Biodiversity in rural gardens in Estonia

Biodiversity of rural gardens has received limited attention in landscape ecology. Urban areas have been discussed (Francis et al. 2016), as has urban garden biodiversity (Dewaelheyns et al. 2011). Rural biodiversity decline has led to the realization that rural gardens are valuable resources for native birds and insects, even though gardens are mainly not of native species. A practical outcome of this is the expansion of urban beekeeping (e.g.; London). The present paper describes a new procedure for the assessment of biodiversity in rural gardens derived from existing published methods.
The standardized recording of habitats described by Bunce et al (2008) was designed principally for rural situations but Marques et al (2016) have now adapted the method for assessing biodiversity in urban areas by developing Urban Habitat Categories (UHCs). This approach uses the same principle, but a Minimum Mappable Unit of 10 m sq is used to obtain more detail. More categories were also added to capture the finer detail in urban land. UHCs include urban features such as squares with trees, as well as the plant life forms together with qualifiers. Vegetation layers are also recorded, as described fully by Marques et al (2016).
Dewaelheyns et al (2011) provide examples of the widely known differences between the composition of gardens and ownership but the present work was initiated from regular excursions to Lahemaa national Park, Northern Estonia, where it had been noted that there were differences between biodiversity in modern and old gardens. The former appeared to have low biodiversity, whereas the latter were diverse with features such as old orchards. In order to test these differences UHCs were adapted to record the composition and structure of biodiversity in gardens. Firstly, a stratification system (Figure 1) was constructed of 1 sq km, which was then used to select gardens for survey because additionally it was observed that villages adjacent to the sea had more modern gardens than inland. Outlines of the patches using standard definitions were initially made from air photos and then checked in the field. The management activity was first recorded followed by the composition of each patch together with qualifiers eg raised beds and species with over 30 % cover (Figure 2). Garden flora will be used to determine the value of the plants as nectar sources for insects. Analyses will then assess the extent of UHCs and their value for biodiversity, for correlation with the age of the garden and relationship to the strata. The paper describes details of this methodology and gives examples of results.