Early performance of Pinus sylvestris and Picea abies – a comparison between seedling size, species, and geographic location of the planting site

Abstract

Small seedlings may be cheaper and establish faster than larger seedlings, but be more sensitive to stress and therefore less competitive. Site factors and species may also influence seedling performance, but the early performance of the most common species in Swedish plantations, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst), has rarely been compared at identical sites. To identify optimal species and size combinations, seedlings were grown in containers of two sizes, 50 and 90 cm3, and planted during two consecutive years at both coastal and inland sites in northern Sweden. The larger Scots pine seedlings grew more rapidly than the smaller and were also the tallest of all seedlings five years after planting. No seedling size-related difference in Norway spruce growth was found. Highest mortality occurred the first three years after planting and pine weevils were one of the major causes. Larger seedlings of both species had a slightly lower mortality compared to smaller. Five years after planting, the proportion of damaged seedlings plateaued for Norway spruce, but not for Scots pine. Consequently, despite a higher growth the Scots pine seedlings remained sensitive to damage during a longer period than Norway spruce. No interactions were found between geographic location and seedling size or species on growth, mortality, or damage.