Banka semena” graba (C. betulus L.) u šumskoj prostirci u srednjedobnoj sastojini za rekonstrukciju na području Morovića

Abstract

Količina zdravog semena graba u sastojinama za rekonstrukciju iz aktuelnog i prethodnih uroda predstavlja element za predviđanje podmlađivanja te vrste i racionalnu primenu herbicida koji se danas koriste u postupku rekonstrukcije. U srednjedobnoj sastojini graba, na staništu mezofilne šume lužnjaka i graba sa poljskim jasenom u neplavnom području Ravnog Srema (Carpino betuli-Quercetum roboris (Anić, 1959) Rauš 1971. subass. Fraxinetosum angustifoliae Tomić, 2007) evidentirano je prisustvo poljskog jasena, klena i poljskog bresta, dok lužnjak, kao primarni edifikator zajednice i privredno najvažnija vrsta drveća, nije bio zastupljen. Istraživana sastojina je stara 55 godina i rezultat je neuspele obnove lužnjaka, usled čega je opredeljena za rekonstrukciju. U neproređivanoj sastojini (OP 1) evidentirano je ukupno 1217 stabala po hektaru, a u proređivanoj sastojini (OP 2) 530 stabala po hektaru. U proređivanoj sastojini zastupljeno je 43,5% od ukupnog broja stabala i 40% od ukupnog broja stabala graba, u odnosu na neproređivanu sastojinu. Srednji (dg) i dominantni prečnici (Dg20) graba u neproređivanoj sastojini iznose 17,4 cm i 23,6 cm, a u proređivanoj 19,0 cm i 27,6 cm. Srednje visine po Loraju i srednje dominantne visine su u rasponu 22,2-23,9 m na OP 1 i 20,5-22,2 m na OP 2. Količina semena graba na površini zemljišta je slična u analiziranim sastojinama. Od ukupnog broja semena po jednom m2 prosečno je u neproređenoj sastojini zastupljeno 1142 kom. m-2 zdravog semena, a u proređenoj sastojini 1117 kom. m-2. Iz rodne 2018. godine, koja je definisana kao godina obilnog uroda graba na području Ravnog Srema, na površini zemljišta u neproređenoj sastojini ukupan broj semena graba iznosio je prosečno 1024 kom. m-2, a u proređenoj sastojini 1041 kom. m-2. Sastojine u kojima je prvobitno grab bio dominantna vrsta drveća, usled efekta proreda sastojina, dominantno postaju meštovite, što je novi elemenat koji definiše postupak njihove rekonstrukcije u većoj starosti. ,,Banku semena'' u srednjedobnoj sastojini za rekonstrukciju pod uticajem različitog gazdinskog tretmana čini zdravo seme 85-88% iz uroda 2018. godine, a 12-15% iz prethodnih uroda.

In a high, middle-aged stand of European hornbeam, on a site of mesophilous pedunculate oak, European hornbeam and narrow-leaved ash in the unflooded part of Ravni Srem (Carpino betuli-Quercetum roboris (Anić, 1959) Rauš 1971. subass. Fraxinetosum angustifoliae Tomić, 2007), the following tree species from the natural forest community were present: narrow-leaved ash, field maple and field elm. Pedunculate oak, a primary edificator of the community and economically the most important species was absent. The stand is 55 years old and originates from a failed regeneration of pedunculate oak. Thus, the silvicultural prescription is restoration. The number of trees in the unthinned part of the stand (EP 1) was 1217 trees per hectare and in the thinned part (EP 2) 530 trees per hectare. In the thinned part of the stand, 43.5% of the total number of trees and 40% of the total number of trees of European hornbeam were counted, compared to the unthinned part of the stand. The quadratic mean diameter (dg) and dominant trees diameter (Dg20) in the unthinned part of the stand were 17.4 and 23.6 cm and in the thinned part of the stand 19.0 and 27.6 cm. The Lorey's mean height and the dominant heights were between 22.2 and 23.9 m on EP 1 and 20.5 to 22.2 on EP 2. The amount of European hornbeam seed on the soil surface in different stands is similar. In the unthinned part of the stand, the mean number of European hornbeam seeds was 1195 pcs m-2 (100%) and in the thinned part 1177 pcs m-2 (98.5%). The mean number of healthy seeds on the soil surface in the thinned and unthinned stands was 1117-1142 pcs m-2. The seeds from previous years participate with 12.2-15.0% (136-171 pcs m-2) and the seeds from the 2018 mast year 85.0-87.8% (971-981 pcs m-2), with 95% of the seeds being healthy (971-981 pcs m-2). Due to the effect of thinnings, the stands that were dominated by European hornbeam become more mixed, which is a new element that defines the process of the restoration in the future. Seedbank in the middle-aged stand designated for restoration under different managing strategies is made up of 85-88% of healthy seeds from 2018, with 12-15% from previous years.