Plant-soil feedbacks and root responses of two Mediterranean oaks along a precipitation gradient
Plant-soil feedbacks (PSFs) have been shown to be relevant drivers of forest community dynamics. However, few studies have explored variation of PSFs along environmental gradients. In a framework of climate change, there is a great need to understand how interactions between plants and soil microbes respond along climatic gradients. Therefore, we compared PSFs along a precipitation gradient in Mediterranean oak forests and included trait responses. Following the Stress Gradient Hypothesis (SGH), we expected less negative or even positive PSFs in the physically harsh dry end of our gradient and more negative PSFs in the wettest end.
We grew Quercus ilex and Quercus suber acorns on soil inoculated with microbes sampled under adults of both species in six sites ranging in annual precipitation. After 4 months, we measured shoot biomass and allocation and morphological traits above and belowground.
We found negative PSFs for Q. ilex independent of precipitation, whereas for Q. suber PSFs ranged from positive in dry sites to negative in wet sites, in agreement with the SGH. The leaf allocation showed patterns similar to shoot biomass, but belowground allocation and morphological traits revealed responses which could not be detected aboveground.
We provide first evidence for context-dependent PSFs along a precipitation gradient. Moreover, we show that measuring root traits can help improve our understanding of climate-dependent PSFs. Such understanding helps to predict plant soil microbe interactions, and their role as drivers of plant community dynamics under ongoing climate change.
KeywordsPlant-soil interactions Root morphological traits Mediterranean oaks Drought Recruitment limitation Intraspecific trait variability Soil microbes
plant soil feedback
leaf mass fraction
root mass fraction
Specific leaf area
Specific root length
Root tissue density
We thank P. Ruiz-Benito and L. Matías for help with the NFI3 and field site selection. L. Matías and S. Soliveres for discussions, and three anonymous reviewers for useful comments on earlier versions of the manuscript. This study was supported by the Swiss National Science Foundation (SNSF) in the context of a mobility fellowship granted to G.R. (P2BEP3_162092). L.G.A. acknowledges support from the MICINN project INTERCAPA (CGL-2014-56739-R).
- Bates D, Maechler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J statistical Softw. 67:1. https://doi.org/10.18637/jss.v.067.i01
- Connell HJ (1971) On the role of natural enemies in preventing competitive exclusion in some marine animals and in rainforest trees. In: Dynamics of populations: proceedings of the advanced study institute on 'Dynamics and numbers in Populations' eds. Den Boer PJ and Gradwell GR Pudoc Oosterbeek, the, Netherlands, pp 298–312Google Scholar
- Gómez-Aparicio L, Domínguez-Begines J, Kardol P et al (2017) Plant-soil feedbacks in declining forests: implications for species coexistence. Ecology. https://doi.org/10.1002/ecy.1864
- Gribko LS, Jones WE (1995) Test of the float method of assessing northern red oak acorn condition. Tree Planters' Notes 46:143–147Google Scholar
- Lozano YM, Armas C, Hortal S, et al (2017) Disentangling above- and below- ground facilitation drivers in arid environments: the role of soil microorganisms, soil properties and microhabitat. New Phytol 216:1236–1246. https://doi.org/10.1111/nph.14499
- Mariotte P, Canarini A, Dijkstra FA (2017) Stoichiometric N: P flexibility and mycorrhizal symbiosis favor plant resistance against drought. J Ecol 105:958–967. https://doi.org/10.1111/1365-2745.12731
- Pérez-Ramos IM, Roumet C, Cruz P et al (2012) Evidence for a “plant community economics spectrum” driven by nutrient and water limitations in a Mediterranean rangeland of southern France. J Ecol 100:1315–1327. https://doi.org/10.1111/1365-2745.12000
- R Core Team (2016). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/
- Smith-Ramesh LM, Reynolds HL (2017) The next frontier of plant-soil feedback research: unraveling context dependence across biotic and abiotic gradients. J Veg Sci 28:484–494. https://doi.org/10.1111/jvs.12519
- Teste FP, Kardol P, Turner BL, et al (2017) Plant-soil feedback and the maintenance of diversity in Mediterranean-climate shrublands. Science 176:173–176. https://doi.org/10.1126/science.aai8291