Tree species distribution comparisons across latitudinal gradients on the Pacific coasts of North and South America under climate change

Dr Taryn Fuentes-Castillo¹, Mr. Matthew Kling², Dr. David Ackerly^2,3, Dr. Rosa Scherson⁴, Dr. Patricio Pliscoff^1,5

¹Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, ²Department of Integrative Biology, University of California Berkeley, Berkeley, United States, ³Jepson Herbarium, University of California Berkeley, Berkeley, United States, ⁴Departamento de Silvicultura, Facultad de Ciencias Forestales y de la Conservación de la Naturaleza, Universidad de Chile, Santiago, Chile, ⁵Instituto de Geografía, Facultad de Historia, Geografía y Ciencia Política, Pontificia Universidad Católica de Chile, Santiago, Chile

The Pacific coastal regions of North and South America exhibit remarkably similar gradients of climate and vegetation across both a subtropical to boreal latitudinal gradient and a steep coastal to montane elevation gradient, inviting comparisons between the biogeographic patterns that have developed independently on these parallel geophysical stages. A correspondence analysis of climate and species distribution of these Northern Hemisphere (NH) and Southern Hemisphere (SH) counterparts has never been explored simultaneously. Following these similar geographical settings, it could be expected that climate change will produce similar responses in distribution changes in both areas.

We analysed the projected distribution of native tree species in each of these two Pacific rim vegetation zones. As a first step, we compared spatial climate patterns and evaluated the spatial correspondence between vegetation formations in NH and SH to find the most suitable bioclimatic variables for species distribution modelling in both areas. Finally, we compared current and projected future distributions of native tree species.

Our results showed a similar bioclimatic spatial pattern across the two regions; these findings are reflected into a geographic correspondence of climatic units. We found an upward elevational displacement of tree species in SA but a downwards displacement in NA as the most frequent response. Finally, we identified a displacement of tree distributions from central zones of NA & SA toward poleward latitudes. These results point out important conservation issues, with the highest future tree diversity losses projected within two highly-threatened biodiversity hotspots (California Floristic Province and Chile winter rainfall-Valdivian forests).

Biography:

Taryn Fuentes-Castillo is a Post-doctoral researcher at the Department of Ecology, Catholic University of Chile. She currently works on the evaluation of spatial patterns of biodiversity using measures such as phylogenetic diversity and species richness, and estimating their behavior in global change scenarios for the flora of two highly endemic Mediterranean-type areas, Chile and California.