Solph is a measure of the acid content of the sol The graph shows the tolerance of earthworms to solph.
Tolerance
Lower limit Zone of Zone of Upper limit
of tolerance stress
stress of tolerance
Optimum range 1
Population
Low
Range of
Soil pH
→ High
In a meadow where earthworms live in the sol the pH gradually decreases from the optimum range into the zone of stress. What is the
MOST LIKELY effect on the earthworm population?