Survival, growth and ectomycorrhizal community development of container- and bare-root grown Pinus sylvestris and Picea abies seedlings outplanted on a forest clear-cut

Selection of high quality seedling material is an essential prerequisite for successful reforestation and characteristics of the seedlings produced under different cultivation systems may differ significantly. The aim of the present study was to assess survival, growth and ectomycorrhizal (ECM) community development of containerised and bare-root cultivated Pinus sylvestris and Picea abies seedlings following their outplanting on a forest clear-cut in Latvia. The experimental plantation 7500 m² in size was established in May 2006. Seedlings of four different treatments were arranged in rows in five replicates. Results showed that during four growing seasons (2006-2009) following seedling outplanting, a gradual decrease in seedling survival was observed each year in both tree species and cultivation systems. As a result, after the fourth growing season in a plantation, generally low survival rates were in both tree species and cultivation systems. In P sylvestris, survival rates were similar between containerised and bare-root seedlings (16.7% ± 2.0SE and 14.3% ± 1.2SE, p > 0.05, respectively) while in P abies these were significantly lower in containerised seedlings (29.5% ± 3.5SE) than in bare-rooted ones (42.6% ± 4.5SE) (p < 0.0003). At the time of outplanting, the height of containerised and bare-root seedlings differed within each of the tree species and similar pattern in seedling height growth remained after the fourth season. Although the communities of ECM fungi detected in a study resembled the ones present in the forest nurseries, a dynamic change from the predominance of Thelephora terrestris in the first season to the dominance of Wilcoxina rehmii and Amphinema byssoides in the later seasons indicated their certain adaptation to the environmental conditions present at the site. The study demonstrated that depending on a tree species the cultivation system may influence both seedling performance in the field and the development of ECM communities.