Okay, we have a small farm in the Great Southern Region of Western Australia. A large chunk of it was cleared for cattle and is kikyu/gass pasture, and we still run a small herd of 8 head. But we're very lucky to have about 3/4s of our land well preserved bushland.
The first thing we did when we bought the place was to plant several broad wind-breaks and shelter-belts with native species in the pasture, forming "corridors". Over the years we've added more -- revegetating the road-verge and encouraging the stuff already there to grow back. We've also planted hedgerows of some other trees that aren't native, but are stock fodder, and the birds and insects love them.
We plant a variety of eucalyptus species, acacias, sheoaks, and a number of melaleuca's and various bushes and shrubs.
This year we enlarged two of our large shelter-belts, extended several of our shade-clumps, and did an ambitious amount of planting along the road verge (which hopefully won't be shredded by the council next time they come along).
It's a drop in the ocean, but it's local, it's something concrete that we can do beyond the rather ridiculous appeasement of separating the recyclables.
Some of the trees we plant will outlive us, and I love that.