Figure 2: Maximum saturation of broadleaf litter (beech,Fagus sylvatica ) and needle litter (spruce, Picea abies ) from laboratory saturation experiments (n = 40 for each litter type). The maximum storage capacity of broadleaf litter is approximately two times higher than that of needle litter.
Water retention in the forest-floor litter layer
The timescales of water retention in the litter layer reflect evaporation and drainage dynamics. We assessed the retention dynamics of broadleaf and needle litter by grab samples taken before, during and after precipitation events, as well as from litter-removal plot experiments. Grab samples taken through three moderate-intensity precipitation events (5.8 mm, 7.5 mm & 8.8 mm) indicate that rainfall is retained in the forest-floor litter layer for approximately 40-48 hours before the litter water content returns to pre-event levels (Figure 3). Retention timescales for saturated litter may be even longer, because in all cases except one (spruce in Figure 3a), the peak storage in our grab samples was less than half of the maximum storage capacity as estimated by the laboratory experiments (dashed lines in Figure 3).