华西雨屏区巨桉人工林凋落物数量及其分解特征

Study on the Characteristics of Litter Production and Decomposition in Plantations of Eucalyptus grandis in Rainy Area of West China

通过原位试验,研究了华西雨屏区巨桉(Eucalyptus grandis)林凋落量、凋落物分解以及养分释放特征。结果表明:①华西雨屏区巨桉人工林的年凋落量为6 247.78kg/hm2;凋落叶是凋落物中的主要组分,占全年凋落量的94.85%;凋落物各组分间凋落量大小顺序表现为:凋落叶>凋落枝>凋落皮。②在不同组分凋落物分解过程中,叶的分解速率比枝条快,分解12个月后,叶的质量残留率为39.56%,枝条的质量残留率为56.35%;叶在分解的5—8月时分解速率较大,而枝则在第4—10月时分解率较大;凋落叶分解95%需要2.989a,枝条分解95%需要4.783a。③经12个月的分解,凋落叶各养分元素年释放速率大小表现为:N>C>P>K;凋落枝各养分元素释放速率大小表现为:C>N>K>P;凋落叶各养分元素释放速率均高于凋落枝;④凋落叶、凋落枝初始C/N分别为43.51、285.78;在分解过程中,各密度凋落叶、凋落枝C/N比变化动态总体均表现为下降趋势。

Litter production, decomposition and nutrient release were investigated in a Eucalyptus grandis plantation in Rainy Area of West China. The results showed that： （1） The annual litter production was 6 247.78 kg/hm2 in this eucalyptus plantation, leaf litter account for 94. 85% of the total production, followed with twig and bark. （2） The leaf litter had higher decomposition rate than twig litter. 39.56% of leaf litter and 56.35% of twig litter remained after 12 months de- composition, The decomposition rate in leaf litter was higher from the 5th month to the 8th month, but which in twig litter was higher from the 4th month to the 10th month compared with other decomposition stages. It would take 2. 989 years and 4. 783 years to decompose 95% of leaf litter and twig litter, respectively. （3） After 12 months decomposition, elements release rates showed the order as： N〉C〉P〉K for leaf litter, and C〉N〉K〉P for twig litter. Elements re- lease rates in leaf litter were higher than those in twig litter. （4） The initial C/N ratios in leaf and twig litters were 43.51 and 285.78. The C/N ratios showed a decreasing trend as leave and twig litter decomposition proceeded.