Like ecampbell said, grass fields are usually burned every year. This is the most cost effecting way to keep forest succession from progressing from a field to a brush/tree stage. Some fields are maintained as such for game and non-game habitat, such as at Howardsville or Stafford Forge and others partly as a wildfire buffer for a prized area, such as Batsto. Forests are burned less often, every half dozen years or so, although some forests immediately around homes or other structures might be burned almost every year, effectively eliminating the shrub layer and giving extra protection from wildfire.
