Exploring the effects of habitat management on grassland biodiversity: A case study from northern Serbia

In the study area, two primary management practices were implemented. Mowing was con- ducted twice a year, which typically occurred in June and September. In addition, the grass- lands experienced moderate grazing, with an average stocking density of 0.6 ewe/lamb pairs per hectare. These grazing activities were carried out under the supervision of shepherds, who ensured that the herds were led to designated pasture locations for specific periods of the year. At the control site C, no management measures have been carried out for 20 years, and the process of secondary succession has led to the formation of the forest-steppe. During 2021 in focus of this investigation, five field trips (in March, April, May, June, and September) were conducted. For plants, eight quadratic plots (1×1 m) were designated at each site during the first field trip, resulting in 224 plots in total. At each plot, we recorded maximum vegetation height (MVH), total vegetation cover (TVC), and coverage percentage for each flowering species. Flowering plants were collected, labelled, and identified in laboratory by consulting relevant literature [30–37]. In addition, in order to gain insights into community dynamics and eco- logical characteristics, we employed Social Behavior Types (SBT) for all plant species. SBT cat- egorizes plant species based on their roles in the community and provides valuable information about community richness, stability, naturalness, niche occupancy, and response to disturbances or deviations from the natural state [38]. All plant material was deposited at

Herbarium BUNS, University of Novi Sad, Faculty of Sciences. During all field visits, diversity and population abundance of pollinators (wild bees and hoverflies) were observed and samples were collected for 60 minutes per site, along two tran- sects of 500 m length. Transect walks were conducted between 9:30 AM and 5:00 PM on sunny days (with over 30% sunlight) when wind speeds were low, and temperatures were above 13˚C if it was sunny and above 17˚C if it was cloudy. During the summer, transect walks and observations were conducted between 7:00 AM and 12:00 PM to avoid high temperatures that reduce bee activity levels [39]. All pollinators were identified to the species level in the field, while some of them were captured using a net and were transported to the laboratory in vials filled with ethyl acetate for identification to the species level. For the identification of soli- tary bees, we used the following resources: Mauss [40], Amiet [41], Schmid-Egger [42], Scheuchl [43] and for hoverflies, we referred to the following publications: Vujić [44], Speight and Sarthou [45], Likov et al. [46]. The captured specimens were subsequently deposited at the Department of Biology and Ecology, University of Novi Sad, Faculty of Sciences. The diversity and abundance of birds breeding on the surveyed sites were assessed based on territory mapping. For this purpose, sites were visited on four occasions during the breeding season, between April 15th and June 15th. Visits were conducted at the peak of daily bird Table 1. Habitat types at investigated sites in the study area.

Site Habitat type according to the National classification of Republic of Serbia (Official Gazette 2010/35) Grazing 1 Panonian steppes on the sand* Grazing 2 Grazing 3 Mowing 1 Mowing 2 Mowing 3 Control Deciduous and xerophilous scrub of Hawthorn and Blackthorn Buffer zone Pannonian forest of Peduculate oak and Narrow-leaved ash *6260 NATURA 2000 habitat type https://doi.org/10.1371/journal.pone.0301391.t001 PLOS ONE Effects of habitat management on biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0301391 March 28, 2024 5 / 19