The Historical State
The California Central Valley Grasslands have historically been dominated by bunchgrass prairies of nassella pulchra, a type of grass endemic to California, and also known as purple needlegrass. Some of the earliest historical records of this dates back to the 1820s where Jedediah Smith, among others, documented the scenery of this area of California. In February 1828, he wrote, “the whole face of the country is a most beautiful green, resembling a flourishing wheat field.” (Holstein 2001). Most of the original environment however has been altered by human activity, including the introduction of exotic plants and grasses. (Garone 2011). The California grasslands are suggested to have been dominated by annual species and xerophytic shrubs (adapted to dry climates). the perennial bunchgrasses were suggested to have only been common on well-watered floodplains. (Wester 1981).
Current Human Impact
The California Central Valley Grasslands used to be one of the most diverse ecosystems that supported many endemic species. However, due to human impact and the changing global climate, the Grasslands has become one of the most endangered ecosystems. The human impact on the California Central Valley Grasslands was so fast and thorough, that information of native species is relatively limited (Stromberg, and Kephart). Even before current human practices, the grasslands were altered with the arrival of European colonists as they introduced non-native species such as oats to the area. Perennial grasses in the Grasslands grow in patches, because non-native species grow in between them and die periodically (Stromberg, and Kephart). Furthermore, in the Grasslands there is an annual exotic grass called the wild oat that has brought a disease called barley and cereal yellow dwarf virus. This virus affected cereals that human settlers grew, but it also jumped onto native bunch grasses (Malmstrom 2005). The virus turns the grasses a yellow or red shade and makes photosynthesis a difficulty, causing native grasses to deplete. The patchy, erratic growth of the native grasses can be explained by the disease as well (Stromberg, and Kephart).
More recently, humans have been practising irresponsible agriculture. Thus, there has been toxic run-off and sediment in the region which has taken a toll on the area (Olson, and Cox). Vernal pools are one of the most unique features of the Grasslands, but 2.8 million acres of vernal pools have been destroyed by humans because of irresponsible agricultural practices (Olson, and Cox). The ecosystem is constantly threatened by human action such as fires, building of dams, cattle grazing, and urbanization (Olson, and Cox). By 2040, it is predicted that urban land 2 miles around the wetlands will double (LAND USE 2001). Native amphibians and their population size are significantly decreasing as well. Furthermore, plant and animal species are affected by fragmentation because it forces them to thrive in isolation, and so migratory species have lost habitats because of this phenomenon (Olson, and Cox).
Table
Table of invasive, exotic species in the Grasslands
Stromberg, Mark R. , Jeffrey D. Corbin, and Carla Marie D'Antonio. California Grasslands: Ecology and Management. Berkeley and Los Angeles: University of California Press, Ltd. , 2007. eBook. <http://books.google.com/books?id=SRBHfbfi5_cC&pg=PA55&lpg=PA55&dq=california central valley grasslands table&source=bl&ots=3B5YZVH1Hp&sig=QFfZ43olqchX6ApOsVdyjIO3kZI&hl=en&sa=X&ei=uzyVUsu0G8L4oATF3YGQDw&ved=0CIABEOgBMAk
Future Prospects
Considering that the Grasslands have already been altered so greatly by human activity, it is important that we make an effort to preserve the remaining native plant species and depleted populations of animal species. Yet, if humans continue with their irresponsible practices, species in California Central Valley grasslands will continue to be altered negatively. If humans do not attempt to correct their agricultural practices to a a safer and more responsible manner, the Grasslands will have more toxic build up. With the changing climate, it is said that the species that habitat vernal pools in the Grasslands are potentially in danger (Pyke, 2005). A study done by Christopher R Pyke suggests that vernal pools were going to be greatly affected by the changing climate by 2100. Many studies have predicted the climate for 2100 with differing opinions. However, Pyke’s study suggests that vernal pools are impacted by all scenarios of change in precipitation in the future. Therefore, if California has little rainfall in the future, species in vernal pools are in danger as they cannot go through the inundation process (Pyke, 2005). Furthermore, a future climate with little rainfall and higher temperature will help exotic grasses to flourish over native species because they are more suited for warmer climates (Sandel, 2012). These larger, annual grasses currently thrive in warmer areas of the Grasslands (Sandel, 2012). Lastly, many animal species and their populations will continue to be affected as the Grasslands become less habitable. For example, the Grasslands is vital for shorebirds but if the grassland continues to shrink in size, the birds will not have anywhere to go during spring migration (WHSRN, 2009). If the Grasslands continue to shrink and become less suited for these migratory birds, these animals species and the food chain will be forced to face the consequences.
What Can Be Done?
The California Central Valley grasslands are currently endangered and in critical condition (Vanderbilt) in large part due to human impact. Today humans are bringing in non-native grasses that are dominating the area and using the lands for agriculture. The agricultural use on the land has been devastating and has led to extreme amounts of fragmentation, meaning that the areas that are unaltered are spread out and isolated (Olson, and Cox). In order to improve the conservation status of the California Central Valley grasslands, native grasses must be planted in order to decrease the amount of fragmentation. Additionally agricultural use must be limited in order to reduce the amount of water diversion and draining which destroys the vernal pools, as well as reducing the amount of logging while planting new trees. Lastly it would be exceptionally beneficial to make this a protected area because so much of the native wildlife has died because their habitat is being destroyed.
C. M. Malmstrom, C. C. Hughes, L. A. Newton and C. J. Stoner
New Phytologist , Vol. 168, No. 1, Plant Evolutionary Genomics (Oct., 2005), pp. 217-230
Published by: Wiley on behalf of the New Phytologist Trust
Article Stable URL: http://www.jstor.org/stable/3694472
California Central Valley grasslands." Bioimages. Vanderbilt . Web. 26 Nov 2013. <http://www.cas.vanderbilt.edu/bioimages/ecoregions/50801.htm>.
Christopher R. Pyke. Ecosystems, Vol. 8, No. 1 (Feb., 2005), pp. 95-105. Published by: Springer
Article Stable URL: http://www.jstor.org/stable/25053805
Garone, Philip. The Fall and Rise of the Wetlands of California's Great Central Valley. Berkeley: University of California, 2011. Print.
Holstein, Glen. "PRE-AGRICULTURAL GRASSLAND IN CENTRAL CALIFORNIA."Madrono 48.4 (2001): 253-64. Print.
"LAND USE AND ECONOMICS STUDY GRASSLAND ECOLOGICAL AREA/ MERCED COUNTY, CALIFORNIA." Project and Studies. Grassland Water District, n.d. Web. 26 Nov 2013. <http://www.traenviro.com/cgwd/pdfs/geasummary.pdf>.
Olson,
David, and Robin Cox . " California Central Valley grasslands." WWF.
World Wildlife Foundation . Web. 25 Nov 2013.
<http://worldwildlife.org/ecoregions/na0801>.
Sandel, B. and Dangremond, E. M. (2012), Climate change and the invasion of California by grasses. Global Change Biology, 18: 277–289. doi: 10.1111/j.1365-2486.2011.02480.x
Wester, Lyndon. "COMPOSITION OF NATIVE GRASSLANDS IN THE SAN JOAQUIN VALLEY, CALIFORNIA." Department of Geography, University of Hawaii (1981): 231-41. Print.
