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The variables and the beetles

Using boxes as an alternative habitat for saproxylic beetles, in green areas near and within cities, seemed to be effective since a much greater proportion (61% of the species and 94% of the individuals were saproxylic) of the beetle species found in the boxes were saproxylic species.

The variable shading had a trend to increase species richness in the boxes. This is contradicting compared to other studies where more sun-exposed habitats generally hosted a greater number of species. One reason for this contradiction could be that a more shaded box had a higher level moisture, which several species and families are dependent on, for example the families LatridiidaeEndomychidae, Cryptophagidae, Mycetophagidae, Scirtidae and Cerylonidae are dependent of moister. 

The amount of buildings surrounding the boxes seemed to have a negative impact on species richness. The buildings may act as barriers against the beetles, which might aggravate dispersal of species

 

 

Comparative study

The comparison between collected beetle fauna from the boxes and the data of saproxylic beetles living in oaks from Thomas Ranius & Nicklas Jansson (2000) showed that 45% of the species dependent of tree trunk hollows could be found in the boxes as well. 

A reason for the lower species richness of dead wood dependent species could be the distance from a dispersal source. Studies has shown a decrease in species as the distance from the dispersal source grew. It has also been shown that some species are more likely to colonize with older and more decomposed substrate, this might also affect the species richness and composition

Another reason for the lower number of species could be the hight of the box. Ranius (2002) showed that species richness was greater in tree trunk hollows whose entrances was situated higher up on the tree than compared to the hollows whose entrances were situated lower on the trees.


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Last updated: 05/24/20