在实验室条件下对黧蒴锥[Castanopsis fissa (Champ. ex Benth.) Rehd. et Wils.]、湿地松(Pinus elliottii Engelm.)和尾叶桉(Eucalyptus urophylla S. T. Blakely)凋落物的分解特征及其对华南赤红壤的pH 值、有机质和碱解氮、速效磷和速效钾含量的影响进行了研究。结果表明:经过1 a 的分解后,黧蒴锥、湿地松和尾叶桉凋落物的失重率分别为26. 48%、13. 80%和28. 15%;3 种凋落物中全氮均为净释放模式,全磷为富集模式,黧蒴锥和尾叶桉凋落物中全钾和有机碳为净释放模式,湿地松凋落物中全钾和有机碳为富集模式。随凋落物分解时间的延长,土壤pH 值呈现逐渐上升至第8 个月达到峰值、之后略有下降的变化趋势;有机质含量呈波动的变化趋势;碱解氮含量呈先升高后降低的变化趋势;速效磷含量呈略有波动但总体下降的趋势;速效钾含量呈“逐渐上升—急剧下降—急剧上升—趋于平稳”的变化趋势,且均在第8 个月最低。与实验初期相比,实验结束时对照组及各处理组的土壤pH 值和碱解氮含量均不同程度增加、有机质含量不同程度降低、速效磷含量显著下降,对照组速效钾含量下降而各处理组速效钾含量明显提高。与对照相比,实验结束时3 种凋落物均导致土壤酸度减弱、速效钾含量增加、但有机质和速效磷含量没有明显提高。3 种凋落物对土壤pH 值及土壤养分含量的影响有明显差异,总体上看,黧蒴锥凋落物覆盖可明显减弱土壤酸度,增加土壤有机质、碱解氮和速效钾含量,对土壤的改良效果最好。研究结果揭示:不同凋落物对土壤pH 值及养分含量的影响与凋落物的成分及生物学特性有关。

Decomposition characteristics of litters of Castanopsis fissa (Champ. ex Benth.) Rehd. Et Wils., Pinus elliottii Engelm. and Eucalyptus urophylla S. T. Blakely and their effects on pH value and contents of organic matter, available alkaline N, available P and available K in lateritic red soil of South China were studied under laboratory condition. The results show that after one-year decomposition, weight loss rate of C. fissa, P. elliottii and E. urophylla litters are 26. 48%, 13. 80% and 28. 15%, respectively, and total N in three litters is net release mode while total P is enrichment mode. And total K and organic carbon in C. fissa and E. urophylla litters are net release mode while those in P. elliottii litter are enrichment mode. With prolonging of litter decomposition time, pH value of soil appears a changing trend of gradually increasing, reaching at peak value in the eighth month, then slightly decreasing; organic matter content appears a fluctuation trend; available alkaline N content appears a changing trend of increasing at first and then decreasing; available P content appears a trend of slight fluctuation but generally decreasing; available K content appears a changing trend of “ gradually increasing-sharply decreasing-sharply increasing-tending to stable” and reaches the lowest in the eighth month. Compared with the beginning of the experiment, at the end of the experiment, pH value and available alkaline N content in soils in the control and three treatment groups increase with different degrees, organic matter content decreases with different degrees and available P content decreases significantly, but available K content in the control group decreases while that in three treatment groups increases obviously. Compared with the control, at the end of the experiment, all of three litters cause weakening of soil acidity and increasing of available K content in soil, but contents of organic matter and available P in soil have no obviously increasing. Influence of three litters on pH value and nutrient content in soil has an obvious difference, and generally, soil improvement effect of C. fissa litter covering is the best due to obviously weakening of soil acidity and increasing contents of organic matter, available alkaline N and available K. It is suggested that influence of different litters on pH value and nutrient content in soil relates to litter composition and its biological features.