Livestock Impacts

Livestock-grazed pastures: Introduced species dominate these cattle and sheep-grazed fields, hills, and swales. Most species are introduced European annual grasses and weedy forbs. Highly palatable and grazing-sensitive native coastal prairie species have been eliminated. Some areas appear mowed, perhaps to reduce coastal bush lupine which is somewhat toxic to cattle. Other patches are grown with silage. Many heavily grazed areas had erosion, headcutting of ravines, multiple trails, mud blow-outs, ATV ruts, and feedlots reduced to bare ground and invasive milk thistle.

Dominant species we observed in the Pastoral Zone grasslands:  

• Poison hemlock (Conium maculatum)—introduced weed, toxic to livestock, increasing on disturbed areas. These stands are actively being removed in restoration activities in such places as East Bay Regional Parks.

• Milk thistle (Silybum marianum)—weed, increases with disturbance. Unpalatable to livestock, indicates severe overgrazing.

• Bull thistle (Cirsium vulgare)—weed, increases with disturbance.

• Wild radish (Raphanus raphanistrum)—invasive weed, planted for silage. Spreads to other areas.

• Ripgut brome (Bromus diandrus)—abundant introduced annual grass, seen over many of the livestock pastures from C Ranch, Home Ranch, to L Ranch. Mid-quality forage grass, increases with disturbance.

• Velvet grass (Holcus lanatus)—introduced European perennial bunchgrass often in wet meadows.

• Rattail fescue (Festuca myuros)—introduced annual grass.

• Hare barley (Hordeum murinum ssp. leporinum)—introduced weedy annual grass of disturbed places.

• Italian ryegrass (Festuca perennis, formerly Lolium multiflorum)—abundant, probably seeded in many places. Introduced, with annual and perennial forms.

• Common bog rush (Juncus effusus)—native but unpalatable and coarse, so not grazed by cattle. This may indicate wet meadow relicts where native grasses such as tufted hairgrass (Deschampsia cespitosa) have been grazed out.

• Douglas iris (Iris douglasiana)—native but unpalatable to livestock so this native species persists in some places.  

Silage fields (actively planted, tilled, mowed, to provide extra forage for livestock):

• Wild radish (Raphanus raphanistrum)—Nitrogen-fixing white-flowering invasive weed.

• Wild mustard (Brassica sp.)—Nitrogen-fixing yellow-flowering invasive weed.

• Field pea (Pisum sativum)—Nitrogen fixing crop.

• Domestic crop grasses such as barley (Hordeum sp.), ryegrass and/or rye (Festuca perennis, Secale cereale), and oats (Avena sp.).

NPS should ban all plantings of silage for supplemental cattle feed, as these species are wholly inappropriate and counterproductive to maintaining native plant communities in a park unit. All mowing of native shrubs, tillage, seeding, and silage-harvesting should halt. These are not historic cultural farming practices, but modern dairy agriculture, using the latest silage seeds that are introducing genetic plant material into native communities. These areas should be restored to native coastal prairie and North coastal scrub. The bulk of the Pastoral Zone, consisting of California introduced annual grasslands dominated by European hare barley, ripgut brome, Italian ryegrass, and rattail fescue, should be rested from cattle grazing.

Only by removing livestock can these continuously disturbed areas begin to stabilize soil loss, improve water quality, increase native plant species, and recover Threatened and Endangered species.

Livestock grazing can lead to soil compaction, massive soil erosion, and sediment flows into streams, which harm fish and aquatic invertebrates in freshwater streams, brackish lagoons, and nearshore ocean habitats. Cattle create trailing, high-impact areas next to feed troughs and water facilities, ranch core areas, and heavily grazed grasslands where topsoils are lost from trampling and erosion. Trampling from beef and dairy livestock also causes increase runoff during rain storms, as well as decreased vegetative cover to hold soils in place.  

This contributes to poor water quality.

The alternative for Seashore management should be to restore deep-rooted coastal prairie and native wet meadow plant communities which would vastly increase soil stability, soil formation, and groundwater retention. Increased live vegetation and dry residual plant matter has been shown to increase soil moisture and rainwater retention. This is the best Climate Change Strategy!

Erosion is also a significant problem in the watershed. Sedimentation from Lagunitas Creek into Tomales Bay resulted from nineteenth century logging and cattle grazing of riparian plants which are needed to slow erosion. Livestock grazing continues to erode slopes, downcut stream headwaters, and remove deep-rooted vegetation such as native bunchgrasses.