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Landowners Guide to Native Grass Enhancement and Restoration

   4. Native Grassland Reestablishment

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

   A landowner who is seriously interested in reestablishing a relatively complete suite of native California grassland species to a patch of land should know that it is an undertaking that involves a balance between agronomy, ecology, philosophy and art. It can be an engaging adventure in exploring your relationship with the land.

    One might as well start with the philosophy of restoring the earth, or at least, a small patch. The first question is what is the goal? What do you want to do with that parcel of ground? Do we intend to grow a list of native plants that is someone’s best guess at what were present in the pre-European natural landscape? How far back should we go? Should it be entirely free of non-native “weeds”? What is the definition of a “weed”, when after all, some of the Mediterranean grasses have been in California for 300 years? Are they naturalized yet? One may have not be interested at all in trying to re-create a patch of our lost wilderness. A reasonable goal might be just to provide a pleasing vista, erosion control or a drought tolerant and low maintenance lawn. Regardless, the result will enhance the local biological diversity on a patch of land near your home.

    Native grasses have been used in many places on the roughs and road sides of California. The grass plantings use little water, require less maintenance, and blend with the surrounding hillsides. Many people have landscaped around their homes or working places with native grasses to provide the complex beauty of native grasses and enjoy the benefits of a landscape that does not require weekly mowing and daily watering. In all cases though, one will need to determine which native grasses are most appropriate for a given site.

   In general, it is most practical to look around the landscape and find the nearest patches of native grasslands. Use these for the model, and set your standards for “weediness” on what you see nearby in the native patches. On some years, there are almost no weeds in the native, relict grass patches. Maybe this is due to the timing and amount of rainfall and number of cold nights over the year. On other years, the native grasses in the same relict patch may be almost hidden by the weeds. The model relict should be chosen from a nearby (1-5 miles) part of the landscape that is roughly similar; having the same soils, elevation, facing into the same direction, and with about the same amount of soil water (dry hillside .Vs. creek edge). You may need to hire a botanist to identify the grasses and dominant wildflowers most appropriate for your site.

    A first reasonable goal is to establish the ecosystem foundation, and that means starting first with the grasses. Once a good layer of native grasses is growing, the spaces between can be systematically planted with a host of beautiful wildflowers. The entire process may take 1 to 3 years and will require some annual management including weed control, and one or two mowing. Once established, the grassland will slowly change over time, especially if the long-term management changes or ceases. Remember, the grassland ecosystem you are starting could be present 500 years from now.

    Generally, steep hillsides make poor candidates for restoration of native, perennial grasslands. Most of the suggestions here apply to sites where you can drive a truck or a tractor. However, hillside restoration is feasible, it just requires more hand labor.

Pre-Planting Treatment
    Just as when managing a relict of native, perennial grasses, weeds are a challenge in reestablishing native grasses. One who attempts to reestablish native grasses on a site must control weeds, before the grasses are started, and after. California’s native grasses generally are slow growing and can be overwhelmed by the numerical and physical advantage of the non-native annuals– and some pretty nasty non-native semi-perennial weeds. There are a number of ways to deal with weeds before you plant your native grass seeds.

    

   The cheapest way to clear the weeds from the site before planting native grasses is simply to till the soil over a long enough period of time to exhaust the seed bank.You till and kill seedlings before they make seeds, then till again to kill the next crop of seeds in the soil. Eventually (2-3 years, with 3-4 tillages cycels each year) the number of seeds in the soil's "bank" of seeds is exhausted. This probably works best in inland California , and may not be as effective on the foggy coast where seed banks seem comparatively much more persistent. We have written a paper describing the 6 years of such a "restoation" project at Hastings on a dry inland series of old fields. You can download a pre-print of thie publication here: (Cheap Till: Stromberg, Kephart, Sicular-Mertens).Here is a summary if don't want to read the paper.

   Start in the fall, after the first rains have delivered a few inches of moisture. Based on techniques discovered in the earliest days of agriculture, one can use a disk to turn over the top layer of soil and bury the existing vegetation. On small areas, a roto-tiller works fine. A small tractor and spring-toothed harrow (see photo) works well. If the soil had been farmed for a long time, a layer of hardpan may be present a few feet below the surface. If that is the case, deep ripping with a bulldozer and a 5-foot long ripping bar may be required. As winter storms later arrive to wet the soil, the soil microbes attack the buried vegetation and break it down into a colloid of nutrients that is quickly bound up on soil particles and surfaces. Continue to uproot seedlings from the surface of the soil (hoes, spring tooth harrow, chain harrow, etc.) each time the seeds in the soils germinate and start to convert the nutrients to living tissue. If tilled before they can set any seed, they die and are returned to organic molecules (nutrients) in the soil. This process can be repeated 5-6 times over a winter. Each time a fine carpet of green seedlings emerges and are harrowed under, there are fewer weeds germinating. If one plows or discs deeply, this will only bring up the deeply buried seeds and increase the weed crop. Deep tilling should only be done once at the beginning of the project. If tillage is not possible, the application of a post-emergent herbicide (glyphosphate) can be substituted. A small ATV can be equipped with a sprayer bar and tank. If the seed bank in the soil is small, one might be able to remove most of the seeds in a single winter. This might be the case where a field had been farmed in the years immediately prior to the project, and all but the crop seeds had been removed for many years. If there is an extensive seed bank in the soil, it may take two winters of repeated harrowing after germination to clear the weeds from the top few inches of soil. Such repeated tillage also eliminates the gopher population from the patch, and gophers can be a major reason why native grass restoration projects fail (Stromberg and Kephart, 1996).

Seed Selection and Seed Sources

    Some consideration should be given to the source of your seeds. For many years, people reestablishing native California grasses were happy to be using a grass native to the area. But it soon was apparent that grasses, like trees, grow better if the seeds are “local” in origin. Seeds of the native California meadow barley (Hordeum brachyantherum) from Carmel Valley, (Monterey County) remain as small and spindly, when grown in the delta soils of the Central Valley near Rio Vista (Solano County). If one were to grow seeds of this same species from a native population near Rio Vista, it might grow tall and robust. There is good evidence that geographic races may exist among native perennial grasses (Dyer and Rice, 1997; Knapp and Rice 1998; Adams, 1999). Many federal and state agencies recognize that “local” seed sources should be used, both to protect the native genetic purity of wild populations, and for better growth and reproduction. How “local” is “local” is a great question that is still being researched in our native grasses (Knapp and Rice, 1994, 1996, 1997). It is best if one could go to the nearby grass patches being used as models for the re-establishment project and collect seeds at these sites. If one cannot do that, then one should purchase seeds from the many native seed sources (Appendix), requesting a source from as close to the site as possible. Recently, California’s Department of Agriculture initiated a seed certification program for native grass seed. Ask for certified seeds and keep records on the geographic origin of the seeds used.

    If you are going to till the soil for a couple of years, one should plan for the potential catastrophic erosion event. Leaving soil newly tilled during an El Niño year could result in massive soil erosion. Consult with a specialist in soil erosion control. A local agent or representative of the National Resource Conservation Service (NRCS) (formerly Soil Conservation Service) may be able to provide assistance.

   But this time spent preparing the soil gives one time to hand collect native seeds and bring them to any of a variety of custom growers (Appendix) who can take a few hundred seeds and return up to 100 pounds of seed in two years. Such seed increases are a common practice and can be contracted by several native grass seed producers.

    A more expensive way to control weeds is the use of chemicals that prevent seeds in the soil from germinating. These “pre-emergents” can be used to prepare a site. Application of these chemicals requires a special license (Pesticide Control Operator) from the state of California. Many landscape contractors have such licenses and can perform the necessary services.

Planting the Seeds

    Timing is critical. Plant only in the fall and early winter after the first good germinating rains have fallen. Generally, this is November or December, but could be as early as October. If you plant earlier, birds and rodents will eliminate the seeds before they germinate. Another problem with planting too early is that the seedlings may germinate but dry out and die if the early rains don't continue into winter. If you plant later, they do not have the cool, wet soil long enough to grow an adequate root system and store enough carbohydrate reserves to survive the long dry season that will start in May.

   There are several options for actually planting. One can use a simple broadcaster, either tractor-mounted or handheld. If you are going to do a small area (1 ac or less), a handheld broadcaster is fine. Walk over a cement pad and see if you are putting out about 20 seeds in the area of an outstretched hand. Expect only one of those seeds to germinate and thrive. Once you are "calibrated" go out and seed the field. Drag a bar over the seeds to cover then, but not with more than an inch of soil. Then compact the soil by either driving on it with a tractor, or walking on it, or drag a ring roller over the seeded area. It is essential to get good seed-soil contact. The native seeds have tiny endosperm (food reserves) and if they are covered by gophers or dry out, they do not survive.

    If planting a large area, use one of the wildland seed drills, and drill the seeds in, crossing the field twice, at right angles. A drill is shown behind the tractor. It is a series of boxes, each with a tube that drops the seed to a pair of plates which cut open a narrow groove into the soil. The tube drops the seed into the slit, and rubber wheels press the soil closed around the seed. Cross-drilling doubles the amount of seed that is planted. This produces a crosshatch of drill rows. Again, adjust drill seed drop rate and tractor speed to get about 20 seeds in an area the size of your hand. Drive the drill over a concrete pad or hard road to count and calibrate. Sweep up the seed each time and drive around till you get it right. Many native grasses can be successfully started when seeded at 3-4 pounds per acre. A lawn should be seeded at least 20 pounds per acre. When done, drag a pipe to cover the seed and then ring-roll the seed.

    If one is planting a lawn or small area, you may decide to cover the area with "remay" cloth to keep the birds from eating all the seed and small rodents from eating all the seedlings. Another alternative to reduce the impacts of rodents is to ring the planted area with a small wall (10-12" tall) of aluminum flashing, using wooden stakes to hold up the flashing.

Planting Plugs

   In some cases, such as steep hillside, ornamental plantings, agronomic or research seed increases, or where success is critical the first time, one can have commercial growers raise grass seed in greenhouses in trays that produce individual plants, each in a small container about the size of an ice cube. The cube of greenhouse soil ("plug") can be pried from the tray, with an individual plant up to 6 inches tall.Using a digging stick, the plants are plugged into the soil. Survivorship is often 95% or better, as the critical time period for native grasses is the seedling stage. Plugs are often used to establish a small plot that is used to increase seed for larger plantings. Collecting a few hundred seed heads will often generate enough seeds for several thousand plugs and subsequently, tens of pounds of seed.

Post-Planting Tips

  Do not fertilize as that will simply encourage the weeds. After seedling establishment, if there is a carpet of broad-leafed weed seedlings, a treatment with post-emergent broad-leafed herbicide (e.g. 24D) may be required. Wait until the seedling grasses have four leaves before using an herbicide on the weeds.

    Once the seedlings are established, one must begin the process of managing the stand of grasses, using the tools described above; mowing, weed control, fire and grazing.