桤木生物量及根系分布规律

采用全部、分层挖取法，研究洞庭湖区9年生桤木人工林的生物量及根系分布规律。结果表明：桤木单株生物量为44.39ks／株，各器官生物量大小排序为树干〉树根〉树枝〉树皮〉树叶；林分总生物量为96.06/hm^2；林分净生产力为10.67/（hm^2·年）。桤木根系发达，根深60～80cm；根系中以根桩和粗根的生物量所占的比例最大，两者之和占根系总生物量的84.27％。在垂直分布上，根系主要分布在0～40cm的土层中，其生物量占根系总生物量的84.51％。在水平分布上，根系主要分布在离树桩0～50cm的范围内，其生物量占根系总生物量的84.49％；特别是粗根，其生物量占根系总生物量的29.47％；茵根的生物量占根系总生物量的0.39％，主要分布在离树桩50～100cm的范围内，该区域根系的生物量占茵根总生物量的70.97％。

Biomass and root distribution of Alnus cremastogyne plantation

The biomass and root distribution of 9-year-old Alnus cremastog）Tte plantation were studied in Dongting Lake area using hierarchical digging method. The results showed that, the biomass was 44.39 kg per plant with the organs biomass order for stem 〉 roots 〉 branch 〉 bark 〉 leaf. The forest biomass was 96.06 t/hm^2 , and the annual net productivity was 10. 67 t/ （ hm^2·a） . The root system of Alnus cremastogyne developed with depth 60 ～ 80 cm. The proportion of pile and coarse root were the most in the total roots biomass, which reached 84.27%. In vertical distribution, root mainly distributed in 0～40 cm soil layer, its biomass was 84.51% of the total root biomass. In horizontal distribution, root mainly distributed in vitro stump within the range of 0 ～ 50 cm, accounting for 84.49% of the total root biomass, especially coarse roots, accounted for 29.47% of the total root biomass. The biomass of the total amount of root rhizobia accounted for 0.39% of the total root biomass, mainly distributed in the 50 ～ 100cm range from stump level, in which the biomass of root accounted for 70.97% of the biomass of the total amount of root rhizobia.