Intraspecific Competition Affects Crown and Stem Characteristics of Non-Native Quercus rubra L. Stands in Germany

Katharina Burkardt,Torsten Vor,Peter Annighöfer,Dominik Seidel,Christian Ammer

doi:10.3390/f10100846

Abstract

Accurate guidelines for silvicultural management of exotic tree species in Germany are sparse. For example, northern red oak (Quercus rubra L.) is the most commonly planted exotic deciduous tree species in Germany, but its response to varying levels of competition intensity has not yet been adequately explored. Here, we used terrestrial laser scanning to non-destructively examine the responses of stem and crown characteristics of Quercus rubra to intraspecific competition. A total of 100 dominant red oak trees were investigated in ten pure red oak stands, located in five federal states of Germany. The external stem quality characteristics namely stem non-circularity and bark anomalies decreased with increasing tree competition. Also, the crown characteristics crown volume, crown surface area, maximum crown area, crown length, and branch length declined by the degree of individual tree competition. We conclude that individual tree properties can be controlled by competition intensity, resulting in improved timber quality as shown for other tree species.

Highlights

Tree species selection and stand density control are usually the most important decisions forest managers can make
Two external stem characteristics and seven crown characteristics were significantly related to competition intensity
Bark anomalies per square meter were significantly related to competition

Summary

Introduction

Tree species selection and stand density control are usually the most important decisions forest managers can make. While the effects of silvicultural treatments that control competition intensity have been studied since the beginning of forest science [1,2,3] and are well known for native tree species [1,2,3,4,5], guidelines for exotic trees species are often lacking or are uncertain [6]. Northern red oak (Quercus rubra L.) is the most commonly planted exotic deciduous tree species in Germany, covering. Several studies have addressed silvicultural management of native oak species in Germany [10,11,12]. While there is general agreement that thinning from above is a suitable treatment [19,20,21,22], the discussion is ongoing regarding both the number of crop trees to be promoted and the degree of individual tree competition that promote timber quality [21,22]

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Discussion

Conclusion