The definition of submontanely in the dictionary is in a manner that is situated on or characteristic of the lower slopes of a mountain. Other definition of submontanely is in a manner that is beneath a mountain or mountain range.
Merrill, p. 2112: Pasam'u, cyrtorhymcha, Gamble, Mat., 75, p. 432. A tree,
distributed from Sumatra through the Malay Peninsula and Borneo to Mindanao
in the Philippines. _In the Peninsula occurring submontanely from Perak
southwards, ...