Restoration Strategies for Drylands: Impact of Hydrogel and Watering Frequency on Oak, Hawthorn and Pine Seedlings Survival

This study investigates the effects of irrigation frequency and soil hydrogel addition on the drought response and survival of seedlings from three tree species—oak (Quercus robur), hawthorn (Crataegus monogyna), and pine (Pinus sylvestris)—in a greenhouse experiment. The objective is to assess these factors' implications for ecological restoration in arid and semi-arid regions. A total of 240 seedlings (80 per species) were subjected to four experimental treatments, varying in watering regimes and soil amendments. Experiments 1 and 3 featured daily irrigation for the first 20 days, while Experiments 2 and 4 involved irrigation five times over the same period, followed by 30 days of drought stress. Hydrogel was incorporated into the soil in Experiments 3 and 4 at a rate of 8-10 grams per 8-10 liters of soil. Seedlings were tracked using unique codes and monitored for wilting and survival. Results showed hawthorn seedlings exhibited the highest survival rates and lowest wilting scores, followed by oak and pine. Seedlings grown in hydrogel-amended soil with daily watering demonstrated reduced wilting. The findings suggest that hydrogel addition and increased irrigation frequency enhance drought resilience, indicating potential benefits for using these methods in ecological restoration efforts in water-limited environments.