Because different mammalian species are dependent on plants for organic matter. Plants provide organic matter for soil communities through the decomposition of leaf litter, by oozing nutrients from roots, or through other methods of deposition of organic compounds into the soil environment. As a result of these diverse methods by which plants supply resources, unique soil communities form under different plant species and under plant communities that differ in composition. If a nonnative plant species invades an above-ground community of flora and fauna, it can alter links between the native aboveground community and the below-ground soil community. For example, an invading nonnative plant could alter the quantity of leaf litter production, which would alter nutrient contributions to the soil.