@rusticana
Hemlock and Douglas-fir “logs” should work well, particularly if they had already started to rot. Hemlock, spruce, alder, cottonwood, silver fir, and maple rots fast, Douglas-fir has a medium rate of decay. Red cedar takes forever to rot and only becomes effective nurse logs once cracks and crevices open up and collect enough broken-down organic debris for seedling to root in.
I have similar projects going. All the hemlocks with stapled-down roots didn’t survive, but it could’ve been something other than the staples that did them in.
Thick moss works well for insulating the spreading roots.
I would wait longer than a year to expose roots, especially if the starting nurse wood was not decadent. Roots need time to work their way into the rotting wood and become established in substrate below.
One of my compositions is a red cedar over maple stump in its 4th year, still mostly covered. Roots in the pot beneath the stump were trimmed in 2024 to encourage more stump-root growth. Surface roots will start to be exposed in 2026. Exposure will happen incrementally in following years, not all at once.
It might interest you to know that rows of mature trees that established on nurse logs are known as
Colonnades.
