Correct Option
The correct option is The southern slopes receive relatively higher precipitation..
Explanation
The variation in vegetation cover between the southern and northern slopes of the Himalayas is primarily determined by climatic factors, specifically precipitation and insolation (exposure to sunlight). In the Northern Hemisphere, south-facing slopes generally receive more direct sunlight and intercept moisture-bearing winds.
Option Analysis
- The southern slopes have higher altitude. is Incorrect: While altitude influences vegetation zonation (e.g., tropical to alpine), it does not explain the disparity in vegetation density between the two slopes. Both slopes possess high-altitude regions, yet the vegetation characteristics differ significantly due to climatic exposure rather than height alone.
- The southern slopes receive relatively higher precipitation. is Correct: The southern slopes of the Himalayas face the Indian subcontinent and directly intercept the moisture-laden Southwest Monsoon winds. This results in heavy orographic rainfall and higher humidity, which supports thick, lush vegetation. In contrast, the northern slopes lie in the rain shadow area or receive significantly less precipitation and are exposed to colder, drier continental winds, resulting in sparse vegetation. Additionally, southern slopes receive more direct sunlight, promoting longer growing seasons.
- The northern slopes are subjected to shifting cultivation. is Incorrect: Shifting cultivation is an anthropogenic activity practiced in specific pockets (primarily in Northeast India). It is not a geographical or climatic factor that universally defines the natural vegetation cover of the northern slopes compared to the southern slopes.
- The southern slopes have more fertile alluvial soil. is Incorrect: Alluvial soil is characteristic of the river plains (such as the Indo-Gangetic plains) formed by deposition. The slopes of the Himalayas generally contain mountain soils (lithosols) or forest soils. The difference in vegetation density is driven by climate (rainfall and temperature) rather than a disparity in soil fertility caused by alluvium.
Key Takeaway
Growth conditions on the southern slopes of the Himalayas are superior due to higher precipitation from monsoon winds and greater insolation, leading to thicker vegetation compared to the drier and colder northern slopes.