Trade-offs between fire hazard reduction and conservation in a Natura 2000 shrub–grassland mosaic

By Vasco Silva, Filipe X. Catry, Paulo M. Fernandes, Francisco C. Rego & Miguel N. Bugalho

Natura 2000 is the EU-wide network of nature conservation areas set up to ensure the conservation of Europe´s plant and animal species and habitat types also providing multiple ecosystem services from which human communities benefit. Ecosystem services range from provisioning services (goods obtained from ecosystems) such as livestock production to regulating services (benefits obtained from the regulation of ecosystem processes) such as pollination. However, it is still unclear how ecosystem services relate to habitat types and to what extent the conservation status will ensure the provision of services.

In southern Europe, Mediterranean shrub-grasslands habitat types have a very high likelihood of burning, but many have simultaneously a high conservation value, recognized by the Natura 2000 network, and provide a multitude of ecosystems services. However, fire hazard reduction is also an important regulating ecosystem service in the Mediterranean regions. Because fuel management is often in conflict with conservation goals, trade‐offs between biodiversity conservation and wildfire prevention should be considered. Natura 2000 habitat types must be managed to maintain a “favourable” conservation status. Management practices, such as prescribed burning, can reduce vegetation fuel loads by preventing the encroachment of woody plants and maintaining an open mosaic of different shrub-grassland habitats. Moreover, fuel management practices may change plant composition and habitat structure, and consequently affect conservation status and ecosystem services delivered by shrub-grasslands.

A detailed survey using plant species and functional traits (plant growth form) was conducted to analyse changes on prescribed burned plots in a mosaic of shrub-grassland habitat types. The study is situated on the western coast of Portugal, in Sintra mountain with a Mediterranean dry climate. We established plots in locations managed with prescribed fire (two, four and six years after burning treatment) and in unmanaged areas (unburned for more than 25 years) and we investigated the influence of the time since the last fire on plant composition, diversity and vegetation structure. Changes in cover and structure of indicator species (Ulex jussiaei, Stipa gigantea) were used to assess the conservation status.

In the short term, prescribed burning increased plant diversity, reduced fuel loads and minimized fire hazard, but also negatively affected habitat conservation status. Both cover and structure of Ulex jussiaei were reduced by prescribed burning, indicating changes in conservation status from favourable to unfavourable. In the burned plots, cover of Cistus salviifolius was higher four years after the treatment, while the cover and phytovolume of Rubus ulmifolius was higher six years later, which can lead to ruderalization of habitat types.

The results show that there are potential trade-offs between fire mitigation and conservation in Natura 2000 shrub-grasslands habitat types and that these must be considered when making fuel management decisions.

This is a plain language summary for the paper of Silva et al. published in the Applied Vegetation Science (https://doi.org/10.1111/avsc.12463). The post was prepared by Vasco Silva, Filipe Catry and Miguel Bugalho.