The influence of growing medium composition on pine and birch seedling response during the period of simulated spring drought

Abstract

Climate change increases the earliness and effect of spring dry spells. The efforts to reduce their negative effects on tree regeneration include improvement in physical properties of soil aimed at an increase in water retention and availability. Clinoptilolite from the group of zeolites belongs among such water-absorbent natural materials. The article aims to assess the effect of clinoptilolite admixture in a growing medium, along with different fertilizer concentration, on the growth of pine and birch seedlings and their development during simulated drought. A common (reference) growing medium was tested along with 4 treatments of the growing medium with clinoptilolite. The birch responded to the fertilizer concentration more intensively than to the clinoptilolite admixture and was more vulnerable to drought damage due to a closer dependence of physiological responses on a decrease in the growing medium moisture. The onset of pine withering was slowest in the reference growing medium. A positive effect of clinoptilolite addition on the growth of pine seedlings was confirmed but its unambiguously positive effect on overcoming of spring dry spells was not demonstrated. Clinoptilolite addition with higher fertilizer rate was found as fully unsuitable.