Creating Biodiversity

On Reddit, FlimFlamandFlamJam asks, "Let's say I bought 1,000 acres of monocropped farm land. What would be the best way to go about converting it back into land with a lot of biodiversity? And let's say it's just me and I don't have a team helping me."

My answer:

First question, is the land flat or hilly?

Second question, you say it's just you. Does that mean just your muscle power, you and any animals you can control, or you and some big machinery you can rent?

Because if it is just your own muscle power, I find 1/4 acre plenty to keep up with unless it was my full-time job, I couldn't even imagine 1000 acres. That said, and if your land is flat, the main thing you can do to increase biodiversity is just start introducing plants that you think will be useful. You can use mixes from places like Ernst Seeds if you want.

If the terrain is hilly, you can start in on a better option for increasing biodiversity: creating ponds. This is best done with the keyline system in any case, but if its just your own muscle power, this is critical.

With heavy machinery, you can go a little crazier, even on flat land. You still really need to pay attention to the contours, but you do have the opportunity to reshape them. In fact, the best thing you can do to increase the biodiversity of flat land is to change it into hilly land by creating hugelkulture beds. You can do this by hand, but on the scale of 1000 acres, it would take several person-lifetimes.
And when you make water features, swimming ponds where you can dive in from the shore are not exactly the best for biodiversity. You want to really emphasize the water's edge and make it as big as possible if you want to encourage biodiversity.

If you have animals, you have the opportunity to do more than just your muscles, but not as drastic as large machines. One thing you can do is look at abandoned areas nearby and see what takes over, and then figure out what will graze on that. That will help keep things in balance without requiring your constant attention. (But don't just graze willy-nilly, or they just might avoid the thing that tends to take over.)