Maintenance of wooden barrels.
Every year I put wine in my barrels, in which it is most often aged from October to March at the latest. So they lie empty in the basement for six months. So it's a period, in which the ubiquitous harmful fungi and bacteria can act. How long does the wine ferment, nothing can harm the barrels for so long. They are filled with a fluid containing a certain amount of alcohol and acid that has a stabilizing effect, and also carbon dioxide formed during fermentation. Young wine, devoid of only yeast and sediment, it also has a stabilizing effect on the barrel.
But if only the barrel is left empty, without any content, it is immediately adversely affected; the residual moisture in the wood causes the formation of mold and fungus. Later the wood dries up, individual staves loosen, especially in very dry cellars. Therefore, I would not recommend barrels, if they are to be stored in cellars where the humidity does not reach 75% (a hygrometer should hang on the basement wall!).