铁尾矿坝沙棘、桑树人工林生物量分配及根系分布研究

Study on biomass and root distribution of the mixed plantations composed of Hippophae rhamnoides L.and Morus alba L.planted on iron tailing

以铁尾矿区沙棘—桑树人工混交林为研究对象,对混交林内各层次、器官生物量以及生长期内沙棘、桑树根系分布状况进行了研究。结果表明:单位面积生物量比较为乔木层>枯枝落叶层>草本层,其中地被层凋落物生物量占到整个人工林总生物量的17.15%,尚无灌木层。桑树、沙棘各器官单位面积生物量比较均为:根>枝>干>叶。桑树单株生物量大于沙棘,但林分内沙棘密度高于桑树,因而单位面积沙棘生物量高于桑树。沙棘根冠比为0.72,桑树的根冠比为0.62。从单株根系生物量看,在0～40 cm土层内桑树大于沙棘;40～80 cm土层内沙棘大于桑树;80～100 cm土层内桑树又高于沙棘。从根系分布密度来看,沙棘<1 mm细根主要分布在根桩附近0～60 cm土层,60 cm以下明显减少;桑树<1 mm细根在0～20 cm土层内分布密度最大,20～80 cm土层内较为均匀,在80 cm以下才开始明显减少。桑树和沙棘存在协作与竞争共存的关系。

The biomass and root distribution of the mixed plantations composed of Hippophae rharnnoides L. and Morus alba L. on iron tailing were studied. The results show that the order of the vegetation＇s biomass allocation is tree layer〉 froest litter 〉 herb layer in the mixed plantations; the order of organs＇ biomass of trees is branch 〉 root 〉 stem 〉 leave. The biomass of forest floor accounts for 17.15 % of the total biomass of the mixed plantations, and there is no shrub layer. The R/T of Hippophae rhamnoides L. is 0.72 while Morus alba L. is 0.62. Moreover, vertically, the amount of Morus alba L. ＇ s root biomass is larger than Hippophae rhamnoides L. ＇ s at the 0 - 40 cm and 80 - 100 cm depth soil layer. Respectively, at 40 - 80 cm depth soil layer, the amount of Morus alba L. ＇ s root is smaller. The root density results show that Hippophae rhamnoides L. ＇ s fine roots （ 〈 1 mm） concentrated at 0 - 60 cm depth soil layer, which sharply decreases below 60 cm depth soil layer. On the contrary, Morus alba L. has the highest density of fine roots（〈 1 ram） at 0 - 20 cm depth soil layer, while the fine roots＇ density is even at 20 - 80 cm depth soil layer, and sharply decreases below 80 em depth. It is concluded that both competition and cooperation exist between these two species.