This area has the highest proportion of tree cover in Thailand, with many forests dominated by Teak (Tectona grandis).

The river valleys have been under pressure from human use: agriculture, teak plantations, and hunting have reduce plant and animal presence.

[1][2][3] The valleys in northern Thailand run north–south between a series a mountain ranges; this ecoregion's middle section covers the easternmost of these.

[6] Large mammals had been mostly eliminated in the wild by the early 1970s, and riverine habitats were disturbed by the construction of the Bhumibol Dam in the 1960s.

Still, the ecoregion has one of the highest forest coverage rates in Southeast Asia, and the protected areas may support rare species.