Okay, kiddo, have you ever seen a tower of blocks? When you try to build the tower taller and taller, at some point it becomes really hard to balance the blocks on top of each other, right? That's what we call "critical depensation" in science.
Critical depensation is a big fancy word that scientists use to talk about what happens when a population of plants or animals gets too small. When there are lots and lots of plants or animals, they can survive and reproduce easily. But when their population shrinks too much, they start having a hard time finding food, water, or mates. This means that they might start dying out even faster!
It’s like a group of kids trying to carry a really heavy treasure chest together. When there are lots of kids, lifting the chest is easy. But if some of the kids go home, suddenly the treasure chest becomes too heavy for the remaining kids to carry. They might not be able to lift it anymore!
So, when a population of plants or animals becomes really small, they might not be able to survive for very long. This is called critical depensation because the population has reached a "critical" point where it can't sustain itself anymore.