Smaller wood has a greater percentage of bark and bark has more nutrient value than the inner wood does. This will affect decomposition and fungal growth. It might help if more nitrogen rich additives are placed with larger rounds.
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Here's an excerpt from ---
Hugelkultur - Good wood , Bad wood --- Lots of good stuff there ---
https://permies.com/t/12206/hugelkultur/Hugelkultur-Good-wood-Bad-wood --- Poplar has what I like to call a high exchange rate. I've dealt with poplar and fir slabs. If two similar slabs are left out in a good, all day rain, the fir slab may be dampened 1/8 inch deep while the poplar slab doubles in weight as it sucks up the rain falling on it as well as absorbing water from the damp ground.
When drying out, poplar quickly wicks water from its core in response to surface evaporation.
So any water locked up in a poplar log is more available.
I don't have an acute water shortage, so there is no reason for it to be in long term, less available storage. All I need is a giant sponge that can react quickly to water supply and demand. Poplar serves that need.