New methods of oak planting require modification of tending prescriptions under high browsing pressure – A case study from north-eastern Poland

Abstract

Interest in oak species in European forestry has been increasing as they are regarded as having high ability to cope with accelerating anticipated climate changes during the next 50 years. However, improvements in regeneration and silvicultural methods are needed due to oak stands’ high management costs and vulnerability to browsing. Thus, three methods of establishing oak stands were compared in terms of effects on growth and browsing damage in an area of north-eastern Poland with high browsing pressure of roe and red deer. The treatments were traditional monoculture, double-row planting and group planting, each at initial planting densities of 6600, 3300 and 2400 seedling per hectare. Three precommercial thinnings (PCTs) were applied in each planting treatment to reduce competition from early successional species: traditional removal close to the ground in spring, topping in spring and topping in summer. Observed frequencies of oak saplings damaged by browsing depended on both the planting method and PCT treatment. The frequencies were lower under group planting than under the traditional and double-row planting treatments. The frequencies also decreased with increases in the oaks’ height. The results indicate that the optimal PCT treatment to minimise browsing damage depends on the planting pattern. The lowest frequency of damage was in plots where group or double-row planting was combined with spring topping and traditional planting was combined with summer topping. Under heavy herbivory pressure, group planting might be optimal due to its potential to both reduce browsing damage and improve profitability by eliminating fencing costs.