Effects of Mineral Soil and Forest Floor on the Regeneration of Pedunculate Oak, Beech and Red Oak

Stefanie De Groote,Kris Verheyen,Dries Bonte,Margot Vanhellemont,Luc Lens,María Carón,Lander Baeten,An Martel

doi:10.3390/f9020066

Stefanie De Groote, Kris Verheyen + Show 6 more

Open Access

https://doi.org/10.3390/f9020066

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Abstract

Early regeneration is a critical life stage that affects the future species composition of forests. Knowledge about regeneration success under different environmental conditions allows better understanding of forest dynamics. We studied the effects of seedbed conditions on the establishment and performance of seedlings of pedunculate oak, beech and red oak. In 50 plots of a tree-diversity oriented research platform in mature forests in northern Belgium (TREEWEB), we installed a field experiment with three treatments (potting soil, mineral soil, mineral soil + forest floor), in which we sowed seeds of each species. We monitored early establishment and survival, height, root and shoot biomass of the seedlings after two growing seasons. Mineral soil negatively affected seedling establishment and performance relative to the potting soil. The negative soil effects did not vary with measured abiotic soil properties. In general, the forest floor did not deteriorate or mitigate the soil effects, and only for root biomass did the forest floor partly compensate the negative soil effects. Forest floor effects did not vary with the measured forest floor properties. In the studied forests, creating bare soil was not enough to promote regeneration; improving soil properties might be important for the success of natural regeneration.

Highlights

The increased interest in close-to-nature forestry to restore and enhance forest functions [1] and the economic pressure to reduce forest regeneration costs favour the use of natural regeneration [2].Successful integration of natural regeneration in forest management is complex and requires thorough knowledge of ecological processes and their interactions with management
The design of the experiment in this study allowed us to focus on the effects of mineral soil and forest floor on seedling establishment and performance without confounding effects of aboveground environmental conditions, competing vegetation and seed predation
Seed quality was an important determinant for the success of natural regeneration

Summary

Introduction

Successful integration of natural regeneration in forest management is complex and requires thorough knowledge of ecological processes and their interactions with management. The forest canopy affects the biotic and abiotic conditions of the seedling environment, both aboveground and belowground. Alterations in light conditions by trees are known to strongly affect seedling regeneration dynamics [8,10,11]. Belowground, trees affect seedlings directly by competing for nutrients and water [12,13,14], and indirectly by influencing the abundance of soil pathogens [15,16] and by modifying the biogeochemistry of the soil [17,18,19]

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