福建柏与杉木人工林细根氮磷养分现存量的动态变化

Dynamics of nitrogen and phosphorus standing stocks in fine roots of Fokienia hodginsii and Cunninghamia lanceolata plantations

对福建柏Fokienia hodginsii与杉木Cunninghamia lanceolata人工林细根氮、磷养分现存量的动态变化进行研究。结果表明,福建柏细根氮、磷养分现存量分别是杉木林的1.8倍和1.7倍;福建柏活细根氮、磷养分现存量为12.948 kg.hm-2和1.692 kg.hm-2,分别是杉木林活细根氮、磷养分现存量(7.106 kg.hm-2和0.896 kg.hm-2)的1.8和1.9倍;而福建柏死细根氮、磷养分现存量为10.410 kg.hm-2和1.192 kg.hm-2,分别是杉木林死细根氮、磷养分现存量(6.216 kg.hm-2和0.780 kg.hm-2)的1.6倍和1.5倍。福建柏与杉木<0.5 mm径级细根是其细根养分循环功能的主体。福建柏活细根氮、磷养分现存量动态变化与杉木的相似,呈双峰型;福建柏死细根氮现存量动态变化则呈单峰型,死细根磷现存量动态变化呈倒“S”型。杉木死细根氮、磷养分现存量动态变化均呈倒“S”型。

Levels of nitrogen （N）and phosphorus （P）in fine roots of two coniferous plantations （Fokienia hodginsii and Cunninghamia lanceolata were studied in 1999 in Sanming, Fujian, China. The results indicated that in fine living roots of F. hodginsii, the mean N level was 12.948 kg·hm^-2 and P was 1.692 kg·hm^-2 , for an N of 1.8 times more and P of 1.9 times more than C. lanceolata. For dead fine roots of F. hodginsii, mean N was 10.410 kg·hm^-2 and P was 1. 192 kg·hm^-2 with N 1.6 times higher and P 1.5 times higher than C. lanceolata. For both F. hodginsii and C. lanceolata, roots with a diameter 〈 0.5 mm were the main source for root nutrient recycling. Like C. lanceolata, the curve of N and P levels changing in the fine living roots of F. hodginsii over study period were double-peaked. In the fine dead roots of F. hodginsii over time, the curve of N level dynamic was single-peaked and that of P was reverse-S shaped, whereas both of N and P for C. lanceolata were reverse-S shaped.