What is the tree girdling? What happens to the plant when that girdle is removed from the stem (below the branches)?
Tree girdling or Malpighi's girdling is the removal from a stem of a complete external girdle containing phloem (that is more external) but preserving xylem (that is more internal).
Although a girdle like that is removed below the branches the plant dies because organic food (sugar) is disallowed to pass to the region below the girdle and thus roots die from the lack of nutrients. Ever since roots die the plant does not get water and mineral salts and dies too.