2种人工林对土壤碳氮磷化学计量特征及阳离子交换量的影响

Effects of two plantations on soil carbon,nitrogen,phosphorus stoichiometry and cation exchange capacity

【目的】土壤碳氮磷生态化学计量可以探明植物受土壤养分的限制情况,土壤阳离子交换量(CEC)直接反映了土壤保肥、供肥性能和缓冲能力。研究旨在揭示华南地区乡土马尾松和木荷人工林对土壤养分及保肥供肥能力的影响。【方法】以广东省鹤山市的马尾松和木荷人工林为研究对象,对2种人工林表层土壤(0~10 cm)有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)和交换性阳离子等指标进行分析测定,探讨不同人工林分对表层土壤碳氮磷和阳离子交换量的影响。【结果】木荷人工林SOC显著大于马尾松人工林,马尾松人工林土壤TK含量则显著高于木荷人工林,但土壤TN和TP含量在2种林分之间的差异不显著;2种林分土壤盐基饱和度(BS)为9.68%~18.00%,木荷林土壤CEC和交换性盐基总量(TEB)均显著高于马尾松林,且2种林分土壤盐基离子含量均呈现Ca^(2+)>Mg^(2+)>K^(+)>Na^(+)。2种林分土壤CEC与SOC显著正相关,BS与pH值显著正相关;马尾松人工林CEC、TEB与土壤含水量呈显著正相关。【结论】研究区森林土壤肥力处于较低水平且保肥供肥能力较弱,但木荷林土壤供肥、保肥和酸碱缓冲能力强于马尾松林。然而,木荷林土壤交换性钙镁离子含量显著高于马尾松人工林,且2种人工林土壤Ca^(2+)∶Mg^(2+)>5,表明研究区人工林土壤未出现生理性缺钙的现象。研究区土壤有机质的矿化速率较高,导致土壤肥力下降,这种趋势在马尾松林中比木荷林更为明显。研究结果对华南地区木荷和马尾松人工林的养分管理具有重要的理论和实践指导意义。

【Objective】The ecological stoichiometry of soil carbon,nitrogen and phosphorus can reveal the limitation of plants by soil nutrients.Soil cation exchange capacity(CEC)directly reflects the soil fertility retention,fertilizer supply performance and buffering capacity.The purpose of this paper was to explore the effects of native Pinus massoniana and Schima superba plantations on soil nutrient status and fertilizer supply capacity.【Method】Taking S.superba Gardn.et Champ.and P.massoniana Lamb in Heshan City,Guangdong Province as the research objects,this study explored the effects of the two plantations on soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),total potassium(TK)and exchangeable cation content in the surface soil(0-10 cm).【Result】The results showed that the SOC in S.superba plantation was significantly higher than that in P.massoniana plantation,while the soil TK(TK)in P.massoniana plantation was significantly higher than that in S.superba plantation.There was no significant difference in the soil TN or TP content between different stand types.The soil base saturation(BS)was ranging from 9.68%to 18.00%.However,the soil CEC and total exchangeable salt base(TEB)of S.superba plantation were significantly higher than those of P.massoniana plantation,and the soil salt base ion contents of the two plantations showed Ca^(2+)>Mg^(2+)>K^(+)>Na^(+).The correlation analysis showed that CEC was positively correlated with SOC and BS was positively correlated with soil pH.The CEC and TEB of P.massoniana plantation were significantly positively correlated with soil water content.【Conclusion】The soil fertility of the study area is at a low level,and the soil fertility is low.However,the soil fertilizer supplement,maintenance and acid-base buffering capacity of the S.superba plantation are stronger than those of the P.massoniana plantation.The exchangeable Ca^(2+)and Mg^(2+)contents in S.superba plantation are significantly higher than that in P.massoniana plantation.The Ca^(2+)∶Mg^(2+)ratio in the soil of the two stand types is higher than 5,indicating that there was no physiological calcium deficiency in the soil of the study area.The mineralization rate of soil organic matter in this study area is high,which leads to the decline of soil fertility.This trend is more obvious in P.massoniana plantation than that in S.superba plantation.The results have important theoretical and practical significance for the nutrient management of S.superba and P.massoniana plantations in south China.