Optimal census method to estimate population sizes of species growing on rock walls: The case of mature Primula pedemontana

Abstract

This study calculates the minimum effort needed to survey the species Primula pedemontana Thomas ex. Gaudin on the vertical walls of Aguja de Pastel in the Curavacas Massif (Spain). The short and variable period of flowering that this plant has, the inaccessibility and the physiognomy of the place in which it grows, the resources needed, as well as the meteorological harshness linked to the time of the year in which the censuses are carried out make it a priority to optimize the time spent on fieldwork. For this reason, we designed a method to reduce the sampling load. This method allows us to reduce the time spent and the material, methodological and human resources used in censuses, while maintaining the highest possible precision. Keywords: Minimal effort, Census optimization, Rupicolous flora, Monitoring, Inaccessibility