The first two photos show progeny of the large dead tree previously killed - it has many open nuts which shed their seed and produced the current crop of trees and saplings in the surrounding area.
Mapped in FieldMaps untreated as woody weeds.
abread111 I tackled the old tree, as I did a number of other old trees further northeast; however, I haven't followed up at this particular site and was shocked about the advanced stage of recruits. I did follow-up further northeast, see Hakea salicifolia subsp. salicifolia (Willow-leaved Hakea)