Influence of Shelterwood and Ground Vegetation on Late Spring Frost Damages of Planted Beech (Fagus sylvatica) and Douglas-Fir (Pseudotsuga menziesii) Saplings

Abstract

Effects of shelterwood and two types of low vegetation cover (shrubs and gramineous) on frost occurence and degree of damages were investigated in young beech (Fagus sylvatica L.) and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plantations. A late frost event was registered at the end of April 2007 which did not affect saplings below a spruce shelterwood (on strip cutting or target diameter cutting plots), but frost damages occurred in open field conditions (on clear cutting plots). The probability of frost damage occurrence increased significantly with light availability in both species, whereas the degree of frost damages (%, proportion of damaged beech leaves and damaged new Douglas-fir needles) decreased with increasing seedling height for both species. A significant influence of field vegetation type (shrubs and gramineous) on the probability of frost occurrence could be detected in beech: in small shrubs the probability was lower than 111 gramineous species (0.48 vs. 0.76). The degree of frost damage decreased from gramineous to small shrubs type in both species, but significantly only in Douglas-fir saplings (from 28.6 % to 15 %, in beech from 30.7 % to 25.2 %). We concluded that at sites which are prone to late spring frost the early regeneration needs protection for successful establishment, and that this protection can be provided by strip cutting along with shelterwood or 011 clear-cut areas by a dense ground vegetation of small shrubs.