黄土高原白羊草、沙棘和辽东栎细根比根长特性

Specific root length characteristics of three plant species,Bothriochloa ischaemum,Hippophae rhamnoidess and Quercus liaotungensis in the Loess Plateau

以黄土高原地区典型草本（白羊草）、灌木（沙棘）和乔木（辽东栎）为对象，研究了3种植物细根比根长在不同土层的分布状况以及与其它细根参数和土壤物理因子之间的相关性。结果表明，3种植物细根比根长的变化范围为6～55ram／rag。在0，80cm土层，白羊草、沙棘和辽东栎细根比根长变化范围分别为18—55mm／mg，14—4JDmm／mg，6—33mm／mg。3种植物0--80cm土层平均细根比根长从大到小依次为白羊草〉沙棘〉辽东栎。3种植物0-10cm土层细根比根长依次为沙棘〉辽东栎〉白羊草，10-80cm依次为白羊草〉辽东栎〉沙棘，表明3种植物细根比根长不仅在这两土层中的分布不具一致性，而且与0-80cm土层平均比根长也不具有一致性，进一步说明3种植物沿土壤剖面的生物量分配策略不同。相关分析表明，3种植物细根比根长与其它细根参数之间的相互关系各不相同，制约程度存在差异。与土壤物理因子的相关分析表明，3种植物细根比根长均随土壤含水量的增加而减少。土壤各级水稳性团聚体和土壤颗粒对3种植物细根比根长并无一致的影响。

Plant traits can be morphological, eco-physiological and phenomenological, studies of plant traits which relate to the key plant functions have primarily concentrated on leaf structure and physiology, however, much less is known about the interspecific variations in root structure and physiology. The specific root length （SRL） is one of the plant traits that are related to plant functions such as resource uptake, biomass allocation and root structure and function. It can not only reflect the environmental change, but also provide information about the shaping of itself by climate, soil nutrients or other factors. The vertical distributions of fine roots in the soil profile （0--80cm） for Bothriochloa ischaemum, Hippophae rhamnoidess, Quercus liaotungensis, which are three typical plant species in Loess Plateau were studied. The fine roots distributed from 0 - 80cm soil depth were collected for each 10 cm interval in each experimental plot, and then the fine root traits, soil water content, soil water stable aggregates and soil granules were determined in this study. The results showed that the SRL of Bothriochloa ischaemum, Hippophae rhamnoidess, Quercus liaotungensis, was ranging from 18-55 mm/mg, 14- 40 mm/mg, 6 --33 mm/mg in the 0- 80 cm soil profile, respectively. Comparatively, the mean SRL （0 -80cm） of three species stood in the following order of Bothriochloa ischaemum 〉 Hippophae rhamnoidess 〉 Quercus liaotungensis. The mean SRL in the 0 - 10 cm soil layer for three species were ranked in the order of Hippophae rhamnoidess 〉 Bothriochloa ischaemum 〉 Quercus liaotungensis, and that in the 10 -- 80 cm soil layer ranked in the order of Bothriochloa ischaemum 〉 Quercus liaotungensis 〉 Hippophae rhamnoidess. It is indicated that three species have different strategies for biomass allocation in different soil profile. The correlation analysis showed that the SRL was negatively correlated with the root biomass and root length density （RLD） for Bothriochloa ischaemum, however, it was positively correlated with the root biomass and RLD for Hippophae rhamnoidess. For Quercus liaotungensis, the SRL was negatively correlated with the root biomass, but positively correlated with the RLD. It is suggested that the interactions between root traits were dependent on species. The SRL of three species were all decreased with the soil water content increased. And the relationships between the SRL and soil water stable aggregates and soil granules indicated that different soil physical factors have different effects on the SRL.