Is this a picture of particle board?
That has a high probability of being particle board. You can doublecheck by looking at where the big gouges are... if the material is small flakes/big sawdust, then it's particle board. (Destructive triplecheck by putting a puddle of water on top and seeing if it puckers up.)

Given that you've got a fair bit of damage, now might be the time to replace it all with some water resistant plywood.