Invasion of Matrix Species in Small Habitat Patches

The diversity, expressed as species richness in equal-sized samples, of wood-living beetles in successional stages of deciduous forest after forest fires approximately 100 years ago did not differ between patch sizes in this study. Thus, the crucial question for conservation is whether the lack of reduction in diversity in small patches means that a number of small patches can elevate the regional diversity as efficiently as can one larger area. In the present study, the smaller patches did not differ from larger patches in substrate availability, quality, or heterogeneity. The frequency of a group of species was measured as the number of occurrences, viz. the number of trees on which a species was found, summed over all species in the group. The number of occurrences of species unique to the specific patch-size group did not differ between large and small patches. The number of occurrences of species that preferred matrix areas (managed coniferous forest and clearcuts) was, however, larger than expected in small patches. The results indicate that small patches, although having high local (alpha) diversity, are more similar in species composition to neighboring matrix areas (reduced beta diversity). Thus, small areas contribute less to the regional (gamma) diversity than do larger areas

Hotade vedinsekter i fem lövbrännor i norra Hälsingland

Vedlevande insekter i brandpåverkade lövskogsområden i Ramsjö socken,Ljusdals kommun i norra Hälsingland inventerades under 1986 till 1989.Fem fragment av lövbrännor med en skog huvudsakligen föryngrad efter brand år 1888 i storlek mellan 7 och 109 hektar undersöktes tillsammans med fem provrutor i rationellt brukade skogsområden.Dessa senare provrutor låg i skog som gallrats,fickats och/eller kalavverkats i områden med en delvis annorlunda brandhistorik.Totalt har 256 vedlevande insektsarter identifierats varav 218 är skalbaggar.Regionala inventeringsrapporter import från MDP 2015-05</p