Answer:
It describes length of measurement...
This is a symbiotic relationship called commensalism if the tree root is the only one to benefit.
The plants are the primary source of food in a food chain or a food web. The animals which feed on plants will be termed as herbivores or primary consumers like the grasshopper. The organisms feeding on primary consumers will be the secondary consumers like mice. The snake is considered to be a tertiary consumer.
If any one of the organisms were to be removed let’s say the plant, all the other consumers would most likely die since their food supply is no longer available for them to eat. The population of other consumers could fall but could also stay somewhat the same if they eat any other food.