Intensive initial care of silver fir using improving compounds: A way to support diverse forests?

In some cases, it is difficult to promote climax tree species in the forest stand composition. In the Czech Republic, silver fir (Abies alba Mill.) is a typical example. This study offers an evaluation of the use of two improving compounds for tree plantations in the initial stage of growth in Central Bohemia. In the experiment, we measured the initial growth performance of a young fir plantation treated with a brassinolide compound (concentration 1 : 100 and 1 : 200) and Bio-Algeen® prior to planting and compared it with control treatment: we assessed height, root collar diameter, vitality and mortality rate during the period 2014-2019. Cumulative mortality rate of the plantation reached 25% at the end of the monitoring period, without any significant differences between variants. Height increment of the variant treated with Bio-Algeen® was significantly (P < 0.05) lower than the growth of brassinolide-treated variants, all treated variants were comparable with the control variant. The plantation underwent a drought-stress period in 2014 and 2015, which resulted in worsened vitality and colour across variants. As a result of the simple economic analysis, the most expensive inputs are planting stock and labour, therefore the price and application of additional substances should not affect decision-making.