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Landowners Guide to Native Grass Enhancement and Restoration

     2. Start Again or Decide to Manage a Native Relict?

by Mark Stromberg, Ph.D. Hastings Natural History Reserve, UC-Berkeley
and Paul Kephart, Rana Creek Habitat Restoration, Inc.

2. Native Grassland Relict Management Options

   Of course, there are many choices of what one can “do” with a native patch of California grasses. One might decide to simply leave it alone, and even this has some consequences. California grasslands evolved to survive for the last 10,000 years or so with a complex cycle of fire, grazing by native herbivores, and climate change. Any given patch of grass was probably burned by the native Indians every 2-5 years (Greenlee and Langenheim, 1990). Lightning-caused fires probably occurred at least every decade. If a patch missed fire for a decade or so, it might have been covered with coyote brush (Baccharis pilularis), but could resurface after the next fire cleared the brush. During wet periods, Monterey Pine (Pinus radiata) may have invaded and hovered over the native grasses, only to be removed by one of the periodic fires. After European’s arrival, fires were suppressed, and a host of non-native weeds, brush and trees may have filled in between the bunchgrasses. Annual, grassy weeds are very persistent, but do not replace the native bunchgrasses in the short (40 yr.) term (Stromberg and Griffin, 1996).

Photo: California Oatgrass on ridge above Carmel River. Long, yellow stems (with seeds hidden inside) lay across and above the basal leaves. This has been mowed and grazed for many decades.

    As a rule of thumb, if you do nothing with your native grassland, you will grow mostly weeds. If you graze it or mow it, you will have mostly grasses but well-timed mowing or fire will promote wildflowers.

A. Leave it Alone
    Simply leaving the native perennial grasslands alone does not reduce the abundance of native grasses in relict patches. On the other hand, leaving an area that had formerly been farmed to “return to nature” does not work either. The vast areas of formerly farmed lands (1860’s to 1930’s) are simply too far from any seed sources of native, perennial grasses. These areas are rapidly covered with non-native weeds, and once established in abandoned agricultural fields, they remain as dominant as ever, probably enhanced by the constant churning of most of the soil surface by gophers. California’s native grasses are very slow growing and may only venture 50 feet into old farm fields, even after the fields have been left alone for 60 years (Stromberg and Griffin, 1997; White 1967). Seeds of native grasses are typical of long-lived plants. Only a relative few are produced each year, and they tend to move only a few feet from the mother plant. Of 1,000 seeds of Purple Needle grass (N. pulchra) planted on deep farm soils, just a few feet from the mother plant, only 3 survived to the third year (Dyer et al. 1996).

B. Grazing
     For most small parcels, grazing and fire may not be viable alternatives. However, one should investigate the possibilities. Grazing by goats can be done in small areas, especially brush-infested areas, for a reasonable price. Several individuals offer the service of goat grazing in wildlands or small areas (Appendix). For larger parcels, grazing with cattle or horses can be done on a seasonal basis, using either fences or a short-term lease. On steep ground, especially with clay soils, cattle trampling can reduce soil productivity by compacting wet soil during the winter. If at all possible, cattle should be brought in at the end of the winter when soils are drying and the annual green flush of natives is present. Brief, seasonal grazing should be continued until the animals remove the shrubby vegetation from the grassland yet one should leave at least 500 pounds per acres of standing vegetation or dry matter. By leaving this standing dry matter and living grasses, the soil is protected from erosion when the rains return in winter, and new annual plants actually grow faster under the protection of some dry litter of the previous year. The litter provides a thermal blanket, keeping the tender new plants warmer during cold fall and winter nights. A great booklet with photos and easy ways to recognize adequate residual dry matter is available (Appendix).

C. Fire
    Prescribed fires can be conducted, and the California Department of Forestry and Fire Protection offer landowners participation in the Vegetation Management Plans (VMP) program. Working with the local CDF Forester, the landowner and CDF share costs of conducting a burn. By conducting such controlled burns, the grasslands can be cleared of invading shrubs and weeds, and fuels can be reduced near buildings, thus reducing the overall cost to the state and landowners for wildland fire suppression during the fire season. Fires on native perennial grasslands are most effective in reducing annual weeds, promoting native wildflowers, and promoting native grasses if one has a some accumulation of dry vegetation to carry a fire and if the fires are repeated over several years at varying seasons (Wirka 1999).

D. Mowing
     Mowing can be an alternative to grazing or burning to help sustain native, perennial California grassland. The native grasses will have to compete for resources with what are predominantly annual weedy grasses. These annual weeds make seeds each year that fall to the ground and germinate the next spring. If they are left in the ground for two or more years, they decompose and do not germinate. So, one way to eliminate annual weeds, and promote the perennial plants, is to let the annuals grow up and then before the annual seeds are viable, mow the annuals to about 4 inches. One needs to wait until the annuals have moved most of their reserves to their large seeds. If you pick out one of the annual weedy seeds(say, Wild Oats or Avena fatua), and if you squeeze it between your fingernails and get a milky, soft mush from the seed, that would be the ideal time to mow. Such seeds are not mature enough to germinate, and the mother plant will not be strong enough to produce a second seed crop. After a few years of mowing the annual seeds before they mature, viable seeds in the soil are not replaced and the annual weedy grasses become relatively rare in the patch of native grass. Mowing keeps any invading brush down to a few inches in height, and so those plants also fail to reproduce, leaving more resources for the native perennials. Mowing also reduces the fuel loads around a house and preserves the views from the house. Generally this mowing should be done when the annual grasses are still green.

An example of a native, perennial grassland patch that has been mowed for decades is the Needlegrass opening pictured here. This is a picnic ground on Jack's Peak, near the summit, in Monterey.

   Here, one can see the encroaching coyote brush kept at low levels, in front of picnic table. Monterey Pines and coyote brush (Baccharis pilularis) are encroaching on this relict grassland on Jack's Peak in Monterey County.

E. Timing-Mowing or Grazing

   Timing of the mowing should be adjusted so that on good wildflower years, the native flowers (Triteleia- above left, Calochortus-above right, etc.) have time to set seed.In general, the native, perennial grasses will start to produce new leaves and mature seeds later than the annual weedy species (Jackson and Roy, 1986). Grazing animals can also be used briefly (in place of mowing) to exploit this difference between timing of growth seed production. If one defers grazing with fences to early spring or late fall, the natives can grow new leaves, store carbohydrates in the roots, and produce a crop of seeds. If the native grasses are grazed year round, their underground root reserves are exhausted, they cannot produce seeds, and they lose vigor.

Photo. Magnificent stand of California Oatgrass, Danthonia californica, above Carmel River. Although this was mowed in the early 1990's, by 2001 the coyote brush was already moving back in. The balance between grass and shrubs/trees is maintained by fire, grazing and mowing.

Weeds

   Weeds are a major concern in managing relict perennial grasslands in California. Weeds are often defined as “a plant out of place”, and in California, 17 percent of the current California flora (or 1,025 species) are now exotic species (Rejmanek and Randall 1994). Each year, new weeds arrive and some have amazing rates of spread. Most weeds are moved by people’s activities and first show up along roadsides. We present information for some of the particular weeds one might expect. In California’s native grasslands, the further one gets away from roads, the fewer weeds one sees, and the dominance of native grasses increase. Thus, partitioning a larger natural area into smaller areas by splitting the area with a new road will degrade the native grassland and introduce more weeds. In general, care should be taken to assure that earthmoving equipment is steam cleaned between jobs, that trucks used to haul feed or cattle are cleaned between deliveries, and other reasonable precautions are taken to minimize the spread of weeds. These same precautions would apply in California to slow the spread of other non-native, disease organisms, for example hoof and mouth (USDA, 2001) and Sudden Oak Death (Storer et al. 2001). For a review of current best management practices in controlling weeds in California wildlands, see Tu et. al. (2001).

   Several weeds can be particularly difficult on California’s perennial grasslands. Some will be discussed briefly here, but there are many more weeds and it is inevitable that new weeds will arrive each year. For more information on current weed management in California, please refer to the California Exotic Pest Plant Council (CALEPPC, 2001) or The Nature Conservancy’s Wildland Invasive Species Program (Tu, 2001). Information on weed management can be found at the University of California Weed Research and Information Center (WIRC, 2001), or California Pest Notes (UC-IPM, 2001). Integrated pest management is the most effective strategy for most weed problems, and may include many different techniques used at once; for example burning, mowing, spraying, introduction of biological control agents and hand removal.