Evenly spaced tree grids produce the weakest reverberation of any forest layout.

Evidence

The open field waveform consists of a direct wave pulse only, while all of the forested sites have many additional scattering and reverberation arrivals after the direct wave pulse. Site 2, the spruce planted on an evenly spaced grid, has the smallest reverberation wave train. — Donald G. Albert, Michelle E. Swearingen, Frank E. Perron, and David L. Carbee, Low Frequency Acoustic Pulse…, 65

Categorization

• QUESTION: Would a random or clustered planting produce a longer reverberation tail than a grid? That comparison isn’t made here but seems testable.