Beskydy 2013, 6, 99-108
The structure analysis of the Norway spruce stands after schematic thinning in the 1st protected zone of water-supply storage
The water-supply storages are important resources of drinking water in some regions of Slovakia, especially in surrounding of Banská Bystrica. Málinec is one of the three storages in this region. In protected zone of this storage are planted Norway spruce (hereinafter „spruce“) stands monocultures because of ensuring required water quality in storage. There are 24 years old spruce stands without admixture of deciduous trees in the upper layer. Understory is formed by blackthorn (PRP 1). On this locality was carried out geometric (schematic) thinning what is not recommended in protected zones because of worse influencing of soil permeability, humus decomposition and open forest edge creating. There was identified one older permanent research plot (PRP) and established one new PRP where was performed own measurements. Into the PRPs there are transekts and remaining area. Acreage of PRP is 0,234 and 0,315 ha. On the whole area were measured tree diameter and assessed tree classes (5 degrees–Polanský 1955). Moreover, on transekts were measured tree and also crown height. Based of measured variables were calculated stand characteristics like slenderness ratio, crown ratio, growing stock and basal area. If it is possible, these were compared with older results. The aim of this work is evaluation of spruce stands structure and their stability after schematic thinning. This kind of silvicultural treatment is absolutely unfit in stands with specific (water-protested) function (Slodičák et al. 2010). These stands are from the perspective of static stability too unfit–basal area and abundance of trees is nearly as in yield tables (Kolektív 1992) but growing stock is much higher and a lot of trees is too slim. The slenderness ratio is from 75 to 90 %. But the crown lenght is quite good with crown ratio 52–64 %. In these ages of stands are crowns reduced too much. Suitable individual thinning has been in these stands neglected (growing stock is higher than normal). There is assumed reduced stand lifetime after schematic thinning. Current stand structure is due to the young age inappropriate.
