The second bee monitoring season across 16 selected sites in Saxony-Anhalt and Lower Saxony was completed in August. The survey methodology and period were optimised as part of previous feasibility studies. A total of five surveys were carried out between March and August 2025, spread across the bee season. These dates correspond to the flowering periods of native plant species. As bee communities are characterised by continuous changes in species composition over the course of the year, phenological anchoring of sampling events ensures that bee communities at different locations and over the years are sampled in a comparable manner (Fig.1). Compared to 2024, the phenological development in the study area was observed to be delayed by several days in 2025.
Preliminary evaluation shows clear annual effects in the distribution of total and bee biomass. Around 14% more total biomass was recorded in 2025 than in 2024. Bee biomass increased by an even greater amount (+25%). Notably, the activity density of bumblebees was almost four times higher in 2025 than in the previous year.
In general, a decline in the recorded activity density of wild bees was observed from spring onwards throughout the rest of the year. This trend probably follows an annual phenological cycle that has also been observed in other studies. However, unlike in 2024, the highest observation values of the year 2025 were noted in July. Over 50% of the annual insect biomass, 30% of the bee biomass and 40% of the total bee activity density occurred in this month.
Over a period of two years, honeybees were detected at all monitoring sites. However, further surveys will be necessary in the coming years to assess annual and seasonal fluctuations in the presence of honeybees in the agricultural landscapes studied.
These results highlight the need to collect monitoring data repeatedly over several years and at various times throughout the year in order to reliably map development trends in bee communities.