The use of scrub vegetation should not remain the same throughout the year. The LIFE ScrubsNet protocol recommends adapting grazing to the season, the type of vegetation and the objectives established for each area, with particular attention to regeneration plots and riparian vegetation.
The dehesa is a dynamic system. Pasture availability, shrub growth, the emergence of new shoots and the vulnerability of seedlings all change throughout the year. Appropriate livestock management therefore depends not only on the number of animals present, but also on when they enter each plot and how much recovery time the vegetation is given afterwards.
The document “Livestock and scrub management for dehesa regeneration”, produced as part of the LIFE ScrubsNet project, proposes an indicative calendar for making livestock farming compatible with the conservation of scrub formations and the renewal of tree cover.
The recommendations distinguish between three types of area: enclosures reserved for regeneration, Mediterranean scrubland formations and riparian vegetation. Each requires a different approach throughout the seasons.
There is no single calendar for the entire holding
The needs of a plot intended mainly for pasture production are not the same as those of a patch where young holm oaks or cork oaks are developing. Nor can scrubland be managed in the same way as a riparian area, where moisture, soil and vegetation composition are different.
The protocol states that grazing should be organised according to the sensitivity of each area, prioritising rest and vegetation recovery at key times.
The season, the condition of new shoots, the availability of herbaceous pasture, stocking rates and the type of livestock present should all be considered before deciding when animals may enter.
Regeneration enclosures: maximum caution during spring
Plots reserved for tree regeneration require special protection, particularly during the first few years.
In autumn, the document allows for light grazing, provided that new Quercus specimens are not damaged. Iberian pigs may also feed on acorns during the montanera season, as long as their presence does not compromise young trees.
During winter, the general recommendation is to rest these areas, although Iberian pig grazing associated with the montanera may continue.
Spring is the most sensitive period. The protocol recommends excluding livestock completely during the first two years. From the third year onwards, patches containing regeneration may be protected while light grazing takes place elsewhere, always with careful monitoring of vegetation condition.
Summer grazing should also remain highly restricted during the early years. Between the second and fifth years, light grazing may be considered at the end of summer if dry grass or crop residues are scarce, but only as an occasional measure and depending on the condition of the regeneration.
Why does spring require so much protection?
During spring, holm oaks, cork oaks and shrubs produce new shoots that are tender and particularly attractive to livestock.
If grazing pressure is high, animals may repeatedly consume these shoots and prevent small plants from gaining height. This damage is especially serious during the first few years, when young trees remain within browsing reach.
Spring rest should therefore not be understood as a lack of management, but as an active measure that allows vegetation to grow and complete an essential stage of development.
Temporarily protecting a plot enables young trees to reach a less vulnerable size and allows shrubs to recover their ability to provide food, shelter and soil protection.
Scrubland: use the resource without exhausting new growth
Climax or successional scrub formations may also be grazed, but the calendar must prevent use from exhausting the plants’ ability to recover.
During autumn, the protocol allows for more intensive grazing before the new autumn grass becomes available. Iberian pigs may also use these areas during the montanera season.
Rest is recommended in winter, although occasional grazing may take place in dry years. This pause allows vegetation to preserve its reserves and prepare for the next growth period.
In spring, new shoots should be browsed only occasionally and must not be completely depleted. The aim is to use part of the available resource without compromising shrub recovery.
Occasional grazing may also take place at the end of summer when dry grass or crop residues are scarce. As with other vegetation types, the decision should be based on the actual condition of the plants rather than applied automatically every year.
Riparian vegetation: rest during winter and spring
Vegetation associated with streams, riverbanks and temporarily wet areas has considerable ecological importance. It protects the soil, retains sediment, conserves moisture and provides refuge for many species.
Because of its sensitivity, the recommended calendar is more restrictive.
Intensive grazing or pruning may take place in autumn until the new autumn growth begins. Winter and spring, however, should both remain rest periods.
This interruption allows vegetation to recover, protects new shoots and reduces pressure on particularly vulnerable areas.
Light grazing may be considered during summer, except in dry years, when the protocol recommends avoiding use altogether.
Rest is also a management tool
Rest is sometimes regarded as a loss of productive use. In reality, it is one of the most important tools for maintaining plant productivity and preventing resource degradation.
When a plot remains free from livestock for long enough, grass and shrubs can regrow, build up reserves and complete their growth cycles. This improves the future availability of forage and helps conserve soil structure.
Rest periods are particularly important when the objective is to regenerate tree cover, restore a scrub formation or protect a riparian area.
Managing grazing therefore means deciding not only when livestock enter a plot, but also when they should leave and how long the land must remain unused.
A calendar that must be adapted to each holding
The protocol provides general guidance, but it does not replace direct observation of each farm.
Annual weather conditions, rainfall, soil condition, grass availability, the presence of young trees and the livestock species involved will all influence the most appropriate time for grazing.
A dry year may require longer rest periods. A particularly favourable spring may produce more biomass, but it may also increase the number of young shoots requiring protection. Similarly, an area with abundant regeneration will need greater caution than one used mainly for livestock production.
Planning should therefore be based on continuous monitoring of vegetation and the ability to adjust the calendar whenever conditions require it.
Grazing at the right time
Sustainable scrub management does not mean permanently excluding livestock. It means using vegetation at the right time, at an intensity compatible with its recovery capacity and while respecting its most sensitive periods.
The LIFE ScrubsNet message is clear: each type of vegetation has its own rhythm and requires an adapted grazing calendar.
Protecting regeneration areas during spring, allowing riparian vegetation to rest in winter and spring, and avoiding the depletion of new scrub shoots are all measures that help reconcile livestock production with the conservation and renewal of the dehesa.
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The LIFE ScrubsNet project is co-funded by the European Union through the LIFE programme, LIFE20 NAT/ES/000978.