To understand the adaptative strategies of different tree species to drought and nutrient-deficient environment in coastal sandy site, leaf functional traits and nutrient resorption of four major silviculture tree species, i.e., Casuarina equisetifolia, Pinus elliottii, Acasia crassicarpa and Eucalyptus urophylla × E. grandis were analyzed. Leaf area and specific leaf area of coniferous species (C. equisetifolia and P. elliottii) were significantly lower, and leaf dry matter content and leaf thickness were significantly higher than those of broadleaved species (A. crassicarpa and E. urophy-lla × E. grandis). Nitrogen and P contents of mature leaf and leaf litter in broadleaved species were higher than those in coniferous species. Nitrogen and P contents of mature leaf were higher than those in leaf litter, but N:P was lower than that in leaf litter. Nitrogen and P resorption efficiencies were higher in coniferous species than those in broadleaved species. The P resorption efficiency in all species was significantly higher than N resorption efficiency. The N resorption efficiency of C. equisetifolia, P. elliottii, A. crassicarpa and E. urophylla × E. grandis was 64.2%, 63.1%, 47.0% and 16.8%, and the P resorption efficiency was 92.5%, 81.6%, 80.3% and 18.0%, respectively. The specific leaf area was significantly positively correlated with leaf N and P contents, but negatively correlated with leaf dry matter content, leaf thickness, and nutrient resorption efficiency. Leaf dry matter content was significantly positively correlated with leaf thickness and nutrient resorption efficiency. Therefore, C. equisetifolia and P. elliottii belonged to slow investment species with a higher nutrient resorption efficiency, while A. crassicarpa and E. urophylla × E. grandis belonged to fast investment species with lower nutrient resorption efficiency. Different tree species developed different adaptive strategies to coastal sandy environments through the interactions between leaf functional traits and nutrient resorption.
为探讨不同树种对滨海沙地干旱贫瘠环境的适应策略,以滨海沙地主要造林树种木麻黄、湿地松、厚荚相思和尾巨桉为对象,研究了不同树种叶片功能性状及养分重吸收特征.结果表明: 阔叶树种(厚荚相思和尾巨桉)的叶面积、比叶面积显著高于针叶树种(木麻黄和湿地松),而针叶树叶干物质含量、叶厚度最高.成熟叶和凋落叶的N、P含量表现为阔叶树高于针叶树,成熟叶高于凋落叶,但凋落叶N∶P较高.针叶树种的N、P养分重吸收效率大于阔叶树种,P重吸收效率明显高于N,木麻黄、湿地松、厚荚相思和尾巨桉的N、P吸收效率分别为64.2%、63.1%、47.0%、16.8%和92.5%、81.6%、80.3%、18.0%.比叶面积与叶片N、P含量呈显著正相关,与叶干物质含量,叶厚度以及N、P养分重吸收效率呈显著负相关;叶干物质含量与叶厚度及N、P养分重吸收效率呈显著正相关.就叶片功能的权衡关系而言,木麻黄和湿地松属于缓慢投资-收益型物种,具有较高的养分重吸收效率,而厚荚相思和尾巨桉属于快速投资-收益型物种,养分的重吸收效率较低.不同滨海沙地造林树种通过叶片功能性状及养分重吸收之间的相互协调实现对滨海沙地特殊生境的适应性.
Keywords: N and P content; coastal silviculture tree species; leaf dry mass content; leaf functional trait; nutrient resorption efficiency; specific leaf area.