Effects of changes in precipitation pattern and of seaweed fertilizer addition on plant traits and biological soil crusts

Abstract

In arid areas precipitation patterns and soil nutrient determine plant survival. To study the effect of fertilizer addition on plant traits and on biological soil crusts under different rainfall intervals we collected and sowed the seeds of three typical psammophyte species from a natural community in China’s Mu Us Desert, and raised their seedlings in pots. During the growing season we added commercial seaweed fertilizer to the pots and irrigated the plants at different intervals. After one growing season we measured plant traits and the biomass of biological soil crusts, and soil nutrient contents. Seaweed fertilizer increased biomass production. The combined effects of seaweed fertilizer and rainfall interval were related to the life history attributes of the species. For a given fertilizer addition, changing the rainfall interval from 3 to 15 days increased the Agriophyllum squarrosum and Achnatherum splendens biomass, but decreased Glycyrrhiza uralensis biomass. Seaweed fertilizer significantly affected plant traits, but the effects of the rainfall interval on plant traits were not significant. Fertilizer addition increased the soil organic carbon and total nitrogen. Fertilizer addition also promoted biological soil crusts and enriched their total nitrogen content. Structural equation modeling showed that the organic carbon, total nitrogen, and chlorophyll a content of the biological crusts played different roles in biomass production of the three species. Soil carbon and nitrogen affected biological soil crusts more than they affected plant biomass production. Our results show that seaweed fertilizer can promote plant growth and biological crust development, making it useful for ecosystem restoration in arid and semi-arid regions.