Leucaena leucocephala is the recommended tree for social forestry purposes.

Benefits of Leucaena leucocephala in social forestry:
1. Fast Growth: Leucaena leucocephala is known for its rapid growth rate, making it an ideal choice for social forestry projects. It can grow up to 3-5 meters per year, allowing for quick establishment and early benefits.

2. Nitrogen Fixation: This tree can fix atmospheric nitrogen through its symbiotic relationship with nitrogen-fixing bacteria in its root nodules. This ability enriches the soil with nitrogen, promoting the growth of other plants in the vicinity.

3. Soil Improvement: Leucaena leucocephala has deep roots that help in improving soil structure and preventing erosion. The tree's extensive root system binds the soil particles together, reducing the risk of soil erosion and promoting soil fertility.

4. Fodder Production: The tree is highly valued for its foliage, which is rich in protein and essential nutrients. It is commonly used as fodder for livestock, providing a sustainable source of nutrition for rural communities.

5. Fuelwood and Timber: Leucaena leucocephala is also a valuable source of fuelwood and timber. Its wood is dense and durable, making it suitable for construction, furniture, and other woodworking purposes. The tree's fast growth rate ensures a continuous supply of wood for fuel and other purposes.

6. Agroforestry Benefits: The tree's ability to fix nitrogen and its dense foliage make it an excellent choice for agroforestry systems. It can be intercropped with other crops, providing shade, mulch, and additional nutrients to the soil, enhancing overall agricultural productivity.

7. Environmental Benefits: Leucaena leucocephala is known for its ability to sequester carbon dioxide from the atmosphere, thus contributing to climate change mitigation. It also provides habitat and food for various wildlife, promoting biodiversity conservation.

Conclusion:
Leucaena leucocephala is a highly recommended tree for social forestry due to its fast growth, nitrogen fixation, soil improvement, fodder production, fuelwood and timber value, agroforestry benefits, and environmental advantages. Its multiple benefits make it a valuable asset for rural communities, promoting sustainable development and improving livelihoods.