Climate change manipulations in drylands: A comparative approach for understanding future ecosystem functioning

Background/Question/Methods

Climatic controls on biogeochemical cycles and primary productivity are particularly relevant in drylands (arid, semi-arid and dry sub-humid ecosystems) considering that their biological activity is mainly driven by water availability. The structure and functioning of drylands are highly affected by rainfall patterns. Water availability in these environments is highly pulsed, and single rainfall events interspersed with drought periods are important components of the annual water supply. Dryland ecosystems do not only respond to rainfall quantity, but also to variations in time, so that relatively small changes in rainfall frequency (i.e., pulsed inputs) may have strong effects on communities. Within the Mediterranean basin, climate change models predict a decrease in mean annual rainfall and more extreme events along with higher temperatures and seasonal changes. However, little is known on the consequences of these future precipitation changes on communities structure, particularly in arid and semi-arid ecosystems. Here, I review and compare experiments that have manipulated rainfall amounts and patterns in arid and semi-arid regions worldwide, and introduce the results of a long-term rainfall manipulation experiment carried out along an aridity gradient in Israel.

Results/Conclusions

This work monitored the effect of rainfall manipulations on different ecosystem processes for 13 years, at the species and community level, concluding that these plant communities showed a great resilience to changes in rainfall, seemingly caused by high inherent spatial heterogeneity and plant adaptation to large intra- and inter-annual rainfall variability. Comparative approaches for studying experimental climate change research in drylands will be further discussed.