nest, dip up, scoop up, come to an end
樔 centers on a container-like action or object: a nest as a holding place, dipping or scooping up something, and by extension coming to an end as if the contents are fully taken.
樔 combines 木 (tree/wood) with 巢 (nest), suggesting a wooden nest or a scoop made from wood. The historical development is uncertain, but the component relationship is visually clear.
A wooden 木 nest 巢 sits in a tree. From that nest you can dip up or scoop out things, and when the nest is empty, things come to an end.
For ソウ, imagine a saw cutting the wooden nest: saw -> ソウ, and the nest is scooped out.