基于内生长土芯法探究不同林龄杉木人工林的营养限制因子

为探究不同林龄杉木林的营养限制因子,以3年生、14年生、21年生、46年生杉木为研究对象,运用内生长土芯法,监测杉木细根对不同施肥处理,即对照、+N溶液处理、+P溶液处理和+NPK混合溶液处理的响应.结果表明:试验进行12个月后,对照,+N、+P、+NPK处理的细根生物量变化范围依次为84.49~155.10、102.90~325.06、82.39~128.69、61.70~115.20 g·m-2,其中+N处理细根生物量变化最大.总生物量表现为对照+N处理+P处理+NPK处理,杉木细根生物量随年龄的增大表现出先增大后减小的趋势,在速生期14 a达到最大值,呈单峰型.样地内3年生杉木人工林施加N、P元素更有利于杉木的生长,14年生杉木主要缺N元素,21年生杉木主要缺乏N、K元素,添加养分对46年生杉木的影响不明显.

Application of root-in growth cores to assess nutrient limiting factors of Cunninghamia lanceolata needle leaves under different ages

To identify nutrient limiting factors of Cunninghamia lanceolata, nitrogen (N), phosphors (P) and compound fertilizer of N, P and potassium ( K) were applied to Cunninghamia lanceolata plantations of 3, 14, 21 and 46 years old. Then how root re-sponse to nutrients was monitored by root-in growth core. The results showed that biomass of fine root from N fertilizer varied the most among all treatments after 12-month application. The total biomass of fine root from different treatments in a descending order was de-ionized water as the control, +N, +P, and +NPK. Vermiculite proved to as a proper holding capacity of water holding capacity of the substrate and promotes the growth of fine root. Fertilizer efficacy firstly increased with stand age and then drop when the stand aged, with biomass peaking at 14-year-old stand. To summarize, N and P fertilization facilitate the growth of 3-year-old stand signifi-cantly. And 14-year-old stand is more likely to be deficient in N and 21-year-old stand will both need N and K fertilizers. While 46-year-old stand did not response to fertilization.