2 1 small question: the answer can be seen from dad's language and expression that dad is also expressing his own feelings. From my father's introduction to poplar, we can see that poplar is loyal, selfless, conscientious, fearless and persistent.

Three tall poplars refer to dad, and several young trees are children. Facing the sandstorm, they refer to the harsh environment. Dad joined the frontier and hoped that his children would be cultivated like small trees and become the pillars of building the frontier.

Looking for references is the result of your own thinking.