While most of North America’s native ecosystems are grasslands, the conservation challenges facing coastal California grasslands are unique. Although it seems counter-intuitive, large scale disturbance processes are needed to maintain our grasslands. Herbivory–the grazing and trampling impact of large ungulate herds—and wildfire create extensive areas free of trees and shrubs allowing native grasses to flourish.
Historically, California’s coastal grasslands hosted a population of approximately 500,000 Tule elk. European settlement in California lead to the eradication of Tule Elk and loss of the natural benefits they provided in removing dead vegetation from grasslands. Wildfire disturbance has also disappeared from California’s wild landscape.
In addition to the suppression and alteration of these two enormous forces, the arrival of exotic plant species from all over the world presented an enormous challenge for grassland ecosystems. Much of California’s remaining coastal grasslands are dominated by non-native grass species and under constant threat from the expansion of invasive weeds and woody plants like milk and Italian thistle, and French broom.
On the Preserve, our land management practices re-introduce disturbance to the landscape. To improve our management, ongoing research using control sites to compare to grazed and un-grazed lands helps us quantify the effect of our grazing program. Our results show that the Conservancy grazing program has had a positive impact on the landscape. We have observed a gradual reduction on our thatch levels, an increase in diversity richness of native grasses and the return of vertebrate endangered species like California tiger salamander and burrowing owls. We are bringing fire back to the ecosystem in a controlled and intentional way using prescribed burns to improve our ecosystem dynamics. These land management techniques help our grasses thrive by reducing competitive invasive species and overgrowth. We are supplementing these proxy natural disturbances with manual and chemical treatments to eradicate invasive plant populations.