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.