Twigs, branches, and dead leaves from natural pruning form the first level of the forest food chain and habitat for organisms on the forest floor, which are important for forest dynamics. The mineralization of leaf and twig litter by organisms aids tree nutrition and energy pathways in the ecosystem. Removing forest litter for burning harms forests by removing food sources and habitats for beneficial organisms like nitrogen-fixing bacteria in pine trees. Removing bark from trees also harms them by damaging the cambium layer responsible for nutrient transport. The forest is a complex system where photosynthesis, respiration, and nutrient balances determine a tree's growth, greatest in dense young forests and slowest in mature forests.