林龄和竞争对日本落叶松各组分生物量异速关系的影响

基于7-、17-、30-和40年生日本落叶松生物量测定数据,应用方差分析和多重比较分析了林龄和林分内树木竞争类型(优势木、平均木和被压木)对各组分生物量分配比例和异速关系的影响,构建了含林龄和树木竞争类型作为哑变量的生物量异速方程,为准确估算日本落叶松人工林生物量和碳储量提供依据。结果表明:(1)林龄显著影响生物量分配比例的异速关系。随林龄增加干生物量比例增大,枝叶生物量比例减小,根生物量逐渐稳定。加入林龄的干、枝和叶生物量方程显著改善。年龄效应在幼龄林阶段作用最显著,需单独构建生物量模型。(2)树木竞争类型对生物量分配的影响小于林龄。立地条件一致下,虽然相同胸径的优势木比劣势木积累更多的枝叶生物量和少的干生物量,但它们分配生物量到不同器官的比例和方式是基本相同的,林内竞争不会导致生物量分配规律由"异速关系理论"向"环境优先理论"转化。因此,常规采用平均木法估算各组分生物量是可行的。(3)在近成熟林分中不同竞争类型树木的根生物量分配比例均较为稳定,采用根茎比比值来估算根生物量是可行的。

Effects of stand age and competition on allometric relationships for biomass partitioning in Larixkaempferi plantation

The effects of stand age and competitive types of trees (dominant and suppressed trees) on biomass allocation ratio and allometric relationship of each component were analyzed using ANOVA and multiple comparison based on a chronosequence approach for 7-, 17-, 30-, and 40-year-old Larix kaempfer plantations. We developed the high-precision allometric biomass equation as the basis of estimating biomass and carbon storage of Larix kaempfer. The results showed that:(1) the stand age had significant effects on the allometric relationship of biomass allocation. With the stand age increased, the proportion of stem biomass increased, but the proportion of branch and leaf biomass decreased, while the root biomass gradually became stable. The biomass model of stem, branch and leaf was significantly improved by adding the stand age variable. Age effect was the most significant in young stand stage, so biomass model should be constructed separately. (2) The tree competition types had also some effects on biomass allocation, but was less than that of the stand age. The dominant trees had more foliage biomass and less stem biomass. When the site conditions were similar, the competition effect could lead to the difference of biomass accumulation in the organs of dominant and suppressed trees, but the proportion and manner of biomass allocation to different organs were almost same. The competition within stand would not result in the biomass allocation strategy in terms of the theory of allometric relationship and the theory of environmental priority. So, when estimating the biomass of each component, the difference of tree grades in stand would not bring more deviation, The conventional method of estimating biomass by intermediate tree is feasible. (3) The root biomass of different competitive types of tree in pre-mature and mature stands was relatively stable. The percentage of root-stem ratio can be used to calculate root biomass.