Enhancing tree sapling growth under drought stress conditions using biostimulants and mulching

This study investigate the effects of biostimulants and mulching on the growth of Scots pine <em>Pinus sylvestris</em> and sessile oak <em>Quercus petraea</em> saplings under drought stress conditions. As climate change increases the frequency and severity of drought events, effective strategies are needed to mitigate their impact on forest ecosystems. We evaluated the influence of a commercial bios− timulant ‘Kaishi’ and Scots pine wood chip mulching, both individually and in combination, on various growth parameters of both species including root mass, stem mass, root collar diameter, and leaf mass. The results demonstrate that the combined use of biostimulant and mulching significantly enhanced root collar diameter in Scots pine and improved multiple growth parame− ters including root mass, stem mass, and root collar diameter, in sessile oak. While mulching alone had a positive effect on root collar diameter, particularly in sessile oak, biostimulant application alone showed limited benefits in both species. These findings suggest that the interaction between mulching and biostimulants may offer greater advantages in improving sapling growth compared to either treatment alone. These results underline the potential of combining bios− timulants and mulching as an effective strategy to enhance the growth of forest saplings under drought stress conditions. However, species−specific responses indicate that further research is needed to better understand the underlying mechanisms and optimize the use of these treatments across different tree species under varying environmental conditions.