Recreational preferences depending on thinning practice in young even-aged stands of pedunculate oak (Quercus robur L.): comparing the opinions of forest and landscape experts and the general population of Denmark

The aim of this study was to investigate to which extent forestry professionals, other “green” professionals (mainly landscape architects) and natural resource students in Denmark agree with the general population regarding their recreational preferences for contrasting stem densities in young, even-aged stands of pedunculate oak (Quercus robur L.). The study was based on five pairs of colour photographs from each of the five recently thinned experimental plots in a 13-year-old stand. The plots represented five different residual stem densities: 7000 (unthinned), 5300 (traditional thinning), 1000, 300 and 100 stems ha^?1. All cut trees were left on the ground. The analysis was carried out as a survey of forest and landscape experts (n=158) and the general public (n=243) based on questionnaires. Interviewees ranked the photographs according to the criterion: “Which forest environment do you prefer as a visitor?” Principal component factor analysis showed that the general public tended to perceptually group photos according to similar overall pattern of openness, presence of row structure and stand accessibility (including presence/absence of slash). As long as a stand appeared accessible, stand density had little influence on their preferences for a wide range of stand densities (5300?300 stems ha^?1). In contrast, foresters, other “green” professionals and students seemed to perceptually group photos according to treatment type, and the presence of slash had little influence on their preferences. This suggests an influence of professional background, making experts visually analyse and evaluate stands according to contemporary management standards and paradigms within their own profession.     

Effects of pruning and stand density on the productionof new epicormic shoots in young stands of pedunculate oak (Quercus robur L.)

Context

Avoidance or control of epicormic shoots is among the major silvicultural challenges for the production of high-quality oak timber. In northern Europe, contemporary oak silviculture aims to produce valuable timber on a relatively short rotation, applying early, heavy thinning combined with artificial pruning.

Aims

The aim of this study was to analyse the effects of pruning and stand density on the production of new epicormic shoots on young trees of pedunculate oak (Quercus robur L.).

Methods

The study was based on two field experiments in even-aged stands of pedunculate oak subjected to different thinning practices and early selection of potential future crop trees. From ages 13 to 15 years, stem density was reduced to 300 trees ha^?1, 1,000 ha^?1 or stands remained unthinned. Pruning was conducted on selected trees at ages 22–24 years. At that age, the stem density in unthinned control plots ranged from 2,500 to 3,100 ha^?1. All treatments were replicated twice within each experiment.

Results

Pruning led to an overall increase in the total production of new epicormic shoots. More epicormic shoots were produced in the lower part of the stem (0–3 m in height) than in the upper part (3–6 m). The number of new epicormic shoots increased with increasing stand density.

Conclusion

Early, heavy thinning combined with high pruning at regular intervals may help shorten the rotation length for pedunculate oak without further reduction in wood quality than that which is caused by wider annual growth rings.