Grasses

Grasses on post-grazing survey, plot 5

Ryan Summers

The Importance of Grass

As a family, grass (or Poaceae) is incredibly important for not only human consumption, but livestock grazing as well. That's not even counting how important they are ecologically, allowing for greater infiltration of water into the soil rather than running off during intense monsoon storms. This replenishes springs, recharges streams through underground flow, and allows the soil to stay moist for longer, which greatly benefits the health of the plants. However, grasses play a central part in the fire cycles of the park as well. During normal years, grasses will burn lightly and restore the ecosystem to a healthier level than previous. However, when grasses are not consumed by herbivores and build up to unnatural levels, more intense and damaging fires can occur (just like in pine ecosystems).

 

Nine-awn pappusgrass, a native species that grows widespread during wet years.

Ryan Summers

Grasses in the Park

Saguaro National Park is home to at least 225 species of grasses, some less than 0.3 meters tall such as fluffgrass (Dasyochloa pulchella) some right around one meter such as nine-awn pappusgrass (Enneapogon desvauxii, pictured) and tall grasses such as Giant Dropseed (Sporobolus giganteus) reaching over 2 meters in height. Most grasses, particularly the bouteloua genus are extremely palatable (edible) for wildlife. These grasses are not as readily consumed as they once were, as the main species of animal, desert bighorn sheep (Ovis canadensis nelsoni) has been extirpated since the 1950's.

As mentioned, native species in the park do not burn very hot and make intense fire, but invasive species such as buffelgrass, crimson fountaingrass and red brome have caused extremely hot fires from 1989-1999 in the park. These fires burn so hot that they kill all species in the area, including saguaros and the fire-tolerant mesquite tree. Learn about the invasive species found in the park.