The Role of Cambio- and Xylophagous Insects in the Process of Dying-Off of Fir Stands in Ojcow National Park Affected by Industrial Imission

1988

S. 17-30

1 Abb., 4 Tab., 16 Lit. Ang.

Unselbständiges Werk

200048413

In the years 1976-1980 in the area of Ojcow National Parkan investigation was carried out on the settling of firs by cambio- and xyloph agous insects as depending on different "dying-off phases" and stand layers from which dead standing trees were self-thinning. With the progressing dying-off process firs from the main stand were settled by insects zonally, beginning from the top parts of trees which were to the greatest degree damaged by industrial immission. The settling of these trees took about 3 years. The dying-off firsfrom the dominated and understoried stand layer occurred simultaneously in who le crowns and trunks of trees, this shortening the settling by insects to one year. The associations of noxious insects settling firs changed under the influence of different factors, such as the phase and period of the dying-off, the site of the given dying off tree, and the extent of immission affecting the firs.The role of particular insect associations which enhance the rate of dying-off of fir stand was different as depending upon the ecological conditions. Thechief role in activating the fir dying-off was played by Pissodes piceae, Pity okteines spinidens, Pityokteines curvidens, Pityophthorus pityographus, Pityokteines vorontzovi, and the Siricidae family. In the dominated and understoried stand layer this role was played by Cryphalus piceae, Pityophthorus pityographus, Obrium brunneum, and Clytus lama. Some xylophagous insects, such as Sirex juvencus, and Serropalpus barbatus settled fir trunks in early stages of dying-off, before the trees were settled by cambiophages.