为探究种间竞争对木麻黄和台湾相思生长的影响,利用相邻混植和独立盆栽试验测定木麻黄和台湾相思生长和养分含量的变化,分析两者的种间竞争差异.结果表明,混植对木麻黄树高和根冠比影响显著(P<0.05),但对地径无显著影响(P>0.05).与单植栽培方式相比,混植栽培方式下木麻黄树高和地上生物量分别增加57.28％、20.92％,而根总长、根总表面积以及根总体积分别减少62.67％、51.25％和285.19％;混植对台湾相思树高影响显著(P<0.01),对其地径、根冠比无显著影响(P>0.05);在混植栽培方式下,台湾相思树高、地径、总生物量、根总长、根总表面积以及根总体积分别减少119.17％、17.72％、35.75％、11.15％、33.79％和44.62％.根系在磷信号刺激下,仅有台湾相思L4和SA4径级增加;木麻黄叶中Na含量降低81.63％,而P元素和K元素分别增加11.38％、12.30％,根中Na、P、K元素含量分别减少26.17％、28.29％和21.45％.台湾相思叶中Na、K元素含量分别降低6.23％、7.78％,P元素增加7.55％,根中Na、P、K元素含量分别增加24.81％、22.05％、24.53％.木麻黄和台湾相思在混植栽培方式下,均通过改变自身形态或营养成分抑制对方,说明邻株竞争可以改变沿海人工林中植物的适应性和群落结构,也表明植物根系在邻株竞争中存在重要作用.因此,研究结果可为沿海防护林的更新恢复和经营管理提供理论指导.

Acacia confusa is an important species in coastal shelter forests. In order to explore the effects of salt and phosphorus fertilization on leaf photosynthesis and nutrient characteristics of the seedlings. NaCl solutions were configured in the concentrations of 0% (B0), 0.2% (B1), 0.4% (B2), 0.6% (B3) and 0.8% (B4), and superphosphate solutions in the concentrations of 0 g·kg-1(P0), 0.5 g·kg-1(P1), and 1.5 g·kg-1(P2). The photosynthesis and nutrient characteristics of the seedlings were determined after being watered by the six combined solutions of salt-phosphorus coupling fertilization. The results were as follows: (1) Salt stress significantly inhibited the growth and development of the seedlings, and the higher the salt content, the greater the effect. Phosphorus application under low-salt stress was unfavorable to the growth of the seedlings, while phosphorus application under medium-high one significantly slowed down the inhibition of the seedling growth. (2) The greater the salt stress, the higher the effects on the photosynthesis of the seedlings. The stomatal closure degree of phosphorus application increased under low and medium salt stress, which aggravated the effect of salt stress on photosynthesis of the seedlings. Appropriate phosphorus application under high-salt stress could significantly improve the photosynthetic capacity of the seedlings. (3) Salt stress significantly reduced chlorophyll content and caused harm to photosystem II. Phosphorus fertilization on the seedlings under low-salt stress had adverse effects on chlorophyll synthesis. Appropriate fertilization of phosphorus in high-salt stress could increase chlorophyll synthesis, stabilize cell membrane structure, and improve the potential photosynthetic capacity of leaves. (4) Salt stress had strong interference on the contents of Fe, Mn, Na, Cu and other metal elements in leaves. Phosphorus application under salt stress could effectively promote the absorption of some elements by seedlings. In conclusion, phosphorus application after salt stress can improve the photosynthesis and nutrient absorption ability of A. confusa seedlings on the whole. The results provides a theoretical basis for improving the salt tolerance and phosphorus utilization rate of A. confusa, and have guiding significance for the sustainable management of coastal shelter forests.