【摘要】 从林下植被多样性、土壤理化性质探讨合理的加勒比松人工纯林改良模式，为提高加勒比松纯林生态稳定性及混交林树种选择提供科学依据。以加勒比松纯林(PP)、加勒比松×灰木莲(MF1)、加勒比松×红锥(MF2)、加勒比松×灰木莲×红锥(MF3)混交林为研究对象，分析4种林分林下植被多样性和土壤理化性质差异。结果显示：1)3种混交林草本层多样性指数均显著高于PP,其中MF1最大，MF3次之；3种混交林灌木层物种丰富度指数均显著提高，Simpson指数、Shannon-Wiener指数仅MF3显著高于PP,Pielou指数差异不显著。2)不同林分间土壤容重差异不显著，3种混交林土壤含水率和土壤孔隙度均高于PP,均为MF3最优。3)除硝态氮外，MF2和MF3的0～20 cm、20～40 cm土层土壤有机碳、全氮、铵态氮、全钾、速效钾和速效磷含量均显著高于PP。4)相关性分析表明，灌木层多样性指数与土壤理化性质的相关性强于草本层，而草本层与土壤速效磷含量的相关性较强；冗余分析表明，土壤有机碳、速效磷是影响林下植被多样性的主要因子。与PP相比，MF1、MF2、MF3均能够显著提高灌木层物种丰富度和草本层植被多样性指数。同时，混交林还改善了土壤水分和孔隙状况，提高了土壤有机碳和氮、磷、钾的全量和有效养分含量，且套种多树种混交改良效果明显优于套种单一树种的混交林。更多还原

【Abstract】 Exploring the reasonable improvement model of artificial pure Pinus caribaea forest from the perspective of understory vegetation diversity and soil physicochemical properties, and provide scientific basis for improving the ecological stability of pure Pinus caribaea forest and selecting mixed tree species.The differences in understory vegetation diversity and soil physicochemical properties of four forest stands were analyzed, including pure Pinus caribaea forest(PP), P caribaea×Magnolia sumatrana(MF1), P caribaea×Castanopsis hystrix(MF2), P caribaea×M sumatrana×C hystrix(MF3) mixed forestsas the research object.The results showed that:(1)The diversity indices of the herb layer of the three mixed forests were all significantly higher than the PP,MF1 is the largest and followed by MF3;The species richness index of the shrub layer of the three mixed forests were all significantly higher, the Simpson index and Shannon-Wiener index were only significantly higher in MF3 compared with PP,while the differences in Pielou index were not significant.(2)The differences in soil density between stands were not significant, soil water content and soil porosity in the three mixed forests were higher than PP,all of which were optimal for MF3.(3)Except for nitrate nitrogen, the soil organic carbon, total nitrogen, ammonium nitrogen, total kalium, available kalium, and available phosphorus contents in the 0～20 cm and 20～40 cm soil layers of MF2 and MF3 were significantly higher than PP.(4)Correlation analysis showed that the correlation between the diversity index of shrub layer and soil physicochemical properties is stronger than that of herb layer, while the correlation between herb layer and soil available phosphorus content is stronger; Redundancy analysis indicates that soil organic carbon and available phosphorus are the main factors affecting understory vegetation diversity.Compared with PP,mixed forests MF1,MF2,MF3 can significantly improve the species richness of the shrub layer and the vegetation diversity index of the herb layer.At the same time, the mixed forest also improves soil water and porosity conditions, increases organic carbon and the total and available nutrient content of soil nitrogen, phosphorus, and potassium, and the improvement effect of intercropping multiple tree species mixed forest is significantly better than that of intercropping a single tree species mixed forest.更多还原