You might be interested by ditaa block for this:
#+name: tree
#+begin_src ditaa
ROOT
|
+--foo
| +----bar
|
+--baz
+--bax
+--src
| +--main
| | +---java
| | | +---something
| | |
| | +---fine
| |
| +--yes
| +--no
#+end_src
typing C-c ` in the src block will put you in artist-mode, a mode made for editing ascii art and that should make editing those tree easier.