Demography of the giant monocarpic herb Rheum nobile in the Himalayas and the effect of disturbances by grazing

Abstract

Background
Perennity of giant rosette species in combination with a single “big bang“ reproduction followed by death of the genetic individual is relatively rare among plants. Such long-lived monocarpic plants are usually slow growing and can be found in deserts, bogs or in alpine regions of the tropics or subtropics. Due to their longevity monocarpic perennials risk to lose everything before reproduction, which make them particularly susceptible to disturbances. Because of the inherent difficulties to assess if long-lived populations are growing or declining, usually neither their demography nor the consequences of increasing grazing pressure are known.

Methods
We used integral projection modelling (IPM) to measure growth rate and passage time to flowering of Rheum nobile, a monocarpic perennial, and one of the most striking alpine plants from the high Himala...