| The overarching aim of this study is to investigate the potential of horses to restore a grazing associated, diverse plant community and associated ecosystem services in semi-natural grasslands. Semi-natural grasslands have high ecological value due to the high diversity of vascular plant species, and their associated faunal communities. In Sweden, this habitat is threatened by both land-abandonment and agricultural intensification. Here horses have the potential to contribute to nature conservation and plant protection because they are abundantly kept for recreational purposes, they are well suited to graze on low-productive and marginal land and they are often kept in smaller units of 5-10 animals. We will investigate how the reintroduction of grazing by large herbivores at abandoned sites might enable restoration of semi-natural grasslands and identify which grazing strategies and landscape features that might impact restoration success (biodiversity).
The study will be based on two sets of already established field sites where grassland restoration is applied. Set-up I is a paired study of horse grazed fields and abandoned fields, set-up II consists of restored fields in Natura 2000 areas in Jämtland.
In both field set-ups we will evaluate restoration effects by throughout inventories of vegetation and pollinators including butterflies, moths, bumblebees, solitary bees and hoverflies.
Within each field, we will record the occurrence and cover of the dominating forbs and grasses as well as rare semi-natural field plants e.g. the orchid Gymnadenia nigra. We will survey butterflies with transect inventories using methods similar to the national butterfly monitoring scheme. This will allow us to use the butterfly inventory data as control data for our study and to compare butterfly communities on horse grazed field with those in other habitats. We will survey moths using a combination of light traps (LED traps) and sugar bait traps. Day-active pollinator communities including bumblebees, solitary bees and hoverflies will be sampled with standardized pan trap stations following standardized pollinator monitoring methods. To map the land use history of the fields and surroundings within this study and also map potential hot spots and connectivity we will use the developed R-script HistMapR. This will be used together with the Swedish NMD-layer to identify important landscape characteristics for grassland-associated biodiversity. The PhD will be recruited in early 2023 and finish in early 2027.
Preliminary results from a study on the vegetation on sites grazed by horses during summer show that horse grazed fields hosted a more ruderal and grazing associated flora than abandoned fields. Several species associated with grazing were found in the horse grazed fields thus indicating that horse grazing is a potential restoration method. The aims of this project lies well within the purpose of Oscar and Lili Lamms foundation because the biodiversity associated with semi-natural grasslands cannot be preserved without active restoration measures. The management of both semi-natural grasslands defined as Natura 2000-habitats and abandoned fields using horses has great potential to become an important contribution to Swedish nature conservation. |