A review of black walnut (Juglans nigra L.) ecology and management in Europe

Valeriu‐Norocel Nicolescu ,Martina Đodan,Michal Pástor,Cornelia Hernea,Nicola La Porta,Tibor Benčať,Sanja Perić,Debbie Bartlett,Siniša Andrašev,Károly Rédei,Torsten Vor,Vasyl Lavnyy,Krasimira Petkova,Victor Sfeclă,Robert Brus,Vílém Podrázský ,Mилaн Maтaругa ,Branislav Cvjetković ,Jean‐Charles Bastien ,Igor Štefančík

doi:10.1007/s00468-020-01988-7

Abstract

Black walnut (Juglans nigra L.) is a light-demanding, competition-intolerant, and tall forest tree species, introduced in Europe from North America at the beginning of the seventeenth century. It has an important economic role in Europe for producing wood and fruits, in agroforestry systems, as an ornamental tree for parks and avenues, for rehabilitation/restoration of degraded lands. The best sites for black walnut growth have warm and mild climates, with frequent and well-spread precipitation, and rich, deep, near neutral, well-drained and moist soils. Black walnut is a fast grower in youth and its height and diameter growth reach their peaks before age 30–35 years. It is globally the best known allelopathic species due to the juglone substance present in all parts of black walnut trees. The species is storm-resistant and not affected by any major pest or disease in Europe. It is regenerated by planting or direct seeding on bare land, in monocultures and mixed stands. The management of stands with black walnut, with a rotation period generally up to 80 years, include weeding (mandatory), cleaning-respacing (in dense stands), thinning (mostly from above), high and formative pruning (mandatory), with the aim of producing valuable wood for sliced veneer, solid furniture, flooring/parquet, cabinetry, panelling, sculpture, musical instruments, gunstocks.

Highlights

Black walnut, considered as ”the most respected of North America’s fine hardwoods” and recognized worldwide as the “aristocrat of the fine hardwoods” (American Walnut Manufacturers Association 1998), is found throughout the central and eastern parts of the United States and in southern Ontario, Canada (Rink 1985)
Near the western edge of its range, black walnut may be confined to floodplains, where it grows either with American elm (Ulmus americana L.), hackberry (Celtis occidentalis L.), green ash (Fraxinus pennsylvanica Marsh.), box elder (Acer negundo L.), or with basswood and red oak (Quercus rubra L.) on lower slopes and other favourable sites (Landt and Phares 1973; Rink 1985; Williams 1990)
Management of black walnut Goals In European countries (e.g. Belgium, Bosnia and Herzegovina, Croatia, Czech Republic, France, Germany, Romania, Serbia, Slovakia, Ukraine) where black walnut is cultivated on different scales, the exclusive goal of its culture is the production of top quality wood for superior uses

Summary

Introduction

Black walnut, considered as ”the most respected of North America’s fine hardwoods” and recognized worldwide as the “aristocrat of the fine hardwoods” (American Walnut Manufacturers Association 1998), is found throughout the central and eastern parts of the United States and in southern Ontario, Canada (Rink 1985). The climate in areas suitable for the cultivation of this species should be warm and mild as black walnut requiries mean annual temperatures of 7-10.6 o C (Belgium, Wallonne Region - https://www.fichierecologique.be/resources/fee/FEE-JN.pdf), 7.5-8.5 o C (Slovakia - Hančinský 1972), over 8 o C (Germany - Ehring and Keller 2006), 9.6-11.4 o C (Bosnia and Herzegovina - Cvjetkovic pers.comm.).

Results

Conclusion