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Potential for the environmental impact of transgenic crops
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ACKNOWLEDGEMENT
It acknowledges all the contributors involved in the preparation of this project. Including me, there is a hand of my teachers, some books and internet. I express most gratitude to my subject teacher Prashant Mohanpuria
, who guided me in the right direction. The guidelines provided by her helped me a lot in completing the assignment.
The books and websites I consulted helped me to describe each and every point mentioned in this project. Help of original creativity and illustration had taken and I have explained each and every aspect of the project precisely.
At last it acknowledges all the members who are involved in the preparation of this project
Environmental Impacts of Agriculture
Introduction
Agriculture is facing the challenge of feeding an increasing global population while natural resources are shrinking due to a combination of factors. Many feel that biotech crops can contribute to meeting global food needs by improving agricultural productivity. Yet, the potential risks associated with the cultivation of biotech crops should be accurately evaluated and managed. The base line in evaluating those risks should be a good knowledge of the impacts and foot prints of the current agricultural systems. Current practices such as tillage, water use, intercropping, crop rotation, grazing and extensive usage of pesticides affect the biodiversity of agricultural fields as well as the environment outside of fields (Tilman, 1999, 2002; Robinson and Sutherland, 2002; Butler et al. 2007, Quemada, 2009).
This subsection gives a brief overview on these impacts and discusses the potential benefits expected from the utilization of the new biotech crops.
Potential for the environmental impact of transgenic crops
Introduction
in agricultural practice associated with the introduction of particular genetically modified (GM) crops might indirectly impact the environment. There is also interest in any effects that might be associated with recombinant and novel combinations of DNA passing into the environment, and the possibility that they may be taken up by microorganisms or other live biological material. From the current state of knowledge, the impact of free DNA of transgenic origin is likely to be negligible compared with the large amount of total free DNA. We can find no compelling scientific arguments to demonstrate that GM crops are innately different from non-GM crops. The kinds of potential impacts of GM crops fall into classes familiar from the cultivation of non-GM crops (e.g., invasiveness, weediness, toxicity, or biodiversity). It is likely, however, that the novelty of some of the products of GM crop improvement will present new challenges and perhaps opportunities to manage particular crops in creative ways.
POTENTIAL CULTURAL IMPACTS
The cultural impacts of genetically modified trees are difficult to quantify since little research has been carried out in this area and determining what constitutes a positive or negative impact can often be a subjective issue. For these reasons, only speculative impacts can be highlighted. One potential positive impact of genetically modified trees is the protection and conservation of culturally important tree species such as the American chestnut (Castanea dentata) or American elm (Ulmus americana) which have been in decline as a result of disease (Farnum, Lucier and Meilan 2007; Merkle et al. 2007; Hayes 2001). Traditional breeding methods used to develop disease and insect resistance in agricultural crops are difficult to apply in forests due to the long lifespan of trees (Merkle et al. 2007). Therefore, for tree species that are in decline, the incorporation of insect or disease resistant traits can increase the viability of selected species. Similarly, increasing the productive potential of genetically modified trees could reduce the harvest pressure that many culturally important species now face.
There are also several cultural concerns with regards to the genetic manipulation of trees. Transgenic escape in particular has the potential to impact the natural landscape by altering its composition and consequently affecting local cultures. A loss of culturally important species could occur as a result of increased competition between modified and non-modified organisms. If the use of genetically modified trees becomes widespread, local tree species might be displaced. The unintentional development of insect and herbicide resistant species resulting from the escape of insect and herbicide genes could alter species compositions and reduce the number of species present in a given location, thus forcing cultures to adapt to changing biodiversity conditions. Peterson et al. (2000) note that genetic modification will potentially reduce the “local specificity and adaptation of agricultural processes, which increases both social dependency on external inputs to agriculture and decreases the ability of local agro ecosystems to adapt to local environmental contexts”. Therefore, the use of genetically modified trees could result in the marginalization of certain groups in the short term and in the loss of traditional ecological knowledge in the long term.
POTENTIAL SOCIO-ECONOMIC IMPACTS
Genetically modified trees have the potential to allow for the development of several economically beneficial traits. These economic advantages are summarized by Thomas (2000) who states that “GM trees offer the opportunity to domesticate trees, to tailor characteristics more closely to the requirement of commercial forestry and the end-user of forest products” (p.93). However, genetically modified trees also present several potential socio-economic drawbacks.
Using genetic engineering to alter the lignin content of trees could be socio-economically beneficial in several ways. Lignin makes up between 15 and 35 per cent of the dry weight of trees and removing this lignin is a costly process (Peña and Séguin 2001). By reducing the lignin content in wood, fewer chemicals and less energy would be required for its processing, thereby increasing its pulping efficiency (Halpin et al 2007; van Frankenhuyzen and Beardmore 2004; Campbell and Asante-Owusu 2001; James et al. 1998). Research conducted on hybrid poplar suggests this possibility (Peña and Séguin 2001). The need for fewer inputs and greater quality of the end product would result in economic gains. Conversely, increasing the lignin content of trees would lead to a higher lumber density and consequently a better quality of timber and a higher value product. For example, Mathews and Campbell (2000) refer to a study conducted in 1997 by Dickson and Walker in which it was estimated that a 25 to 50 per cent increase in the stiffness of the corewood of Monterey Pine (Pinus radiata) would translate into an increase of $250 million in New Zealand‟s timber exports (Mathews and Campbell 2000).
Similarly, engineering trees to have desired physical characteristics, such as increased timber uniformity, could increase the overall market value of genetically modified timber (Mathews and Campbell 2000). It has also been hypothesized that trees could be modified to suit different management regimes (Johnson and Kirby 2001). For example, fruit trees could be developed to grow to a limited size and height allowing for more trees to be planted in an orchard and allowing for more efficient and cost effective fruit harvesting (Peña and Séguin 2001).
However, the potential socio-economic consequences of using trees with modified lignin content are not all positive. Mathews and Campbell (2000) caution that since trees have been naturally selected through evolutionary processes to provide stability and effective nutrients transport (as opposed to improved pulping efficiency), attempts to manipulate tree lignin may have adverse impacts on tree health leading to productivity losses. Van Frankenhuyzen and Beardmore (2004) present a similar perspective and suggest that trees with altered levels of lignin may be less viable than their non-modified counterparts. As a consequence, trees engineered with this trait may have adverse economic impacts as a result of higher tree mortality.
With regards to pest resistance, the use of genetically modified trees may provide several economic advantages. For example, it was found that apple, poplar, spruce and larch engineered to express the Bt toxin experienced fewer larval feedings (Peña and Séguin 2001). Similarly, Lachance et al. (2007) report that several lines of white spruce (Picea glauca) engineered to express the cry1Ab gene from Bt were lethal to spruce budworm (Choristoneura fumiferana) larvae. Aside from increasing the viability of trees and reducing losses to folivores, fungi and bacteria, these types of modifications could also decrease the need for pesticides and consequently reduce the input costs associated with tree production (Mathews and Campbell 2000). The United States Department of Agriculture estimates that
there are billions of dollars of forest products at risk from the Emerald ash borer (Agrilus planipennis or Agrilus marcopoli) alone, for which the only currently effective treatment is to destroy infected trees and those in the surrounding area (USDA 2006). Similarly, the use of herbicide-resistant trees will allow producers to apply broad-spectrum herbicides to control weeds, thus reducing the need for traditional and costly methods of weed control such as multiple herbicide applications and tilling (Mathews and Campbell 2000). Furthermore, with fewer weeds present in plantations there will be less competition for resources, and trees will be able to grow more efficiently (Johnson and Kirby 2001).
Trees modified to express disease-resistant traits could also result in increased productivity and the development of safer and/or more nutritious foods with longer shelf lives (Thomas 2000). For example, through genetic engineering, scientists have been able to develop varieties of papaya which are resistant to the papaya ring spot virus (Gonsalves et al. 2007). Similarly, Prunus plants have been modified to be resistant to the plum pox virus and transgenic apple and pear have been modified to be resistant to the bacteria Erwinia amylovora, which leads to the development of fire blight (Peña and Séguin 2001). Therefore, genetically modified trees have the potential to influence the financial well-being of fruit producers and to impact food security.
Increased resistance of genetically modified trees to abiotic stress could mean a more efficient growth, consequently improving productivity (Johnson and Kirby 2001). Moreover, by engineering species to be more resilient to adverse growing conditions, trees could be planted on soils where they have not previously been able to survive. This would also allow the use of trees in the phytoremediation of contaminated soils, creating a cost effective method of restoring land that could not be used otherwise (Farnum, Lucier and Meilan 2007; Peña and Séguin 2001). Furthermore, Gartland, Kellison and Fenning (2002) note that forestry initiatives using air and soil pollution tolerant trees promise to generate investment returns, especially when used in urban environments. In addition, economically valuable species could be modified to be grown in various locations outside their traditional range, allowing for greater production areas (Mathews and Campbell 2000).
Another positive economic impact related to the genetic modification of trees is the reduced amount of time required to develop improved phenotypes. Rather than relying on standard cross breeding methods, which have traditionally been lengthy development processes, genetic engineering allows for much quicker phenotype development and for breeding goals to be met rapidly (Mathews and Campbell 2000). For example, it was shown that the flowering of a variety of transgenic aspen was possible after 7 months of vegetative growth, whereas this would have required between 8 and 20 years under normal circumstances (Peña and Séguin 2001). Therefore, by making the breeding results observable more rapidly and reducing development times, genetically modified trees can potentially generate economic benefits.
Genetically modified trees represent numerous potential economic advantages. However, experts have raised several general economic concerns associated with their use. For example, Hayes (2001) suggests that the use of high productivity plantations could lead to a decrease in the perceived social and economic value of non-modified trees or natural forest as the economic gains from these types of forests would not be as large as those received from genetically modified forest plantations. Hayes (2001) goes on to suggest that this change in people‟s perceptions could lead to an increase in the conversion of natural forests to transgenic plantations. If this trend develops, it would most likely result in a loss of forest biodiversity. A further economic concern relates to the fact that poor wood producers will not be able to have access to genetically modified trees given their relatively high cost (Thomas 2000). Therefore, producers who lack economic resources will be denied access to new tree species and markets. For this reason, Thomas (2000) raises the concern that genetically modified trees will generate profit for certain actors in the private sector while poorer communities will be further marginalized.
One of the economic concerns related to the use herbicide and pest resistant trees is the potential evolution of resistant pest species. Should pest species become resistant to currently effective chemical and biological control methods, the cost of controlling pest outbreaks would increase (Mathews and Campbell 2000).
In monetary figures, Farnum, Lucier and Meilan (2007) cite a report by Sedjo where the use of herbicide resistant trees is estimated to reduce production costs by approximately US$ 1 billion per year and that trees modified to have lower lignin levels could generate between US$ 7.5 and US$ 11 billion per year worldwide. However, while there could be economic advantages associated with the development and use of genetically modified trees, with exceptions such as the papaya example cited above, these advantages have yet to be clearly demonstrated and quantified (El-Lakany 2004). Moreover, since implementing improved silviculture practices continue to offer significant potential for economic gains, the economic rational for introducing genetical modification technology is unclear (El-Lakany 2004). The long time period between the beginning of research projects on genetically modified trees and when benefits begin to accrue makes tree engineering a risky economic proposition (van Frankenhuyzen and Beardmore 2004).