To study the influence of decomposition characteristics of litter on their water holding capacity under simulated nitrogen (N) deposition so as to provide a theoretical basis for the study of nutrient and water cycling in forest ecosystem under N deposition. The evergreen broad-leaved forest and Quercus semicarpifolia forest in central Yunnan Plateau were selected to conduct in situ leaf litter and twig decomposition experiment with four N treatment levels of 0 (control check CK)

10 (low nitrogen LN)

20 (medium nitrogen MN) and 25 (high nitrogen HN) g/(m2·a)N. Litterbag method and the laboratory immersion method were used to explore the variation characteristics of mass remaining rate

water holding capacity

water holding rate and water absorption rate of leaf litter and twig litter under different treatment. The results showed that: (1) The mass remaining rate of leaf litter and twig litter in two forest types decreased with the extension of decomposition time. Compared with the mass remaining rate of CK

LN treatment had no significant effect on leaf litter and twig litter in two forest types. MN and HN treatments increased leaf litter decomposition in evergreen broad-leaved forest at 16

19

23

24 months and HN treatment increased leaf litter decomposition in Q. semicarpifolia forest at 16 months by 5.05%~7.45%

7.88%~8.62% and 4.72%

respectively. (2) Compared with the CK

LN treatment increased the time required for 95% decomposition of leaf litter and twig litter in evergreen broad-leaved forest and twig litter in Q. semicarpifolia forest by 0.549

0.366 and 0.402 years

respectively

while that of leaf litter in Q. semicarpifolia forest decreased by 1.011 years

and that of leaf litter and twig litter in two forest types under MN and HN treatment increased by 0.236~3.638 years. (3) The decomposition time

nitrogen deposition and their interaction significantly affected the maximum water holding capacity

maximum water holding rate

maximum water absorption of leaf litter and twig litter (p<0.001). Compared with the CK

the maximum water holding capacity

maximum water holding rate

maximum water absorption of leaf litter in evergreen broad-leaved forest under LN and MN treatments decreased by 21.99%

6.47%

54.47%

16.14%

4.15% and 1.25%

respectively

and those under HN treatment increased by 0.24%

0.80%

and 0.96%

respectively

and in LN and MN and HN treatments

those of twig litter in evergreen broad-leave forest and leaf and twig litter in Q. semicarpifolia forest increased by 8.03%~38.22%

5.47%~60.00% and 0.46%~5.72%

respectively. (4) The relationship between water holding capacity and the water holding rate of leaf litter and twig litter in two forest types and immersion time was a logarithmic function (m=a+bln t)

and the water absorption rate was exponentially related to immersion time (v=at-b). (5) The mass remaining rate of leaf litter in evergreen broad-leaved forest and that of twig litter in Q. semicarpifolia forest were significantly and positively correlated with their maximum water holding capacity

maximum water holding rate and maximum water absorption rate

respectively (p<0.05). In conclusion

the water holding capacity of litter was affected by the decomposition stage and nitrogen deposition.