Functional response of Quercus robur L. to taproot pruning: a 5-year case study

Joanna Mucha,Marcin Zadworny,Piotr Łakomy,Bartosz Bułaj,Jacek Oleksyn,Adrian M Talaśka,Andrzej M Jagodziński

doi:10.1007/s13595-018-0708-8

Abstract

Key messageQuercus roburseedling mass was affected more by planting density than by taproot pruning. Root pruning enhanced stem biomass at the expense of roots in later growth stages. Alteration of biomass allocation due to nursery practices may result in greater susceptibility to injury and death of the seedlings under unfavorable environmental conditions.ContextPlants adjust their growth and modulate the resource allocation in response to applied treatments and environmental conditions.AimsThe aim was to examine how taproot pruning in seedlings grown at different densities affected long-term growth of Quercus robur.MethodsSeedlings, sown as acorns at two planting densities, with or without pruned roots were harvested in the second, fourth, and fifth years of growth. The effect of root pruning on biomass allocation was determined by measuring leaf, stem, and root mass fractions; carbohydrate concentrations in the roots; and C/N ratios. Specific leaf area and root length were also determined to assess morphological adaptations to growth conditions.ResultsTotal seedling mass was affected more by planting density than by taproot pruning. After 4 years of growth, root mass fractions were lower and stem mass fractions were greater in seedlings planted at a higher density. Five-year old root-pruned seedlings also had a lower root mass fraction and higher stem mass fractions than unpruned seedlings. Specific root length was not affected by root pruning or planting density.ConclusionDecrease of relative root biomass with simultaneous increase of stem biomass may be a long-term consequence of taproot pruning of Q. robur, and the effects may manifest years after the seedling stage.

Highlights

Effective forest management relies on high-quality seedlings that have a balanced root/shoot ratio
Specific root length was not affected by root pruning or planting density. & Conclusion Decrease of relative root biomass with simultaneous increase of stem biomass may be a long-term consequence of taproot pruning of Q. robur, and the effects may manifest years after the seedling stage
Plants grown at the higher planting density accumulated less biomass after 4 years of growth than plants grown at the lower planting density

Summary

Introduction

Effective forest management relies on high-quality seedlings that have a balanced root/shoot ratio. The ability of a plant to compensate for lost roots, largely depends on plant species (Peter and Lehmann 2000; Tsakaldimi and Ganatsas 2006) Other factors, such as planting density, can affect seedling root systems (Moreno and Cubera 2008), and may modify the effect of root pruning on water and nutrient uptake (Dong et al 2016; Dumroese et al 2013; Poni et al 1992). The effects of root pruning and high planting densities on seedling allometry in a nursery, and on nutrient acquisition traits, are not well understood. It is not known if these factors have a longterm effect on specific plant organs or on whole tree growth. Determining the impact of root pruning and planting density on root traits are of particular importance because of the essential role the root plays in resource acquisition (Bonan 2008)

Objectives

Methods

Results

Discussion

Conclusion