Impacts of Quercus suber irrigation on improving floristic diversity and soil quality in 10‑year‑old stands

Abstract

We analyzed the dynamics of floristic diversity and soil characteristics in a 10-year-old fertirrigated cork oak (Quercus suber) stand, a species of high ecological, social, and economic importance in the Mediterranean region. Given the decline of cork oak in recent decades, long-term research on newly established stands using fertirrigation was initiated to accelerate tree growth until productive maturity. The study was conducted over a 6-ha area, subjected to various fertirrigation treatments. Across the study site, 4 × 8 m sample plots were established under three canopy cover classes. The aim of this study was to assess soil recovery and floristic composition in relation to canopy cover. Soil recovery was evaluated by comparing the current chemical composition with the initial soil status. For floristic composition, the Zürich-Montpellier School method was applied within each sample plot. Conservation status was assessed by the quality and quantity of plant bioindicators. Hierarchical Cluster Analysis and Principal Component Analysis were used to determine the degree of similarity between plant communities. The main results indicated an overall soil recovery that was not associated with canopy cover. In contrast, the diversity and quality of floristic composition differed significantly in areas with higher canopy cover compared to more open areas, though plant diversity was lower under dense canopies. These findings suggest that irrigating cork oaks accelerates ecological recovery, facilitating the establishment of new forest ecosystems in a shorter time frame. The most positive impacts were observed in the improvement of floristic composition and a reduced need for heliophilous shrub control.