Effect of tree shelters on the survival and growth of coniferous tree species in Central South Bulgaria

The effects of tree shelters on the survival, height and diameter growth of three coniferous tree species – Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and Silver fir (Abies alba Mill.) were observed. The study was conducted in two experimental plantations, established in the spring of 2016 in the Training and Experimental Forest Range Jundola (Central South Bulgaria). Three experimental variants with tree shelters – Tubex Ventex Classic, Layflat Shelterguard, Layflat Treeguard and a control one (without tree shelters) were used. Twenty to twenty-five seedlings in three replications of each variant and tree species were planted. The experimental plantation 1 included Scots pine and Norway spruce and was established on a south east-facing terrain at an altitude of 1400 m. The soil is Cambisols (FAO) mixture of clay and sandy, medium stony, medium deep to deep. The habitat is medium rich, slightly moist. The experimental plantation 2 is of Silver fir and was located on an east-facing terrain at an altitude of 1400 m. The soil is Cambisols (FAO) mixture of clay and sandy, medium stony, medium deep to deep. The habitat is medium rich, slightly moist to moist. In the autumn of the fifth year after the establishment, inventories and measurements of heights, height increment and groundline diameter of the seedlings were made. The survival in both experimental plantations was higher in the variants with tree shelter. The height growth of all tree species was better in tree shelter variants, with the highest average height in the variant with Tubex Ventex Classic. The biggest height increment was established in the variant with Layflat Shelterguard for Norway spruce and Silver fir and in variant without tree shelters for Scots pine. The ground line diameter was highest in control variant for Scots pine and Norway spruce and in the variant with Layflat Treegard for the Silver fir.