Final answer:
About fifteen staple crops account for 90% of the calories people eat every day, including maize, rice, wheat, potatoes, and cassava. The specific number of species accounting for 80% of the world's forage of crops is not mentioned. The information emphasizes the significance of these staple crops and the need for their sustainability in food production.
Step-by-step explanation:
About fifteen staple crops account for 90% of the calories people eat every day. The top five, including maize (corn), rice, wheat, potatoes, and cassava, account for nearly three quarters of these calories.
Although it is not specified in the given information how many species account for 80% of the world's forage of crops, it is likely that a small number of key species contribute to a significant portion of the world's crop production. These key species are the major staple crops that provide the majority of the calories people consume.
The information provided highlights the importance of these staple crops and the need to ensure their sustainability for future food production.