海南岛滨海沙生植物叶片功能性状分异及其与土壤因子的关系

为探讨滨海沙生植物对环境的适应策略，对海南岛滨海沙生植物单叶蔓荆、苦郎树、马缨丹、飞机草、假马鞭、厚藤的叶片主要功能性状分异特征及其土壤因子的关系进行了研究。结果表明，热带滨海沙生植物叶片功能性状存在明显的种间分异，叶片功能性状不仅受植物种类的影响，还受土壤因子影响；比叶面积呈现草本>灌木>藤本的规律；叶片的N/P为7.78~10.85，热带滨海沙生植物生长受土壤氮限制；叶片功能性状中Na含量的变异系数最大(18.46%~76.36%)，说明不同植物对Na+的吸收存在较大差异，这将影响其在滨海沙地的自然分布；比叶面积、叶干物质含量与叶片的K、Na含量呈负相关，叶N/P与土壤Na+含量呈负相关，叶片Na+含量与土壤有机质、全磷、全钾呈负相关，土壤盐分限制植物对氮磷的吸收，滨海沙生植物通过比叶面积变化来适应盐胁迫。因此，在滨海沙生植被恢复中，施加土壤肥力是其快速恢复的重要措施，叶片Na+含量可作为滨海沙生植物耐盐性筛选的主要指标。

Difference of Leaf Functional Traits of Coastal Psammophytes in Hainan Island and Its Relationship with Soil Chemical Properties

Leaf functional traits are closely related to plant growth strategies and resource utilization ability. In order to explore the adaptation strategies of psammophytes to environment in Hainan Island, the leaf functional traits of Vitex trifolia, Cl erodendrum Inerme, Lantana Camara, Eupatorium odoratum, Stachytarpheta Jamaicensis and Ipomoea pes-caprae and their relationships with soil chemical properties were analyzed. The results showed that the leaf functional traits of tropical psammophytes were different among species, which were affected not only by species but also by soil factors. The specific leaf area of species were in the order of herb>shrub>vine. The N/P ratio of leaves ranged from 7.78 to 10.85, suggesting that the growth of tropical psammophytes was restricted by soil N. The variation coefficient of Na content in leaves was the highest, ranging from 18.46% to 76.36%, indicating that species had a great difference in the absorption of Na+, which would affect its natural distribution in coastal sandy land. The specific leaf area, leaf dry matter content had negative correlations with K and Na contents in leaves, as well as N/P ratio of leaves with Na content in soil, Na content in leaves with soil organic carbon, total P andtotal K, implying that sandy plants adapted to salt stress through specific leaf area change. Therefore, applying soil fertilizer would be an important measure for rapid restoration of coastal sandy vegetation, and the Na+ content in leaves could be used as the main index for salt-tolerance screening of sandy plants in tropical coast.