不同龄组天然常绿阔叶林与杉木人工林林下草本层生物量分配特征

以福建省天然常绿阔叶林及人工杉木林下草本层为研究对象,对其地上生物量(y)与地下生物量(x)分配关系进行研究,并对方程lg y=b+ a lg x中的生长指数(a)和生长常数(b)进行计算分析,初步揭示不同森林类型草本层植物生物量分配及其随乔木层林龄变化的基本特征,探究其是否符合等速生长规律。结果显示:①天然常绿阔叶林草本层生物量随林龄增加而下降,人工杉木林草本层生物量在成熟林时期最大,幼、中龄林次之,近熟林最小; ②天然常绿阔叶林幼龄林及成熟林草本层地上-地下生物量分配遵循等速生长规律,中龄林及近熟林生长指数a的95%置信区间上限接近理论值1,各林龄生长常数以成熟林<幼龄林<中龄林<近熟林; ③人工杉木林草本层地上-地下生物量分配均遵循等速生长规律,各林龄生长常数以幼龄林>成熟林>近熟林>中龄林。研究表明,人为干扰对草本层地上-地下生物量分配有影响,但并未破坏其等速分配生长的规律。

Above and below ground biomass allocation on herb layer of natural evergreen broad-leaved forest and Chinese fir plantation with different age classes

To explore the above and below ground biomass allocation patterns of herb layer, two different forest type including the natural evergreen broad-leaved forest and Chinese fir plantation with various age classes in Fujian Province were analyzed using the logarithmic equation: lg y=b+a lg x, and the isometric above and below ground biomass allocation theory was also detected using the above and below ground biomass of herb layer. The results indicated that the herbaceous layer biomass of natural evergreen broad-leaved forest decreased with the increasing of stand age. On the contrary, in Chinese fir plantations, the total biomass of herb layer was the highest in the mature forest stage, and the total biomass was the minimum in the pre-mature forest. Additionally, the ratios of above to below ground biomass were different for the two forest types. In different forest age, the scaling exponents(a)of above and below ground biomass in natural evergreen broad-leaved forest herb layer were 0.785, 0.757, 0.760 and 1.232, respectively. The above ground biomass scaled isometrically with below ground biomass of young and mature forest herb layers in natural evergreen broad-leaved forest, with the 95% confidence interval including the theoretical value of 1.0. Furthermore, the 95% confidence interval of the scaling exponents were close with 1.0 in the middle age and pre-mature forests. For the scaling constants(b), it followed the order of mature forest a)of herb layer ground in Chinese fir forests were all consistent with the isometric biomass allocation theory. For the scaling constants(b), it followed the order of young forest >mature forest > pre-mature forest > middle-age forest. The result support the theory that above ground biomass of herb layer scales i ometrically with below ground biomass.