This study was aimed at determining the amount of downed fine woody debris (FWD) in managed stands and nature reserves of the Niepołomice Forest, comparing it with the amount of downed coarse woody debris (CWD), and identifying the factors affecting FWD. The measurements were carried out in 99 study plots established in mixed (pine-dominated) and deciduous forests. The volume of FWD in managed stands ranged from 0.9 to 16.9 m³ ha⁻¹. The median value for FWD (5.0 m³ ha⁻¹) was twice that for CWD volume. The share of FWD in the total volume of downed woody material ranged from 7.7% to 100% (median 64.4%). In the reserves, CWD dominated; its volume was between 13.2 and 175.4 m³ ha⁻¹ and its share was ~80%. The type of forest significantly affected FWD; its volume was higher in deciduous forests. Among other stand parameters, the number of tree species correlated most with FWD volume (r_S = 0.41, p < 0.0001). The study showed that FWD constitutes a significant part of the deadwood pool in managed stands and, as such, can be important in shaping the diversity of deadwood-dependent organisms.