The Galápagos Islands are globally renowned both for their ecological value and as a world symbol of scientific discovery; however this unique region currently exhibits some of the highest extinction rates in the world. One of the greatest ecological threats is the detrimental impact of non-native plant species introduced since European contact almost 500 years ago. Baseline data regarding the timing of introduction and impact of the introduced species need to be determined in order to provide appropriate conservation programs. To date there are more than 800 introduced plant species on the Islands, however the historical impact on the native flora is unknown. There are also 62 species of vascular plants that have been classified as ‘doubtful natives’, species for which the arrival method and native status remains unclear. This research combines the analysis of plant macrofossils and testate amoeba in sedimentary records to help address the questions regarding the ‘doubtful natives’, previous vegetation dynamics, and human impact on highland ecosystems over the past 500-1000 years.
Results/Conclusions
While paleoecological proxies are a novel approach for restoration and field conservation the preliminary findings reveal that several of the species which were once considered ‘doubtful natives’ are in truth native to the islands. To date the macrofossil work has found four species, Ageratum conyzoides, Brickellia diffusa, Solanum americanum, and Hibiscus diversifolius (classified as an invasive habitat transformer) to be native to the islands. All of these species were present over 1000 years prior to human arrival, which provides clear evidence of the plants’ native status. In addition to the ‘doubtful native’ findings, seeds have been discovered from an aquatic species (family Elatinaceae genus Elatine) previously unknown in Galápagos in the fossil record. Current work is exploring the exact time of disappearance from the islands and the previous distribution of the Elatine sp. on two of the main islands, Santa Cruz and San Cristobal. The findings of this study combine long-term historical data with modern data to provide an ecological baseline – information that is fundamental to the conservation and restoration of native biodiversity on the Galápagos Islands.
