Nature Abhors a Vacuum

maybe a more gardening friendly way is 'A niche will be filled', or one Rosemary Morrow​ says is "Soil doesn't like to be naked' :)

Where there is naked soil some plant will try to fill it.
Also soil is a living thing and like us, it gets cold, or sunburnt or wind blasts it and is more comfortable and healthy with something covering it.

There are a few practical effects of this:

Don't make bare soil unless you intend to use it.

Plant densely. Help the plants you like fill the space. Plant big plants such as trees, and medium things like shrubs in between, and ground cover in between them. Don't give weeds or grass anywhere to use.
This is part of the value of the Food Forest concept.


Use mulch. If you do have bare soil, mulch is pretty much always a good idea. Consider the leaf litter on a forest floor. Cover the soil in leaves, or bark or old cardboard or shredded paper, even rocks. Something that stops the soil drying out from the sun and wind, something that breaks down safely into soil (so you don't need to move it off again), something that lets rain through.
Mulch also can be used to make use of fertiliser such as cow poop or chicken coop flooring and watering easier as it slows the release of that flow into the soil.

My picture here is my garden up at the gate. It is very zone 2, I drive past it but don't actually walk past often so I don't want to weed it or have to pay it much attention at all. Any grass and bare earth I just cover with cardboard as mulch and drop a shovel of cow poop on top to stop it blowing away.

This bed also uses a few middling sized rocks as mulch for a few reasons, a lot to do with the quite windy spot this bed is in. Again it stops the cardboard blowing away. The rocks give thermal mass and so keep the beds temperature more stable and warm. Rocks tend to attract moisture as they cool over night, especially off wind. The biggish rocks also act as a wind break so the baby plants have a bit of time to grow before they have to deal with the wind.