Loss of biodiversity in a region may not lead to:

The correct answer is Option (2) → Decreased variability in certain ecosystem processes

A region rich in species keeps its ecosystem more productive and more stable. When the region loses biodiversity, three things may happen: plant production falls, the ecosystem resists stresses such as drought less well, and some ecosystem processes become more variable (less steady).

(1) Decline in plant production — A result of biodiversity loss. With fewer species, the ecosystem produces less plant matter.

(2) Decreased variability in certain ecosystem processes — Not a result of biodiversity loss. The change goes the other way. Loss of biodiversity increases the variability of processes such as plant productivity, water use and pest and disease cycles.

(3) Lowered resistance to environmental perturbations such as drought — A result of biodiversity loss. An ecosystem with fewer species is less able to withstand disturbances.

(4) Increased variability in pest and disease cycles — A result of biodiversity loss. Pest and disease cycles are among the processes that become more variable.

NCERT Extract:
Loss of Biodiversity –