IB Environmental Systems and Societies Practice Exam 2025 – Comprehensive Study Guide

Detritus refers specifically to decomposed organic matter, which plays a significant role in ecosystems. This term encompasses the remnants of dead plants and animals, as well as waste products, which are broken down by various decomposers such as bacteria and fungi. The decomposition process releases nutrients back into the soil, making them available for plants and other organisms. This cycle is essential for nutrient recycling in ecosystems, as it ensures that energy and matter flow continually support life.

In contrast, living plant material refers to currently thriving vegetation, which does not represent the process of decomposition or the recycling of nutrients. Nutrients in the soil can arise from various sources, including detritus, but are not the same as detritus itself. The primary energy source for producers is sunlight, which plants use in photosynthesis to create their own food, rather than being derived from decomposed matter. Thus, the definition of detritus as decomposed organic matter is key to understanding its role in nutrient cycling within ecosystems.