Effects of forest management on stand leaf area: Comparing beech production and primeval forests in Slovakia

The productivity and water consumption of forests depend on stand leaf area, which may vary with tree age, forest structure, and environment. How forest management affects leaf area and whether production forests have different leaf areas than unmanaged natural forests, is not clear. We compared the leaf area index (LAI) of production forests of European beech (Fagus sylvatica) with that of primeval forests (three forests in each case) in Slovakia and analyzed the LAI change from early to late stages of the natural forest development cycle. Optically determined LAI (LAI2000 Plant Canopy Analyzer) was on average 7.1 m2 m−2 (2.8-11.0 m2 m−2) in the primeval forests and 7.4 m2 m−2 (4.3-11.2 m2 m−2) in the production forests. Model results show that transforming beech primeval forests into even-aged production forests would reduce LAI by ∼1.6 units, if stem density is kept constant. Complex primeval forest canopies thus promote the formation of higher LAIs. However, this effect was compensated for by the higher stem densities of the production forests, resulting on average in similar LAIs of production and primeval forests. In the terminal stage of natural forest development with tree death and gap formation, plot-level LAI was not lower than in the earlier growth and optimal stages, probably because neighboring beech trees were rapidly filling gaps with foliage. This suggests that stand-level productivity is not reduced in the terminal stage of forest development, since LAI is rapidly restored after the death of individual trees. Our results provide insights into the functional role of structural complexity in temperate forest canopies and how European beech maintains dominance across the full forest development cycle.