Experiment
Prior to the leaching incubation experiment, 1 L experimental bottles
and ventilation equipment were washed with phosphorus-free detergent,
and rinsed with 0.1 M HCl solution, and then rinsed with distilled
water. We cut the dry leaf litter using scissors to mimic the initial
decomposition process of detritivores and immersed the cut dried leaf
litter into 1 L experimental bottles containing 800 mL distilled water.
Two replicates of the leaching bottles were set up for each leaf litter
species. These bottles were aerated and placed in dark incubators at 20
°C for 28 days. The dry weight of leaf litter used for leaching
incubation was 7−385 mg, depending on the tree species: for tree species
with low leaf litter P, a larger amount of leaf litter was added into
experimental bottles to ensure that the P in leachate would be the same
concentration level and thus minimizing and equalizing measurement
errors.
During the experiment, we shook the bottles manually to mix the leachate
once a day. On days 1, 3, 7, 14, 21, and 28, we sampled 50 mL of the
supernatant of the leachate after all leaf litter had settled down to
the bottom of the bottle. These samples were used to measure the DOC,
TDN, and TDP in the leachate. DOC and TDN in the litter leachate were
measured using a TOC/TNb analyzer (multi N/C 3100, Analytik Jena GmbH,
Jena, Germany). For TDP measurements, 10 mL of leaf litter leachate was
autoclaved with potassium persulfate and measured using the
ascorbate-reduced molybdenum blue method.