The Mediterranean shrub Phlomis purpurea provides an example of how the value of scrub extends well beyond forage or shelter. The LIFE ScrubsNet protocol highlights that this species contains two triterpenes that contribute to limiting the spread of areas affected by decline associated with Phytophthora cinnamomi, revealing another important but less visible service provided by shrub vegetation.
When considering the role of scrub on a livestock holding, attention often focuses on browsing, fruit production, shelter for animals or habitat for biodiversity. However, some of its functions are much less obvious.
The LIFE ScrubsNet document “Livestock and scrub management for dehesa regeneration” explains that woody species can provide numerous services in addition to food. These include nutraceutical and medicinal properties, as well as microbial communities and aromatic substances associated with limiting the spread of Phytophthora cinnamomi.
Within this context, the protocol draws particular attention to Phlomis purpurea.
A familiar Mediterranean shrub with an unexpected function
Phlomis purpurea forms part of Mediterranean shrub communities and appears in the document among the woody species considered in dehesa management.
In this case, its relevance is not primarily related to livestock feeding, but to a much less visible service.
The protocol reports that Phlomis purpurea contains two triterpenes that contribute to halting the spread of decline foci caused by Phytophthora cinnamomi.
This statement is based on a scientific study by Fernández-Calleja and colleagues published in 2023 and cited in the document. The study addressed the isolation of two triterpenoids from Phlomis purpurea, one of which showed activity against Phytophthora cinnamomi.
Scrub is not simply competition for space
This example illustrates one of the central messages of the protocol: judging scrub only by the area it occupies or by how much grassland it may replace gives an incomplete picture of its role.
Woody species can provide shade and protection from cold, rain and wind; contribute to water and soil retention; add organic matter; create favourable microclimates; provide habitat for beneficial fauna; and protect natural tree regeneration.
These functions are complemented by less visible services associated with nutraceutical substances, medicinal compounds and other ecological interactions.
Phlomis purpurea is a particularly interesting example of this second group.
Greater plant diversity can mean more ecosystem services
A dehesa containing a variety of shrubs and trees forms a vegetation mosaic in which different species can perform different functions.
Some provide forage. Others protect holm oak and cork oak seedlings. Some provide resources for pollinators and birds, while others influence soil processes or help create favourable microclimates.
The protocol describes woody plants in grassland as “islands of biodiversity” providing a wide range of ecosystem services. It also highlights functions such as livestock diet diversification and several benefits related to soil, vegetation and wildlife.
The potential contribution of Phlomis purpurea in relation to dehesa decline adds another dimension to this picture.
Conservation also requires knowledge
Not every scrub patch is the same, and not every species performs the same functions. Before removing shrub vegetation, it is therefore important to understand which plants are present and what services they may provide.
Management aimed solely at reducing scrub cover could remove species whose benefits are not immediately visible.
The case of Phlomis purpurea shows why knowing the composition of the vegetation is an essential part of management.
Identifying the species present allows more precise decisions to be made: which areas can be grazed, which should temporarily rest, where regeneration should be encouraged and which shrubs may be particularly valuable to conserve.
Services that are not always visible
Many of the functions performed by shrub vegetation cannot be observed immediately.
A shrub may appear to be of little direct value to livestock while simultaneously providing shelter, supporting biodiversity or containing compounds with significant ecological interest.
Phlomis purpurea and its relationship with the spread of decline caused by Phytophthora cinnamomi provide a particularly illustrative example.
The LIFE ScrubsNet protocol conveys a clear message: the value of scrub should not be measured only by what it produces directly, but also by the services it provides to the wider ecosystem.
Maintaining a diverse dehesa therefore also means recognising these less visible functions before deciding which vegetation to conserve, manage or remove.
The LIFE ScrubsNet project is co-funded by the European Union through the LIFE programme, LIFE20 NAT/ES/000978.