关键词: 桉树人工林, 凋落物, 淋溶过程, 淋溶水质

Abstract: To understand the decomposition characteristics of the litters in different forest plantations and the effects of released substances during litter decomposition on the leachate quality, litter samples (leaf, shoot, and cortices) were collected from five forest plantations (1 year-old Eucalyptus urophylla × E. grandis,  EU₁; 4 year-old Eucalyptus urophylla × E. grandis, EU₄; 7 year-old Acacia mangium × A. auriculaef, AM; 13 year-old Pinus massoniana Lamb, PL; and mixed broadleaved softwood, BL), and incubated at 28 ℃, using water leached for 255 days. In the first 105 days, the litter leachates of EU₁ and EU₄ had significantly higher coloration and N and P contents and lower pH than those of AM, PL, and BL. On the 255th day, the cumulative chemical oxygen demand (COD) in the leaf litters leachates of EU₁ and EU₄ was 193.9  and 212.8 g·kg^-1, being 4.2, 4.0, and 4.3 times and 5.3, 4.4, and 4.7 times higher than that of AM, PL, and BL, respectively. The mass loss rate and the N and P leaching rate of the leaf litter of EU₁ were significantly higher than those of AM, PL, and BL. The mass loss rate of cortices of EU₁ was significantly higher than that of PL. No significant difference was observed for the leaching rate of the shoot litters between AM, PL, and BL.Among the litter samples, leaf litter was easiest to be decomposed,while shoot litter was most difficult to be decomposed. The pH value of the litter leachates of Eucalyptus plantations was significantly negatively correlated with leachate chroma and COD, and the COD had significant positive correlations with the concentrations of total N and P in the leachates.

Key words: Eucalyptus plantation, litter, leaching process, leachate quality