Occurrence of Psocoptera in boreal old-growth forests

Abstract

We aim to assess habitat and host-tree preferences of psocids (Insecta: Psocoptera) sampled in old-growth-forest biodiversity studies conducted during 1997–2003 in central and southern Finland. Thirty-one out of the recognized sixty-nine Finnish species were found in the samples, four of which (Elipsocus abdominalis, Reuterella helvimacula, Stenopsocus lachlani and Trichadenotecnum majus) might be associated with old-growth forests or with old trees. Psocidus flavonimbatus, a rare taiga species only previously known from the 19th century holotype from Estonia, was repeatedly collected in Kuhmo region, eastern Central Finland. This species is possibly associated with boreal spruce-dominated old-growth forests and likely to prefer Norway spruce as a host tree. We also provide new distribution data for several species and discuss their host-tree preferences.

Taxonomy, habitat choice and distribution of <i>Kimunpsocus flavonimbatus</i> (Rostock, 1879) comb. n. (Psocodea: ‘Psocoptera’: Psocidae)

“…A total of 133 sites, of which 16 and 117 sites represented managed mature and semi-natural spruce forests, respectively, were included in the habitat-choice analyses. Consistent with earlier results (Kanervo & Várkonyi 2007), not a single K. flavonimbatus was found in the managed sites. The occurrence of K. flavonimbatus was clearly associated with the semi-natural spruce-dominated forests at both spatial scales (Table 1).…”

“…Kimunpsocus flavonimbatus was discovered in 13 new sites (cf. Kanervo & Várkonyi 2007) and recorded as a new species to the municipalities of Suomussalmi, Hyrynsalmi and Sotkamo in Kainuu, and to Valtimo in North Karelia (Fig. 4).…”

“…Our data strongly suggest that K. flavonimbatus is a habitat specialist species, confining its occurrence to pristine and semi-natural spruce-dominated forests. This hypothesis was originally put forward by Kanervo & Várkonyi (2007), but only our extensive survey in both (semi-) natural and managed spruce forests made it possible to test the hypothesis. Found in one-fourth (24.8%) of the oldgrowth sites, K. flavonimbatus seems to be relatively rare even in the semi-natural forests.…”

“…To address the basic habitat requirements of K. flavonimbatus, we first compared its incidences in semi-natural vs. managed mature spruce-dominated forests using all available data, collected using various methods between 1997 and 2008, at two spatial scales. At the scale of individual study sites, beating sites, sites with window traps, a single site with a light trap and a single site where K. flavonimbatus was reared from a sample of wood block, were considered as sampling units (for details see Kanervo & Várkonyi 2007 and Fig. 1 within).…”

“…It was not until 1997 that the species was rediscovered in Kuhmo, eastern Central Finland (see Lienhard & Kanervo 2002). During the following decade, a total of 42 specimens were obtained from semi-natural spruce-dominated forests in Kuhmo (see Kanervo & Várkonyi 2007). Since K. flavonimbatus was never collected in any other habitat nor in any other region in Finland, Kanervo & Várkonyi (2007) suggested that this species is associated with oldgrowth forests and restricted to the easternmost part of the country.…”