The correct option is (a).
Explanation
Deforestation refers to the large-scale removal of trees from forests or other lands for the facilitation of human activities. It significantly alters the biogeochemical cycles, particularly the carbon cycle and the hydrological cycle, impacting soil properties and atmospheric composition.
Statement-wise Analysis
- Statement 1 is Correct: Trees act as natural carbon sinks by absorbing carbon dioxide (CO2) from the atmosphere during photosynthesis. When forests are cleared, this absorption ceases. Furthermore, if the wood is burned or decomposes, the stored carbon is released back into the atmosphere as CO2. Consequently, deforestation is a major contributor to the increase in atmospheric greenhouse gases.
- Statement 2 is Incorrect: Trees and their root systems play a crucial role in maintaining soil structure and adding organic matter (humus). Humus significantly increases the water-holding capacity of the soil. Deforestation leads to the loss of organic matter and soil structure, thereby decreasing the soil's ability to retain water.
- Statement 3 is Incorrect: Vegetation cover slows down the flow of rainwater over the surface, allowing more time for the water to seep into the ground. Root systems also create channels (macropores) that facilitate water movement. The removal of vegetation accelerates surface runoff and reduces the infiltration rate, often leading to increased soil erosion and flash floods.
Key Takeaway: Deforestation disrupts environmental stability by increasing atmospheric carbon dioxide levels and degrading soil hydrological functions, specifically reducing both water-holding capacity and infiltration rates.