For restoration of highly degraded areas, plantation of which is recommended?

Correct option is D

The correct answer is (D) Nitrogen-fixing tree seedlings

Explanation:
• Highly degraded areas often suffer from extreme nutrient depletion, especially a lack of nitrogen, and poor soil structure.
• Nitrogen-fixing trees (like those from the Fabaceae family, e.g., Acacia, Leucaena, Prosopis) are recommended because they have a symbiotic relationship with bacteria (like Rhizobium) that convert atmospheric $N_2$ into a usable form.
• This biological nitrogen fixation enriches the soil naturally, making it more hospitable for other plant species to establish later (pioneer species effect).
• These trees often have deep root systems that help stabilize eroded soil and bring up nutrients from deeper layers.
• Their leaf litter provides high-quality organic matter rich in nitrogen, which speeds up the recovery of the soil's biological fertility.

Information Booster:
•
• This process is part of 'Ecological Restoration' or 'Reforestation'.
• In India, species like Prosopis juliflora were widely planted in degraded lands for this reason, though some have now become invasive.

Additional Knowledge:
• Tree seedlings (Option A): General seedlings may fail if the soil is too poor in nitrogen.
• Grasses (Option B): Useful for immediate surface erosion control, but they don't improve deep soil fertility as effectively as nitrogen-fixing trees.
• Fast-growing seedlings (Option C): May exhaust the limited soil nutrients even faster if they are not nitrogen-fixers.