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Habitat requirements and preservation of the beetle community associated with hollow oaks at a landscape level

Short presentation of me

I have been studying insects from my early childhood. I was a partime PhD student 2003-09 and are a doctor in Ecology since then. I have research going on in Sweden and Turkey, mainly concerning saproxylic beetles, old trees and nature conservation. Im teaching in faunistic and ecology and supervising Master students in ecology. I also work at the County administration Board of Östergötland, Sweden, since 1995 and this is my major employers. Among other things, here I work with insect surveys, coordinate environmental monitoring and other nature conservation projects. Im also a member of redlist commities for beetles in Sweden and for saproxylic beetles in Europe.


Old oaks in Brokind nature reserve south Linköping
Old oaks (Quercus robur and Quercus petrea) sustain the most diverse fauna of saproxylic beetles in Sweden . When oaks get old, hollows with wood mould often form in the trunks. Wood mould is grind wood colonized by fungi, often with remains from animal nests and insect fragments and droppings from insect larvae. Trunk hollows with wood mould harbour a specialized fauna, mainly consisting of beetles and dipterans but also pseudoscorpions.
Saproxylic insects associated with old trees are one of the most endangered invertebrate groups, as their habitat has severely decreased. In Sweden old oaks harbour a large proportion of red-listed saproxylic insect species. These insects are living in fungal fruit bodies, dead wood outside the tree (in branches or parts of the trunk) or inside the tree in hollows.
In Sweden old hollow oaks, have decreased severely since the beginning of the 19th century. The reason is that from 1558 until 1830 the oaks on peasant land belonged to the Swedish state, and was forbidden to cut down without permission. When this ban disappeared, nearly all old oaks were felled.

Projects and questions

What method works best for collecting different saproxylic beetle species living on hollow oaks?

A window trap in an hollow oak (Quercus cerris in Turkey).

The method I use for collecting the insects in my studies are window traps and pit fall traps. In a paper from 2002 (se below), I and Thomas Ranius (SLU, Uppsala, Sweden) compared these methods with ”wood mould sampling”. A method used by Thomas in the same environment. I have used the trapping method in more than 100 sites with old hollow trees in southern Sweden.
Ranius, T. & Jansson, N. 2002. A comparison of three methods to servey saproxylic beetles in hollow oaks. Biodiversity and Conservation. 11: 1759-1771.

How important is the light conditions and the size of the oak tree for the species composition?

In a field study in 1994 with traps we caught saproxylic beetles arround old hollow oaks in different light conditions. We found a positive correlation between light and large trunk size. The result is published in the paper bellow.
Ranius, T & Jansson, N. 2000. The influence of forest regrowth, original canopy cover and tree size on saproxylic beetles associated with old oaks. Biological Conservation 95 (2000) 85-94.
The relation between light and trunk diameter and number of saproxylic beetle species on old oaks


Is it possible to create artificial hollow trees? And if yes, how far from a dispersal source can saproxylic beetles colonize them?

Me filling the oak boxes with artificial wood mould
To study if it is possible to create habitats helping species living in cavities in old trees we (Thomas Ranius, SLU, Uppsala and I) have mounted (starting in 2002) big boxes (50), similar to bird nesting boxes for larger owles in the oak landscape south of Linköping in Sweden. They are made of oak wood and filled with different stuff, simulating the real wood mould in hollow trees. We are studying the colonization of the boxes during 10 years. After three years we made the first study and got very interesting results. In total 70% of the species inhabiting old hollow oaks in the region had colonized the boxes. We have also 120 other boxes studying the effect of single and clustering of boxes.

Jansson, N., Ranius, T., Larsson, A. & Milberg, P. 2009. Boxes mimicking tree hollows can help conservation of saproxylic beetles. – Biodiversity & Conservation    18,  3891–3908.

Can we find species indicating high species richness of red-listed beetles in old oaks?

Osmoderma eremita and Elater ferrugineus, two indicator candidates?
Insect surveys are time consuming and cost a lot. It would be of great value for the nature conservation, if some of the species could indicate the sites of greatest value. We work with my results from trappings of saproxylic beetles in 75 sites with old oaks, spread in three counties in southern Sweden (Östergötland, Örebro and Halland) together with Mats Jonsell, SLU, Uppsala and his studies in the Stockholm region. We tested the effect of number of indicators, collecting method, importance of abundance data and the transferability of indicator sets to other regions.

Jansson, N., Bergman, K-O., Jonsell, M. & Milberg, P. 2009. An indicator system for identification of sites of high conservation value for saproxylic oak ( Quercus spp.) beetles in southern Sweden . – Journal of Insect Conservation 13: 399-412.



How much can saproxylic oak beetles gain from habitats on other tree species?

To understand the importance of other tree species for saproxylic beetles living on oak (Quercus robur) at a landscape level we compare the fauna caught with traps in and on old hollow trees of Tilia, Fraxinus and Hippocastanea with Quercus in southern Sweden. In Sweden we often find the other trees in avenues allong roads. Preliminary results show a high overlap between the four studied tree species.

How similar is the saproxylic beetle fauna living on old living oaks with dead fallen oak logs?

To get a picture of the saproxylic beetle fauna living on old oaks and dead fallen oak logs we used window traps during one season in an oak landscape in southern Sweden. Preliminary results show a smaller overlap than we expected between the species communities.

One of the investigated sites in Turkey and two Lamelicornia species from Sweden (upper: Liocola marmorata and Potosia cuprea) and from Turkey (Protaetia speciosa & Protaetia merifica)

How rich are the saproxylic beetle fauna on old oaks in Turkey?

Turkey are a country with high diversity in many animal and plant groups. There are at least 18 species of Oaks (Quercus spp) in Turkey. The fauna living on these trees are poorly studied. The habitats with old oaks are threatened by forestry activities and we aim to reveal the high biodiversity. From 2005 I have (together with entomologists from five Turkish Universities (Cukurova University in Adana, Adiyaman University, Antakya University, Suleyman Demirel University in Isparta and Balikesir University) studied the saproxylic beetle fauna of old oaks in Turkey. So far we have studied the fauna in 10 oak areas and have nearly completed the identification the beetles from four of the areas. The species lists are very long and the result are very interesting. So far we have described 25 new species to science.

- Ruzieka, J., Jansson, N. & Coskun, M. 2006. Complementary description of Catops hanusi (Coleoptera: Leiodidae: Cholevinae), with notes on its bionomy and occurrence in Turkey . Entomol. Probl. 36(2): 43-46.

- Schillhammer, H., Snäll, S., Coskun, M. & Jansson, N. 2007. The West Palearctic species of Hesperus Fauvel, 1874, with description of three new species from Turkey (Coleoptera: Staphylinidae: Staphylininae). - Koleopterologische Rundschau 77: 123- 132.

- Novak, V., Jansson, N., Avci, M., Sarikaya, O., Coskun,, M., Atay, E. & Gürkan, T. 2011. New Allecula species (Coleoptera: Tenebrionidae: Alleculinae) from Turkey studies and reports. - Taxonomical Series 7: 335-346.

- Platia, G., Jansson, N., Avci, M., Sarikaya, O., Coskun, M. & Kayis, T. 2011. New species of click beetles from Turkey (Coleoptera, Elateridae). - Boletín de la Sociedad Entomológica Aragonesa 48: 207-215.

- Sama, G., Jansson, N., Avci, M., Sarikaya, O., Coskun, M., Kayis, T, & Özdikmen   H. 2011. Preliminary report on a survey of the saproxylic beetle fauna living on old hollow oaks (Quercus spp.) and oak wood in Turkey. - Munis Entomology and Zoolology 6: 819-831.

- Avgin, S.S, Magri, D., Antonini, G., Mancini, E,. Jansson, N., Lason, A., Cline, A.R. & Audisio, P. 2012. Review of the cedar och oak forest-associated Epuraea latipes species group (Coleoptera: Nitidulidae, Epuraeinae), with description of a new species from southern Turkey . – Entomol. Fenn. 23: 49-62.

How similar is the saproxylic beetle fauna on oaks in different parts of Europe and Mediterranean region?

Together with entomologists from Turkey, Italy, Spain, France, UK, Czech republic, Poland and Israel we will compare my Swedish studies with their similar studies of the saproxylic beetle fauna on old Oaks. 

Responsible for this page: Per Jensen
Last updated: 08/21/13