Effects of biological soil crusts on plant growth and nutrient dynamics in the Minqin oasis-desert ecotone, Northwest China

Biological soil crusts (BSCs) play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas. However, the specific effects of BSCs on growth status and nutrient accumulation of plants are still unclear in different arid areas. This study analyzed the effects of three different BSCs treatments (without crust (WC), intact crust (IC), and broken crust (BC)) on the growth, inorganic nutrient absorption, and organic solute synthesis of three typical desert plants (Grubovia dasyphylla (Fisch. & C. A. Mey.) Freitag & G. Kadereit, Nitraria tangutorum Bobrov, and Caragana koraiensis Kom.) in the Minqin desert-oasis ecotone of Northwest China. Results showed that the effects of three BSCs treatments on seed emergence and survival of three plants varied with seed types. The IC treatment significantly hindered the emergence and survival of seeds, while the BC treatment was more conducive to seed emergence and survival of plants. BSCs significantly promoted the growth of three plants, but their effects on plant growth varied at different stages of the growth. Briefly, the growth of G. dasyphylla was affected by BSCs in early stage, but the effects on the growth of G. dasyphylla significantly weakened in the middle and late stages. However, the growth of N. tangutorum and C. koraiensis only showed differences at the middle and late stages, with a significant enhancement in growth. Analysis of variance showed that BSCs, plant species, growth period, and their interactions had significant effects on the biomass and root: shoot ratio of three plants. BSC significantly affected the nutrients absorption and organic solute synthesis in plants. Specifically, BSCs significantly promoted nitrogen (N) absorption in plants and increased plant adaptability in N poor desert ecosystems, but had no significant effects on phosphorus (P) absorption. The effects of BSCs on inorganic nutrient absorption and organic solute synthesis in plants varied significantly among different plant species. The results suggest that BSCs have significant effects on the growth and nutrient accumulation of desert plants, which will provide theoretical basis for exploring the effects of BSCs on desert plant diversity, biodiversity conservation, and ecosystem management measures in arid and semi-arid areas.