Forest inventory is like a big count of all the trees and plants that live in a forest. Just like when you count all your toys, or all the books in your room, people count all the trees in a forest. They do this to learn more about the forest and make sure it is healthy.
To do this, people walk through the forest, and look at all the trees. They write down information on each tree, like what kind of tree it is, how tall it is, and how wide it is. They also look at the leaves, branches, and trunk of the tree to see if it looks healthy, or if it has any bugs or diseases. They might also dig a little bit in the soil to see if there are any special animals living in the ground.
Scientists also use special tools, like measuring tapes and compasses, to help them measure the trees and find their way around the forest. They might also use special cameras or drones to take pictures of the forest from above.
Once they have counted all the trees and plants, scientists can use this information to figure out things like how much air the forest is making, how much water it is drinking, and how much food it is making for animals. They can also see if there are any problems in the forest that need to be fixed, like if there are too many bugs eating the leaves, or if there are too few trees in one area.
So, forest inventory is a big count of all the trees and plants in a forest that helps us learn more about the forest and make sure it is healthy for all the animals and plants that live there.