A controlled presence of shrubs can provide food for livestock, protect the soil, support biodiversity and help young holm oaks and cork oaks become established. The key is not to remove all scrub, but to manage it properly.
For many years, scrub vegetation on livestock farms was associated with a loss of grazing land, lower productivity and a greater risk of wildfire. In many cases, this perception led to its almost complete removal.
However, a dehesa made up only of mature trees and herbaceous pasture loses part of the diversity it needs to remain healthy and regenerate. The document “Livestock and scrub management for dehesa regeneration”, produced as part of the LIFE ScrubsNet project, highlights that shrubs can perform essential ecological and productive functions when their presence is carefully controlled.
In this new article, LIFE ScrubsNet proposes a change of perspective. Rather than asking how scrub can be removed, it is more useful to consider where it should be retained, what functions it can perform and how it can be integrated into farm management.
More resources for feeding livestock
Herbaceous pasture forms the basis of many extensive livestock systems, but its availability and quality vary throughout the year. During periods of scarcity, certain shrub species can provide leaves, shoots, browse, flowers or fruit that supplement livestock diets.
Hedges, scrub patches and other areas of woody vegetation can diversify the food available and provide additional resources when grass is scarce, particularly during the summer or at other critical times.
Not all species have the same forage value or respond to browsing in the same way. Their use should therefore be planned according to local conditions, the livestock species and breed, each plant’s ability to regrow and the management objective for the area.
Shelter and animal welfare
Scrub vegetation also provides protection from heat, wind, rain and cold. Hedges and shrub patches can create shaded and sheltered areas that improve animal welfare, especially in very open landscapes.
This function is becoming increasingly important in a context of extreme temperatures and more intense weather events. Woody vegetation helps to create small microclimates, reduce direct exposure to sunlight and provide resting areas within the farm.
The value of scrub should therefore not be measured only by the amount of food it produces. Its contribution to animal comfort is also an important part of its role in livestock systems.
A natural barrier against erosion
Shrubs help retain soil, slow down water during heavy rainfall and improve infiltration. This is particularly important on slopes, in stony areas and where soils are shallow.
Their roots help stabilise the ground, while the organic matter that accumulates beneath them gradually improves soil structure and fertility. Hedges and vegetation along watercourses can also reduce erosion, filter water and limit sediment loss.
Removing this cover completely can leave the soil more exposed to rainfall impact, run-off and nutrient loss. Retaining it strategically can strengthen the stability and resilience of the farm.
Islands of biodiversity within the dehesa
A patch of scrub is much more than a group of shrubs. It can act as a small island of biodiversity, providing food, shelter and breeding sites for many species.
Birds, pollinators, small vertebrates and beneficial wildlife find resources in these areas that are not available in completely open grassland. This diversity supports ecosystem functioning and can encourage processes such as pollination, biological pest control and nutrient cycling.
A livestock landscape made up of a mosaic of grassland, trees, hedges, scrub patches and riparian vegetation is more stable than a completely uniform surface.
Shrubs that protect young trees
One of the most important functions of scrub is its ability to support the natural regeneration of tree cover.
Holm oaks and cork oaks grow slowly during their early years. At this stage, seedlings are particularly vulnerable to browsing, trampling, intense sunlight and lack of moisture.
Some shrubs can act as nurse plants, creating a more favourable microhabitat beneath their canopy. They provide shade, help retain soil moisture, contribute nutrients and make it more difficult for herbivores to reach young trees.
The success of natural regeneration and reforestation can therefore be greater when seedlings grow alongside these protective plants rather than in completely open spaces.
A limited presence of dense, thorny or unpalatable shrubs can help young holm oaks and cork oaks survive their most vulnerable stages until they grow beyond the reach of livestock.
Management does not mean allowing uncontrolled growth
Recognising the benefits of scrub does not mean supporting its unrestricted spread. Excessive cover can reduce the area available for grazing, make livestock movement more difficult and increase certain risks, including wildfire.
LIFE ScrubsNet advocates controlled scrub development, adapted to the characteristics and objectives of each farm. Scrub can be retained along boundaries, in hedges, patches, sloping areas, riparian zones and places set aside for regeneration, while other areas remain primarily dedicated to grazing.
Management tools may include targeted or rotational grazing, temporarily excluding livestock from particular enclosures, protecting selected patches and choosing livestock species or breeds with different browsing behaviours.
The most suitable combination will depend on the objective: producing forage, creating biodiversity refuges, protecting the soil or supporting tree regeneration.
Restoring balance in the dehesa
A dehesa is not simply a landscape of trees and grass. Its stability depends on the relationships between trees, pasture, shrubs, livestock, soil and water.
When scrub disappears completely, many of the services it provides are also lost. When it spreads without management, it can conflict with other farm uses. The challenge is to find the right balance for each property.
The LIFE ScrubsNet message is clear: scrub is not the enemy. When properly managed, it can become an ally for extensive livestock farming, biodiversity and the natural regeneration of holm oaks and cork oaks.
The answer is not to remove everything, but to decide how much scrub to retain, where to retain it and how to benefit from it without undermining the balance of the system.
The LIFE ScrubsNet project is co-funded by the European Union through the LIFE programme, LIFE20 NAT/ES/000978.