lxmx values are used to calculate:
“Net reproductive rate” for lxmx values are used to calculate. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“Death rate”, “Birth rate”, “Survival index”—refer to different states, processes, or scales and therefore do not
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 10