Small covers or tarps on brush piles?

I’ve seen many, many times where brush piles have a small plastic tarp or maybe even just a plastic bag on top of them. The cover is tied down to the pile. These piles are big, standing as tall as 8’ or more and probably 20’ across. The piles consist of branches, underbrush, etc., so not just leaves or other small detritus. The cover barely covers the pile at all. It is maybe a few feet across (generally rectangular). It certainly won’t keep any significant portion of it dry.

Why are these covers on there?

I can think of several reasons, but none seem right.

  1. Keeping the top of the pile covered keep the top stuff from blowing away. This will reduce the amount that gets blown away since the stuff on the sides or underneath aren’t going anywhere if the top stuff doesn’t blow away.
  2. Keep the center of the pile dry (sorta) so later it can be burned. Once you can get the center to burn hot, the rest, even if still wet or somewhat wet, will catch due to the center being burned.
  3. Provide a dry environment inside the pile for animals to make shelters. Clearing out the underbrush and other plants wipes out a lot of habitat for the creatures in the area. Keeping a cover on the piles provides a dry (even if only in the middle) stop for creatures to hide out.
  4. Promote decay. The cover keeps moisture trapped inside the pile, promoting breakdown of the material.

Does anyone know why these covers are put on the piles, especially when the covers seem to cover a relatively small portion of the pile?

If you totally cover a pile of something you later intend to burn (slash pile, firewood, etc.) it will get wet!

However if you just cover the top and allow air to flow through the sides, it will dry out.

Slash pile…

Here is an example:

This kind of shows one. You can see the tarp on top, but the ones I’ve seen the tarp is sometimes smaller and is generally more spread out, not just tossed on top. The idea is the same, though.