中文摘要：

【目的】探讨土壤C、N、P化学计量学在岩溶生态系统中的生态指示作用，揭示岩溶生态系统各组分之间的养分循环规律，为阐明岩溶生态系统的稳定性提供参考。【方法】分别在岩溶区次生林地采集山脚、山腰和山顶3个地貌部位表层土壤样品，测定土壤有机C、全N和全P含量，并分析不同地貌部位土壤的C、N、P的生态化学计量特征。【结果】岩溶区次生林地中土壤有机C、全N和全P含量分别为28．09～189．98g／kg、1．19～8．79g／kg和0．50～1．62g／kg。土壤P元素含量较稳定，土壤C和N变异程度相似。土壤C／N为3．66~47．27，C／P为26．25～189．06，N／P为1．52～12．80，其中C／N和C／P均不符合正态分布，N／P符合正态分布（DO．05）。土壤有机C和全N含量均为山脚部位最高，并且与山腰和山顶部位的差异达显著水平（P〈0．05，下同）；土壤全P含量则为山顶部位显著高于山脚和山腰。土壤C／N随着海拔的升高而变大，而C／P和N／P的趋势恰好相反，即随着海拔的升高而逐渐变小。土壤有机C、全N和全P含量两两之间均呈极显著正相关（P〈0．01，下同）；C／N与C／P呈极显著正相关，与N／P呈极显著负相关；C／P与N／P呈极显著正相关。【结论】岩溶区土壤的有机质含量高于同气候带下其他类型土壤，营养元素N和P含量相对丰富，但能被作物吸收利用的有效态的N和P含量不足，有效性偏低，且土壤C、N、P化学计量受地貌部位影响较明显。

英文摘要：

[ Objective ]The carbon, nitrogen, and phosphorus stoichiometry, as the ecological indicators, were investigat- ed to interpret the nutrient cycle between each ingredient in karst area,as well as to illuminate the stability of karst e- cosystem. [ Method]Surface soil samples fromsummit of hill, hillside tothe foot of a karst hill were collected respectively in secondary forest of karst area. Soil organic carbon （SOC）,total nitrogen （TN）and total phosphorus （TP）were tested to re- veal the soil carbon,nitrogen,and phosphorus stoichiometry in different karst landforms. [Result]The contents of soil or- ganic carbon,total nitrogen and total phosphorus range from 28.09 to 189.98 g/kg, 1.19 to 8.79 g/kg,and 0.50 to 1.62 g/kg respectively.The content of P in soil was stable,and the variation of C and N was similar.Soil C：N ratio ranges from 3.66 to 47.27,C：P ratio ranges from 26.25 to 189.06 and N：P ratio ranges from 1.52 to 12.80. C/N and C/P were not normal distri- bution,while N/P was normal distribution （P〉0.05）. The contents of SOC and TN were the highest at the foot of the moun- tain and have a significant difference with that of hillside and peak of the mountain （P〈0.05 ,the same below）. The content of TP at the peakwas significantly higher than that of the foot of the mountain and hiflside.The C/N increases with the in- crease of altitude,while the trend of N/P and C/P was the opposite, that was,with the increase of the altitude, N/P and C/P was gradually smaller.And there were significant differences between different landforms. Between two of SOC,TN and TP, there was extremely significant positive correlation （P〈0.01, the same below）.The relationship between C/N and C/P wasex- tremely significantpositive correlation, and between C/N and N/P was extremely significant negative correlation,whilethe re- lationship between C/P and N/P wasextremely significantpositive correlation. [Conclusion]The contents of soil organic mat- ter is higher than that of other soils in the same clima