Full-text - Norsk entomologisk forening

with heather moor, willow thickets, birchshrubs, and former fields and/or meadows indifferent regrowing stages. Agricultural impacton vegetation decreases to the north andthe south. In the north the birch forest stretchesdown to the valley bottom before shrubor heather moor take over. To the south theriver mainly flow through shrub or heathervegetation.2) The terrain against GAvAlia (abt 940 to1000 m a.s.l.). In the south and south-easternparts of the sampling area, against GAvAlia,there is a rather large poorly-wooded terrain,in which bogs and tarns alternate with heathersand ridges. The drier parts are largelycovered by shrubs dominated by Salix glaucaL., Salix lapponum L., and Betula nana L.,and, more scattered, Juniperus communis L.3) The subalpine birch forest (840 to 1100m a.s.l.). Both blueberry and meadow birchforests are present. In some localities, especiallyon the western side of the Drivdalenvalley, a luxuriant understory vegetation ispresent, often dominated by Aconitum septentrionaleKoelle and Geranium sylvaticumL.4) The lowalpine region (abt 1100 to1300-1450 m a.s.l.). Due to different propertiesof the rocky ground, a more diversealpine flora is present in the Knutsh6s areacompared to alpine areas on the western sideof the Drivdalen valley. However, on bothsides of the Drivdalen valley, there is a zonecharacterized by willow species just abovethe tree border. In particular, this kind ofvegetation is well developed in the slopes upto Midtre Kmitsh6 mountain, and the dominatingwillow species are Salix phylicijoliaL., S. glauca, S. lapponum, Salix lanata L.,and Salix myrsinites L.5) The middle-alpine region (1300-1450to 1684 m a.s.l.), is characterized by grassesand Cyperaceae species. No part of the samplingarea reach up to the high-alpine.MATERIAL AND METHODSCollecting methods included net-sweepingand beating vegetation over a plastic tray.Specimens were removed from the tray or thenet by a moistend tiny martenhair brush, oran aspirator. Also, specimens were washedoff infested vegetation in soap-containingwater in a special apparatus (e.g. Tayler &Smith 1955, Ota 1968). For separating thripsspecimens from vegetation and litter a batteryof ten Berlese-Tullgren funnels, modifiedaccording to Macfadyens (1955) smallfunnel extractor with air conditioning wasemployed. Flying specimens were caught inthree suction traps of the «exposed conetype» (Johnson 1950, Taylor 1951, 1962)without any segregation mechanism. In additionwater traps of different colours wereused.The material was collected into AGA(Mound et Pitkin 1972, Mound et al. 1976),and afterwards transferred to 60% alcohol. ALeitz binocular, ordinary with 10X oculars,and a standard plankton counting chamber (aplate of plexiglas, 129 x 68 x 8 mm, with fourgrooves, each 120 x 5 x 5 mm, the bredthmeasured at the bottom) were used for countingspecimens. For identification and structuralinvestigations a number of specimenswere mounted on microscope slides in CanadaBalsam or Hoyers mountat. The microscopeused was a Standard WL Zeiss researchmicroscope, with 12.5X oculars, 2.4X, 10X,25X, 40X, and 60X objectives, phase contrast,ocular and optovar (0.8X-l.6X).All the material is deposited in the collectionsof The University of Trondheim, TheMuseum, Zoological department.DISTRIBUTION AND HABITAT/HOSTPLANT OF THE THRIPS SPECIESWiTHIN THE SAMPLING AREA INTHE DOVREFJELL MOUNTAINSIn Tab. 1 the available data on guest/hostrelationships and habitat preference of thethrips species at Dovrefjell are summarized.However, we should bear in mind that thripsare small insects easily spread by wind, andsome of the records may refer to animalsaccidently settled on unrelated vegetation.It is very difficult to judge how far theobserved distribution (Tab. 2) agrees withthe real species distribution in the area, becausethe collection effort varied from placeto place. In addition, several of the recordedspecies apparently have extremely low populationdensities at Dovrefjell and may therefore,by chance, have been missing in some ofthe collections. Nevertheless, it seems reasonablethat the observed distribution patternreflects differences in the climate and vegetationalcover between the localities. Thus, therelativly high number of thrips species recordedin the mixed vegetation along the Driva81