Thinning effects on biomass and element concentrations of roots in adjacent hornbeam and oak stands in Istanbul, Turkey

Serdar Akburak,Ender Makineci

doi:10.1186/s40663-020-00279-4

Abstract

BackgroundThinning is a commonly used treatment in forest management which affects the tree root systems. The effects of thinning on element concentrations and seasonal change of roots were evaluated in adjacent oak (Quercus frainetto Ten.) and hornbeam (Carpinus betulus L.) stands according to the different root diameter classes.MethodTwo replicated control and thinning plots (50 m × 50 m) were set for each species (hornbeam and oak). Thinning treatments (November 2010) reduced 50% of the basal area in both oak and hornbeam stands. Roots were assessed by seasonal collection over 2 years (from October 2010 to October 2012). The roots were then sorted into diameter classes of 0–2 mm (fine roots), 2–5 mm (small roots) and > 5 mm (coarse roots). C, N, P, K, Ca, Na, Mg, S, Mn, Fe, Al, Zn, Pb, Ni, Cu and Cd were analyzed.ResultsExcept coarse roots, the highest root biomasses were determined in April-2011 in all plots. Fine-root biomass in oak was found significantly higher in control plots. In contrast to the oak, the fine-root biomass in the thinned hornbeam plots was higher than in the controls. The small-root biomass did not significantly differ between the thinned and the control plots in both oak and hornbeam stands. However, the coarse-root biomass showed significant differences between the control (1989 g∙m− 2) and thinned plots (1060 g∙m− 2) in oak, while no difference was detected in hornbeam. The concentrations of C, Al, Pb, Cd, Ni, Zn, Mn, Na, K, Mg and P in the fine roots of oak were significantly higher in the thinned plots. However, the concentration of Pb, Cd and Fe in the fine roots was significantly higher in the thinned plots of hornbeam. Significant differences were observed between the species for all elements in the fine roots except for C, N and P. In particular, elements in the fine roots tended to increase in July in the oak. In the hornbeam, all element concentrations in the fine roots (except C, N, and S) in the thinned plots showed a tendency to increase in April. The concentrations of Pb, Ni, Al, Fe, Cu, Ca, Na, K, Mg and P in the hornbeam control plots increased during the April 2011 period.ConclusionThe results indicated that thinning effects on temporal changes and concentrations of elements in the roots could be attributed to species-specific characteristics.

Highlights

Thinning is a commonly used treatment in forest management which affects the tree root systems
The results indicated that thinning effects on temporal changes and concentrations of elements in the roots could be attributed to species-specific characteristics
The present study aimed to evaluate the effects of thinning treatments on the element concentrations and seasonal change of roots according to the different root classes in oak (Quercus frainetto Ten.) and hornbeam (Carpinus betulus L.) forest stands

Summary

Introduction

Thinning is a commonly used treatment in forest management which affects the tree root systems. Tree root systems play a vital role in forest ecosystem functions (durability, uptake of water and nutrients, synthesis of various key components including growth regulators, improvement of soil and water infiltration, root canal aeration and prevention of soil erosion) (John et al 2001; Jose et al 2004; Thevathasan and Gordon 2004; Jose 2009; Ramachandran Nair et al 2009). Since a significant proportion of the total biomass in the ecosystem is composed of belowground plant parts, the contribution of the roots in the introduction of nutrients and organic matter into the soil is important for the continuity of the carbon budget and soil fertility (Lehmann and Zech 1998). Tree roots are important in serving all biomass components in many ecosystems (Brunner and Godbold 2007). Researches on root dynamics and production play an important role in the impact of environmental degradation on ecosystem processes and in the assessment of net primary production of terrestrial ecosystems (Yang et al 2010)

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Conclusion