d_tree_layer_bd

CODE DESCRIPTION FROM_YEAR TO_YEAR
1 1 layer (one dominant tree layer) 1984  
2 2 layers (dominant tree layer plus 1 sublayer) 1984  
3 3 layers (dominant plus 2 sublayers) 1984  
4 More than 3 layers 1984  
5 0 layer, no tree layer 1984