Step 1: Understanding the Concept:
In an ecosystem, organisms are classified based on their nutritional role. Green plants can manufacture their own food using sunlight, water and CO2 through photosynthesis.
Step 2: Naming the Role:
Because they produce food (organic matter) from inorganic raw materials, green plants are called producers or autotrophs.
Final Answer:
\(\text{Producer (autotroph)}\)