SQLite's SELECT statement doesn't support any syntax like "for xml path()".
In a SQL database, you should expect to store values like this
baumkataster:
baum_ID boden_verd
1 2
2 1
2 3
3 1
3 2
3 3
or like this.
baumkataster:
baum_ID boden_verd
1 value2
2 value3
2 value3
3 value1
3 value2
3 value3
Exceptions to this are relatively rare. (And supported by a dbms that provides xml functions or array functions.)