1 Finzi, A. C. et al. Coupled biochemical cycles: responses and feedbacks of coupled biogeochemical cycles to climate change. Examples from terrestrial ecosystems. Front. Ecol. Environ 9, 61–67 (2011)

2 McGill, W. B. & Cole, C. V. Comparative aspects of cycling organic C, N, S and P through soil organic matter. Geoderma 26, 267–286 (1981)

3 Peñuelas, J. et al. The human-induced imbalance between C, N and P in Earth’s life system. Glob. Change Biol. 18, 3–6 (2012)

4 Schlesinger, W. H. et al. Biological feedbacks in global desertification. Science 247, 1043–1048 (1990)

5 Vicente-Serrano, S. M. et al. Dryness is accelerating degradation of vulnerable shrublands in semiarid Mediterranean environments. Ecol. Monogr. 82, 407–428 (2012)

6 Austin, A. T. et al. Water pulses and biogeochemical cycles in arid and semiarid ecosystems. Oecologia 141, 221–235 (2004)

7 Schwinning, S. & Sala, O. E. Hierarchy of responses to resource pulses in arid and semi-arid ecosystems. Oecologia 141, 211–220 (2004)

8 Whitford, W. G. Ecology of Desert Systems (Academic, 2002)

9 Gao, X. J. & Giorgi, F. Increased aridity in the Mediterranean region under greenhouse gas forcing estimated from high resolution simulations with a regional climate model. Global Planet. Change 62, 195–209 (2008)

10 Feng, S. & Fu, Q. Expansion of global drylands under a warming climate. Atmos. Chem. Phys. Discuss. 13, 14637–14665 (2013)

11 Dai, A. Increasing drought under global warming in observations and models. Nature Clim. Change 3, 52–58 (2013)

12 Schlesinger, W. H. Biogeochemistry, an Analysis of Global Change (Academic, 1996)

13 Walker, T. W. & Syers, J. K. The fate of phosphorus during pedogenesis. Geoderma 15, 1–19 (1976)

14 Vitousek, P. M. Nutrient Cycling and Limitation: Hawai’i as a Model System (Princeton Univ. Press, 2004)

15 Nannipieri, P. et al. Phosphorus in Action (Soil Biol. 26, Springer, 2011)

16 Liebig, J. et al. Chemistry in its Application to Agriculture and Physiology 3rd edn (Owen, 1842)

17 Reynolds, J. F. et al. Global desertification: building a science for dryland development. Science 316, 847–851 (2007)

18 Schimel, D. S. Drylands in the Earth system. Science 327, 418–419 (2010)

19 Maestre, F. T. et al. It’s getting hotter in here: determining and projecting the impacts of global environmental change on drylands. Phil. Trans. R. Soc. B 367, 3062–3075 (2012)

20 Cross, A. F. & Schlesinger, W. H. Biological and geochemical controls on phosphorus fractions in semiarid soils. Biogeochemistry 52, 155–172 (2001)

21 Li, J. et al. Quantitative effects of vegetation cover on wind erosion and soil nutrient loss in a desert grassland of southern New Mexico, USA. Biogeochemistry 85, 317–332 (2007)

22 Sinsabaugh, R. L. et al. Enzymes in the Environment (Oxford Univ. Press, 2002)

23 Olander, L. P. & Vitousek, P. M. Regulation of soil phosphatase and chitinase activity by N and P availability. Biogeochemistry 49, 175–191 (2000)

24 Schimel, J. P. & Bennett, J. Nitrogen mineralization, challenges of a changing paradigm. Ecology 85, 591–602 (2004)

25 Evans, S. E. & Burke, I. C. carbon and nitrogen decoupling under an 11-year drought in the shortgrass steppe. Ecosystems (N. Y.) 16, 20–33 (2013)

26 Thornton, P. E. et al. Influence of carbon–nitrogen cycle coupling on land model response to CO2 fertilization and climate variability. Glob. Biogeochem. Cycles 21, GB4018 (2007)

27 Scheffer, M. et al. Early-warning signals for critical transitions. Nature 461, 53–59 (2009)

28 Maestre, F. T. et al. Plant species richness and ecosystem multifunctionality in global drylands. Science 335, 214–218 (2012)

29 Hijmans, R. J. et al. Very high resolution interpolated climate surfaces for global areas. Int. J. Clim. 25, 1965–1978 (2005)

30 Grace, J. B. Structural Equation Modelling Natural Systems (Cambridge Univ. Press, 2006)

31 Robertson, G. P. & Groffman, P. Soil Microbiology and Biochemistry (Springer, 2007)

32 Rovira, P. & Vallejo, V. R. Labile and recalcitrant pools of carbon and nitrogen in organic matter decomposing at different depths in soil: an acid hydrolysis approach. Geoderma 107, 109–141 (2002)

33 Neff, J. C. et al. Breaks in the cycle: dissolved organic nitrogen in terrestrial ecosystems. Front. Ecol. Environ 1, 205–211 (2003)

34 Sardans, J. et al. The C:N:P stoichiometry of organisms and ecosystems in a changing world: a review and perspectives. Perspect. Plant Ecol. Evol. Syst. 14, 33–47 (2012)

35 Chantigny, M. H. et al. Soil Sampling and Methods of Analysis (CRC, 2006)

36 Bray, R. H. & Kurtz, L. T. Determination of total, organic, and available forms of phosphorus in soils. Soil Sci. 59, 39–46 (1945)

37 Olsen, S. R. et al. Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circ. 939, (1954)

38 Tiessen, H. & Moir, J. O. Characterization of Available P by Sequential Fractionation. Soil Sampling and Methods of Analysis (Lewis, 1993)

39 Carreira, J. A. et al. Phosphorus transformations along a soil/vegetation series of fire-prone, dolomitic, semi-arid shrublands of southern Spain. Biogeochemistry 39, 87–120 (1997)

40 Schoenau, J. J. et al. Forms and cycling of phosphorus in prairie and boreal forest soils. Biogeochemistry 8, 223–237 (1989)

41 Bowman, R. A. & Cole, C. V. Transformations of organic phosphorus substrates in soils as evaluated by NaHCO3 extractions. Soil Sci. 125, 49–54 (1978)

42 Cross, A. F. & Schlesinger, W. H. A literature review and evaluation of the Hedley fractionation: applications to the biogeochemical cycle of soil phosphorus in natural ecosystems. Geoderma 64, 197–214 (1995)

43 Lajtha, K. & Bloomer, S. H. Factors affecting phosphate sorption and phosphate retention in a desert ecosystem. Soil Sci. 146, 160–167 (1988)

44 Roberts, T. L. et al. The influence of topography on the distribution of organic and inorganic soil phosphorus across a narrow environmental gradient. Can. J. Soil Sci. 65, 651–665 (1985)

45 Anderson, J. M. & Ingramm, J. S. I. Tropical Soil Biology and Fertility: A Handbook of Methods 2nd edn (CABI, 1993)

46 Tabatabai, M. A. & Bremner, J. M. Use of p-nitrophenyl phosphate for assay of soil phosphatase activity. Soil Biol. Biochem. 1, 301–307 (1969)

47 Delgado-Baquerizo, M. et al. A dissolved organic nitrogen in Mediterranean ecosystems. Pedosphere 21, 309–318 (2011)

48 Helmut, G. The Causes and Progression of Desertification (Ashgate, 2005)

49 Michael, B. et al. Human Impact on Environment and Sustainable Development in Africa (Ashgate, 2003)

50 Johnson, P. J. Governing Global Desertification: Linking Environmental Degradation, Poverty and Participation (Ashgate, 2006)

51 Food and Agriculture Organization. Arid Zone Forestry: A Guide for Field Technicians Ch. I (Food and Agriculture Organization, 1989)

52 Vitousek, P. M. et al. Towards an ecological understanding of biological nitrogen fixation. Biogeochemistry 57, 1–45 (2002)

53 Maestre, F. T. et al. Potential of using facilitation by grasses to establish shrubs on a semiarid degraded steppe. Ecol. Appl. 11, 1641–1655 (2001)

54 Reynolds, J. F. et al. Impact of drought on desert shrubs: effects of seasonality and degree of resource island development. Ecol. Monogr. 69, 69–106 (1999)

55 Maestre, F. T. et al. Positive, negative and net effects in grass-shrub interactions in Mediterranean semiarid grasslands. Ecology 84, 3186–3197 (2003)

56 Eldridge, D. et al. Interactive effects of three ecosystem engineers on infiltration in a semi-arid Mediterranean grassland. Ecosystems (N. Y.) 13, 499–510 (2010)

57 Cerdà, A. The effect of patchy distribution of Stipa tenacissima L. on runoff and erosion. J. Arid Environ. 36, 37–51 (1997)

58 Cornelis, W. S. Dryland Ecohydrology (Springer, 2006)

59 Blanco, H. & Rattan, R. Principles of Soil Conservation and Management (Springer, 2010)

60 Yerima, P. K. et al. Introduction to Soil Science: Soils of the Tropics (Trafford, 2005)

61 Marshall, K. C. Clay mineralogy in relation to survival of soil bacteria. Annu. Rev. Phytopathol. 13, 357–373 (1975)

62 Stotzky, G. Activity, ecology, and population dynamics of microorganisms in soil. Rev. Microbiol. 2, 59–137 (1972)

63 Kandeler, E. Physiological and Biochemical Methods for Studying Soil Biota and Their Function. Soil Microbiology and Biochemistry (Springer, 2007)

64 Tietjen, T. & Wetzel, R. G. Extracellular enzyme-clay mineral complexes: enzyme adsorption, alteration of enzyme activity, and protection from photodegradation. Aquat. Ecol. 37, 331–339 (2003)

65 Sugiura, N. Further analysis of the data by Akaike’s information criterion and the finite corrections. Commun. Stat. Theor. M. A7, 13–26 (1978)

66 Zomer, R. J. et al. Carbon, Land and Water: a Global Analysis of the Hydrologic Dimensions of Climate Change Mitigation Through Afforestation/Reforestation. Research Report 101 (International Water Management Institute, 2006)

67 Schimel, D. S. et al. Climatic, edaphic, and biotic controls over storage and turnover of carbon in soils. Glob. Biogeochem. Cycles 8, 279–293 (1994)

68 Schmidt, M. W. I. et al. Persistence of soil organic matter as an ecosystem property. Nature 478, 49–56 (2011)

69 Oades, J. M. The retention of organic matter in soils. Biogeochemistry 5, 35–70 (1988)

70 Shipley, B. Cause and Correlation in Biology: a User’s Guide to Path Analysis Structural Equations and Causal Inference (Cambridge Univ. Press, 2001)

71 Morford, S. L. et al. Increased forest ecosystem carbon and nitrogen storage from nitrogen rich bedrock. Nature 477, 78–81 (2011)