Increased drought combined with extreme episodes of heatwaves is triggering severe impacts on vegetation growth, particularly for plant communities in arid and semiarid ecosystems. Although there is an abundance of short-term field drought experiments in natural ecosystems, remaining knowledge gaps limit the understanding and prediction of vegetation growth to ongoing and future climate scenarios. Here, we assessed the impacts of long-term (1999–2016) experimental drought (ca. −30% rainfall) on the vegetation growth of a Mediterranean high (H) and low (L)-canopy forests and an early-successional shrubland, as indicated by above-ground biomass increment (ABI) and standing density, respectively. We found habitat context (impact of historical climate change, soil depth and successional status) of the study sites significantly affected the magnitude of climate impacts; there were synergistic effects of experimental drought and meteorological drought (Standardised Precipitation–Evapotranspiration Index, SPEI) as well as extreme dry years on vegetation growth. Long-term experimental drought decreased the ABI for the two forest canopy types and the standing density for the shrubland. Water availabilities in winter–spring (SPEIs) were positively correlated with the ABI and standing density. Moreover, experimental drought decreased the vegetation growth in extreme dry years for the shrubland. We propose that future work not only study the vegetation dynamics with physiological, phenological and demographical changes in long-term processes and across climate gradients, but also should explore the changes of multiple functions simultaneously (e.g. multifunctionality) under long-term processes and extremes. This type of analysis of long-term data is essential to understand and predict biodiversity loss, composition shifts, declines in ecosystem function and carbon budgets at temporal and spatial scales, to enable policy makers to design and implement strategies for the maintenance of sustainable ecosystem function under future climate change scenarios.
Bibliographical noteFunding Information:
We thank the people who managed and maintained the long-term experiments and collected data. Funding for this research was provided by the Spanish government project CGL2016-79835-P, the Catalan government project SGR2017-1005, the European Research Council Synergy grant ERC-2013-SyG-610028 IMBALANCE-P and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 758873, TreeMort).
© 2020 International Association for Vegetation Science
- Mediterranean ecosystems
- above-ground biomass increment
- decadal drought experiment
- habitat context
- standing density
- vegetation growth
ASJC Scopus subject areas
- Plant Science