Temporal Dynamics of Growth and Reproductive Investment in the Endemic Relict Juniperus navicularis (Cupressaceae)

Abstract

Juniperus navicularis Gand. is a dioecious gymnosperm with a restricted distribution in the southwestern Iberian Peninsula and is considered virtually endemic to Portugal. It is a medium-sized shrubby juniper that occurs mainly in stabilized coastal dune systems, often forming part of the understory of seaside pine forests. Despite its high ecological value, this species is currently under threat due to habitat destruction and fragmentation, largely driven by increasing urban, touristic, and agricultural development within its core distribution area. Although some botanical studies have been conducted on Juniperus navicularis, significant knowledge gaps remain, particularly regarding plant growth and reproductive effort. The aim of this study was to assess the growth and reproductive effort of this species within its core distribution area along the southwestern coast of Portugal. Five populations, varying in size, pine density, and distance from the sea, were analyzed. The number of cones, strobili, apices, and galls were recorded, along with individual plant characteristics. Growth length was also measured. The main findings of this study are presented and discussed in this work.