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

摘要

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 sub-tropics. Due to their longevity, monocarpic perennials risk losing everything before reproduction, which make them particularly susceptible to disturbances. Because of the inherent difficulties in assessing whether long-lived populations are growing or declining, usually neither their demography nor the consequences of increasing grazing pressure are known.