Enter technology, and food production can be optimized. Combine those processes with others, and you can create plants that don't exist yet but are much better at creating food.
Technology doesn't mean that plants are outright destroyed. But it is very likely that new processes will be more efficient. To hedge against the threat of not knowing, seed banks will be kept. A risky move compared to keeping nature alive, but I doubt that anybody in power will maintain a rain forest over using the area for more efficient means of energy and resource creation.
Maintaining nature only makes sense if we are interested in knowledge as the primary driver. But the primary driver is power. Like Alexandria and Baghdad, there is no way that knowledge will be maintained when it stands in the way of power.