Some of them look like pokeweed seedlings. All those bird-poop weeds have been sitting there forever, and now that they are getting some sun, watch out! Just hoe/rake/cultivate them up; the roots are still small right now.

agree on pokeweed.. and whatever else shot out the butt of a bird that used the previous bush to perch on ...

i grow in glacial sand ... that soil is not horrible.. nor lacking in nutrients ... imo .. you are making an assumption .. or presumption ... dont make future mistakes based on such ...

isnt it obvious... the weeds are enjoying it.. in record time ...

if you actually have a plan ... perhaps if you can rearrange it and you can cover the ground with mulch.. you might be able to stop whats coming your way.. if you leave the soil bare ...

ken

Remaining conifer appears to be yellow thread branch cypress - a popular decorative shrub > tree. Way to determine mineral content of soil is to send sample to soils lab for testing and analysis.