Santa Monica Mountains National Recreation Area - Grasses

Two types of grassland occur in the Santa Monica Mountains: native perennial and alien annual grasslands. Perennial bunch grasses are considered to be the original native grassland of California, while annual grasses were those introduced by the European and Spanish settlers for their livestock. The golden rolling hills of California are largely a result of the introduction of these annual grasses, since bunchgrasses often remain green even during summer drought.

Perennial bunch grasses differ from annual grasses in that they put much of their energy during their first several years into establishing a well-developed root system that will sustain them through regular summer drought. Their roots penetrate deeply into the soil, providing nutrients and water and holding soil particles firmly in place thus decreasing the erosive effects of wind and water. Unlike annual grasses, they don't produce seeds the first year, but rather as the years continue, produce an abundance of seed at maturity. The tufted parent increases in size every year.

Over 100 years of livestock grazing in California, some very intense, has converted former native perennial grassland to alien annual grassland. Native perennial grasslands historically covered nearly 20 percent of California, but today cover less than 0.1 percent. Today, approximately 18 million acres or 17 percent of California is considered valley grassland (containing both alien annual and native perennial species) (Keeley 1990). The California Natural Diversity Database (CNDDB) identified Purple Needlegrass Grassland as a community needing priority monitoring and restoration. The CNDDB considers grasslands with 10 percent or greater cover of Nassella pulchra to be significant, adding that these should be protected as remnants of California prairie.