The relict sands of the Antioch Dunes National Wildlife are populated today by a suite of native, non-native, and invasive plant species. Common natives such as telegraph weed, pallid California poppies, and red-stemmed deerweed make up much of the refuge’s unique natural habitat. Many such plants are tied to the ever-shifting, windblown sands. The Antioch Dunes evening primrose, for example, requires a dynamic, disturbed substrate for its seedlings to germinate. Similarly, along the north-facing river bluffs, Contra Costa wallflowers emerge from the unstable slopes where other plants are hard-pressed to compete.
Exotic grasses and vetch now carpet parts of the dunes like Astroturf. Before European non-native weeds like wild oat and red-stemmed filaree—first recorded here in 1853—were introduced, significant portions of the dunes were sparsely vegetated: here and there, as you’d expect in a desert landscape. Now, a suffocating ground cover stabilizes what’s left of the dunes, absorbing water and trapping what should be wind-borne sands in the weeds’ moist root-balls.
Elsewhere, the dunes were populated with what Padre Font, a member of the Spanish Captain Juan Bautista de Anza’s 1776 expedition, described in his diaries as a sierra emboscada, or “wooded ridge,” of coast live oaks that then peppered the dunes. Since then, on the Stamm Unit oaks like these were felled and sold for cordage. The venerable oak that stands sentinel along the Stamm’s bluffs today is one of the few that remain. Although the oaks stabilize the dunes—potentially making it more difficult for the primrose and wallflower to thrive—slumping, erosion, and natural weathering provide enough disturbance and exposed sand for these plants to become established. The Sardis Unit still retains a more natural assemblage of oaks, which somehow avoided the axe and wildfire.
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