Green treasures: Investigating the biodiversity potential of equine yards through the presence and quality of landscape features in the Netherlands

new epoch (the Anthropocene era) to denote the impact human beings have had on the earth’s ecosystems [6]. As a result, there is an urgent need for innovative solutions that help mitigate the effects of human activities such as land use and climate change, while also assisting society to adapt to current and future situations. Nature itself is increasingly being viewed as one of the most important assets to mitigate the effects of climate change [1]. The concept of ecosystem services as a means to raise awareness to the benefits of the ecological environment to human society was devised in the late 1970s and early 1980s [7, 8]. However, the increasing threat of climate change has accelerated the need to understand how anthropogenic management of landscapes might affect the function- ing of the natural environment [9]. Small landscape features (LF) have long since been considered important elements of such ecosystem services. Small LFs are defined as ‘small fragments of non-productive natural or semi-natural vegetation in agricultural landscapes which provide ecosystem services and sup- port for biodiversity [10]. Examples include hedges, ponds, individual trees, trees in lines or groups, field margins and stone or earth walls [10, 11]. LFs have numerous functional uses, such as the provision of windbreaks and shelter for livestock, regulation of, and protection from, soil erosion, management of water quantity and quality, enhancement of air quality, CO2 sequestration, as well as the maintenance and protection of biodiversity [9, 11–16].

In the EU, around 45% of land cover is occupied by agriculture [10], meaning that many of the efforts to protect, maintain, restore and create LFs have been integrated into the Common Agricultural Policy (CAP). This was meant to be achieved by a number of legal requirements covered in several regulations, rural development programmes and greening measures, which included the creation and retention of Ecological Focus Areas (EFA) [11]. In order to acknowl- edge agricultural, ecological and cultural differences, EU Member States were able to deter- mine which types of areas to include in their national EFAs, in order to convert at least 10% of agricultural area into high-diversity landscape features by 2030 [17]. However, despite the undeniable significance of LFs in preserving biodiversity and ecosystems, member states exhibited hesitancy in incorporating landscape features as EFAs, favouring options such as green cover, catch crops, and fallow fields instead [10, 11]. Consequently, LFs currently account for less than 2% of the total EFA area at the EU level [10]. It seems clear that more concerted efforts are needed to accelerate the integration of LFs across Europe [10, 18]. Up until now, the equine sector has largely been overlooked as a player in the current agro- ecological transition [19, 20]. In part, this may be due to differences in the legal definition of horses in different countries, which depend on their definition of purpose, i.e. leisure, com- panionship, sport, therapy, agriculture, forestry and more [21]. However, regardless of their

legal designation, the keeping and management of horses may offer considerable environmen- tal benefits. Recent research has identified five ‘Green assets’ [20], including Equine grazing, domestic biodiversity, land use, tourism and equine work. As highlighted by Rzekęć et al., [20], due to their physiological and ethological needs, horse keeping is generally associated with considerable land use. In fact, across the EU, the land coverage associated with horses is estimated at six million hectares of primarily permanent grassland [22]. Not surprisingly, therefore, the limited research efforts that have been undertaken, have largely focused on the equine industry in terms of grassland management [19, 20, 23–25]. As opposed to grassland in an agricultural setting, equine grassland is largely non-productive and may provide ecosystem services more commonly associated with LFs. Furthermore, it stands to reason that equine properties offer considerable potential regarding the integration of different types of LFs. After all, much of the traditional uses of LFs, i.e., to offer shelter from the elements, provide addi- tional feed sources, or be used as means of enclosure, or for the separation of different fields, PLOS ONE Biodiversity potential of equine yards through landscape features PLOS ONE | https://doi.org/10.1371/journal.pone.0301168 April 11, 2024 2 / 16 decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.