氮肥对闽楠人工幼林生长的影响

Effect of N Fertilizer on Growth Performance of Young Stands of Phoebe bournei

闽楠(Phoebe bournei)人工幼林生长缓慢是闽楠培育研究长期攻而未克的难题。闽楠人工幼林地抚育研究表明割灌除草可显著促进闽楠幼林生长,而施肥能否显著促进闽楠幼林生长却有相反的研究结果。为进一步探清施肥对闽楠人工幼林生长是否具有显著影响,本研究以广东省梅州市平远县的闽楠人工幼林为研究对象,以尿素(含N46%)作为试验氮肥,采用随机完全区组试验设计,设置0(对照)、100、200、300、400、500 g/株等6个施用量水平,每年1次,连续施用2年,对试验林的树高、地径、胸径和冠径等指标连续监测2年。研究结果表明,施肥闽楠幼林的树高、地径和冠径生长节律与未施肥闽楠幼林的生长节律相似,从当年9月至翌年的3月为生长停滞期,9月、12月和3月3个月间的树高、地径与冠径没有显著差异;3—9月为高速生长期,每3个月树高、地径和冠径就有一般显著、显著或极显著的提升。施肥闽楠幼林的树高、地径、冠径虽然比未施肥闽楠幼林略有提高,但差异不显著。由此可见氮肥施用1年或2年对闽楠幼林生长没有显著影响,其原因可能是土壤含有的养分可满足闽楠幼林的生长,也有可能是氮肥需要连续施用3年以上才能显现出显著的生长差异。

Phoebebournei is a traditional value timber and ornamental tree in China. It grows well at humid valleys, while its young stand grows slowly across a whole slope, which extends time taken for the stand to close its canopy, to be a forest and to be harvested. Tending studies show that weeding and partly shading improve growth performance significantly for youug slands of P. bournei, however,there is discrepancy in effect of fertilization on growth performance of young stands of P. boumei.Aiming to resolve the discrepancy, nitrogen fertilizer was applied to young stands at Pingyuan, a county located in north- eastern Guangdong province. Five levels of fertilization doses were applied to 1 year otd stand for P. bournei with the de- sign of random complete blocks. Tree keight, diameter at collar, crown diameter, volume per tree, and volume per hec- tare were employed to assess the effect of fertilizers on young stand. Growth dynamics are observed similar between fer- tilized stands with non-fertilized stands in height, diameter, crown diameter, volume per tree and volume per ha. Trees growth is not different significantly from September to next year March. no significant differences are found among differ- ent months during that period. Trees grown rapidly from March to year September. general, significant or very significant differences are found between June and March and similar results are found b＇etween September and June. Young stands applied with nitrogen fertilizer grow better than those without fertilizer appli＇ed, however, the increment is not significant- ly different. It is concluded that applying nitrogen fertilizer can be excluded for tending young Stands Of P. bournei.