不同林龄樟子松人工林针叶-凋落叶-土壤生态化学计量特征

为明确科尔沁沙地引种樟子松人工林生态系统的C、N、P含量及化学计量特征,采用时空互代的方法,在章古台地区选取4种不同林龄(15,25,35,45年)、立地条件基本一致的樟子松人工林作为研究对象,比较针叶-凋落叶-土壤的C、N、P含量及化学计量比的差异,探讨它们随林龄的变化及其相互间的关系。结果表明:(1)C、N、P含量表现为针叶凋落叶土壤,C/N、C/P、N/P表现为凋落叶针叶土壤,且在3个库之间都有显著差异;(2)林龄对针叶-凋落叶-土壤的C、N、P及C/N、C/P有显著影响,均在35年生樟子松林中针叶-凋落叶-土壤的C、N、P含量最高;(3)相较于其他地区,针叶和凋落叶均表现出高C、P和低N的特征,具有较高的C/N、C/P和较低的N/P;(4)各林龄针叶N/P均小于14,表明该地区樟子松林整个生长过程始终受N的限制,但不同林龄间差异不显著;(5)针叶-凋落叶-土壤的C、N、P含量及其C/N、N/P之间存在显著的相关性,说明该樟子松林生态系统的C、N、P元素在针叶、凋落叶和土壤3个库之间存在运输转换,但其内在维持机制需要进一步深入研究。

Ecological Stoichiometry Characteristics of Needle Leaves-litter-soils in Pinus sylvestris var. Mongolica Plantations with Different Forest Ages

In order to understand the characteristics of carbon, nitrogen, phosphorus, and the stoichiometry characteristics of Pinus sylvestris var. Mongolica plantation ecosystem in Horqin Sandy land, we used the space-temporal exchanging method and selected four forests with different stand ages (15, 25, 35, and 45 years) but with similar site condition as the objects. The contents of carbon, nitrogen, phosphorus, and the stoichiometry characteristics in the needle leaf, litter, and soil were analyzed, then their changing characteristics as stand age increasing and the relationships between them were explored. The results showed that:(1) The contents of C, N, and P were in order of needle leaf > litter > soil, C/N, C/P, and N/P were in order of litter > needle leaf > soil, whose differences were significant among needle leaf, litter, and soil. (2) There were significant differences for C, N, P concentrations, and C/N, C/P stoichiometry ratios among forests with different stand ages. The C, N, and P contents of leaf, litter, and soil were the highest in the 35-years-old forest. (3) Compared to other regions, the leaf and litter performed the same characteristic with higher C and P, lower N, higher C/N, higher C/P and lower N/P. (4) The N/P ratios of all forests with different ages were lower than 14, but there was no significant difference between them, which indicated that the P. sylvestris plantation was restricted by N, but the N limitation was not significant between forest ages. (5) There were significant correlations between the contents of C, N, P and C/N, N/P ratios of the leaf, litter and soil, which indicated that the C, N, P elements of P. sylvestris plantation were transferred between 3 libraries of the conifer, litter, and soil, but its internal maintenance mechanism needs further study.