资源环境科技发展态势分析平台

Forests and woodlands are considered as the most important sources of honey bee forage in many European countries with several tree species providing nectar and/or honeydew flow. Slovenia boasts with high number of beekeepers and high colony count per square kilometer. We have investigated the impact of availability of natural resources and colony density on honey yield.

Data presented here were collected on 57 locations with monitor hives, equipped with scales, over years 2011-2016. Locations were selected according to site vegetation, ensuring identified source of nectar or honeydew flow. The source of the flow was recorded and verified by contract beekeeper. We investigated (1) the relationship between abundance of the flow source expressed as the quantity of growing stock and net mass gain of the monitor colony during the flow and (2) the relationship between colony density expressed as the number of colonies against growing stock volume and net mass gain of the monitor colonies.

We found an asymptotic exponential relationship between colony mass gain and growing stock of the species, providing flow. The exception was the spruce where the relationship was determined as linear (k = 0.023 +/- 0.009). The tau of the exponential approach in the case of acacia flow was 9.8 +/- 5.6 and in case of linden flow 6.6 +/- 3.9 (mean +/- SE). Colony density then determined the colony mass gain due to the flow. In cases of acacia, linden and spruce flow we have determined the relationship between colony density and mass gain as decaying exponential (tau = 283.9 +/- 60.6, tau = 1.6 +/- 0.4 and 3.0 +/- 1.3, respectively, all mean +/- SE). Combined linden/chestnut flow was fitted best with linear equation (k = - 0.08 +/- 0.019). Most likely, another variable should be used in the case of spruce flow: population of dew-producing insects. Periodical monitoring of eight acacia locations show differences in mass gain between years, thus allowing prediction of colony densities which guarantee profit: these locations are determined as those with colony density less than 50 hives/10(3) m(3) growing stock gained more than 10 kg/hive in 83% of cases, regardless of the year.

Our results indicate that a cap on the total number of colonies at one location should be considered to maximize beekeepers' profit.