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South African Grass Invades Arizona, Threatens Natives
19 Oct
Summary
- Lehmann lovegrass, native to South Africa, was introduced in Arizona in 1932.
- Planted on 172,000 acres, it now dominates 347,000 acres.
- Its dominance may decrease wildlife diversity and increase fire frequency.
Lehmann lovegrass, a perennial grass originating from South Africa, was first introduced to Arizona in 1932. Between 1940 and 1980, ranchers and land managers established it on over 172,000 acres, primarily in southeastern Arizona. By 1988, this foreign grass had become a major species on approximately 347,000 acres, indicating significant, unintended spread.
A long-term study conducted from 1954 to 1989 on the Santa Rita Experimental Range revealed its aggressive nature. The grass was present on over 85% of non-seeded plots by 1989, forming over 40% of all perennial grass individuals. Researchers found its spread was independent of livestock grazing.
This prolific grass has transformed at least 350,000 acres of semi-desert grassland. It produces two to four times more biomass annually than native grasses, displacing species like Arizona cottontop and threeawn grasses. Its earlier seed maturation and prolific growth threaten native ecosystems.
Experts conclude that the dominance of Lehmann lovegrass is likely to decrease wildlife diversity and increase fire frequency. They strongly advise careful consideration of these ecological impacts before introducing new species for land management.
