Fine root dynamics across a chronosequence of upland temperate deciduous forests

Abstract

Following a major disturbance event in forests that removes most of the standing vegetation, patterns of fine root growth, mortality, and decomposition may be altered from the pre-disturbance conditions. The objective of this study was to describe the changes in the seasonal and spatial dynamics of fine root growth, mortality, and decomposition that occur following removal of standing forest vegetation. Four upland temperate deciduous forest stands in southern Indiana, USA were chosen for this study. The ages of the stands, as represented as the number of growing seasons since forest overstory removal, were 4, 10, and 29 years at the beginning of the study in 1995. A mature stand, ≈80–100 years since last harvest, was chosen to represent the pre-harvest conditions. A combination of soil cores and ingrowth cores were used to assess stand-level rates of fine root growth, mortality, and decomposition. Results show that fine root growth increases significantly after harvesting, but declines as the stand matures. In all stands, fine root mortality and decomposition are nearly equal to or greater than fine root growth. Fine root growth in the A horizon (0–8 cm) is significantly greater than in the B horizon (8–30 cm) in the 4, 29, and 80–100-year-old stands. In the 4- and 10-year-old stands fine root growth in the A horizon peaks earlier in the year than in the B horizon. Fine root biomass recovers rapidly in these upland hardwood stands following forest removal due to high rates of fine root growth; however, the distribution of fine root growth between the A and B soil horizons differs from pre-harvest conditions during the first 10–30 years.