Spatial variability in early reproductive characteristics of Ulex europaeus L. (Fabaceae) invading in the high-mountain of central Colombia

The early reproductive traits of invasive plants enhance their colonization to spread in new environments. However, altitude can act as an environmental filter against the invasion process. In this study, we evaluated the reproductive dynamics of the shrub Ulex europaeus along time since introduction and spatial variability in the high-mountain ecosystems of the Central Andes of Colombia. Four sites were selected, ranging from 2710 to 3636 m above sea level (a.s.l), with introduction periods varying between 18 and 40 years. At each site, we quantified the proportion of reproductive individuals, fruit set, seed set, seed rain, germination and number of seedlings. Significant differences were found in the proportion of reproductive individuals, seed rain, and number of seedlings. Specifically, time since introduction showed that sites with a longer introduction time have a lower proportion of reproductive individuals. Lower altitudes exhibited more favorable climatic conditions for reproduction, however, altitude did not act as an environmental filter for seed germination. In conclusion, U. europaeus demonstrates a strong spatial variability that facilitates its persistence and colonization across the altitudinal gradient in high-mountain ecosystems.