Effects of human disturbance on reproductive success and population viability of<i>Serapias cordigera</i>(Orchidaceae)

Abstract

Fragmentation of habitats by roads, railroads, fields, buildings and other human activities can affect population size, pollination success and fruit production, especially in plants showing pollinator limitation, such as Mediterranean orchids. In this study, we investigated the effect of human activity on the population dynamics and reproductive success of the orchid Serapias cordigera. Three anthropic and three natural populations were monitored over 14 years (1999–2012), classifying individuals into five stage classes and evaluating reproductive success. Population growth rates differed between anthropic and natural populations. Our results demonstrated that small anthropic populations have lower population viability compared with large natural populations. The proportion of flowering plants, the number of reproductive plants and the percentage of fruits were significantly lower in anthropic than in natural populations. This strong decline in fruit production in populations in urban areas may reflect lower pollination attraction and higher inbreeding in small than in natural populations. Calculation of extinction probabilities showed that the anthropic populations will drop below the survival threshold of 15–20 years. This study highlights that continued monitoring is needed to improve information on population viability and for appropriate conservation management.