Management interventions

When designing for more biodiversity, management and maintenance should be considered. It is well known that disorders such as uncut grass, leaving deadwood and leaf litter are beneficial for increasing species richness and diversity (Kraus et al, 2016; Lecture w. Iben M. Thomsen 2020; Lerman et al 2018). This is because wild growing grass can function as overwintering habitats and floral resources with nectar availability (Lerman et al 2018). Deadwood can function as microhabitats for invertebrates and bats as they offer nesting opportunities with a variation in temperature, humidity and size and can provide water availability in cracks (Bat conservation trust 2012; Kraus et al, 2016). Terrain elevation can additionally function as microhabitats as they offer different inflow of light and moisture (Ejrnæs, 2020).

Flowering meadows are both, if native, supporting various arthropod species (Threlfall et al. 2017) and appreciated by humans because of their colourful aesthetics. To achieve these forb communities, the best suggested method is broadcasting native seed mix from Danish seed sources without the use of any topsoil, as the nutrients would favor few common species and thus result in lower species diversity (Miljøstyrelsen, 2020). Broadcasting of seed is also suggested by Anderson and Minor (2020) as a method for establishing native vegetation. This should be done by hand as evenly as possible into turned over and weeded soil. This is suggested as it is a low-cost and easy to use method that resulted in the highest plant diversity compared to the other methods studied (Anderson and Minor, 2020).

Even though management should be minimal, some are required to keep open spots. If no maintenance is carried out, natural succession will turn areas into dense forest (Bjørn et al, 2016). In Threlfall et al’s study (2017) it is argued that different strata levels, and especially understorey volume, are important for arthropod species together with open meadow vegetation according to the Bat Conservation Trust (2012). Therefore areas turning into dense forest will hinder suitable habitats. On the opposite, woodlands are especially important to bats, therefore letting some areas turning in to dense forest would be benificial in this case. In nature, grazers can keep areas open, but as green spaces in cities are too small, grazers are often not a solution, and humans thus have to interfere with wild areas in order to keep them biodiverse (Per Stadel, lecture 2020). The management needed involves making rotational interventions in smaller patches on the site, eg. by cutting, mowing and rotating soil. These disturbances should be done at different times, creating a habitat mosaic of different points of succession (Mathey and Rink, 2010).

Manual hay harvesting two times a year could be a good management solution as it removes hay, and therefore nutrients (Miljøstyrelsen, 2021), as it cuts the plant without damaging them and as it creates an opportunity for connecting with nature and for learning about species and biological processes (Vild med vilje, 2012). Another solution could be humans functioning as herbivores. This includes trampling, making disorders and removal of undesired plants (As invasive and exotic species). These methods are time consuming, though, but they could be incorporated into the educational program of the school, activating the children in nature management. Management of the hedge rows at the site should preferably be done only every third year with a rotational approach to protect some overwintering invertebrates on site (Bat Conservation Trust 2014).