Existence analysis of populations of Mosla hangchowensis, an endangered plant

Abstract

Mosla hangchowensis Matsuch is an annual herb, which is found only on the seacoast of Zhejiang province in southeast China. The species has declined in numbers and is now endangered. The survival ratio, seminal power, reproductive success ratio, and density as well as other factors were measured from 1993 to 1996, and an existence analysis was performed. There are two environmental sieves during the life history of this species, and the survival curve is between the Deevey-I and Deevey-II. A constant proportion of individuals died throughout the life cycle. The optimum niche of M. hangchowensis is a habitat with soil depth 20-30cm, with moderate to slightly wet conditions, with neither too intense nor too shaded light. The realized niche now is on the top of rocky hills or along gravel roadsides. Sites are few and dispersed. Loss of the optimum niche and a decrease of realized habitats as a result of human activities, the disparity between the realized niche and the optimum, and a low dispersal ability of populations are currently contributing to the endangerment of M. hangchowensis.