不同年龄日本落叶松人工林生物量、碳储量及养分特征

以7、17、30和40年生4个发育阶段(幼龄、中龄、近熟和成熟阶段)的日本落叶松人工林为对象,研究了林龄对生物量、碳储量和养分特征的影响.结果表明: 在单木水平上,不同发育阶段干、枝、皮、叶、根生物量和养分浓度差异显著.随年龄增加,各器官生物量呈增大趋势,N、P、K浓度呈下降趋势,Mg浓度先降后升,Ca浓度持续升高.优势木、平均木和劣势木的各器官生物量之间差异显著,但养分浓度差异不显著,表明竞争对各器官养分浓度影响不大.在林分水平上,总生物量、碳储量和养分储量随林龄增加呈增大趋势,与幼龄林相比,成熟林分别增加217.9%、218.4%和56.4%,表明日本落叶松林生长后期能以较少的养分生产较多的干物质,养分利用效率较高.5种元素的积累量除P和K在近熟林(30年生)略有降低外,其他元素都随林龄增加而增加.N集中在叶中,Ca集中在树干,K和Mg主要集中在根,P在不同器官中的分配较均匀.日本落叶松林分年均生物量积累率、固碳率和养分积累率均随林龄的增加而降低,从幼龄林每年7.16 t·hm^-2、3.40 t·hm^-2、104.64 kg·hm^-2降低到成熟林的3.99 t·hm^-2、1.89 t·hm^-2、28.64 kg·hm^-2,表明日本落叶松林幼、中龄阶段固碳潜力大,但养分消耗也高.

Biomass,carbon storage and nutrient characteristics in Larix kaempferi plantations at diffe-rent stand ages

Based on 7-, 17-, 30-, and 40-year-old Larix kaempferi plantations, this paper studied the influence of tree age on biomass, carbon storage and nutrient characteristics. There was significant difference in biomass and nutrient concentration of stem, bark, needle, branch and root at different development stages at individual tree level. The biomass of each organ showed a trend of increase with the increasing age. The concentrations of N, P, K decreased, Mg concentration increased at first and then decreased, and Ca concentration continued to rise with the increasing age. There was significant difference in biomass of each organ for dominant, intermediate and suppressed trees, but no significant difference in nutrient concentration. It indicated that nutrient concentration of each organ was not affected by competition. At stand level, the total biomass, carbon storage and nutrient accumulation increased with the increasing age. Compared with young stand, the growth rate of biomass, carbon storage and nutrient accumulation were increased by 217%, 218% and 56% in mature stand, respectively. It indicated L. kaempferi had a high nutrient use efficiency, and could utilize less nutrient to produce more dry matter. Except that the accumulation of P and K had a slight decrease in pre-mature stand (30 years old), other elements increased with the increasing age. N mainly concentrated in needle, Ca concentrated in stem, K and Mg concentrated in root and P was distributed evenly in different organs. The annual accumulation rates of biomass, carbon and nutrient of L. kaempferi stands decreased with the increasing age, from 7.16 t·hm^-2, 3.40 t·hm^-2 and 104.64 kg·hm^-2 for young stand to 3.99 t·hm^-2, 1.89 t·hm^-2and 28.64 kg·hm^-2 for mature stand, respectively. It indicated that L. kaempferi plantations had great carbon sequestration potential and high nutrient consumption during young and middle ages.