Elephants are a “keystone species”. Cast your mind back, if you will, to history class, where you learned that the keystone is the final piece put in place to complete a stone arch. Without the keystone, the arch cannot be self-supporting. An arch with no keystone will not look like an arch anymore; it will be sight more akin to the aftermath of a great tragedy than a triumph of the human collective.
Without elephants, the African savanna would not be the savanna anymore. Mega herds of wildebeest, for example, play a great role in keeping down the scrub and trees to maintain the grasslands, but none play so big a part as the elephant. Consuming copious amounts of vegetation – at least 200-250kg of food per day – roaming across vast distances, the elephant spreads seed and fertilizer like no other, not to mention their penchant for scratching against anything resembling a post until it is reduced to mere twigs.