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Landowners Guide to Native Grass Enhancement and Restoration

   1. Introduction and Background

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


Sorry about the heavy dose of text. But it is a good story...

INTRODUCTION

    Grasslands in California are among the most endangered ecosystem in the United States and in California are on the decline. An area of approximately 11,000,000 ac (about 10% of the area of California) has been converted to annual grassland dominated by non-native annuals primarily of Mediterranean origin. Conversion to non-native annual vegetation was so fast, so extensive and so complete that the original extent and species composition of native perennial grasslands is unknown, however the prairies of California contain many elements of the original habitat. Vast areas, including large parts of the Central Valley, that were formerly converted to annual non-native grasslands have now been converted to agricultural or urban land uses.


    For our time, ownership of this land gives us a unique link to life on earth. Grasslands express the land’s vigor, biological wealth and tolerance of human uses. Grasslands are the threads of the living carpet that covers the earth.

    Native grasses are interesting characters. They can be amazingly old. Many bunches of purple needlegrass are at least 200 years old and some might live as long as 1,000 years. As one of the old Califorñios, they deserve our respect as tough survivors. Using roots that extend up to 18 feet, they tap into nutrients and water found deep in the soil, and so remain green even in the hot, dry months of fall. They have survived many long California droughts, attacks by insects and the impact of fire. They tolerate mowing, grazing and even foot traffic. Each year, they produce a modest crop of graceful seeds and sometimes these give rise to a few new plants. Our native grasses almost always occur in patches with bare ground between them. Wildflower often grow in these open spaces. Grasslands protect views from our dwellings and protect buildings from wildfires. They provide green fodder for wildlife and domestic animals, and cover for wildlife to build nests and hide. They harbor beneficial insects. Our native grasses provide a stunning visual diversity; indeed a window into the earth. When we take the time to look at a simple square foot of prairie grasses, an amazing complex of textures, colors and forms swirls before us.

    The root systems of native perennial grasses gently form delicate long tubes deep into the dry soil- when the winter rains finally arrive, the rain percolates along the roots of the grass plants where it is stored deep in the soil. The native grass root systems filter pollutants and catch soil eroded from above and stabilize steep hillsides. When they eventually die, the roots of the native grasses become carbon and other nutrients that promote soil formation and deep soil nutrient enrichment.


      For all these reasons, we will present here a brief summary of what we know about the management options people can use to preserve and enhance the grasslands they own or manage. A great deal more needs to be known, but the guidelines presented here will provide a good start. Native Perennial California Grasslands


     Almost any square mile of Monterey County, or California, has at least a tiny patch of native grass. Sometimes they occur as larger open areas, or “potreros” as the Spanish settlers called them. Some patches may be as large as a soccer field. Sometimes they are a few square feet under a tree, or an area the size of a parking space on a hillside.

    California’s grasslands are cloaked in a mystery of loss. As we look across the landscape, we see that 99% of the golden rolling hills of California are covered in annual grasses from the barnyards of Spain. An observant landowner can recognize the native grasses and see that our perennial, native grasses are missing from much of the landscape. Knowing this, it makes owning an intact relict of native perennial grassland so much more valuable. But one might ask then, how did such a vast landscape become converted over such a large landscape and to such an extent?

 

BACKGROUND


   

 

   If we understood why the native grasslands have become reduced, we will find the clues we need to manage or restore the native California grasslands. And, we have a few clues to help us in the process of discovering the answer to this mystery.

     First, California is one of only five places on the earth where it does not rain in the summer, and where late winter rains are common. These “Mediterranean” climates are widely separated; as if they were five islands scattered across the earth (other are in Chile, Turkey-Spain, South Africa, Australia). Such “islands”, like all other true islands, tend to have many species that are found nowhere else on earth (“endemic” species). And like on most islands, the native plant and animals often have few defenses against invading newcomers (“weeds”, diseases, etc.). In Hawaii, for example, most of the nearly 1,200 native species are endemic. Extreme endemism, combined with a large number of non-indigenous plants and major habitat alteration by both Polynesians and Europeans, has made 61% of Hawaii's suite of native plants the most threatened of any state. California is the second (32%) in the list of states with the most threatened flora. Of some 4,800 plant species in the California Floristic Province (which extends north to Gold Beach, Oregon and south to Enseñada, Mexico) 2,500 are endemic–they occur nowhere else on Earth. (Doyle, 1997 Myers et al., 2000).

     Here is another clue to the decline of native California grasslands; an invasion of exotic species occurred in California, indeed in most of North America. Certainly by the 1500s, Europeans from the Mediterranean started to arrive in California and brought with them non-native (“exotic”) plants accidentally, as ship ballast, for trade or intentionally as food, medicine or ornamental use (Brossard et al 200). Bricks in the first Spanish missions, made from mud mixed with soil from around the building site have very few seeds of these introduced weeds. As the missions were built, the brick had ever increasing amounts of seeds of these invaseive, aggressive non-native plants (Barbour and Withworth, 1992). Among these were the filaree (Erodium spp.) as well as ripgut (Bromus diandrus), wild oats (Avena spp.) and other small bromes (B. hordaceous) and fescues (Vulpia myuros, etc.). By the 1700s, Europeans had brought a suite of hundreds of non-native, short-lived (annual) Mediterranean-European plants that were, by chance, pre-adapted to thrive in this Mediterranean climate. And thrive they did! By the late 20th century, in most of California’s grasslands, most of the plant species present are exotic (Withers et al. 1999).

 

 

Exotic Invasions of North America (Maps-above). The percentage of plants that were non-native in regional and local floras, based on either a larger scale (left) or local scale (right) in about 1900 (top) and in 1996 (botton). Even "Kentucky" bluegrass is not native, and it was among many grasses brought into the east coast with the first wave of European settlement. The wave of non-native species has swept west at either scale. For mor information, see Withers et al. 1999.

    

   Native grasslands often include areas of bare ground between the grass plants. This bare area once provided a place for annual flowers, and these can be seen in profusion in the Carrizo Plain, where distance between native bunch grasses are much greater than in this photo of Carmel Valey. This bare ground also provided an opening for Mediterranean plants that, by chance , were from a nearly identical environment. Many of California's non-native weeds spread through the entire state in less than a hundred years.Yellow star thistle, Centaurea solstitialis, and tumbleweed, Salsola tragus, are examples.

Photo. Purple needlegrass (Nassella pulchra) in upper Carmel Valley. Note the spacing between the plants. The dry, dead material between the green clumps of graass is mostly Erodium and Vulpia. During very dry periods, the mother plants can so deplete the deep soil moisture that they kill the smaller seedlings. Thus, like many other desert plants, these Nassella plants are farther apart than you would expect at random. The distance between them, like trees in a orchard, reflects the long-term balance between rainfall and the number of plants that can survive.

 

    We know the approximate time of this invasion of non-natives into the California scene. Clues are found in early adobe bricks used in Spanish settlements made from native soil. The soil would include many of these types of seeds. Such debris was trapped in bricks that can give us approximate dates of introductions of non-natives. The oldest adobe buildings built in 1769 by Junipero Serra contain only the seeds of three common European weeds, including red filaree (Erodium spp.). As the missionaries moved north, the bricks contained more and more of the European weeds (Barbour and Withworth, 1992). Our native grasses persist, but during the spring, these annual invaders rapidly turn green, make big, abundant seed, drop them by the millions and then die. Only later in the year (photo) can one see how the deep-rooted native perennial grasses are still green. Studies done at the Hastings Natural History Reservation in upper Carmel Valley show that these clumps (see photo) survive at least 200 years and probably 1,000 years (Hamilton, 1997).


    Clearly a massive invasion of non-native plants filled in the open spaces between our long-lived perennials. But, we have almost no data on what plant species were there before the Europeans arrived. Ecologists from the mid-west prairies visited California in the early 20th century and surmised that Purple Needlegrass (Nassella pulchra) was the dominant grass across the vast central valley simply because small patches were found in remaining native vegetation. There is good evidence that much of the native grasslands were covered with a riot of colorful annual spring flowers (Hamilton, 1999). California native grasslands relict patches continue to provide homes to a host of colorful native wildflowers in the spring. In fact, in most California grasslands, there are fewer species of grass and grass-like plants and far more species of colorful, broad-leafed plants. Our small patches of native grassland scattered across the landscape are often the only clues we have to what species of native grasses that were once prominent. The relict stands found on Californiaare providing clues to the nature of the natural vegetation of California and points of reference for any restoration or conservation projects.

   Another factor in the rarity of native perennial grasslands is that much of the natural carpet of life on the soil of California has been dramatically altered by human activity. Only about a quarter of California’s natural vegetation remains (Edgar, 2000). Even more problematic, the grasslands in California have been particularly hard hit, less than 1% of the original grasslands remain (Huenneke, 1989). Our coastal grasslands have almost entirely disappeared. Most of the reduction in California grasslands has been due to historical land use. The potreros were often the first places to have been plowed and planted with Spanish barley. Then, the deep, level soils of the valley bottoms saw their grand valley oaks removed and the areas planted to more grain. After the 1849 Goldrush, new homesteaders (1860s-1890s) sought a living by farming any available open land in Monterey County. Eventually, most of the arable land in Monterey County, like much of California's more productive soils, was disked or plowed each year. With each pass of a steel farm implement, the sensitive growing points of the native perennial grasses, located a few inches beneath the soil level, were removed and the grass plants died.

   Exponential growth of the human population in California has converted much of the grassland and oak savanna into housing and associated roads, paved areas and disturbed lands.

  

 

 

  What is “exponential growth”? An example might help; if a pond was being covered with lilies growing at an exponential rate, andyou knew it took 100 days to entirely cover the pond, on which day would half of the pond be covered? The 99th day.

 

 

 

 

 

     Was historical intensive grazing a factor in the decline of native California grasses? California did not have extensive herds of grasslands animals, like buffalo in the Great Plains. Scattered herds of elk, deer, antelope other grazing animals were abundant. Unlike the Great Plains, where over the last 10,000 years many species of dung beetles developed, California has no native or endemic dung beeltes. This is clearl evidence that herds of dung-producing grazing animals were not part of the evolutionary background in California, as they were in the Great Plains (Mack and Thomson, 1982). Nevertheless, huge herds of sheep and cattle were introduced to California. From the early 1800’s to 1880’s millions ofof wild cattle ranged across central California. Tens of thousands of hides were shipped out of Monterey Bay each year by skinners in the 1850’s who left the cattle carcasses to rot. One might think that the history of intensive grazing would have lead to the demise of large areas of native grasses. However, this is probably not so. Certainly some patches could be so heavily impacted by cattle that the native grasses were destroyed, for instance corrals and gathering areas. However, there are many examples from across the state that show moderate grazing, even a history of short-term intense grazing by cattle and sheep can be compatible with native grasses. Grazing lands are often the last significant refuges for areas with native California vegetation, including many patches of native grasses.


      Another clue to the mystery of why native California grasslands are so rare emerged just recently. Recall that isolated populations that have not been exposed to foreign diseases are often particularly susceptible? California was effectively sealed off from much of the rest of the biological world by the vast interior deserts to the east and south and the Pacific Ocean to the west. When the Europeans arrived, they brought their annual Mediterranean weedy grasses, but also some crops. In the 1950s, scientists in California described the Barley Yellow Dwarf Virus (Brunt et al. 2001) that infects barley crops and is a major economic problem with barely production. Unfortunately, this virus has made the jump from cereal crops to our native grasses (Malmstrom, 1998). Spread by aphids, this virus attacks the vascular system of a grass, turning the leaves yellow (see photo) or bright red and is most damaging during drought conditions. This virus now has a worldwide distribution, and was probably present in the barley seeds brought by European settlers. If so, Barley Yellow Dwarf virus has had over 300 years to spread across the wildlands of California and infect the native grass populations. One might envision this disease wiping out much of the original distribution of native perennial grasses in California, as many wildlands are devoid of native grasses yet have clearly never been plowed or otherwise farmed.This would also explain the patchy distribution of the native grasses; the patches are those populations that are resistant to the virus.