Vegetation trends over eleven years on mountain summits in NW Argentina

CARILLA, JULIETA; HALLOY, STEPHAN; CUELLO, SOLEDAD; GRAU, ALFREDO; CUESTA C., FRANCISCO; MALIZIA, AGUSTINA

Quito

Congreso; Segundo Congreso Latinoamericano de Biogeografia; 2019

International Biogeography Society

Alpine plant communities are expected to move upward following their climatic niche, as climate change leads to warmer and dryer conditions in the central Andes. Species range shifts are predicted to have major impacts on alpine communities by reshuffling species composition and abundances. Using a standardized protocol, we surveyed alpine plant communities in permanent plots on four high Andean summits in NW Argentina, which range from 4040 to 4740 m a.s.l; surveys were done in 2006-2008, in 2012, and in 2017. We found a significant decrease in plant cover, species richness and diversity across the elevation gradient in the three censuses, and a strongly decrease in soil temperature along the elevation gradient. We found a high plant community turnover (37-49%) among censuses, higher in the lowest summit (49%) and on the northern (47%) and western (46%) aspects. Temporal patterns in community changes were represented by increases in plant cover in the highest summit, in species richness in the lower summit, and in diversity (Shannon index) in the four summits, over time. We suggest that the observed trend in plant community dynamics responds to short term temperature and precipitation variability, which is influenced by El Niño Southern oscillation (ENSO), and due to time-lags in plant community response, it may take much longer than one decade for the observed trends to become stables and statistically significant. Our study provides an important foundation for documenting more profound changes in these subtropical alpine plant communities as global climate change continues.