การเขียนเชิงบูรณาการ TOEFL

📖 เนื้อเรื่อง

The introduction of invasive species to new environments often leads to ecological disruption, but some scientists argue that certain invasive plants, such as the common reed (Phragmites australis), can provide unexpected benefits. This view is supported by three main arguments. First, invasive plants like Phragmites can improve water quality by absorbing excess nutrients, such as nitrogen and phosphorus, from agricultural runoff, thereby reducing algal blooms and hypoxia in coastal waters. Second, these plants may offer habitat for native wildlife; for example, dense stands of Phragmites provide nesting sites for some bird species like the least bittern, which has been observed using these areas in the absence of native wetlands. Third, invasive plants can be economically valuable as a renewable resource; Phragmites, for instance, can be harvested for biofuel production or used in thatching and paper manufacturing, creating local employment and reducing pressure on native timber forests. Proponents argue that rather than focusing solely on eradication, we should consider the potential benefits of these adaptable species in degraded landscapes where native vegetation may struggle to thrive.

🎧 การบรรยาย

The professor challenges the reading's claims about the benefits of invasive plants like Phragmites. First, regarding water quality, while Phragmites does absorb nutrients, it also disrupts the natural hydrology by outcompeting native plants with deeper root systems that promote infiltration. Moreover, the rapid growth of Phragmites leads to large die-offs in winter, releasing nutrients back into the water at once, which can actually worsen algal blooms. Second, although some birds nest in Phragmites, studies show that these stands support lower bird diversity than native wetlands; for example, least bitterns prefer native cattails and sedges, and Phragmites monocultures reduce the availability of open water foraging areas for wading birds. Third, the economic benefits are overstated: harvesting Phragmites for biofuel is expensive due to its high silica content, which damages processing equipment, and the market for thatch is limited. Meanwhile, the costs of controlling its spread—such as herbicide application and mechanical removal—run into millions annually, outweighing any marginal gains. Thus, the reading's arguments are not supported by ecological or economic evidence.