Supporting Information Notes S1 and Table S3 & S4 Notes S1 List of all the references used in the meta-analysis. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Alvarez M, Huygens D, Olivares E, Saavedra I, Alberdi M, Valenzuela E. 2009. Ectomycorrhizal fungi enhance nitrogen and phosphorus nutrition of Nothofagus dombeyi under drought conditions by regulating assimilative enzyme activities. Physiologia Plantarum 136(4): 426-436. Asensio D, Rapparini F, Peñuelas J. 2012. AM fungi root colonization increases the production of essential isoprenoids vs. nonessential isoprenoids especially under drought stress conditions or after jasmonic acid application. Phytochemistry 77: 149-161. Ashraf M, Shabaz M, Ashraf MY. 2001. Influence of nitrogen supply and water stress on growth and nitrogen, phosphorus, potassium and calcium contents in pearl millet. Biologia Plantarum 44(3): 459-462. Ayub G, Smith RA, Tissue DT, Atkin OK. 2011. Impacts of drought on leaf respiration in darkness and light in Eucalyptus saligna exposed to industrial-age atmospheric CO2 and growth temperature. New Phytologist 190(4): 1003-1018. Corell M, Garcia MC, Contreras JI, Segura ML, Cermeño P. 2012. Effect of water stress on Salvia officinalis L. bioproductivity and its bioelement concentrations. Communications in Soil Science and Plant Analysis 43(1-2): 419-425. Danielsen L, Polle A. 2014. Poplar nutrition under drought as affected by ectomycorrhizal colonization. Environmental and Experimental Botany: doi: 10.1016/j.envexpbot.2014.01.006. Ghanbari A, Siahsar B, Tavassoli A, Esmaeilian Y, Babaeian M. 2011. Effects of uniconazole and cycocel on growth, yield and nutrients uptake of pearl millet under drought stress condition. American-Eurasian J. Agric. & Environ. Sci. 10(5): 857-862. Gholamhoseini M, Ghalavand A, Dolatabadian A, Jamshidi E, Khodaei-Joghan A. 2013. Effects of arbuscular mycorrhizal inoculation on growth, yield, nutrient uptake and irrigation water productivity of sunflowers grown under drought stress. Agricultural Water Management 117: 106-114. Harvey HP, van den Driessche R. 1999. Poplar nutrient resorption in fall or drought: influence of nutrient status and clone. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere 29(12): 1916-1925. Hu YC, Burucs Z, Schmidhalter U. 2006. Short-term effect of drought and salinity on growth and mineral elements in wheat seedlings. Journal of Plant Nutrition 29(12): 2227-2243. Inclán R, Gimeno BS, Dizengremel P, Sanchez M. 2005. Compensation processes of Aleppo pine (Pinus halepensis Mill.) to ozone exposure and drought stress. Environmental Pollution 137(3): 517-524. Jin J, Wang GH, Liu XB, Pan XW, Herbert SJ, Tang CX. 2006. Interaction between phosphorus nutrition and drought on grain yield, and assimilation of phosphorus and nitrogen in two soybean cultivars differing in protein concentration in grains. Journal of Plant Nutrition 29(8): 1433-1449. Krizek DT, Carmi A, Mirecki RM, Snyder FW, Bunce JA. 1985. Comparative Effects of Soil-Moisture Stress and Restricted Root Zone Volume on Morphogenetic and Physiological-Responses of Soybean [Glycine-Max (L.) Merr.]. Journal of Experimental Botany 36(162): 25-38. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. Lee BR, Muneer S, Avice JC, Jung WJ, Kim TH. 2012. Mycorrhizal colonisation and P-supplement effects on N uptake and N assimilation in perennial ryegrass under well-watered and drought-stressed conditions. Mycorrhiza 22(7): 525-534. Mahouachi J. 2009. Changes in nutrient concentrations and leaf gas exchange parameters in banana plantlets under gradual soil moisture depletion. Scientia Horticulturae 120(4): 460-466. Peuke AD, Rennenberg H. 2004. Carbon, nitrogen, phosphorus, and sulphur concentration and partitioning in beech ecotypes (Fagus sylvatica L.): phosphorus most affected by drought. Trees 18(6): 639-648. Sánchez-Rodríguez E, Rubio-Wilhelmi MDM, Cervilla LM, Blasco B, Rios JJ, Leyva R, Romero L, Ruiz JM. 2010. Study of the ionome and uptake fluxes in cherry tomato plants under moderate water stress conditions. Plant and Soil 335(1-2): 339-347. Sardans J, Rivas-Ubach A, Estiarte M, Ogaya R, Peñuelas J. 2013. Fieldsimulated droughts affect elemental leaf stoichiometry in Mediterranean forests and shrublands. Acta Oecologica-International Journal of Ecology 50: 20-31. Song CJ, Ma KM, Qu LY, Liu Y, Xu XL, Fu BJ, Zhong JF. 2010. Interactive effects of water, nitrogen and phosphorus on the growth, biomass partitioning and wateruse efficiency of Bauhinia faberi seedlings. Journal of Arid Environments 74(9): 1003-1012. Tobita H, Uemura A, Kitao M, Kitaoka S, Utsugi H. 2010. Interactive effects of elevated CO2, phosphorus deficiency, and soil drought on nodulation and nitrogenase activity in Alnus hirsuta and Alnus maximowiczii. Symbiosis 50(1-2): 59-69. Turtola S, Manninen AM, Rikala R, Kainulainen P. 2003. Drought stress alters the concentration of wood terpenoids in Scots pine and Norway spruce seedlings. Journal of Chemical Ecology 29(9): 1981-1995. Xia MZ. 1997. Effects of soil drought during the generative development phase on seed yield and nutrient uptake of faba bean (Vicia faba). Australian Journal of Agricultural Research 48(4): 447-451. Yarie J, VanCleve K. 1996. Effects of carbon, fertilizer, and drought on foliar chemistry of tree species in interior Alaska. Ecological Applications 6(3): 815-827. Zhang J, C. YY, Streeter JG, Ferree DC. 2010. Influence of soil drought stress on photosynthesis, carbohydrates and the nitrogen and phophorus absorb in different section of leaves and stem of Fugi/M.9EML, a young apple seedling. African Journal of Biotechnology 9(33): 5320-5325. Zhang LH, Shao HB, Ye GF, Lin YM. 2012. Effects of fertilization and drought stress on tannin biosynthesis of Casuarina equisetifolia seedlings branchlets. Acta Physiologiae Plantarum 34(5): 1639-1649. Wood TE, Silver WL. 2012. Strong spatial variability in trace gasdynamics following experimental drought in a humid tropical forest. Global Biogeochemical Cycles 26: GB3005, doi:3010.1029/2010GB004014. Matías L, Castro J, Zamora R. 2011. Soil-nutrient availability under a globalchange scenario in a Mediterranean mountain ecosystem. Global Change Biology 17(4): 1646-1657. Yahdjian L, Sala O, Austin AT. 2006. Differential controls of water input on litter decomposition and nitrogen dynamics in the Patagonian steppe. Ecosystems 9(1): 128-141. Table S3 Summary of results from the meta-analyses on plant [N], [P] and N : P by using the complete dataset (n = 155) and by using one random observation per study (n = 25). Effect sizes (LogeR) are shown in bold when 95% bootstrapped intervals (95% CI) did not overlap with zero. Dataset Nutrient n LogeR (%) 95% CI Max -1.00 1.61 Complete dataset One random observation per study N 155 25 -3.73 -5.07 Min -6.45 -11.49 Complete dataset One random observation per study P 155 25 -9.18 -9.26 -13.38 -19.07 -4.72 3.37 Complete dataset One random observation per study N:P 155 25 6.98 6.78 2.13 -3.52 12.23 17.62 Table S4 Summary of results from the meta-analyses on plant [N], [P] and N : P. Effect sizes (LnR) are shown in bold when 95% bootstrapped intervals (95% CI) did not overlap with zero. Differences among functional group type, N-fixation and experiment categories are indicated by Qbetween and Prandom. Nutrient Category Group n LogeR (%) Plant [N] Functional group type tree shrub grass 80 7 67 -1.01 -4.67 -6.77 N-fixation No Yes Experiment Plant [P] 95% CI Min Max -4.72 2.82 -18.18 11.06 -10.60 -2.78 Qbetween Prandom 4.47 0.13 122 -5.06 32 1.25 -8.08 -5.00 -1.95 7.90 3.34 0.07 Pot Field 107 -1.78 47 -8.36 -5.01 -13.10 1.54 -3.36 4.90 0.03 Functional type tree shrub grass 81 7 67 -10.27 -10.61 -7.80 -15.54 -29.44 -13.51 -4.68 13.24 -1.72 0.41 0.85 N-fixation No Yes 122 -10.18 32 -5.17 -14.34 -13.88 -5.82 4.41 1.05 0.37 Experiment Pot Field 107 -9.52 47 -8.42 -14.04 -15.27 -4.76 -1.02 0.07 0.82 Plant N : P Functional type tree shrub grass 81 7 67 N-fixation No Yes Experiment Pot Field 10.80 5.79 2.90 3.54 -18.96 -4.32 18.59 38.11 10.67 2.21 0.32 123 6.15 32 10.21 0.64 -0.99 11.96 22.67 0.40 0.52 107 10.45 47 -0.53 4.54 -8.60 16.70 8.24 4.33 0.04