Drought changes the structure and elemental composition of very fine roots in seedlings of ten woody tree species. Implications for a drier climate
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Background and aims
Water availability is often one of the most limiting factors for plants. Climate change predictions for many areas suggest an intensification of water limitation. The ability of a plant to modify its root characteristics can be an important mechanism for preventing drought stress.
We studied the drought response of seedlings of 10 woody species and compared the biomass allocation, vertical root distribution across different root diameters, and the key traits of very fine roots (root diameter <0.5 mm) under two water regimes (no water limitation and severe drought).
Under drought conditions, the very fine roots had a higher specific root length (SRL, root length: biomass ratio), smaller root diameter and higher root tissue mass density, as well as a lower nitrogen concentration. A higher value of the mean root plasticity index was related to higher drought resistance. A quantitative literature review showed that there was a wide variation in the effect of the drought on SRL, thus there was not a clear effect of drought on SRL.
Certain species have the necessary root traits and plasticity to survive drought. We have identified plasticity in root characteristics as a whole-plant trait which plays a significant role in separating out species into those which are vulnerable and those which are resistant to drought.
KeywordsBiomass allocation Drought Plasticity Vertical root distribution Root traits Specific root length Survival
This study was supported by an FPI-MEC pre-doctoral fellowship awarded to BL (BES-2009-016985), the coordinated Spanish MEC projects INTERBOS (CGL2008-04503-CO3-02) and DIVERBOS (CGL2011-30285-C02-02), the ANASINQUE project (PGC2010-RNM-5782), the Life + Biodehesa Project (11/BIO/ES/000726) and FEDER funding. We thank the Consejería de Medio Ambiente (Junta de Andalucía, Spain) for providing the seedlings for this experiment. Mar Ávila and Daniel Sánchez helped in the experiment and Simón Cuadros let us use the WinRHIZO analysis equipment. Thanks to Enrique Garcia de la Riva and José Luis Quero for their comments aimed at improving the manuscript. Our research group is a member of the GLOBIMED network (http://www.globimed.net/).
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