Abstract: In order to examine the influence of dominant species on the fertility of vegetation-growing concrete substrate, we collect the rhizosphere (R) and non-rhizosphere (N-R) soils of three dominant species (Pueraria lobata (PL), Arthraxon hispidus (AH) and Pennisetum alopecuroides (PA)) from the vegetation-growing concrete at Xiangjiaba and investigate the stoichiometric ratio of soil nutrient and microbial biomass. Results reveal that: (1) The rhizosphere, showing obvious enrichment, has higher content of nutrient and microbial biomass regardless of vegetation species than non-rhizosphere. The enrichment of nutrients except from available phosphorus in PL is more evident than that in AH and PA, and no significant difference is observed between AH and PA for most nutrient enrichment. The non-rhizosphere soil nutrient and microbial activity of PL are lower than those of AH and PA. (2) The ratios of carbon (C), nitrogen (N) and phosphorus (P) of rhizosphere soil of different plants are higher than those of non-rhizosphere soil, and in particular, the C/N and C/P in rhizosphere of PL are higher than those of AH and PA. There is no significant difference in MBC/MBN of rhizosphere soils among the three plants. The MBC/MBN and MBC/MBP in non-rhizosphere soil of AH and PA are significantly higher than those of PL (P<0.05); whereas the MBC/MBP and MBN/MBP in rhizosphere soil of PL are significantly higher than those of AH and PA (P<0.05). Compared with the average soil level in China and abroad, the C/N and MBC/MBN in the rhizosphere and non-rhizosphere soils of the three plants are higher, while C/P, N/P, MBC/MBP and MBN/MBP are lower. (3) Correlation analysis demonstrates that there is a very significant positive correlation among MBN, organic carbon, total nitrogen, total phosphorus and available nitrogen (P<0.01). However, MBP has a significant positive correlation only with available phosphorus (P<0.01). Comprehensive analysis indicates a positive role of plant in the nutrient storage of the vegetation-growing concrete substrate and a stronger nutrient enrichment ability in the rhizosphere of PL. In addition, an excessively high P content and inadequate amount of N imply the imbalanced proportion of nutrients in the substrate.

Key words: vegetation-growing concrete, ecological restoration, rhizosphere, soil stoichiometry, microbial stoichiometry