Most of the coastal prairie that once existed in the lower Salinas Valley and in northern Monterey County has been converted to agricultural fields, although some has been urbanized as well. Much of the remaining prairie has been impacted by large-scale community shifts from indigenous grasses and forbs to exotic, mostly European, species. This transformation, beginning in the 1700s, coincided with the loss of native herbivores and Native American burning regimes, as well as the concurrent introduction of highly-competitive exotic plants and over-grazing by domestic livestock. The role that each factor played in the conversion remains uncertain.
Regardless of the mechanisms, these losses have obscured the past distribution and composition of historical prairie. The earliest explorers to the Monterey region visited the area in late fall, and they described local grasslands in only the broadest terms. They found 1) that large areas of the lower Salinas Valley grasslands were home to “vast numbers of [pronghorn] antelopes” and were burned by Native Americans, 2) “swampy plains,” and tule elk between the Elkhorn Slough-Moro Cojo-Tembladero Slough estuarine wetlands, 3) “good grasses” on knolls east of previously wide-spread freshwater wetlands, and 4) “hills of pure earth and grass, with some live oaks,” in a valley just east of today’s Elkhorn Slough National Estuarine Research Reserve (Elkhorn Slough NERR) (Brown 2002, Palou 1930). Early naturalists in the late 1700s collected native annual and tufted hairgrass, giant wildrye, buttercup, yarrow, several rushes, and hairy wood-sorrel in the Monterey Bay area; but did not otherwise describe local grasslands (Eastwood 1924, Presl 1830). Detailed accounts of Monterey area grasslands did not appear until the mid-1800s, and by this period many changes had taken place. Several European exotic forbs were common throughout the central California coast, and cattle were abundant (Hooker 1841, Hartweg 1846). Nonetheless, many native wildflowers were evident during springtime. In 1846, John Fremont (Jackson and Spense 1973) wrote:
“Over the face of the country between Santa Cruz and Monterey, and around the plains of San Juan, the grass which had been eaten down by the large herds of cattle, was now everywhere springing up and flowers began to show their bloom. In the valleys of the mountains bordering the Salinas plains wild oats [non-native Avena sp.] were three feet high and well headed. . .”
Today, even the best prairie assemblages are highly invaded, and non-native grasses and exotic forbs often dominate remnant native patches (Stromberg et al. 2001).
Unfortunately, changes to historical coastal scrub in north Monterey County are not well documented. Early explorers in the region did not describe shrubs in detail, and did not clearly distinguish between coastal scrub and chaparral. Botanists’ records only hint at the past distribution and composition of coastal scrub assemblages. In the early 1790s, a Scottish naturalist described scattered pockets of “Pasture & Thickets of Brush-wood” near Point Pinos, which included various shrubs that he could not identify, several species of Artemisia, and “a great variety” of birds. In 1854, the U.S. Surveyor General described “oak scrub and sage” near the eastern reaches of Long Valley, and mapped patches of unnamed bushes (apparently distinct from chaparral) in Hidden Valley (Freeman 1854). Today, many of these areas appear to have been replaced by oak or eucalyptus woodland. In 1906, the Los Angeles Times reported that the hills of the Empire Gun Club, today part of the Elkhorn Slough NERR, were “covered with scrub” where “quail multiply and thrive” (Los Angeles Times 1906). Aerials from the 1930’s suggest that this scrub was later cleared for agriculture; but today, coyote brush and other associated scrub species have returned naturally to at least some of these slopes. However, many of these patches appear to be threatened by encroaching fennel, poison hemlock, and jubata grass.
Despite dramatic losses locally and statewide, some remnant coastal prairie and intact coastal scrub persists in the Elkhorn Slough watershed and on the Elkhorn Slough NERR. The Reserve will give priority to identifying and preventing the establishment of new invasive exotic plants in these areas on the Reserve.
The Elkhorn Slough NERR will also work to restore degraded grassland and scrub assemblages. Using historical ecology, we will identify areas best-suited for grassland and scrub restoration, and develop a target mosaic of the two related habitats. In areas deemed best for coastal scrub, we will reduce non-native plant cover, and where necessary, replant native scrub species. In areas best-suited for prairie, we will test the effectiveness of potential grassland restoration strategies. Coastal prairie restoration is an evolving science, and research is still needed. Grasslands with cattle grazing have been shown to have higher native annual forb richness and cover relative to ungrazed sites (Hayes and Holl 2003a), and the removal of cattle from prairie has been shown to lead to decreases in native California oat grass (Hatch et al. 1999). Grazing can also prevent the conversion of grasslands to coastal scrub. This argues against the removal of cattle from currently grazed prairies, but it is still unknown if the reintroduction of cattle to currently ungrazed, degraded grasslands can restore native grasses and forbs. Reintroducing clipping alone has been unsuccessful at restoring forbs at three coastal prairie sites (Hayes and Holl 2003b). This and other recent research suggests that the reintroduction of native grassland seeds or seedlings may also be necessary to help restore populations of native grassland species in areas that are currently dominated by exotic species (Corbin and D’Antonio 2004, Seabloom et al. 2003), but, again, more research is needed. We will implement a well-replicated experiment, comparing alternative strategies (grazing, mowing, and seed additions) in a robust design. The Reserve will monitor appropriate indicators, ideally with collaboration from academic researchers. The eventual result will be a published manuscript that will help guide the Reserve’s own work and help coastal prairie managers elsewhere better manage their lands.
Finally the Reserve will work other decision-makers and land managers to build support for regional grassland and scrub management and restoration, both through education and collaborative management efforts.
B. ESNERR Objectives and Strategies
Staff from the Reserve’s Stewardship, Coastal Training, Education, and Research Programs are involved in the following objectives and strategies
Objective 1: Reduce abundance of selected non-native plant and animal species in Reserve coastal prairie and coastal scrub assemblages.
Objective 2: Help build support for regional Coastal Prairie and Coastal Scrub projects.
Objective 3: Implement research that informs regional restoration strategies.
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