Correct Option
The correct option is (a) 1 only.
Explanation
The Amazon Basin supports the world's largest tropical rainforest. The ecosystem relies on a delicate balance between the dense vegetation cover and the soil. In tropical rainforests, the nutrient cycle is rapid, and the majority of nutrients are stored in the biomass rather than the soil. The forest canopy plays a critical role in protecting the soil from the direct impact of heavy tropical rains.
Statement-wise Analysis
- Statement 1 is Correct: In the Amazon Basin, the topsoil is held in place by the intricate root systems of the dense vegetation. When deforestation occurs for agriculture or settlement, this protective cover is removed. Consequently, the heavy rainfall characteristic of the equatorial region strikes the bare ground directly, causing severe soil erosion. The topsoil is washed away, often rendering the land barren and unsuitable for long-term cultivation.
- Statement 2 is Incorrect: The Amazon rainforest has been significantly affected by developmental activities. Projects such as the construction of the Trans-Amazon highway, mining, logging, and the expansion of agricultural settlements have led to substantial deforestation and fragmentation of the lush forest, altering its biological integrity.
- Statement 3 is Incorrect: The destruction of forests has a profound impact on the river's ecosystem. Deforestation leads to increased surface runoff and soil erosion, which causes siltation in the rivers. This increased sediment load affects water quality, disrupts aquatic habitats, and alters the hydrological cycle of the basin.
Key Takeaway
Deforestation in tropical rainforests leads to the rapid loss of topsoil due to heavy rainfall and the absence of root structures to bind the soil, resulting in permanent ecological degradation and barren landscapes.