Landscape poly count problem

Hi, I made a quick scene iesterday for a mobile demo. I used all low poly models (off course), but i saw that, after build, the app crash every time after only 1 frame is displayed. So I went check the statistics to see what happened an i found this:

grass total → 6000 polys
trees total → 4000 polys
landscape → 508000 FIVE HOUNDRED EIGHT THOUSANDS poly… WHAAAAT?! How is this possible? The landscape is an ultra simple hill in the center of a square landscape, with just one tree on the top. Nothing more.
Is there any method to simplify landscape geometry or i should re-make the entile scene in a different way?

Thank you.

Are you using tessellation on terrain?

How do I check this?