氮添加对武夷山米槠径向生长的影响
Effects of Nitrogen Addition on the Radial Growth of Castanopsis carlesii in Wuyi Mountain

摘要 通过设置对照(0)、低氮(50 kg N/(hm2·a))、中氮(100 kg N/(hm2·a))和高氮(150 kg N/(hm2·a)) 4 种水平的氮添加实验, 研究武夷山米槠(Castanopsis carlesii)径向生长的季节特征及其对模拟氮沉降的短期响应。结果表明, 米槠的全年生长可分为水分恢复期、快速生长期和缓慢生长期3个阶段。不同生长阶段对施肥的响应不同, 低氮和中氮处理对米槠的全年胸径相对生长速率有显著促进作用, 这种影响主要在快速生长期(6—10月)产生, 氮添加在缓慢生长期(11—4月)对米槠径向生长无显著影响。氮添加对不同径级树木生长的影响存在差异, 低氮和中氮处理显著促进低径级(5 cm25 cm)米槠径向生长无显著响应。中氮处理显著提高研究区内米槠群落的生物量增长速率 (p<0.05), 其他处理的效果不显著。
Abstract The authors carried out a N enrichment experiment in Wuyi Mountain with four N addition levels (control (0), low N (50 kg N/(hm2·a)), medium N (100 kg N/(hm2·a)) and high N (150 kg N/(hm2·a))) This study was designed to study the seasonal characteristics of DBH (diameter at breast height) growth of Castanopsis carlesii and its short term response to simulated nitrogen deposition. Results show that the Castanopsis carlesii annual growth can be divided into 3 periods: water recovery period, fast growth period and slow growth period. N additions play different roles on the growth of Castanopsis carlesii. In the fast growth period (June to October), low N and medium N significantly increase the relative growth rate of annual DBH. Relative DBH growth in slow growth period (November to April) has no significant response to N addition. Among different diameter classes, N additions affect the DBH growth differently: low and medium N additions significantly promote growth in low diameter class (5 cm25 cm) does not show significant response to N deposition. The study also finds that medium N addition significantly increase the biomass growth rate of Castanopsis carlesii in the study area (p<0.05).