Nitrogen mineralization in soils of the oldest climax communities


Thesis Type: Doctorate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2020

Thesis Language: Turkish

Student: Fatma Selcen Sakar

Supervisor: GÜRCAN GÜLERYÜZ

Abstract:

In this study, nitrogen mineralization and annual net yield in two different soil layers (0- 5 cm and 5-20 cm) of oldest pure Abies bornmuelleriana (AB) Fagus orientalis (FO) and Pinus nigra, (PN) communities and mixed A. bornmuelleriana-P. nigra (AP) and A. bornmuelleriana - P. nigra - F. orientalis (APF) communities of which are in association with them was investigated using by the field incubation method for one year. Sampling sites were selected from an altitude range of 1300 to 1600 m in mountain belt of Mount Uludağ, Bursa, Turkey. These forest communities were compared according to annual net mineral nitrogen yield and some soil properties [total N, organic C, C/N ratio, moisture (%), pH and water holding capacity (%)], and total phenolic compounds and hydrolyzed tannic acid of litter. While annual net Nmin yield was highest in F. orientalis (43,9 ± 4,8 kg / ha / year) it was lowest in A. bornmuelleriana - P. nigra - F. orientalis (25,8 ± 7,2 kg / ha / year). The net Nmin yield of other compositions was estimated as 37,8 ± 4,9 kg / ha / year for A. bornmuelleriana, 30,5 ± 4,2 kg / ha / year for P. nigra, 37,0 ± 10,3 kg / ha / year for A. bornmuelleriana - P. nigra. These results indicate that tree species and seasonal soil moisture contents play important roles in N cycling in oldest forest ecosystems. In addition, it has been shown that total phenolic compounds and hydrolysed tannic acids play an important role in controlling nitrogen turnover in forest ecosystems. It was revealed that nitrification are inhibited by both total phenolics and tannic acid in litter, in contrast the total phenolics compounds stimulate the ammonification.