Antarctic Peninsula biogeography is unique due to its extreme geographical isolation and pronounced latitudinal gradients. Mosses and lichens are the dominant macrophytes in the terrestrial Antarctic ecosystem, and research has highlighted the Peninsula’s vulnerability to accidental human-mediated introduction of both native and alien species. Tourism has increased exponentially since the late 1980s, and both tourists and wildlife are concentrated in the relatively tiny fraction of Antarctica that is coastal and ice-free in the summer. The aim of this work was to test biogeographic determinants of the richness of mosses and lichens on the Antarctic Peninsula, particularly on the scale of individual islands. Understanding the drivers of Antarctic biogeography is essential for tracking any future changes in these patterns and serves as a critical component in the effective management of this fragile ecosystem. We collected lichen and moss occurrence data from existing databases and used geographic information systems to analyse biodiversity patterns. We then analysed how island area, latitude, distance from potential source continents, years since glacial retreat and penguin colony size may affect species richness. We also considered the challenges of assessing patterns of biodiversity in the Antarctic stemming from poor and highly heterogeneous sampling.

Results/Conclusions

We observed significant heterogeneity among the islands regarding the number of surveys each received, amount of records collected, and number of species found. We found a positive correlation between species richness and the total ice-free area of the islands, as well as a significant relationship between richness and total penguin colony size. We also found that the northern portion of the Peninsula hosts more species than the southern portion. The minimum age of available land showed a possible limiting effect on species richness. Apparent floral richness also displayed a clear relationship with the number of sampling visits to each island, highlighting the challenges posed by sparse and heterogeneous sampling of the Antarctic region. Other factors considered, such as distance to South America or the Antarctic mainland, were not significantly correlated with island richness. Our work provides an analysis of individual islands that offers a unique perspective and complements existing data concerning the Antarctic Peninsula as a whole. Heterogeneous sampling presents a major hurdle to collecting accurate observations in the Antarctic Peninsula region, and our analyses have revealed the potential for this problem to result in misleading information on the importance of various biogeographic factors acting on the Antarctic Peninsula system.