高磷土壤对矿区先锋植物马桑生物量分配与根系构型的影响

Effects of High Soil Phosphorus on Biomass Allocation and Root Morphology of the Pioneer Plant Coriaria nepalensis

【目的】研究马桑(Coriaria nepalensis)对高磷土壤环境的适应策略,为区域植被恢复提供科学依据。【方法】采集昆阳磷矿(高磷)和自然恢复次生林(中磷)的原位土壤,利用根箱试验研究马桑在高磷和中磷环境下的生物量分配和根系形态变化,并利用ImageJ软件分析马桑的根系参数。【结果】(1)高磷胁迫可显著降低马桑的生物量积累,具体表现为叶片数减少了64.2%,地上部生物量降低了19.1%。(2)高磷和中磷土壤条件下,马桑地下部生物量的差异不显著;但高磷可导致其根尖数、根表面积、比表面积、根系内部连接数和外部连接数均显著降低,根系分支拓扑指数也有所减小。(3)不同土壤磷水平改变了马桑地下部和地上部生物量的积累,且地上部生物量与地下部生物量的异速生长关系在2种磷水平条件下存在极显著差异(P<0.01);在高磷土壤条件下,地下部生物量的增长速度大于地上部生物量,最终表现为地下部生物量占比提高,占总生物量的55.0%。【结论】马桑倾向于通过增加地下部生物量的占比、增加根系粗壮程度、减少根系分支来适应高磷环境。研究结果为马桑的生态适应性研究和退化富磷山地植物恢复和引种研究提供了科学依据。

[Purpose]To study the adaptive strategies of Coriaria nepalensis to high-phosphorus soil conditions,providing a scientific basis for regional vegetation restoration.[Methods]Situ soil samples from Kunyang phosphate mine(high phosphorus,HP)and natural restoration secondary forest(medium phosphorus,MP)were collected,and a root box experiment was used to study the bio-mass allocation and root morphology changes of C.nepalensis under HP and MP environments.ImageJ software was used to analyze the root parameters of C.nepalensis.[Results]1)HP stress resulted in a significant decrease in biomass accumulation of C.nepalensis,as evidenced by a 64.2%decrease in leaf number and a 19.1%decrease in aboveground biomass.2)There were not significant differences in underground biomass accumulation of C.nepalensis between HP and MP environments;however,HP could lead to a significant decrease in the number of root tips,root surface area,specific surface area,the number of internal root connections,and the number of external root connections,as well as a decrease of topological index of root branching.3)Different soil phosphorus levels changed the biomass accumulation in the underground and aboveground of C.nepalensis,and the allometric growth relationship between the biomass of aboveground and underground was extremely significantly different under two phosphorus levels(P<0.01).Under HP soil conditions,the growth rate of underground biomass was higher than that of aboveground biomass,and the proportion of underground biomass was increased,accounting for 55.0%of total biomass.[Conclusion]C.nepalensis tends to increase the proportion of underground biomass and the robustness of root systems,and reduce root branching to adapt to HP environments.This study provides a scientific basis for the ecological adaptability research and the restoration and introduction research of degraded phosphorusrich mountain plants in C.nepalensis.