Due to the catastrophic pollution of the planet, the balance in nature has been considerably distorted. Many food chains were also broken thus causing the extinction of one species and the abundance of another. The same problem undergoes the Redwood forest in Northern California that is suffering from the invasion of two poisonous plants – tansy ragwort (Seneco Jecobaea) and gorse (Ulex europaeus). Therefore, there exist numerous programs directed at the elimination of those plants; they also on the California Exotic Pest Council’s list of Exotic Pest Plants (Noss et al. 2000).
The first plant, tansy ragwort, also known as senecio jacobaea, was firstly described by Carolus Linnaeus. This species derives from the genus of sunflower family that embraces 21000 species all over the world. The most part of the senecios are ecologically important plants but many of them are weeds that quickly occupy pastures and leaving no for food for animals. This term ragwort is explain by the ragged form of the leaves; the term itself originates from English language (Mitich 1995). Tansy ragwort is a biennial, perennial plant being widely spread in the climatic regions of Northern California, western Washington, western Oregon and all maritime regions of the Pacific Northwest (Sharrow 1982).The plant can develop rootstock that branches into other fleshy roots reaching 30 cm depth (Mitich 1995). The great level of tenacity is predetermined by its capability to multiply by two different ways: vegetative and by means of pollination. Tansy ragwort usually germinates in autumn or spring and further forms a rosette and a flowering stem. After the flowers appear, it dies thus closing the monographic life cycle. The highest level of mortality occurs at the rosette stage but, in the course of growing, the plant becomes hardly vulnerable (Myers et al p. 93).
Tansy ragwort was first distributed to America from the British Isles being introduced as a medicinal herb in 1950 (British Columbia n. d.). However, it was further found that the plant comprised pyrrolizidine alkaloids, which were extremely poisonous for grazing animals, especially goats, horses and cattle (Mittich1995). The deadliest effect is imposed on the liver so that after its digestion it is converted into pyrroles that cause dysfunction and death. The invasion of tansy ragwort on the pasture has also deprived the animals of the forage thus encompassing vast areas (British Columbia n. d.). Therefore, the Redwoods of California have been much damaged by this weed.
Considering another dangerous plant – gorse (Ulex europaeus) – it should be stressed that this plant also fosters forest deterioration. This species has also become problematic for the Californian regions (Ornduff 1974, p. 125). Gorse is considered as on the most evident fire conductors, as it burns very quickly thus introducing a considerable level of fire hazard.
Gorse is an evergreen shrub that predominantly appears in the Mediterranean region. In the end of seventeenth century, it was introduced to the West Coast of Northern American. This infested weed belongs to the pea family and produces a lot of seeds containing and average plant of 0.5 inch long. The seeds of gorse are extremely tenacious, as they can be kept in the soil up to 30 years. This plant can also be reproduced by a vegetative method so that if it is cut, it can revive very quickly (Oregon State University 2008). Apparently, gorse was originated from Western Europe and North Africa; its variety, gorse weevil, was also presented in the United States in 1953 for controlling the rapid expansion of gorse (Bovey 2001, p. 52). However, this plant does not decrease the number of the existed plants but hampers its further proliferation. Despite the fact that gorse adapts relatively infertile soil and stand soil acidity than other legumes, it can still appear in the regions with more fertile soils (Price. 2003, P. 51).Gorse has also rather piceous and can destroy vast grazing areas. In California, this weed can invade disturbed sites and even sands and overgrazes pastures. Apart from the biological control of gorse mentioned earlier, another method of gorse growing prevention can lie is the mechanical method, namely a mere pulling of the weeds with a full removal of the root system. Unlike tansy ragwort, gorse can be easily consumed by the grazing animals without any harm for them. This method is the cheapest one, and one of the most efficient approach of gross elimination. The chemical approach is rarely used in Californian, as it is dangerous for other plants so there used the safest but the most effective types of herbicides (Bossard et al. 2000, p. 321).
As it can be viewed, both weeds are extremely dangerous the Redwood forest in California, as it distorts the balance of flora and fauna in this region. However, tansy ragwort causes more destruction effect on the grazing animals living in the redwoods, as it contains some poisonous substances doing harm to them. This plant also deteriorates the pastures and hampers the growing of other species of plants. Common gorse is less harmful, but still, it is necessary to take certain measures for its elimination.
Reference List
Bossard, C.C., Randall, J. M., and Hoshovsky, M. C. (2000). Invasive plants of California’s wildlands. US: University of California Press.
Bovey, R. (2001). Woody plants and woody plant management: ecology, safety, and environmental impact. CRC Press.
Invasive Weeds in Forest Land.(2008). Oregon State University. Web.
Mitich, L. (1995). Tansy Ragwort. Weed Technology. 9(2) 402-404.
Myers, J. H., and Bazely, D. (2003). Ecology and control of introduced plants. US: Cambridge University Press.
Noss, Reed, and Save-the-Redwoods League. (2000). The redwood forest: history, ecology, and conservation of the coast redwoods. US: Island Press.
Ornduff, R. (1974). An introduction to California plant life. US: University of California Press.
Price, E. A. C. (2003). Lowland grassland and heathland habitants. NY: Routledge.
Sharrow, S. H. Sheep as a Biological Control Agent for Tansy Ragwort. Journal of Range Management. 35(4) 480-482.
Tansy Ragwort in British Columbia. The B. C. Ministry of Agriculture and Food. Web.