Step 1: Understanding the Concept:
The choice of agroforestry tree species depends on the climate zone of the region and the farmer's multi-product requirements (such as fuel, fodder, and timber).
Step 2: Detailed Explanation:
1. Prosopis cineraria (Khejri) is the state tree of Rajasthan and is referred to as the "Kalpvriksha" of the Indian desert.
2. It is highly adapted to the harsh conditions of the arid and semi-arid zones.
3. It serves multiple purposes:
- Fuelwood: It provides excellent quality fuel with high calorific value.
- Timber: Its wood is strong and used for house construction and agricultural implements.
- Forage: Its leaves, locally known as "loong," are highly nutritious fodder for sheep, goats, and camels, especially during dry seasons.
4. Other species like Artocarpus hirsutus and Gmelina arborea are characteristic of humid/sub-humid tropical climates.
Step 3: Final Answer:
The tree grown in arid and semi-arid regions for fuelwood, timber, and forage is Prosopis cineraria.