Biomass and its allocation of undergrowth Vitex negundo L. in different age classes of mixed cypress forest
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摘要:
灌木是森林生态中一个重要组成部分，以柏木林下主要灌木种-黄荆为研究对象，研究其在不同年龄柏木林下的生物量以及分配格局，同时利用简单指标对其生物量建立估测模型。研究表明：①随着林分年龄的增加，林下黄荆单丛生物量以及各器官生物量也随之增加，其中枝生物量相差值最大，差距达24.3倍,而生物量最小的叶片，其差距也达6.9倍。 ② 黄荆地上各器官生物量分配大小表现为干生物量＞枝生物量＞叶生物量＞皮生物量；根系生物量的分配以粗根和中根生物量为主，其中根桩和粗根生物量所占比重随着林分年龄的增加而增加，中根、小根和细根生物量所占比重则随着林分年龄的增加而减小；地上生物量所占比例较大，并随着林分年龄的增加逐渐降低，并最后趋于稳定。 ③ 建立生物量模型的简单指标以基径（D）作为自变量优于利用株高（H）和HD2模型的建立；最优预测模型多为二次或三次次曲线模型。其中干、枝和粗根生物量、地上生物量、地下生物量、单丛生物量建立的预测模型较好，其模型的相关系数在0.8107—0.9293,达到极显著水平；皮生物量和根桩生物量的次之，模型相关系数分别为0.7689和0.7926；中根和小根的生物量预测模型相对最差，模型的最大相关系数仅在04410—0.4830。
Abstract:
The bush is an important component in forest ecosystem. In the hilly area of central Sichuan Basin，the biomass and its allocation of undergrowth Vitex negundo L. in different age classes of mixed cypress forest were measured and analysed, and the biomass allometric equations has been established.The results showed that: ①With the increase of forest age, the biomass and its components of the undergrowth single Vitex negundo L. increased. In which the difference of branch biomass is biggest, the disparity achieves 24.3 times; leaf biomass is the smallest which achieves 6.9 times. ②The aboveground biomass allocated in the order stem biomass>branch biomass>leaf biomass>bark biomass. The coarse roots and middle roots dominated the underground biomass. With the increase of forest age, the biomass proportions of stump and coarse roots increased，while those of middle roots, small root and fine root reduced. As a main part of biomass, the proportion of aboveground biomass in total biomass decreased with the increase of forest age and finally tended to stabilize. ③ The biomass as well as its component are more relevant to basal diameter (D) alone than the height (H) and HD2.
