Litter stoichiometry versus release stoichiometry
No significant effects of the leaf litter content onV max were detected for any of the elements
(Figure S4a, e, i and Table S2). However, we found thatV max of DOC was positively associated with P
content in the leaf litter (Figure 3a; Table S2).
We estimated TRA C, TRA Nand TRA P, using V max and
the mass of these elements in the leaf litter (Figure S5). TheTRA C (y = 7.82x + 78.29,r 2 = 0.347374859, p = 0.044; Figure 3b)
and TRA P (y = 0.41x + 0.32,r 2 = 0.79, p = 0.00011; Figure 3c) were
significantly and positively related to leaf litter P content but not to
N and C contents. TRA N was not related to any
elemental content in the leaf litter.
Finally, we plotted molar C:P, C:N and N:P ratios of TRA against
those ratios of the leaf litter biomasses (Fig. 4). The results showed
that both the TRA C:P andTRA N:P were considerably lower than the C:P and
N:P ratios of leaf litter, while TRA C:N was
considerably higher than the C:N ratio of leaf litter. TheTRA C:P varied considerably (6.4 to 262.6) among
the leaf litter and was higher in Japanese maple and zelkova (1 and 2 in
Figure 4a). It was significantly and positively related to the C:P ratio
of leaf litter biomass (y = 0.065x − 15.12,r 2 = 0.77, p = 0.00011; Figure 4a). The
slope of the regression equation indicated that the release efficiency
of P was, on average, 15 times higher than that of DOC compared with the
elements in leaf litter biomass. Among the leaf litter,TRA C:N ranged from 20.43 to 528.31 and was the
highest in Japanese hemlock (8 in Figure 4b);TRA N:P ranged from 0.05 to 3.24 and was higher in
oak (aged) compared to the other leaf litter species (3 in Figure 4c).
However, these ratios were not related to the C:N and N:P ratios in leaf
litter biomass, respectively.