S. Mahunka szerk.: Folia Entomologica Hungarica 57. (Budapest, 1996)

3. Are there significant differences in the braconid species assemblages between the mixed oak forest stands (i.e. approaching natural conditions) and the pure oak forest stands (i.e. merely with oak trees in the canopy brought about by the forestry activity)? 4. Does the phenology of the braconid species exhibit fluctuations in the oak forest stands in one vegetation season as well as in successive years? In the years 1986 and 1987 an investigation was carried out with Ichneumoninae spe­cies (Hymenoptera: Ichneumonidae) in the pine forest (Peucedano-Pinetum) of Puszcza Bialowieska, Poland (Sawoniewicz 1995). The following collecting method was applied: "Ichneumoninae were captured into Moericke's pitfall traps (yellow bowls) placed on the ground or in the litter cultures, and hung in canopies of pines in other stages." The study sites were extended to four developmental stages of the pine forests as follows: cultures of the 2-4 year-old pine seedlings, 15-22 year-old young stand, 40-60 year-old pole forest stand and 90-130 year-old mature forest stand. Concerning species composi­tion of Ichneumoninae the following ecological establishments have been disclosed by Sawoniewicz (I.e.): 1. "Shannon-Wiener index of species diversity reached its highest value (H' = 5.3) in the Ichneumoninae community from young stands of pine"; 2. "In the pole wood and mature stands, canopies of pines are a relatively uniform habitat at a height of 15-25 m, ... Due to that, the value of H' decreases as the stand grows older, from 5.3 through 4.5 to reach 4 in the mature stand. This is, however, accompanied by the formation of the core of the Ichneumoninae community, peculiar to that (i.e. canopy) forest layer". STUDY AREA The research project has been carried out in two areas near Budapest: Csobánka (about 20 km NW from Budapest) and Gödöllő (about 30 km E from Budapest): 1. Csobánka, Hosszú Mt., 300^100 m a.s.l., slope with ENE exposition: a) Elder (80 years old) mixed oak forest stand with the dominance of sessile oak and hornbeam trees (Querco petraeae-Carpinetum); b) Elder (70 years old) pure oak forest with the dominance of sessile and Turkey oak trees (Quercetum petraeae-cerris); c) Young (15 years old) oak forest stand with sessile and Turkey oak trees (Quercetum petraeae-cerris). The three oak forest stands were situated near to one another about 2-3 km. 2. Gödöllő, Babat, 250-300 m a.s.l., expositions rather on the tops of the hills: a) Elder (80-100 years old) mixed oak forest stand with the dominance of Tatarian maple, sessile oak and white oak trees (Aceri tatarico-Quercetum); b) Elder (70 years old) pure oak forest stand with the dominance of sessile oak and Turkey oak trees (Quercetum petraeae-cerris); c) Young (12 years old) oak forest stand with sessile and Turkey oak trees (Quer­cetum petraeae-cerris). The three oak forest stands were situated near to one another within about 4-5 km. The geobotanical description of the two forests has been presented for Csobánka by Zólyomi (1958) and for Gödöllő by Fekete (1965).

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