2.2 Field estimation of litter storage and retention dynamics
In a second experiment, samples of litter were collected before and
after precipitation events and weighed in situ to assess the
litter-layer retention capacity. We used standard coffee filters to
collect broadleaf and needle litter grab samples of approximately equal
volume at different time steps after precipitation events (see
supplementary Figure S1 for pictures of the procedure). Coffee filters
are well suited for this purpose, as they retain the drip water of the
litter with only minor losses, and they also can be dried in the oven
with the litter inside. For three rainfall events we took 20 broadleaf
and 20 needle litter samples for at least four timesteps: before the
event, 2 hours after the event, 24 hours after the event, and around 40
to 48 hours after the event. We weighed the samples directly on site and
dried them for 24 hours at 70 °C as suggested in Carnol and Bazgir
(2013) to evaluate the water content for each sample. In a third
experiment, we measured soil moisture at two pairs of 1x1 m plots at 10
cm and 30 cm depths, to evaluate how water retention in the litter layer
affects soil-water content dynamics. Each pair had one plot covered with
the naturally present broadleaf-litter layer, and one plot from which we
regularly removed all litter. Volumetric water content in the soil was
measured with 5TE dielectric permittivity sensors and recorded using
EM50 Loggers (formerly Decagon, now Meter Group). The sensors were
installed in the middle of each plot to minimize boundary effects. Data
were recorded at 10-minute intervals.