秦岭山区人工林地枯落叶客置对土壤生物、化学性质的影响

通过对秦岭山区日本落叶松、油松、灰楸和锐齿栎4种典型人工纯林2年的枯落叶客置试验，探讨了枯落叶客置对土壤生物、化学性质的影响，以及不同树种的种间关系.结果表明：阔叶林枯落叶的年分解速率高出针叶林33.70%.当针叶林枯落叶被客置到阔叶林地后，年分解速率提高8.35%～12.15%，而当阔叶林枯落叶被客置到针叶林地后，年分解速率下降5.38%～9.49%.针阔树种间的枯落叶客置均能不同程度地提高土壤有机碳、速效氮、速效磷和速效钾的含量，且针叶林地的增幅(8.70%～35.84%)明显大于阔叶林地(3.73%～10.44%)，其中针叶林地客置灰楸枯落叶后的增幅(24.63%～35.84%)大于客置锐齿栎枯落叶(8.70%～28.15%). 客置阔叶林枯落叶使针叶林地土壤由偏酸向中性方向发展, 土壤酶活性、微生物量C、N含量及其微生物数量提高，其中，客置灰楸枯落叶的增幅大于客置锐齿栎枯落叶；客置针叶林枯落叶后阔叶林地土壤酶活性、微生物量C、N含量及其微生物数量变化因树种而异，其中锐齿栎林地土壤酶活性和微生物量C、N含量有所提高，而灰楸林地却有所下降.客置阔叶林地枯落叶可改善针叶林地的土壤性质，而客置针叶林枯落叶后阔叶林地的效应则因树种而异.说明在人工纯林土壤退化的防治过程中，引入其他树种形成混交林或进行枯落叶客置都应注意种间关系的方向性.

Effects of leaf litter replacement on soil biological and chemical characteristics in main artificial forests in Qinling Mountains.

Through 2 years leaf litter replacement experiments in 4 typical artificial pure forests Larix kaempferi, Pinus tabulaeformis, Catalpa fargesii, and Quercus aliena var. acuteserrata in Qinling Mountains of China, this paper studied the effects of leaf litter replacement on soil biological and chemical characteristics and the interspecific relationships between different tree species. The results showed that the annual decomposition rate of broad-leaved litter was 33.70% higher than that of needle-leaved litter. The annual decomposition rate of needle-leaved litter increased by 8.35%-12.15% when replaced to broad-leaved forests, whereas that of broad-leaved litter decreased by 5.38%-9.49% when replaced to needle-leaved forests. Leaf litter replacement between needle and broad-leaved forests could increase the contents of soil organic-C and available N, P and K, and the increments were obviously higher in needle-leaved forests (8.70%-35.84%) than in broad-leaved forests (3.73%-10.44%). In needle-leaved forests, the increments with the replacement of C. fargesii litter (24.63%-35.84%) were higher than those with the replacement of Q. aliena var. acuteserrata litter (8.70%-28.15%). Furthermore, the replacement of broad-leaved litter could make the soil pH in needle-leaved forests changed from light-acid to neutral, and increase soil enzyme activities, microbial amounts, and microbial biomass C and N contents. The increments with the replacement of C. fargesii litter were higher than those with the replacement of Q. aliena var. acuteserrata litter. The soil enzyme activities, microbial amounts, and microbial biomass C and N contents in broad-leaved forests after the replacement of needle-leaved litter differed with broadleaved tree species. Q. aliena var. acuteserrata forest had the higher soil enzyme activities and microbial biomass C and N contents, while C. fargesii forest was in adverse. It was suggested that in the control of soil degradation under artificial pure forests, much attention should be paid to the direction of interspecific relationship in mixed forestation and leaf litter replacement.