Společenstva xylofágního hmyzu v lužním lese: distribuce a hostitelská specificita

Mgr. Štěpán VODKA

Master's thesis

Communities of xylophagous insects in floodplain forest: distribution and host specificity

Abstract:

Lesy středoevropské krajiny prošly během své historie mnoha změnami (od otevřeného porostu k zapojeným lesům), což způsobilo razantní úbytek jejich diverzity. Tato studie testuje mikrohabitatové preference xylofágního hmyzu metodou vychovávání hmyzu z exponovaných návnad a zabývá se vlivem lesního managementu na tento hmyz. První část práce (nepublikovaný rukopis)testuje 5 lesních stanovišť (podrost a koruna uvnitř lesa, podrost a koruna na okraji lesa, louka se solitérními duby) na dub žeroucí xylofágy. Výsledky jasně ukázaly, že druhově nejbohatší je podrost okraje lesa, tedy struktura podobná pařezině. Množství odumřelé dřevní hmoty nemělo žádný vliv. Druhá část pojednává vertikální stratifikaci a vlivu oslunění habitatu na xylofágy žeroucí na 8 druzích dřevin (Alnus glutinosa, Populus alba, P. x canadensis, Salix alba, Carpinus betulus, Quercus robur, Tilia cordata, Ulmus laevis). Výsledky ukazují, že společenstva hmyzu odráží evoluční historii hostitelské dřeviny a mají různé preference k vertikální srtatifikaci i oslunění u různých stromů. Nicméně mnoho xylofágů preferuje osluněné habitaty a zdržují se pouze na okrajích lesa. To ukazuje na potřeby změny k managementu lesů směrem k více prosvětleným porostům. Bezzásahový management se neukázal jako nejvhodnější řešení.

Abstract:

During the last century the forests of Central Europe changed from open woodlands to even-aged stands with closed-canopy. This change resulted in severe decline of forest biodiversity. This study examines how, and why such change affected xylophagous insects. I have studied microhabitat preferences, i.e. distribution of xylophagous insects in canopy and understorey of closed forests, forest edges and wooded meadows. I used method of rearing insect from timber baits exposed to ovipositing females of xylophagous insects in different situations in the forest at the beginning if vegetation season. After one season of exposition,the baits were collected enclosed in fly-wire cages, where emerging insects were collected for two seasons. This thesis consists of two parts: The first part is an unpublished manuscript dealing with effect of habitat insolation, vertical stratification, forest structure and amount of dead wood on community of long-horned beetles (Cerambycidae) and jewell beetles (Buprestidae) feeding on wood of pedunculate oak (Quercus robur). Baits were exposed in the canopy and the understorey of forest interior, the canopy and the understorey of forest edge and on solitary trees on wooded meadows. Most insect species do prefer insoled wood for their development, and were more common in the understorey than in the canopy. Insolation of bait was thus the prime factor affecting composition of reared insects. No relation was found between dead wood volume and species composition or abundance of reared insects This shows that insolation of the dead wood is crucial to conservation of most xylophagous insects. The second part of the thesis studies effect of vertical stratification and insolation on distribution of xylophages feeding reared from wood of 8 tree species (Alnus glutinosa, Populus alba, P. x canadensis, Salix alba, Carpinus betulus, Quercus robur, Tilia cordata, Ulmus laevis) and host specificity of xylophages. Results show that: (i) community composition of xylophages reflects evolutionary history of their host plants; (ii) communities reared from different trees exhibit different preferences for forest strata and insolation of the habitat, probably in connection to preferred growth conditions of the host plant, (iii) many xylophagous insect species exhibit strong preferences to insoled habitats, and are thus confined to forest edges in extensively managed forests as well as in unmanaged forest reserves.

Keywords

Xylofág, mrtvé dřevo, vertikální stratifikace, management lesa, historie lesa, pařezina, střední les, pastevní les

Language used: Czech

Date on which the thesis was submitted / produced: 23. 4. 2007

Accessible from:: 23. 4. 2007

Identifier: 3940

Thesis defence

• Date of defence: 28. 5. 2007
• Supervisor: Mgr. Lukáš Čížek, Ph.D.

University of South Bohemia in České Budějovice

Faculty of Science

Master programme / field:
Zoology / Zoology