Objective To understand the distribution pattern of carbon, nitrogen and phosphorus and the stoichiometric characteristics of Eucalyptus urophylla×E. grandis fast-growing plantation ecosystem in the Leizhou Peninsula.

Method The temporal-spatial method was used to select four E. urophylla×E. grandis fast-growing plantations with different ages (1, 3, 5, 7a) as the subjects. The contents of C, N, P and their ratio were analyzed in the leaf, litter, and soil.

Result The results revealed that the C and N contents followed the pattern of leaf > litter > soil, the content of P followed the pattern of leaf > soil > litter and there was an obvious difference among the three warehouses. Soil C content could increase with the raising of plantation age; but N and P differed little. The ratio of soil C:N increased with rising age, indicating that soil decomposition rate declined gradually. The ratio of litter C:N varied in the range of 54.07-92.18 (>25), increased at first and then declined. It showed that litter decomposition rate was comparatively low and restricted by N. The ratio of N:P in leaf was between 10.8 and 12.98 which also demonstrated that plant growth was limited by N. The correlation analysis showed that the litter N content was limited by the leaf, and the soil N was limited by the litter. Inside the ecosystem, the C, N and P elements had realized the transportation and transformation among the plants, litter and soil.

Conclusion The decomposition rate of soil organic matter and litter of young and middle aged E. urophylla×E. grandis plantations on the Leizhou Peninsula is comparatively slow. The soil organic matter and litter decomposition rate decline with age and is restricted by N. The growth of plantation is also limited by N.