Bumblebee (Bombus spp.) occurrence in relation to vegetation height, variation in vegetation height and flower abundance
Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
Bumblebees are a group of valuable pollinators that are declining all over the world. The main reason is believed to be habitat loss due to the changes in agriculture. The changes in agriculture influence the structure of the vegetation and flower abundance, which are of great importance to the abundance of bumblebees. The aims of this study were to get a better understanding of bumblebees and what preferences they might have regarding vegetation height and flower abundance in semi-natural grasslands. This study is based on data collected by a Swedish national environmental monitoring program in 2006-2010. Data on twelve bumblebee species were analysed using a generalized linear model based on the dependent variables of occurrence/ non-occurrence. The target variables used in the analysis were flower abundance, vegetation height and standard deviation of vegetation height. The species-wise analyses mostly showed no or weak positive relationships between the bumblebee occurrence and the three target variables. Grouping the species-wise results into ecologically meaningful guilds and analysing them did not increase the explanatory power of flower abundance or vegetation characteristic, but vegetation height showed significant (positive) results in relation for the forest dwelling species and the species group non-parasite and parasite. The results of this study were considerably weaker than expected. Flower abundance and variation in vegetation height could not explain the occurrence of bumblebees. However, the results of this study show that vegetation height is of importance to the occurrence of bumblebees. Bumblebees in general seem to prefer a higher vegetation height. Based on the findings of this study I would recommend a low intensity of grazing in semi-natural grasslands.
Place, publisher, year, edition, pages
2014. , 14 p.
Grazing, management recommendations, nectar, pollinator, seminatural grassland, Sweden
Natural Sciences Ecology
IdentifiersURN: urn:nbn:se:liu:diva-108671ISRN: LiTH-IFM- Ex--14/2873--SEOAI: oai:DiVA.org:liu-108671DiVA: diva2:731481
Subject / course
Milberg, Per, Professor