不同生长期山核桃林碳氮磷生态化学计量特征

C,N and P Stoichiometric Characteristics in Carya Cathayensis and the Forest Soil in Different Seasons

摘要:

采用生态化学计量学原理，以人工山核桃林为研究对象，分析了山核桃林地土壤、山核桃细根、和山核桃叶的 C、N、P 化学计量学季节变化特征。结果表明，土壤有机 C 和 N 含量均是在 7 月表现最高，分别为 42.00 ~g?kg?1 和 1.75 g?kg?1，P 在 6 月最高，为 1. 31 ~g?kg?1；土壤 C∶N、C∶P 均是在 10 月叶凋落期最高。绿叶有机 C 在 7 月份最高，为 497.30 g. kg，凋落叶中有机 C 为 505.60g?kg，明显高于绿叶。绿叶 N 和 P 含量最高分别在 6 月和 5 月，分别为 23. 27 ~g?kg?1 和 2.28 ~g?kg?1，说明山核桃对 N、P 吸收的时间差异性。山核桃在不饱和脂肪酸合成关键期 (8~9 月)，受到 N 限制。山核桃叶片 C∶N 和 C∶P 分别为 26.41 和 310.56，高于全球植物平均水平 22.5 和 232，说明山核桃对营养利用效率较高。山核桃 N、P 重吸收率分别为 32.26% 和 15.48%，N 重吸收率显著高于 P 重吸收率，明显低于全球水平的 N、P 重吸收率 (约 50%)。相关分析表明，增加山核桃林地土壤有机质含量，对于提升 P 含量有促进作用。

Abstract:

To examine the seasonal variation characteristics of carbon, nitrogen, and phosphorus (C: N: P) stoichiometry and its relationship with N and P resorption, we took the artificial hickory forest as the research object. The hickory forest soil, hickory fine root, and hickory leaf were analyzed. The results showed that soil organic C and N contents were the highest in July at 42.00 1. 75 ~g·kg?1, respectively, and P was the highest at 1. 31 ~g·kg?1 in June; C∶N, C∶P in soil was the highest in October, namely the defoliating period. The highest organic C content of green leaves was 497. 30 ~g·kg?1 in July, and 505.60g·kg in leaf litter, which was significantly higher than that of green leaves. The contents of N and P in green leaves were highest in June and May, respectively 23.27 and 2.28 ~g·kg?1, indicating the time difference of N and P assimilation in the Hickory. The critical period(8 to 9 months)of the unsaturated fatty acid synthesis in nuts, was limited by N. C∶N and C∶P in hickory leaf were 26.41 and310.56, higher than the global plants average of 22.5 and 232, indicating that hickory had higher usage efficiency as N and P. The N and P reabsorption rates were 32.26%and 15.48%respectively, and the N - reabsorption rate was significantly higher than P, and they were significantly lower than the global N, P reabsorption rate(about 50%). Correlation analysis showed that certainly increasing organic matter content in hickory forest soil could promote P content.