Impacts of changing rainfall patterns on mycorrhizal status of a shrub from arid environments

Climate models predict for semi-arid Mediterranean regions a decline in mean annual rainfall as well as a seasonal re-distribution, leading to larger events separated by longer drought spells and increased winter rainfalls. These changes may affect arbuscular mycorrhizal fungi (AMF) and therefore have implications for terrestrial ecosystems. To assess these consequences we focused on AMF in semi-arid plant communities from SE Spain. We monitored root length colonization in Artemisia barrelieri, a shrub species endemic from the most arid systems in SE Spain, growing in plots subjected to different precipitation regimes according to scenarios predicted by the IPCC for this region. Our results showed that mycorrhizal associations responded to changing precipitation regimes. Specifically, vesicles decreased with decreasing annual precipitation and arbuscules increased with stronger seasonal drought but decreased with lower annual precipitation and other seasonal changes. It may then be expected that dryer conditions in arid ecosystems caused by climate change will alter arbuscular mycorrhizal interactions in different ways depending on the intensity of the drought, thereby influencing the dynamics of extant plant communities.

► Mycorrhizal associations responded to changing precipitation regimes.
► Vesicles decreased with decreasing annual precipitation.
► Arbuscules increased with longer seasonal drought.
► Mycorrhizal changes will affect plant performance and therefore community dynamics.