Lessons learned from oak cluster planting trials in central Europe

Abstract

Oaks (Quercus spp.) are becoming increasingly important for future forest management as the climate in central Europe warms. Owing to the high costs of conventional row planting, artificial oak stand establishment in the form of "clusters" became popular in central Europe beginning in the 1970s. In cluster plantings, oaks are planted either in groups of ca. 20-25 at 1 m spacing between trees (i.e., group planting) or in denser groups with 20-30 oaks·m −2 (i.e., nest planting). In both cases, the clusters are spaced apart at a distance that represents the target density of future crop trees. A comprehensive review of the history, growth, tree quality development, and economic aspects of oak cluster plantings suggests that initial growing space was the most important factor influencing development of oaks in clusters. Consequently, survival, growth, quality, and biomass production were comparable in group and row plantings but lower in nest plantings. In addition, group plantings resulted in greater stand-level tree species diversity than nest or row plantings. We conclude that oak group planting is a comparatively inexpensive option for the artificial regeneration of oak-dominated broadleaved forests for a range of situations such as reforestation of disturbed areas or the afforestation of abandoned agricultural land. Future research needs regarding development and tending of forests established by oak group planting are highlighted.Key words: oak regeneration, tree quality and growth, species diversity and productivity, plant competition, forest restoration.Résumé : L'importance des chênes (Quercus spp.) pour l'aménagement forestier du futur augmente avec le réchauffement du climat de l'Europe centrale. En raison des coûts élevés de la plantation conventionnelle en rangée, l'établissement de chênaies artificielles selon une répartition par grappes est devenu populaire en Europe centrale au cours des années 1970. Dans les plantations en grappes, les chênes sont plantés en groupes d'environ 20 à 25 avec un espacement d'un mètre entre les arbres (c.-à -d. la plantation en groupes) ou en groupes plus denses de 20 à 30 chênes par m 2 (c.-à -d. la plantation en nids). Dans les deux cas, l'espacement entre les grappes est déterminé de façon à obtenir la densité cible des arbres d'avenir. Une analyse complète de l'histoire, de la croissance, du développement de la qualité des arbres et des aspects économiques de la plantation de chênes en grappes indique que l'espacement initial entre les plants est le facteur qui influence le plus le développement des chênes dans les grappes. Ainsi, la survie, la croissance, la qualité et la production de biomasse étaient semblables dans les plantations en groupes et en rangées, mais étaient moindres dans les plantations en nids. De plus, à l'échelle du peuplement, une plus grande diversité en espèces d'arbres a été observée dans les plantations en groupes comparativement aux plantations en nids ou en rangées. Nous concluons que la plantation de chênes en groupes est une opti...

Post-Fire Restoration Plan for Sustainable Forest Management in South Korea

“…Planting oak is a viable option when there are not enough sprouts and under conditions of high mortality [20]. The recommended oak restoration method is group planting, which was introduced to Europe in the 1980s and 1990s as an economic and ecological alternative to traditional row planting for reforestation of distributed areas [40][41][42]. Group planting uses larger seedlings or saplings (0.8-1.5 m tall) and a wider initial spacing (1 × 1 m).…”

“…Irrespective of the group design, spacing between the group centers was kept at 10 × 10 m or 10 × 12 m, resulting in 80-100 groups ha −1 . Group planting resulted in greater stand-level tree species diversity than did row planting [40][41][42]. Oak group planting is a comparatively inexpensive option for the artificial regeneration of oak-dominated broad-leaved forests for a range of situations such as reforestation of disturbed areas.…”

“…However, oak planting based on row planting in burned areas indicates that the tree species richness has not been achieved [40][41][42]. Based on other studies, group planting of oak is recommended as an alternative to traditional row planting for greater stand-level tree species diversity and natural regeneration, which may result from an increase in the size of the unplanted area between groups [40][41][42]. Recreational forests aim to improve recreational value to visitors and residents while preserving the ecological value.…”

“…Despite the gradual recovery of the forests in the burned areas, oak and pine do not produce high-quality harvestable trees [37]. In addition, the lack of natural regeneration of other tree species and the low species diversity reported for row planting are undesirable attributes of this classic type of crop cultivation [40][41][42]. Overall, these factors motivated this study to seek alternatives to the conventional row planting approach for establishing crop stands.…”

“…Overall, these factors motivated this study to seek alternatives to the conventional row planting approach for establishing crop stands. Group planting represents a reforestation method that not only offers the opportunity to produce high-quality oak timber but also promotes the natural regeneration of additional tree species between the groups [40][41][42]. This increases woody species diversity and possible productivity and allows natural successional processes to occur.…”