understorey

Forests are important habitats for birds and, in temperate forests, small mammals which inhabit the dense understorey.

森林对鸟类来说是重要的栖息地，而且在温带森林里，小型的哺乳动物居住在稠密的森林下层。

Tropical forest is wetter and usually supports only knee-high fires that spread slowly through the understorey.

热带森林，通常只能使火烧到及膝高度，并缓慢地在下层植物中蔓延。