Grades 3–5 · Organisms
What happens to matter in dead leaves?
A fallen leaf gradually loses its familiar shape because fungi and bacteria use its material as they grow. These decomposers break leaf matter into smaller substances, moving it into other living and nonliving parts of the environment while using stored chemical energy.
Many decomposers release enzymes, substances that help chemical reactions break large molecules into smaller ones. The organisms can absorb some of the products. A leaf's disappearance is therefore not matter vanishing: some becomes decomposer material and some remains in changed organic material in the soil.
During respiration, decomposers use some of the leaf's chemical energy and release carbon dioxide to the air. The illustrated snapshot follows six invented carbon units. Four have reached the air as carbon dioxide and two remain in decomposer or soil material. All six still exist, and the retained two may move again later.
The Dead leaf starts with six invented carbon units: four move onward as CO₂ and two remain retained. Heat disperses labels a different route from the carbon moving through air, organisms and soil.
In the diagramDecomposition: matter continues movingSoil organic matter and mineral nutrientsDead leaf6 carbon unitsDecomposers2 retained4 as CO₂PlantHeat dispersesMatter cycles; usable energy is not recycled.
Other nutrient elements can become forms roots take up, helping a later plant build new material along with carbon dioxide. Energy follows a different route and much eventually disperses as heat. Matter can cycle into another leaf, but ecosystems still need a continuing energy supply.
About this explanation
Starting knowledge: Distinguish living things from dead material and follow matter arrows.
Sources
- OpenStax Biology 2e — Biogeochemical Cycles
- OpenStax Biology 2e — Classifications of Fungi
- OpenStax — Biology 2e: Characteristics of Fungi