The brown patches are actually culivated fields. On these steep slopes I have enquired before regarding erosion but they say it's not a big problem...I can't imagine but not only in Cebu but also in Northern Luzon where we are more familiar many slopes are cultivated but some are also terraced. I have to assume that the terraces were created to solve a problem...

If you look closely roads appear non-existent but several homes are visible accessable only by walking trails or two wheeled tracks.