Downy brome (cheatgrass) is so successful as an invasive species because it can “engineer” its own soil environment, says a study published in the current issue of Invasive Plant Science and Management.
A release from the magazine say the authors grew downy brome in soil from the northern Great Basin of California that had and had not already been invaded by the plant. They then sampled and compared the root mass and soil at three depths and the plant biomass.
After one season, downy brome grown in invaded soil had 250 per cent more biomass and almost twice the root mass of plants grown in the non-invaded soil. By the second growing season, biomass in the invaded soil was still almost double the amount in the non-invaded soil, while root mass had decreased and was similar between invaded and non-invaded soils.
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The authors also found that downy brome became more competitive when it received more nutrients, particularly nitrogen, phosphorus and manganese. They found that the plant increased these nutrients in the soil for its own benefit.
The authors speculated that the plant can take over areas filled with supposedly resistant plants by increasing and then exhausting the soil nutrients, causing downy brome to thrive and native plants to struggle.