PT  - JOURNAL ARTICLE
AU  - Sara Tomiolo
AU  - Mark C. Bilton
AU  - Katja Tielbörger
TI  - Whole plant community transplants across climates reveal total community stability due to large shifts in species assemblage
AID  - 10.1101/475046
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 475046
4099  - http://biorxiv.org/content/early/2018/11/22/475046.short
4100  - http://biorxiv.org/content/early/2018/11/22/475046.full
AB  - Climate change will decrease average precipitation and increase rainfall variability in Eastern Mediterranean regions. This may affect the performance of many plant species either directly or via altered biotic interactions in ways that are hard to predict. In such highly fluctuating climates, year-to-year community variation may override long-term selection processes, thus masking directional community responses to climate change.Here we tested short-term responses of dryland plant communities to sharp changes in climatic conditions, by means of whole community reciprocal transplants of soil and seed banks. We exposed annual plant communities to two very different climates (Mediterranean and semi-arid) and measured changes in community composition, total biomass, plant density, and species diversity. In addition, we grouped species into dry-adapted and wet-adapted species in each community.Our results revealed that climate played a large role in determining community assembly. For both community origins, we observed a relative increase of dry-adapted species when exposed to the drier climate, and a relative increase in wet-adapted species in the wetter climate. However, the compositional shifts were much larger in semi-arid origin communities. At the same time community density, biomass and species richness remained remarkably stable across climates, indicating that community stability was maintained between climates by predictable asynchronous shifts of species. Similar but smaller shifts were present in the Mediterranean origin communities, where exposure to the drier climate reduced biomass and species richness.Our study suggests that large asynchronous variation in species abundances, matching high year-to-year rainfall variability, may provide a mechanism for community homeostasis, and slow down selection processes in response to climate change. However, increased occurrence of extreme droughts exceeding the climatic fluctuations to which species are adapted may, in the long-term, lead to loss of wet-adapted species.