How were the brown barb equals a-loots harmed as more truffula tress were chopped down?

The Brown Bar-ba-loots were harmed as more Truffula trees were chopped down because these trees were their main source of food, the Truffula fruits. With fewer trees available, the Bar-ba-loots faced food scarcity, leading to malnutrition and potentially endangering their survival as a species.