Fragmented landscapes affect honey bee colony strength at diverse spatial scales in agroecological landscapes in Kenya

Abstract

Landscape fragmentation and habitat loss at multiple scales directly affect spe-cies abundance, diversity, and productivity. There is a paucity of information about the effectof the landscape structure and diversity on honey bee colony strength in Africa. Here, we pre-sent new insights into the relationship between landscape metrics such as patch size, shape,connectivity, composition, and configuration and honey bee (Apis mellifera) colony strengthcharacteristics. Remote-sensing-based landscape variables were linked to honey bee colonystrength variables in a typical highly fragmented smallholder agroecological region in Kenya.We examined colonies in six sites with varying degrees of land degradation during the periodfrom 2017 to 2018. Landscape structure was first mapped using medium resolution bitemporalSentinel-1 and Sentinel-2 satellite imagery with an optimized random forest model. The influ-ence of the surrounding landscape matrix was then constrained to two buffer distances, i.e.,1 km representing the local foraging scale and 2.5 km representing the wider foraging scalearound each investigated apiary and for each of the six sites. The results of zero-inflated nega-tive binomial regression with mixed effects showed that lower complexity of patch geometriesrepresented by fractal dimension and reduced proportions of croplands were most influentialat local foraging scales (1 km) from the apiary. In addition, higher proportions of woody vege-tation and hedges resulted in higher colony strength at longer distances from the apiary(2.5 km). Honey bees in moderately degraded landscapes demonstrated the most consistentlystrong colonies throughout the study period. Efforts towards improving beekeeper livelihoods,through higher hive productivity, should target moderately degraded and heterogeneous land-scapes, which provide forage from diverse land covers.