Variation of vegetative and reproductive traits in Cistus laurifolius: evidences of a response to contrasting habitat conditions

Environmental changes can affect the distribution and conservation of plant populations, therefore the study of the ability to modulate reproductive and vegetative traits is of large interest. Cistus laurifolius is a shrub typically occurring in Mediterranean open vegetation, often under different degrees of habitat light intensity. In the present work, we investigated reproductive and leaf traits to assess the ability of this species to cope with unfavorable / suboptimal conditions. We quantified fruit set, seed set and seed mass under different conspecific plant density and light conditions, whereas vegetative traits were assessed through the measurement of plant height, Specific Leaf Area (SLA), and Leaf Dry Matter Content (LDMC). Results show that plants of Cistus laurifolius are able to adjust both SLA and LDMC under shaded conditions, but produce fewer seeds with reduced seed mass compared with plants under full light. We conclude that plants are able to modulate their vegetative traits maximizing the carbon gain under shaded conditions, but they are not able to offset the carbon balance deficit and therefore fail to convoy adequate resources to reproductive traits. Our results also highlight that the reproductive fitness is positively affected by conspecific plant density, but negatively affected by canopy coverage.