourism, training on forestry sciences and mushroom harvest. A rotational grazing system in which the cattle use the entire surface of the farm (516 ha) is the main livestock management practice for animal feeding, together with supplementary food (fodder, hay, straw and cereal). During the montanera (November-February), most of the surface of the farm is used by pigs. Night herding is carried out with sheep, achieving an annual herding surface of 20 hectares. From June 20 to October 20, the sheep herd performs transhumance to the mountain passes of northern Spain, being of vital importance for the cattle discharge of the farm during the most critical months, where the availability of water is the most limiting factor. Water availability is represented by 12 ponds, 2 reservoirs, 6 wells and 2 cisterns. Although the import of water is not necessary, the farm uses a system for moving water from wet to dry areas.

The natural regeneration of tree layer is good and is composed mainly by Q. ilex, Q. suber and Q. fagineaAn exhaustive monitoring is carried out to guarantee the presence of natural regeneration. These techniques consist of protecting all the seedlings coming from natural germination of seeds. On the other hand, there are some wooden feeders for corvids and pigeons filled with acorns, to use fauna as seed disperser.

There is a stratum of scrub formed by rockroses, heaths, gorse and broom where the predominant species are sticky rockrose, curly rockrose, gorse, lavender and heather. The regeneration of the scrub stratum depends on the climatic and orographic conditions of the different areas of the farm. Currently, the scrub management model of the farm is based on a clearing work carried out in those areas where there is a monospecific shrub layer, mainly represented by Cistus species such as C. crispus, C. monspeliensis, C. ladanifer, accompanied by Genista hirsuta. In the clearing work, the noble scrub, represented by broom, mastic, torvisco and cornicabra, is always respected. The clearing work is carried out without removal of the land, as well as the margins are respected of streams and valleys, in order to protect the soil against possible laminar erosion.

In terms of biodiversity of fauna, the endangered species Black Vulture, Red Kite and Imperial Eagle are present in the farm. Two ringing processes are carried out per year and at least 80 nest boxes for birds are distributed among the farm.

The health of the habitat is in general good, but there are certain areas that can be significantly improved in terms of scrub management. Since 2012, an area affected by P. cinnamomi have been observed, as well as damage by Cerambyx sp. and Coroebus florentinus. The affected area is close to 80 hectares.

After two study visits, the farmer and the consortium agree to implement the following actions in three different areas of the farm:

1. Naturalization of a reservoir area in Valdebují

2. Improving rabbit population in a fenced area of approximately half a hectare (El Toril)

3. Improving scrub layer and soil in a fenced area in El Toril

4. Improving scrub biodiversity in 3 fenced corridors of 1.5 m x 80 m in the area La Vieja

A preliminary census of bushes along the farm is available. The farmer will make specific census of every project area.

2. Actions

2.1 Naturalization of the reservoir area (Valdebují)

A reservoir has been constructed to storage water in case of fire occurrence. The reservoir is partially fenced, but it is accessible to livestock in case of water supply is needed. Their surroundings have low density of scrubs and the regeneration of Quercus is low in this area. The downstream drainage channel near the floodgate is eroded (Figure 1).

The scrub layer is composed mainly by Cistus crispus, Cistus monspeliensis and Genista hirsuta. Some  individuals of “espino negro” (Rhamnus lycioides) are also present in this area.

The following measures will be taken in order to prevent erosion and improve biodiversity:

• Half of the reservoir will be fenced to impede livestock access and test the effect of conservation actions (planting of aquatic plants in the shores) on biodiversity. A number of existing protective cages at the end of the pond will be used to plant riverside tree vegetation, as they are currently available for use.

• A gabion will be installed in the downstream channel near the reservoir floodgate to prevent erosion by reducing water velocity. A mesh fence will be installed at both sides of the water channel, from the installed gabion to the floodgate, to preserve the existing vegetation from
livestock. Hedge shrubs will be planted inside the protected area in the shores (from the gabions to the floodgate).

2.2 Actions for improving scrub biodiversity in fenced corridors (“La Vieja”)

At least 8 fenced corridors are already present in the farm where different species of noble bushes were planted few years ago without success. Currently, some individuals of Pistacia lentiscus and Lavandula stoechas are present, but the fenced area within the corridors show low density of scrubs. C. crispus, C. ladanifer and G. hirsuta are the most common species of bushes in this area. The proposal is acting on 3 of the 8 available corridors, thanks to their accessibility and also because some individuals are already grown up inside. The actions within the corridors will include:

• Removal of Cistus spp., inside the corridors and in the surrounding area, if necessary.

• Plantation of a diversity of noble bushes

• Formation pruning: directed to scrubs of interest inside the corridors.

• Installation of an irrigation system