Palaeoecological perspective on non-native vegetation on islands globally
2 BioInvasions, Global Change, Macroecology Group, Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
3 Bayreuth Center of Ecology and Environmental Research (BayCEER) & Bayreuth Center of Sport Science (BaySpo), University of Bayreuth, Bayreuth, Germany
4 6CREAF Center for Ecological Research and Forestry Applications, Barcelona, Spain
P 2.13 in Poster Session Friday (14:45-15:30)
Current human-mediated changes in island vegetation are caused among others by the introduction and spread of alien plant species. While current invasion statuses are well-known and insular biodiversity is continuously being monitored, a perspective on alien plant species abundance and the speed and magnitude of introductions predating historical documentation is largely missing. By matching fossil pollen data with status information of plants (i.e., non-native, native), we quantify the changes caused by alien plants on 29 islands globally during the last 5000 years. In general, alien plants have been present in many insular systems but started to increase massively only during the last 1000 years, without any signs of slowing down. Trajectories differ between single islands and are linked to idiosyncratic settlement histories. We show that palynological data can be used to obtain a historic perspective on the development of alien plant abundance on islands.
(a) Maximum (light red) and minimum (dark red) percentage of pollen of non‐native vegetation for the past 5000 calibrated years Before Present (cal. years BP). (b) Pollen of non‐native vegetation for the last 2000 cal. years BP, showing piecewise regression models of non‐native pollen in time with resulting break points at 575 (break point 1, bp1) and 102 (break point 2, bp2) cal. years BP. (c) Percentage of non‐native pollen correlates with the number of pollen taxa during each time step and (Pearson's r = 0.5, p < 0.001).