DOI: 10.5061/dryad.ksn02v79k
title: Dissolved C, N, and P release efficiency from temperate tree leaf litter

description: Dissolved organic matter and inorganic nutrients released from forest leaf
 litter through leaching are important energy and nutrient sources that
 support the production of aquatic food webs. Leaf litter-derived dissolved
 organic carbon (DOC) is a critical energy source for aquatic heterotrophic
 microbes, and inorganic nitrogen and phosphorus can enhance primary
 production. In this study, we experimentally measured the release
 efficiencies and amounts of DOC, total dissolved nitrogen (TDN) and total
 dissolved phosphorus (TDP) of the leaf litter from 11 temperate tree
 species by soaking the leaf litter in water for 28 days. We found that the
 maximal release efficiency (% of element released per estimated mass of
 the element) was the highest for P and lowest for N. These efficiencies
 were species-specific. Additionally, the DOC:TDP, DOC:TDN, and TDN:TDP
 ratios varied among the leachate of different leaf litter species. DOC:TDP
 increased with the C:P ratio in leaf litter biomass but is considerably
 lower; TDN:TDP was lower than the N:P ratio in leaf litter biomass as
 well; DOC:TDN ratio was higher than the C:N ratio in leaf litter biomass.
 These results suggest that the ratios of DOC to dissolved N and P
 nutrients released into water are related to, but not the same as, the
 stoichiometry of leaf litter biomass. Based on these findings, we
 concluded that changes in the vegetation with different leaf litter
 stoichiometry can alter the relative importance of detrital and grazing
 food chains in aquatic ecosystems.
description: We examined 11 tree species
 commonly found in the mountainous areas of northeast Japan. These shed
 leaves were collected at Zao (N38.122, E140.451) on October 3, 2020, at
 Kawatabi (N38.745, E140.757) on October 15, 2020, and at Aobayama
 (N38.259, E140.837) on November 19, 2020, in Miyagi Prefecture, Japan
 (Fig. 1 and Table 1). All leaves were collected on top of other leaf
 litter on the ground and therefore did not directly come into direct
 contact with the soil. The leaf litter was dried at room temperature
 (approximately 20°C) in
 paper bags until it was used for measuring its C, N, and P contents. Prior
 to the experiment, the C and N contents in the leaf litter were measured
 using an elemental analyzer (2400 Series II CHNS/O Analyzer, Perkin Elmer,
 Shelton, Connecticut). For estimating the P content in the leaf litter,
 the weighed amount of dry leaf litter was first combusted (420°C) for 2 h to turn the leaf litter
 into ash, which was suspended in 10 mL of distilled water. The mixture of
 ashes and distilled water was autoclaved with potassium persulfate for 30
 min to oxidize organic phosphorus compounds and the total orthophosphate
 concentration was measured by the ascorbate-reduced molybdenum blue method
 (Murphy and Riley 1962, Menzel and Corwin 1965). 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 2°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 and did not refill the bottle
 with new distilled water. 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.
description: We saved the data of leaf litter stoichiometry and dissolved C,
 N, and P release as Excel files. R can be used to open and analyze the
 dataset.