Based on environment:
* Desert: A dry, barren area with little vegetation.
* Ocean: A vast body of water with little land.
* Tundra: A cold, treeless region with low-lying vegetation.
* Open field: A large, flat area of land without trees.
Based on density:
* Clearing: An open space within a forest.
* Meadow: A grassy area with few or no trees.
Based on the presence of trees:
* Urban area: A densely populated city with buildings and little natural vegetation.
* Farmland: Land used for agriculture, often with few trees.
The best "opposite" depends on the context and what you want to emphasize.