Step 1: (a) Define stratification:
Stratification is the vertical distribution of different species occupying different levels in an ecosystem.
Step 2: (b) Stratification in a forest:
Trees occupy the top vertical layer, which is the canopy.
Shrubs occupy the second layer, below the trees.
Herbs and grasses occupy the bottom layer, the ground level.
Final Answer:
Stratification is the vertical layering of species. A forest has trees on top, then shrubs, then herbs and grasses.