When you say "diversity" I think of many things. So I have many answers:
1. People. Different people farming, means different plants and animals
2. Planting Crops. Planting different crops can prevent soil erosion and or soil exhaustion.
3. On the market. Different crops and meats on the market provides consumers with different products and nutrients they may need.
Idk if this helps, there wasn't much detail. Hope it helps! ;)