海南尖峰岭檀香心材和边材的矿质养分含量差异

目的 了解檀香Santalum album L.人工林心材和边材的矿质养分分布规律，为深入研究檀香心材的形成过程提供参考。方法 以海南尖峰岭21年生檀香人工林为研究对象，从东、南、西、北4个方位在髓心、心材中部、心材外部和边材部位分别取样测定主要矿质养分——氮(N)、磷(P)、钾(K)、钙(Ca)和镁(Mg)的含量，分析其差异性。结果 海南尖峰岭21年生檀香人工林不同矿质养分含量在心材和边材的分布规律因元素种类而异。P、K、Ca含量在径向自外向内依次降低，边材、心材外部、心材中部以及髓心的P质量分数依次为0.153、0.032、0.020和0.020 g·kg^-1，K质量分数依次为1.883、0.529、0.190和0.182 g·kg^-1，Ca质量分数依次为2.414、1.417、1.321和1.281 g·kg^-1。边材中P、K、Ca的含量均显著高于心材(P<0.01)，而N的分布规律相反，心材中的N含量显著高于边材(P<0.01)。Mg含量在径向上差异不显著(P=0.132)。各矿质养分含量在东、南、西、北4个方位的差异均不显著(P>0.05)。结论 檀香心材形成过程中P、K、Ca元素会逐渐由心材转移到边材中进行循环利用，以提升养分利用效率。N在心材中保持较高含量，表明檀香能从寄主植物或土壤中获得足够的N源。

Mineral nutrient content variations between heartwood and sapwood of sandal (Santalum album L.) located in Jianfeng Mountain of Hainan

Objective To investigate the rules of mineral nutrient concentrations in heartwood and sapwood of sandal (Santalum album L.) plantation, and provide references for further study of heartwood formation process.Method Variations of mineral nutrient contents of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) at different positions (pith, middle heartwood, outer heartwood, sapwood) and directions (east, south, west, north) in 21-year old sandal plantation in Jianfeng Mountain, Hainan Island were investigated. Result The distribution patterns of mineral nutrients between heartwood and sapwood in 21-year old sandal plantation in Jianfeng Mountain were element-specific. The contents of P, K and Ca decreased in turn from outside to the central pith, the P contents in sapwood, outer heartwood, middle heartwood and pith were 0.153, 0.032, 0.020 and 0.020 g·kg^-1 respectively, the K contents were 1.883, 0.529, 0.190 and 0.182 g·kg^-1 respectively, and the Ca contents were 2.414, 1.417, 1.321 and 1.281 g·kg^-1 respectively. The contents of P, K and Ca in sapwood were statistically higher than those in heartwood (P<0.01), while N content got a complete opposite distribution pattern, meaning that N content in heartwood was statistically higher than that in sapwood (P<0.01). However, there was no significant difference of Mg content across radius (P=0.132). No significant difference of all above mineral nutrient contents between heartwood and sapwood was observed among four azimuths including east, south, west and north (P>0.05).Conclusion P, K and Ca are recycled from heartwood to sapwood during heartwood formation in sandal, which can improve nutrient use efficiency. N keeps a higher content in heartwood than that in sapwood, indicating that sandal can acquire enough N from its hosts or soil.