Why cant human settlement enhance the natural surroundings?

Sadly in almost all cases, human settlement results in a anthropomorphically degrading affect on natural habitat as opposed to a constructive one. Why cant a countryside human habitation increase the abundance of forests? Well one advantage to a human moving into town is the influx of nutrients in the form of the food they pick up from the market and bring back to their home. Sadly this is rarely taken advantage of, but it is possible to put this to great use by starting an Earth Worm Farm in your backyard using all the leftover organic scraps and compostable material. Earth Worms are an essential part of life because they almost magically and exclusively turn decaying nutrients into water-soluble ones that are ready for plants to digest and use. Bacteria also serves this functions but takes a lot longer than these constantly active complex organisms which turn loads of ground overnight. Earth Worms have many other really beneficial effects on soil including aeration and increasing the mineral count by mixing soil from deeper level of the earth. Scientists have discovered they have the peculiar behavior of living within 2 feet of the surface (the zone where the majority of plant's roots are and the most beneficial place for them to be) but periodically dive to depths of around 6 feet into the mineral rich deeper soils of the earth and bring the valuable minerals back to where the plants can access it. With enough earthworms you could turn a desert into a jungle. Once the soil is teaming with Earth Worms, the only thing left to do is feed nutrients into the virtuous cycle. Additionally, if you perhaps if you are producing your own energy through bio-fuel gasification, you might be able to use the ash by-product in Bio-Char production. Bio-Char or Terra Preta, is another way great of increasing soil capacity.

Of earthworms: "It may be doubted whether
there are many other animals which have played so important a part in the history of the world as have these lowly organized creatures."
         -Charles Darwin