Weed Impact on Biodiversity - Coursework Example

Weed Impact on Biodiversity: Bitou Bush Introduction Invasion of weed to natural ecosystems is one of the greatest threats to the environment especially in the temperate Australia. Weeds lead to the degradation of the natural environments in areas such as national parks, wilderness, and bush lands by offering competition and displacement of the native plants to reduce the invasion of such weeds understanding of their biological and the ecological impacts of the weeds to toe environment. One such weed that has invaded Australia is the Bitou Bush. Bitou Bush is a weed that that is of great national significance in Australia and one of the worst bushes due to its invasive nature and the impacts it has on the environment and economy. The Bush threatens the vegetation on the coastal dune on the East Coast (Downey, Cherry, Winkler & Hamilton, 2012). The Bush competes with the other plants and in several cases replaces them altering the natural habitat for birds and animals. The bush grows in many habitats and spreads very fast posing a threat to the Australian ecosystem. The Bitou Bush poses threats to the environment and biosecurity in the New South Wales Coastline. History of Bitou Bush Bitou Bush was noted in Australia in 1908 near Newcastle in the New South Wales when ships dumped ballast from South Africa. The plant was planted to re-vegetate the coastal areas from 1946 to 1968 after sand mining that left the area bare (Native Plants Species at Risk from Bitou Bush Invasion, 2015). . The plant was also used for dune stabilization in the coast by providing vegetation cover to the bare environments. Bitou Bush invasion stands at 80 percent in the NS coastline and other areas. The plant now forms the dominant vegetation cover in the New South Wales coastline where it has invaded many of the native plant species such as the beach-dune vegetation and the coastal woodlands. The invasion of the plant in many areas was declared a threat to the NSW Threatened Species Conservation Act (TSC Act) as it poses a threat to more than 30 plant species (Native Plants Species at Risk from Bitou Bush Invasion, 2015). Overview of the Bitou Bush menace The weed grows perennially to about 1-2m high and sometimes forms canopies growing up to 10m high, which have covered the undergrowth preventing them from accessing sunlight. The bush sprawls and covers a large area with branched stems which are woody. The shallow roots of the plants making it difficult to pull as the fibrous root system do not allow it (Native Plants Species at Risk from Bitou Bush Invasion, 2015). When slashed, it sprouts and flowers producing more seeds spreading to the other areas and increasing the area under coverage. The invasive nature of the bush poses a lot of difficulties for the authorities tasked with controlling its spread. The bush has an extensive root system and is very hard to control its spread than the other plants such as the bone seed. The flowers appear dustered at the on the branches’ ends and are yellow in colour, and 20mm in diameter. The bush produces tiny berries with a green fleshy skin that turns brown once they mature, which attract birds that feed on them facilitating dispersal in other areas. The single seed contained in the fruit is egg-shaped and 5-7mm long and black in colour once it dries. The germination of the seeds is throughout the year although in autumn it is more due to the favourable conditions making it quite difficult for the authorities to eliminate it. The growth is very fast with some plants flowering within the first year after germination although some plants can take as long as 18 months or 3 years before flowering and lowers throughout the year. Plants growing in the North flower earlier than the ones growing in the South coast of New South Wales making the infestation of the plant difficult to control. Each Bitou plant produces about 50, 000 seeds in a year and the dispersal are by animals and birds, which lead to the spread of the bush in several areas (Native Plants Species at Risk from Bitou Bush Invasion, 2015). Birds are the main means of seed dispersal as they eat the fruit and disperse the seeds several kilometres the other animals that feed on the fruits are rabbits and foxes, which pass the seeds in their stool facilitating seed dispersal (Schoeman, Buckley, Cherry, Long & Steadman, 2010). The other means of dispersal are human activities, water, and windblown sand. Present Bitou Bush Problem Bitou Bush is spreading very fast and further into the forests and woodlands in the coastal strip as the recent mapping has shown that infestations are up to 10 km inland. Hamilton, Winkler, and Downey (2008) assert that there are many other areas outside the current invasions of the plants, which are at risk of the invasion by the bush especially the whole of Tasmania and Southern Australia. The bush can form dense stands making the growth of the native plants a problem. In fact, bitou is the dominant plant in many of the Australian coasts leading to the elimination of some vegetation communities such heathlands and woodlands. The plant is also posing a threat to the fauna as plants that are a source of food and habitats are becoming extinct. The vegetation has a big threat to the vegetation diversity and reduces habitat for native fauna. The bush has invaded many of the beach dunes, especially in Port Stephens Hamilton (Winkler, & Downey, 2008). The Australian government is faced with the challenge of recovering the coastlines from the invasion of the Bitou Bush due to its nature of dispersal that facilitate the spreading of the plants to the interior. The Commonwealth government has declared the plant as a weed of national significance. The weed is also in the category of the noxious weed category 3 in Port Stephens Area. Environmental threat of the BitouBush The Bitou Bush has replaced many of the native plants to become the most dominant species leading to less variety of native plants. The effect to the less native plants is a reduction of the numbers and variety of mammals, birds, and insects in the area (Hamilton, Winkler & Downey, 2008). Since the weed is highly competitive, it smothers the native plants and destroys the natural habitats and sources of food for native animals. The bush also poses threat to the native plant species such as the shrubs, short trees, orchards, herbs, and ferns. Due to its spreading nature, it does not allow enough light for the undergrowth making it difficult for them to grow to maturity. Populations of indigenous plants and animals also reduce due to the invasion by the plant which is spreading very fast into the interior. Many of the indigenous growths are the favourable habitats for animals and birds, which means that they may face extinction. The other threatened communities are the ecological communities such as in the Eastern Suburbs Banksia Scrub and Kurnell Dune Forests. Extinction of such natural features threatens the economy of Australia especially the NSW (King & Downey, 2008). National parks are facing a major threat as the bush invades the natural habitat for the wild animals. The bitou plants have a lot of impacts on the native plants diversity especially on the dwarf grass heath land vegetation in the northern New South Wales. There at least two nationally threatened population species which are Zieriaprostrata and Thesium austral. There is fear that if the spread of the bush is not controlled, the two plants will become extinct due to the extensive invasion. The analysis of the bitou invasion and its impacts below and above ground is severe that has led to the decline in the richness of the local plant species and their abundance. The bush has the ability to form dense stands hindering the growth of the native species of plants. A number of pests find habitats in the dense thickets of the bush such as foxes, currawongs, and some birds. The animals feed on the Bitou Bush and disperse the seeds expanding the infestation of the plant in many areas. Once the bush has spread and thickened, it threatens the coastline diversity by exclusion of the other species. It has taken over the native vegetation by creation of a monoculture in which the habitat of the local fauna is reduced. It can difficult to recover the coastlines from the invasive weed and get back the native fauna and flora. The ability of the seedlings to flowering within the first year and flowering throughout the year makes the bush more competitive compared to the native plants. More so, a single plant can produce up to 8,000 seedlings in a year that can remain viable for about10 years (Schoeman, Buckley, Cherry, Long& Steadman, 2010). The seed dispersal is facilitated by the appealing appearance of the fruit of birds and animals that feed on them and disperse the seeds to other areas. The plant can tolerate salt, mild frost, and water-logged soils, therefore, grow in the coastal environments. The bush has been declared a threat to biodiversity in NSW, a noxious weed by the Noxious Weeds Act 1993, and as a weed of national significance (Ens, Bremner, French&Korth, 2009). Biosecurity Implication of Bitou Bush Bio security is an important part of the government as it tries to respond, prevent, and recover from invasion by various species of plants that threaten the Australian economy and the environment. Environmental biosecurity in Australia is trying to deal with the invasive species of plants such as Bitou Bush to the environment and biodiversity. The bush has several invasive impacts on the economy and the environment and the biosecurity department deals mostly with agriculture. The conservation requires that the biosecurity focuses on protecting individual and native species from extinction according to French, Ens, Gosper, Lindsay, Mason, Owers, and Sullivan (2008). Many invasive species threaten the environment but the Bitou Bush has taken the greatest attention. Most of the research and resources are channelled to controlling the spread of the bush and eradicate its presence in many areas. The biosecurity department is tasked with raising awareness on the adverse effects of the Bitou Bush on the ecosystem. The main problem is containments and eradication initiatives to help deal with the bush that has covered several areas on the coast. The national Bitou Bush and boneseed Program has the task of incurs a lot ofcosts in awareness materials such as posters, banners, and flyers to enable the locals participate in reducing the spread of the plant. Eradication and containment of the bush requires a lot of research by the department of plant biosecurity to ensure that the right methods are applied to give the best results. The South Coast Bush Task Force came up with a plan for containing the spread of the bush to areas without invasion prioritizing the areas with large infestations as asserted by Markula and Csurhes (2015). Other bushes and plants require containment such as the boneseed but much of the attention is given to the bitou plant, which has threatened many plants from thriving. Departments in the fishing and primary industries have their focus on the eradication of the Bitou Bush as they aim to establish a bitou-free zone on the along the NSW. The program will cost the stakeholders about $80,000 in a year and will take many years as the infestation is quite large according to Sinden, Downey, Hester, and Cacho (2008). The biosecurity department will have to make several follow-ups ensure that the process of eradication and containment goes on smoothly. In addition, Landcare and Coastcare groups are working hard dedicating several hours to try and control the weed and restore the beaches to their original condition. A lot of energy and resources have been dedicated to the eradication of the Bitou Bush in the NSW to ensure that the plant is eliminated to allow the other flora to grow and flourish. Present solutions for Controlling the Bitou Bush The Bitou Bush grows in various environments such as the open places and in shade forests. The plant tolerates salinity, shades, water, wind-blow, sand, drought, fire, low nutrients, and strong wind, which make it difficult to eliminate it completely. There are a number of measures to control and eliminate the weed especially prevention of the spread of the weed to areas without it. Some simple solutions is destruction of the young plants in the gardens before they start flowering as highlighted by Cherry, Willsherand and Whyte (2008). The use of herbicides such as the ones registered for controlling the Bitou Bush is a good way of killing the existing plants especially during winter. The spraying can be done from the ground or from above in areas without dust or seaspray cover. In the NSW, helicopters are used to spray ensuring that large areas get treated quickly without destroying the native species as asserted by Toth, and Winkler (2008). The other management strategies to control the bush through minimizing the quantity of seed the plants produces is detection of many plants in areas that are difficult to access such as inside the forests. Several biological control agents exist but the plant lacks natural enemies to attack it. Biological control is a slow process and may not control the plant completely. However, it is applied in areaswhere methods such as spraying are inappropriate or will affect the native plants. One of the biological control in use is the Bitou tip moth that eats and destroys developing leaves, flowers, buds, and minimizes seed production (Edwards, Adair, Wanjura, Bruzzese & Forrester, 2009). Another biological control in use is the Bitou seed fly that destroys the seeds. The others are bitou leaf-rolling moth, and buckle mite which is under testing to determine its effects (Adair, Morley, Morin, Julien, McFadyen & Cullen, 2012). Fire is also another control method in use to kill the mature bushes although some may resprout and grow. Fire can also kill the seeds in the litter or at the top of the soil although it stimulates the germination of seeds in the lower soil profile. These seedlings must be removed before they flower to prevent it from spreading. Mature plants initially killed by herbicides reduce the seedbank in the soil making it suitable for areas that are highly sensitive to fire. Grazing is another effective method of controlling the Bitou Bush especially by cattle as it prevents further spreading. However, use of animals such as cattle may have other adverse effects such as erosion, destruction of the native plants, and spread of other undesirable weeds. Integrated management approaches necessary to control the spread of the weed such as weed control programs in natural ecosystems, the natural regeneration that helps in eradicating the Bitou Bush and follow-ups. Disposal of the dead Bitou Bush after spraying by fire or any other means is important to avoid regermination. Spot spraying, mechanical removal, and biocontrol are appropriate for controlling the bush in rain forests to avoid destruction of the native plants. The other control measure is legislation by the Australian Quarantine and Inspection Service that prohibits the entry of the plant into the region. The areas declared for the controlling of the Bitou Bush are New South Wales, Queensland, Victoria, Western Australia, and South Australia. The formation of the Threat Abatement Plan was important to highlight the actions that would help in reducing the impacts of the Bitou Bush on biodiversity (Hamilton, Turner, Rendell & Downey, 2010). Recommendations for Possible Control of Bitou Bush The control of Bitou Bush requires a lot of caution as it has many ways of seed dispersal. The bush requires special attention due to its high spreading rate in Australia, especially at the coasts. In fact, the Bitou Bush should be declared a noxious plant in all the states and territories through amendment of Agricultural Acts (King, & Downey, 2008). The methods for controlling the weed should be certified by the appropriate authorities to avoid it spreading further into new areas. Responsibility is very important when controlling the weed when controlling the noxious weeds such as Bitou Bush. The government should take the obligation of ensuring that it takes reasonable steps to eradicate the plant. Government programs involving adequate research should be implemented to the letter to prevent reinfestation. The enforcement of the laws that require landowners to take control responsibilities should be of great importance in reducing the spread of the bush. Investigations play an important role in eradicating the noxious plants by such means as providing the needed funds for carrying out research programs, controlling the weed, community education, and involvement (Cherry, Downey & Winkler, 2008). A survey of the areas infested with the Bitou Bush should also be a priority for the investigations and projects funding. Surveys will display the areas with large tracts of the bush and assist in selecting the best eradication method. The federal government must make sure that the program managers for eradicating the spread of the bush take full responsibility by initiating their research and coordinate the elimination programs. Governments in the Australian states should also avoid control measures that pose a threat to other native ecosystems or the integrity of the environment. Before the measures are applied to control the weed, the government should scrutinize and ensure that the methods are not harmful to the other native plants or animals. The Agricultural Conservation Foundation AFC should encourage the biological means to control the Bitou Bush and other invasive plants in Australia (King & Downey, 2008). The governments should always augment previous research concerning the eradication measures. The research will assist in finding out the effectiveness of the method in the eradication process. Conclusion Invasion of the native plants in the NSW of Australia poses a great threat to the native plant communities. The plant is in the list of the threatening species under the NSW Threatened Species Conservation Act 1995 in 1999. The Threat Abatement Plan highlighted the actions that would help in reducing the impacts of the Bitou Bush on biodiversity. The plant has many negative impacts on the environment such as competition with the native plants and destruction of the natural habitats for birds and animals. There several control measures such as aerial spraying, burning, and biological methods. Some of the recommendations for controlling the infestations by the bush more research on the favourable control methods, responsibilities by the authorities, and community education on the best eradication methods. Studying the patterns of the invasive weeds and their adaptive behaviour will help in the eradication of the Bitou Bush. References Adair, R. J., Morley, T., Morin, L., Julien, M., McFadyen, R., & Cullen, J. (2012).Chrysanthemoidesmonilifera (L.)T. Norl.–Bitou Bush and boneseed.Biological control of weeds in Australia. CSIRO, Melbourne, 170-183. Cherry, H., Willsher, L., & Whyte, B. (2008).Bitou Bush and boneseed eradication and containment in Australia.Plant Protection Quarterly, 23(1), 38. Cherry, H., Downey, P. O., & Winkler, M. A. (Eds.). (2008). Bitou Bush management manual: current management and control options for Bitou Bush (Chrysanthemoidesmonilifera ssp. rotundata) in Australia. NSW Department of Environment and Climate Change. Downey, P., Cherry, H., Winkler, M., & Hamilton, M. (2012).Changes in the distribution and density of Bitou Bush ( Chrysanthemoidesmonilifera subsp. rotundata (DC.) T.Norl.) in eastern Australia. Retrieved 8 May 2015, from http://www.weeds.org.au/WoNS/Bitoubush/docs/Hamilton_et_al-Changes_in_D&D_of%20Bitou_bush-PPQ_Vol_27_no.1_PPQ.pdf Ens, E. J., Bremner, J. B., French, K., &Korth, J. (2009). Identification of volatile compounds released by roots of an invasive plant, Bitou Bush (Chrysanthemoidesmonilifera spp. rotundata), and their inhibition of native seedling growth.Biological Invasions, 11(2), 275-287. Edwards, P. B., Adair, R. J., Holtkamp, R. H., Wanjura, W. J., Bruzzese, A. S., & Forrester, R. I. (2009). Impact of the biological control agent Mesoclanispolana (Tephritidae) on Bitou Bush (Chrysanthemoidesmonilifera subsp. rotundata) in eastern Australia. Bulletin of entomological research, 99(01), 51-63. French, K., Ens, E., Gosper, C. R., Lindsay, E., Mason, T., Owers, B., & Sullivan, N. (2008). Management implications of recent research into the effect of Bitou Bush invasion. Plant Protection Quarterly, 23(1), 24. Hamilton, M. A., Turner, P. J., Rendell, N., & Downey, P. O. (2010).Reducing the threat of a nationally significant weed to biodiversity: four years of implementation of the NSW Bitou Bush Threat Abatement Plan.In Proceedings of the 17th Australasian Weeds Conference, ed. SM Zydenbos (pp. 166-9). Hamilton, M. A., Winkler, M. A., & Downey, P. O. (2008).Native plant species at risk from Bitou Bush invasion: a field guide for New South Wales. Department of Environment and Climate Change. King, S. A., & Downey, P. O. (2008).Assessing the recovery of native plant species following Bitou Bush control-the need for monitoring.Plant Protection Quarterly, 23(1), 40. Markula, A., &Csurhes, S. (2015). Department of Employment, Economic Development and Innovation Biosecurity Queensland Steve Csurhes and Anna Markula —December 2010 Note: Please send any additional information, or advice on errors, to the author at steve.csurhes@deedi.qld.gov.au PR10_5592 Bitou Bush Chrysanthemoidesmonilifera subspecies rotundata Weed risk assessment. Retrieved 8 May 2015, from https://www.daf.qld.gov.au/__data/assets/pdf_file/0006/72825/IPA-Bitou-Bush-Risk-Assessment.pdf Native Plants Species at Risk from Bitou Bush Invasion. (2015). Retrieved 8 May 2015, from http://www.environment.nsw.gov.au/resources/pestsweeds/07239idguidepartA.pdf Toth, J., & Winkler, M. A. (2008).Bitou Bush aerial spraying in New South Wales-what have we learned?.Plant Protection Quarterly, 23(1), 43. Schoeman, J., Buckley, Y. M., Cherry, H., Long, R. L., & Steadman, K. J. (2010).Inter‐population variation in seed longevity for two invasive weeds: Chrysanthemoidesmonilifera ssp. monilifera (boneseed) and ssp. rotundata (Bitou Bush).Weed research, 50(1), 67-75. Sinden, J., Downey, P. O., Hester, S. M., &Cacho, O. (2008). Economic evaluation of the management of Bitou Bush (Chrysanthemoidesmonilifera subsp. rotundata (DC.) T. Norl.) to conserve native plant communities in New South Wales. Plant Protection Quarterly, 23(1), 34. Read More