A large percentage of the highlands on San Cristobal is covered in blackberry (Rubus niveus) – an invasive species that has been described as “the worst weed in the Galápagos” and that is threatening native plant diversity and preventing the establishment of agriculture. LAVA Invasives aims to conduct scientific research about and for the agricultural sector to inform the reactivation of agricultural lands. The project is in its beginning phases, and the studies performed in summer 2019 provide the groundwork for its expansion and progression in the future.
For our investigation, we cleared areas that were heavily infested with blackberry in both sunny and shady conditions, as the blackberry is known to reproduce more rapidly in sunny conditions. Twelve square plots, each four square meters in area, were cleared and marked in both sun and shade for a total of 24 plots. Each plot was assigned randomly into four treatments, for a total of three replications of each treatment in both the sun and shade areas. For the first treatment option, we transplanted a nonnative grass species (Brachiaria decumbens). For the second treatment option, we transplanted native leatherleaf ferns (Rumohra adiantiformis), which are believed to fill a similar niche to the blackberry in the native ecosystem. For the third treatment option, we planted three familial bean seeds in nine holes within each plot, in the standard manner of agricultural use. The fourth treatment was a control, and nothing was planted in these plots.
Our initial measurements showed blackberry regrowth beginning about 10 days after clearing, with a greater number of sprouts in the sunny plots. As the months progress, we will measure the relative rates of blackberry regrowth in each plot and determine whether any of our proposed treatment options are effective at outcompeting the blackberry and reducing the infestation. Measurements will be taken at monthly to bimonthly intervals over the next year. We hope that the results from the study will inform the development of agricultural strategies to effectively clear and control the blackberry. This in turn will improve the efficiency and abundance of local agriculture, contributing to the community’s ability to locally and sustainably source their food.