The Velký a Malý Bezděz Nature Reserve is located in Ralska Upland, ca. 50 km north of Prague. Hill-tops and steeper slopes of two hills (Velký Bezděz, 603 m a. s. l. and Malý Bezděz, 578 m a. s. l) are mostly covered by low, semi-open forests with no or sparse undergrowth. The surroundings of the Nature Reserve is covered mainly by pine plantations with fragments of beech forest remaining on other several hill-tops. The most significant animal species, as well as the main subject of the protection in the Nature Reserve, is the beetle Rosalia longicorn (Rosalia alpina), although other rare saproxylic beetle species are also present (e.g. Necydalis ulmi, Osmoderma barnabita or Elater ferrugineus).
Three hills (Velký Bezděz, Malý Bezděz and Slatinné Hills) inhabited by the Rosalia longicorn were selected to carry out the mark- recapture survey in 2008, 2009 and 2015. At each site, suitable trees and coarse woody debris were selected and searched for adult beetles on a regular basis. Discovered individuals were marked by a unique number on elytra using a black permanent marker and immediately released to their original positions. We found out that the total population at the three studied sites consisted of ~2000 individuals a year and it was comparable to all studied years, although some fluctuations in population size could be observed. Also, we recorded that adults frequently move among sites within a habitat patch, and are able to cross considerable distances. For more details see the reports below (in Czech).
The studied population of the Rosalia longicorn in Ralska Upland is probably the last population surviving in Central Europe north of the Alps and west of the Carpathians. It is isolated from other known populations by hundreds of kilometres, and it has been probably for decades. To increase chances for its survival it is vital to (i) stop logging and (ii) dead-wood removal in old beech forest remnants, (iii) increase the area of semi-open beech woodlands, particularly on hill-tops and slopes; and (iv) restore active management of beech pollarding/coppicing/shredding to create trees of preferred habitus.
Demography and Dispersal Ability of a Threatened Saproxylic Beetle: A Mark-Recapture Study of the Rosalia Longicorn (Rosalia alpina)Drag et al. 2011, PLoS One.