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There was a total of 46 captures of Elater ferrugineus, including 10 recaptures, at 16 out of the 99 trap locations. 

Which hollow group is important?

All tree hollow groups showed significant relationship with the occurrence of the beetle. Strongest effect was shown by  large hollow and non-hollow trees.

Species richness in hollow trees increases as the tree girth increases, and hence with age. When the tree grew older, the quantity of wood mould is higher. This explained the strong relationship between the occurrence of the beetle and the density of large hollow tree. Strong effect showed by non-hollow tree could be due to high number of individuals compared to large hollow trees and small non-hollow trees. Another possible reason is that there might be some hollow trees with very small hollow entry to be noticed during the tree survey. 

Which tree group best explain the occurrence of the beetle?

  • The beetle  showed significant relationship between its occurence and the density of  oaks, and two other deciduous tree groups: Noble 1 (hornbeam, beech, elm) and Noble 2 (ash, chestnut, maple, lime).
  • Among all trees, oaks showed the strongest effect on the beetle’s occurence.
  • The scales where oak density best explained the beetle’s occurence were at 327 m and 4658 m. These two spatial scales were used in predicting the beetle’s distribution. 

The occurrence of the beetle showed strong effect to oak density because the mould was more abundant and had slower decomposition rate compared to other tree species. 

Where are the suitable patches?

The beetle's predicted distribution maps were cross validated with the sampling data from: a) study area, b) strategic sampling within the study area and c) strategic sampling in the entire Östergötland.
  • After the prediction map was cross validated with beetle sampling data, it was shown that most of the occupied traps were located in sites that had the two spatial scales overlapped (327 m & 4658 m).
  • This indicates that the amount of substrates in smaller scale alone is not enough for the beetle to be present.
  • The amount of substrate at larger scale is important for the occurrence of the beetle.

Responsible for this page: Agneta Johansson
Last updated: 05/20/12