Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Widespread woody plant use of water stored in bedrock

Nature volume 597, pages 225–229 (2021)Cite this article

Subjects

Abstract

In the past several decades, field studies have shown that woody plants can access substantial volumes of water from the pores and fractures of bedrock1,2,3. If, like soil moisture, bedrock water storage serves as an important source of plant-available water, then conceptual paradigms regarding water and carbon cycling may need to be revised to incorporate bedrock properties and processes4,5,6. Here we present a lower-bound estimate of the contribution of bedrock water storage to transpiration across the continental United States using distributed, publicly available datasets. Temporal and spatial patterns of bedrock water use across the continental United States indicate that woody plants extensively access bedrock water for transpiration. Plants across diverse climates and biomes access bedrock water routinely and not just during extreme drought conditions. On an annual basis in California, the volumes of bedrock water transpiration exceed the volumes of water stored in human-made reservoirs, and woody vegetation that accesses bedrock water accounts for over 50% of the aboveground carbon stocks in the state. Our findings indicate that plants commonly access rock moisture, as opposed to groundwater, from bedrock and that, like soil moisture, rock moisture is a critical component of terrestrial water and carbon cycling.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Over 45% of the wooded land area across the CONUS is underlain by shallow (<1.5 m deep) bedrock.
Fig. 2: Bedrock water use by woody plants is spatially extensive and can be routine.
Fig. 3: Magnitude of bedrock water contribution to ET across Texas, California and field studies.
Fig. 4: Bedrock hosts a large fraction of root-zone water storage capacity.

Similar content being viewed by others

Data availability

All of the datasets generated in this study are available in the Hydroshare repository at https://doi.org/10.4211/hs.a2f0d5fd10f14cd189a3465f72cba6f351. The precipitation data are available from the PRISM Climate Group56 at https://prism.oregonstate.edu/. The evapotranspiration data are available from Penman–Monteith–Leuning Evapotranspiration V2 (PML_V2)58 at https://github.com/gee-hydro/gee_PML. The snow cover data are available from NASA’s MODIS/Terra Snow Cover Daily64 at https://nsidc.org/data/MOD10A1/versions/6. The soil data are available from the USDA’s gNATSGO41 database at https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcseprd1464625 and in the Hydroshare repository. The landcover data are available from the USGS’s National Land Cover Database40 at https://www.usgs.gov/centers/eros/science/national-land-cover-database?qt-science_center_objects=0#qt-science_center_objects. The biome data are available from NASA’s MODIS/Terra+Aqua Land Cover Type Yearly65 at https://lpdaac.usgs.gov/products/mcd12q1v006/. The Köppen66 climate data are available at https://people.eng.unimelb.edu.au/mpeel/koppen.html. The above ground biomass19 data are available at https://daac.ornl.gov/VEGETATION/guides/Global_Maps_C_Density_2010.html. With the exception of the gNATSGO and aboveground biomass data, all of the raster datasets are accessible via Google Earth Engine62. Google Earth Engine access URLs can be found in the code accompanying this study (see Code Part 2, Section 1). Source data are provided with this paper.

Code availability

Codes are available from https://github.com/erica-mccormick/widespread-bedrock-water-use or https://doi.org/10.5281/zenodo.4904036.

References

  1. Schwinning, S. The ecohydrology of roots in rocks. Ecohydrology 3, 238–245 (2010).

    Google Scholar 

  2. Rose, K., Graham, R. & Parker, D. Water source utilization by Pinus jeffreyi and Arctostaphylos patula on thin soils over bedrock. Oecologia 134, 46–54 (2003).

    Article  CAS  PubMed  ADS  Google Scholar 

  3. Rempe, D. M. & Dietrich, W. E. Direct observations of rock moisture, a hidden component of the hydrologic cycle. Proc. Natl Acad. Sci. USA 115, 2664–2669 (2018).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  4. Schwinning, S. A critical question for the critical zone: how do plants use rock water? Plant Soil 454, 49–56 (2020).

    Article  CAS  Google Scholar 

  5. Fan, Y. et al. Hillslope hydrology in global change research and Earth system modeling. Wat. Resour. Res. 55, 1737–1772 (2019).

    Article  ADS  Google Scholar 

  6. Brantley, S. L. et al. Reviews and syntheses: on the roles trees play in building and plumbing the critical zone. Biogeosciences 14, 5115–5142 (2017).

    Article  CAS  ADS  Google Scholar 

  7. Chaney, N. W. et al. POLARIS soil properties: 30-m probabilistic maps of soil properties over the contiguous United States. Wat. Resour. Res. 55, 2916–2938 (2019).

    Article  ADS  Google Scholar 

  8. Uhlig, D., Schuessler, J. A., Bouchez, J., Dixon, J. L. & Blanckenburg, F. V. Quantifying nutrient uptake as driver of rock weathering in forest ecosystems by magnesium stable isotopes. Biogeosciences 14, 3111–3128 (2017).

    Article  CAS  ADS  Google Scholar 

  9. Wald, J. A., Graham, R. C. & Schoeneberger, P. J. Distribution and properties of soft weathered bedrock at 1 m depth in the contiguous United States. Earth Surf. Process. Landf. 38, 614–626 (2013).

    Article  ADS  Google Scholar 

  10. Nimmo, J. R., Creasey, K. M., Perkins, K. S. & Mirus, B. B. Preferential flow, diffuse flow, and perching in an interbedded fractured-rock unsaturated zone. Hydrogeol. J. 25, 421–444 (2017).

    Article  CAS  ADS  Google Scholar 

  11. Leshem, B. Resting roots of Pinus halepensis: structure, function, and reaction to water stress. Bot. Gaz. 131, 99–104 (1970).

    Article  Google Scholar 

  12. Hahm, W. J. et al. Low subsurface water storage capacity relative to annual rainfall decouples Mediterranean plant productivity and water use from rainfall variability. Geophys. Res. Lett. 46, 6544–6553 (2019).

    Article  ADS  Google Scholar 

  13. Hahm, W. J. et al. Lithologically controlled subsurface critical zone thickness and water storage capacity determine regional plant community composition. Wat. Resour. Res. 55, 3028–3055 (2019).

    Article  ADS  Google Scholar 

  14. Eggemeyer, K. D. & Schwinning, S. Biogeography of woody encroachment: why is mesquite excluded from shallow soils? Ecohydrology 2, 81–87 (2009).

    Article  CAS  Google Scholar 

  15. Madakumbura, G. D. et al. Recent California tree mortality portends future increase in drought-driven forest die-off. Environ. Res. Lett. 15, 124040 (2020).

    Article  ADS  Google Scholar 

  16. McDowell, N. G. et al. Mechanisms of a coniferous woodland persistence under drought and heat. Environ. Res. Lett. 14, 045014 (2019).

    Article  CAS  ADS  Google Scholar 

  17. McEvoy, D. J., Pierce, D. W., Kalansky, J. F., Cayan, D. R. & Abatzoglou, J. T. Projected changes in reference evapotranspiration in California and Nevada: implications for drought and wildland fire danger. Earths Future 8, e2020EF001736 (2020).

    Article  ADS  Google Scholar 

  18. Hauwert, N. M. & Sharp, J. M. Measuring autogenic recharge over a karst aquifer utilizing eddy covariance evapotranspiration. J. Water Resour. Prot. 6, 869–879 (2014).

    Article  Google Scholar 

  19. Spawn, S. A., Sullivan, C. C., Lark, T. J. & Gibbs, H. K. Harmonized global maps of above and belowground biomass carbon density in the year 2010. Sci. Data 7, 112 (2020).

    Article  PubMed  PubMed Central  Google Scholar 

  20. Goulden, M. L. & Bales, R. C. California forest die-off linked to multi-year deep soil drying in 2012–2015 drought. Nat. Geosci. 12, 632–637 (2019).

    Article  CAS  Google Scholar 

  21. Hahm, W. J. et al. Oak transpiration drawn from the weathered bedrock vadose zone in the summer dry season. Wat. Resour. Res. 56, e2020WR027419 (2020).

    Article  ADS  Google Scholar 

  22. Cannon, W. A. The Root Habits of Desert Plants 131 (Carnegie Institute of Washington, 1911).

  23. Daily reservoir storage summary. California Department of Water Resources https://info.water.ca.gov/cgi-progs/reservoirs/RES (2020).

  24. USGS water use data for California. United States Geological Society https://waterdata.usgs.gov/ca/nwis/water_use/ (2020).

  25. David, T., Ferreira, M., Cohen, S., Pereira, J. & David, J. Constraints on transpiration from an evergreen oak tree in southern Portugal. Agric. For. Meteorol. 122, 193–205 (2004).

    Article  ADS  Google Scholar 

  26. Querejeta, J. I., Estrada-Medina, H., Allen, M. F. & Jimenez-Osornio, J. J. Water source partitioning among trees growing on shallow karst soils in a seasonally dry tropical climate. Oecologia 152, 26–36 (2007).

    Article  PubMed  ADS  Google Scholar 

  27. Carrière, S. D. et al. The role of deep vadose zone water in tree transpiration during drought periods in karst settings—insights from isotopic tracing and leaf water potential. Sci. Total Environ. 699, 134332 (2020).

    Article  CAS  Google Scholar 

  28. Rambal, S. Water balance and pattern of root water uptake by a Quercus coccifera L. evergreen scrub. Oecologia 62, 18–25 (1984).

    Article  CAS  PubMed  ADS  Google Scholar 

  29. Montaldo, N. et al. Rock water as a key resource for patchy ecosystems on shallow soils: digging deep tree clumps subsidize surrounding surficial grass. Earths Future 9, e2020EF001870 (2021).

    Article  ADS  Google Scholar 

  30. Corona, R. & Montaldo, N. On the transpiration of wild olives under water-limited conditions in a heterogeneous ecosystem with shallow soil over fractured rock. J. Hydrol. Hydromech. 68, 338–350 (2020).

    Article  Google Scholar 

  31. Nardini, A. et al. Water ‘on the rocks’: a summer drink for thirsty trees? New Phytol. 229, 199–212 (2021).

    Article  PubMed  Google Scholar 

  32. Ruiz, L. et al. Water balance modelling in a tropical watershed under deciduous forest (Mule Hole, India): regolith matric storage buffers the groundwater recharge process. J. Hydrol. 380, 460–472 (2010).

    Article  ADS  Google Scholar 

  33. Ding, Y., Nie, Y., Chen, H., Wang, K. & Querejeta, J. I. Water uptake depth is coordinated with leaf water potential, water-use efficiency and drought vulnerability in karst vegetation. New Phytol. 229, 1339–1353 (2021).

    Article  CAS  PubMed  Google Scholar 

  34. Dawson, T. E., Hahm, W. J. & Crutchfield-Peters, K. Digging deeper: what the critical zone perspective adds to the study of plant ecophysiology. New Phytol. 226, 666–671 (2020).

    Article  PubMed  Google Scholar 

  35. Salve, R., Rempe, D. M. & Dietrich, W. E. Rain, rock moisture dynamics, and the rapid response of perched groundwater in weathered, fractured argillite underlying a steep hillslope. Wat. Resour. Res. 48, W11528 (2012).

    Article  ADS  Google Scholar 

  36. Harsch, M. A., Hulme, P. E., McGlone, M. S. & Duncan, R. P. Are treelines advancing? A global meta-analysis of treeline response to climate warming. Ecol. Lett. 12, 1040–1049 (2009).

    Article  PubMed  Google Scholar 

  37. Kapnick, S. & Hall, A. Causes of recent changes in western North American snowpack. Clim. Dyn. 38, 1885–1899 (2012).

    Article  Google Scholar 

  38. Tune, A. K., Druhan, J. L., Wang, J., Bennett, P. C. & Rempe, D. M. Carbon dioxide production in bedrock beneath soils substantially contributes to forest carbon cycling. J. Geophys. Res. Biogeosci. 125, e2020JG005795 (2020).

    Article  CAS  ADS  Google Scholar 

  39. Hasenmueller, E. A. et al. Weathering of rock to regolith: the activity of deep roots in bedrock fractures. Geoderma 300, 11–31 (2017).

    Article  CAS  ADS  Google Scholar 

  40. Yang, L. et al. A new generation of the United States National Land Cover Database: requirements, research priorities, design, and implementation strategies. ISPRS J. Photogramm. Remote Sens. 146, 108–123 (2018).

  41. Soil Survey Staff Gridded National Soil Survey Geographic (gNATSGO) Database for the Conterminous United States (USDA, 2019); https://nrcs.app.box.com/v/soils

  42. QGIS Development Team QGIS Geographic Information System (Open Source Geospatial Foundation, 2019); http://qgis.org

  43. O’Geen, A. T. et al. Southern Sierra Critical Zone Observatory and Kings River Experimental Watersheds: a synthesis of measurements, new insights, and future directions. Vadose Zone J. 17, 180081 (2018).

    Article  CAS  Google Scholar 

  44. Anderson, M. A., Graham, R. C., Alyanakian, G. J. & Martynn, D. Z. Late summer water status of soils and weathered bedrock in a giant sequoia grove. Soil Sci. 160, 415–422 (1995).

    Article  CAS  ADS  Google Scholar 

  45. Hubbert, K. R., Graham, R. C. & Anderson, M. A. Soil and weathered bedrock: components of a Jeffrey pine plantation substrate. Soil Sci. Soc. Am. J. 65, 1255–1262 (2001).

    Article  CAS  ADS  Google Scholar 

  46. Bornyasz, M., Graham, R. & Allen, M. Ectomycorrhizae in a soil-weathered granitic bedrock regolith: linking matrix resources to plants. Geoderma 126, 141–160 (2005).

    Article  ADS  Google Scholar 

  47. Sternberg, P., Anderson, M., Graham, R., Beyers, J. & Tice, K. Root distribution and seasonal water status in weathered granitic bedrock under chaparral. Geoderma 72, 89–98 (1996).

    Article  ADS  Google Scholar 

  48. Graham, R. C., Sternberg, P. D. & Tice, K. R. Morphology, porosity, and hydraulic conductivity of weathered granitic bedrock and overlying soils. Soil Sci. Soc. Am. J. 61, 516–522 (1997).

    Article  CAS  ADS  Google Scholar 

  49. McCole, A. A. & Stern, L. A. Seasonal water use patterns of Juniperus ashei on the Edwards Plateau, Texas, based on stable isotopes in water. J. Hydrol. 342, 238–248 (2007).

    Article  ADS  Google Scholar 

  50. Schwinning, S. The water relations of two evergreen tree species in a karst savanna. Oecologia 158, 373–383 (2008).

    Article  PubMed  ADS  Google Scholar 

  51. McCormick, E. L. et al. Dataset for “Evidence for widespread woody plant use of water stored in bedrock”. Hydroshare https://doi.org/10.4211/hs.a2f0d5fd10f14cd189a3465f72cba6f3 (2021).

  52. Jackson, R. B. et al. A global analysis of root distributions for terrestrial biomes. Oecologia 108, 389–411 (1996).

    Article  CAS  PubMed  ADS  Google Scholar 

  53. Schenk, H. J. & Jackson, R. B. The global biogeography of roots. Ecol. Monogr. 72, 311–328 (2002).

    Article  Google Scholar 

  54. Schenk, H. J. & Jackson, R. B. Rooting depths, lateral root spreads and below-ground/above-ground allometries of plants in water-limited ecosystems. J. Ecol. 90, 480–494 (2002).

    Article  Google Scholar 

  55. Fan, Y., Miguez-Macho, G., Jobbagy, E. G., Jackson, R. B. & Otero-Casal, C. Hydrologic regulation of plant rooting depth. Proc. Natl Acad. Sci. USA 114, 10572–10577 (2017).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  56. Daly, C. et al. Physiographically sensitive mapping of climatological temperature and precipitation across the conterminous United States. Int. J. Climatol. 28, 2031–2064 (2008).

    Article  Google Scholar 

  57. Daly, C., Smith, J. I. & Olson, K. V. Mapping atmospheric moisture climatologies across the conterminous United States. PLoS ONE 10, e0141140 (2015).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  58. Zhang, Y. et al. Coupled estimation of 500 m and 8-day resolution global evapotranspiration and gross primary production in 2002–2017. Remote Sens. Environ. 222, 165–182 (2019).

    Article  ADS  Google Scholar 

  59. Gan, R. et al. Use of satellite leaf area index estimating evapotranspiration and gross assimilation for Australian ecosystems. Ecohydrology 11, e1974 (2018).

    Article  Google Scholar 

  60. Dralle, D. N., Hahm, W. J., Chadwick, K. D., McCormick, E. L. & Rempe, D. M. Technical note: accounting for snow in the estimation of root-zone water storage capacity from precipitation and evapotranspiration fluxes. Hydrol. Earth Syst. Sci. 25, 2861–2867 (2021).

    Article  ADS  Google Scholar 

  61. Wang-Erlandsson, L. et al. Global root zone storage capacity from satellite-based evaporation. Hydrol. Earth Syst. Sci. 20, 1459–1481 (2016).

    Article  ADS  Google Scholar 

  62. Gorelick, N. et al. Google Earth Engine: planetary-scale geospatial analysis for everyone. Remote Sens. Environ. 202, 18–27 (2017).

    Article  ADS  Google Scholar 

  63. Singh, C., Wang-Erlandsson, L., Fetzer, I., Rockstrom, J. & van der Ent, R. Rootzone storage capacity reveals drought coping strategies along rainforest savanna transitions. Environ. Res. Lett. 15, 124021 (2020).

    Article  CAS  ADS  Google Scholar 

  64. Hall, D., Riggs, G. & Salomonson, V. MODIS/Terra Snow Cover Daily L3 Global 500m Grid, Version 6 [Data set] (NASA National Snow and Ice Data Center Distributed Active Archive Center, 2016).

  65. Friedl, M. & Sulla-Menashe, D. MCD12Q1 MODIS/Terra+ Aqua Land Cover Type Yearly L3 Global 500m SIN Grid V006 [Data set] (NASA EOSDIS Land Processes DAAC, 2015).

  66. Peel, M. C., Finlayson, B. L. & Mcmahon, T. A. Updated world map of the Koppen–Geiger climate classification. Hydrol. Earth Syst. Sci. Discuss. 4, 439–473 (2007).

    ADS  Google Scholar 

  67. Harris, I., Jones, P. D., Osborn, T. J. & Lister, D. H. Updated high-resolution grids of monthly climatic observations—the CRU TS3.10 dataset. Int. J. Climatol. 34, 623–642 (2014).

    Article  Google Scholar 

  68. Funk, C. et al. The climate hazards infrared precipitation with stations—a new environmental record for monitoring extremes. Sci. Data 2, 150066 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  69. Niemeyer, R. J. et al. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient. J. Hydrol. 544, 21–35 (2017).

    Article  ADS  Google Scholar 

  70. Pedrazas, M. A. et al. The relationship between topography bedrock weathering and water storage across a sequence of ridges and valleys. J. Geophys. Res. Earth Surf. 126, e2020JF005848 (2021).

    ADS  Google Scholar 

  71. Arkley, R. J. Soil moisture use by mixed conifer forest in a summer-dry climate. Soil Sci. Soc. Am. J. 45, 423–427 (1981).

    Article  ADS  Google Scholar 

  72. Zwieniecki, M. A. & Newton, M. Water-holding characteristics of metasedimentary rock in selected forest ecosystems in southwestern Oregon. Soil Sci. Soc. Am. J. 60, 1578–1582 (1996).

    Article  CAS  ADS  Google Scholar 

  73. Hellmers, H., Horton, J. S., Juhren, G. & O’Keefe, J. Root systems of some chaparral plants in southern California. Ecology 36, 667–678 (1955).

    Article  Google Scholar 

  74. Cardella Dammeyer, H., Schwinning, S., Schwartz, B. F. & Moore, G. W. Effects of juniper removal and rainfall variation on tree transpiration in a semi-arid karst: evidence of complex water storage dynamics. Hydrol. Process. 30, 4568–4581 (2016).

    Article  ADS  Google Scholar 

  75. Twidwell, D. et al. Drought-induced woody plant mortality in an encroached semi-arid savanna depends on topoedaphic factors and land management. Appl. Veg. Sci. 17, 42–52 (2013).

    Article  Google Scholar 

  76. Davis, E. A. Root system of shrub live oak in relation to water yield by chaparral. Proceedings of the 1977 Meetings of the Arizona Section of the American Water Resources Association and the Hydrology Section of the Arizona Academy of Sciences. Hydrol. Water Resour. Ariz. Southwest 7, 241–248 (1977).

    Google Scholar 

  77. West, A. G., Hultine, K. R., Burtch, K. G., & Ehleringer, J. R. Seasonal variations in moisture use in a piñon–juniper woodland. Oecologia 153, 787–798 (2007).

    Article  CAS  PubMed  ADS  Google Scholar 

  78. Seyfried, M. S. & Wilcox, B. P. Soil water storage and rooting depth: key factors controlling recharge on rangelands. Hydrol. Process. 20, 3261–3275 (2006).

    Article  ADS  Google Scholar 

  79. Dietrich, W. E. & Dunne, T. Sediment budget for a small catchment in mountainous terrain. Zeitschrift Für Geomorphologie 29, 191–206 (1978).

    Google Scholar 

  80. Litvak, M. E., Schwinning, S. & Heilman, J. L. in Ecosystem Function in Savannas (eds Hill, M. J. & Hanan, N. P.) 117–134 (2010).

Download references

Acknowledgements

We thank R. Breunig. We acknowledge funding support from the USDA Forest Service Pacific Southwest Research Station, the National Science Foundation Graduate Research Fellowship Program and the US Department of Energy, Office of Science, Office of Biological Environmental Research under award number DESC0018039.

Author information

Authors and Affiliations

  1. Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA

    Erica L. McCormick, Alison K. Tune, Logan M. Schmidt, K. Dana Chadwick & Daniella M. Rempe

  2. Pacific Southwest Research Station, United States Forest Service, Davis, CA, USA

    David N. Dralle

  3. Department of Geography, Simon Fraser University, Burnaby, British Columbia, Canada

    W. Jesse Hahm

Authors
  1. Erica L. McCormick
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. David N. Dralle
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. W. Jesse Hahm
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Alison K. Tune
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Logan M. Schmidt
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. K. Dana Chadwick
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Daniella M. Rempe
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

E.L.M. led the data acquisition and analysis and coordinated the manuscript preparation. E.L.M. and D.M.R. drafted the initial manuscript. D.N.D., K.D.C. and W.J.H. contributed to writing and data analysis. A.K.T. contributed to data acquisition. All authors contributed to the interpretation and presentation of the results, editing and review process, and approved the final version. D.M.R. conceptualized and led the study.

Corresponding author

Correspondence to Erica L. McCormick.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Ying Fan, Huade Guan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Flow chart of the methodology for bedrock storage deficit and capacity calculations.

Workflow for the calculation of total and annual bedrock water storage deficits (Sbedrock and Dbedrock,Y, respectively). Data products (solid thick border) are reported with their spatial resolution. Calculations and thresholds are reported in white boxes (Methods). Masking procedures exclude areas where output fluxes significantly exceed input fluxes (top right) and include areas where woody vegetation is established on shallow soils (middle right). These masks are applied to the water budget calculation (left and bottom) to arrive at conservative estimates of Sbedrock and Dbedrock,Y at the CONUS scale.

Extended Data Fig. 2 Maps of soil and aboveground carbon input products used in this study.

a, Aboveground carbon sourced from Spawn et al.19 (Mg ha−1). b, Soil available water storage capacity (mm) for the CONUS. Soil available water storage sourced at 90-m resolution from the USDA gNATSGO41 product and provided for the upper 1.5 m (Methods).

Extended Data Fig. 3 Annual bedrock water storage deficit for four years across the CONUS.

a–d, Annual bedrock water storage deficit, Dbedrock,Y, for 2011 (a), 2014 (b), 2015 (c) and 2017 (d).

Extended Data Fig. 4 Median annual bedrock water storage deficit constitutes more than a quarter of mean annual precipitation in some places.

The magnitude of median Dbedrock divided by mean annual precipitation shown as a percent for California (left) and Texas (right). Mean annual precipitation was calculated in Google Earth Engine62 in the Google Colaboratory environment using the PRISM Daily Spatial Climate Data set AN81d data product56,57.

Extended Data Fig. 5 Bedrock water storage capacity across the CONUS, California and Texas.

The distribution of bedrock water storage capacity, Sbedrock, for locations meeting masking and calculation criteria. Where Sbedrock is greater than zero, bedrock water storage is needed to explain observed ET (Methods).

Extended Data Fig. 6 Distribution of bedrock water storage capacity varies by Köppen climate type and biome.

a, Boxplots show median, interquartile range and 1.5 times the interquartile range of Sbedrock across Köppen climate type66 (left) and biome (MODIS landcover classifications65) (right) for locations which meet analysis criteria (Methods). The number of pixels in each category is given above each box. The 25th percentile is non-zero for many biomes and climates. b, Maps indicating the locations associated with each climate (left) and biome (right). Biome and climate subgroups with less than 2,000 km2 are excluded. Summary statistics of groupings are presented in Extended Data Table 1. Post hoc tests (Kruskal–Wallis and Dunn’s tests) reveal statistically significant differences (P = <0.001) of median Sbedrock between all climate group pairings and between all biome group pairings. Boxplots and statistical analyses were processed using the Google Earth Engine62 Python API.

Extended Data Fig. 7 Soil and bedrock water storage capacity at locations where rock moisture use by plants has been documented.

Soil water storage capacity Ssoil (brown) and median Dbedrock,2004–2017 (blue) for locations with documented plant use of rock moisture, that is, bedrock water storage from the unsaturated zone. Superscripts denote locations that are masked, for not being classified as woody vegetation (‡), having soil depth greater than 1.5 m (*) or because the cumulative 2003–2017 evapotranspiration exceeds precipitation (†) (Methods, Extended Data Fig. 1). Data were sourced from the literature review (Methods). References for field studies: refs. 20,69,70,71,72,73,74,75,76,77,78,79,80

Source data.

Extended Data Fig. 8 Comparison of Sbedrock and median Dbedrock to calculations using double the published soil water storage capacity values.

a, Bedrock water storage capacity (Sbedrock) assuming soil water storage capacity (Ssoil) is double that reported by gNATSGO41 to account for the possibility of soils providing water to ET at saturation, which is commonly estimated as double field capacity. b, Sbedrock without doubling of Ssoil. c, d, Median annual bedrock water storage deficit, Dbedrock,2003–2017, with doubled (c) and original (d) Ssoil.

Extended Data Fig. 9 Bedrock water storage capacity calculated with published values of root-zone storage capacity.

a, b, Two versions of bedrock water storage capacity (Sbedrock) are calculated using root-zone storage capacity (Sr) published by Wang-Erlandsson et al. 61 at a 0.5° (roughly 50 km) resolution with input and output fluxes from Climatic Research Unit Time Series version 3.22 (CRU TS3.22)67 (a) and Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS)68 (b). To arrive at Sbedrock, Ssoil is subtracted from the maximum Sr reported in Wang-Erlandsson et al. 61.

Extended Data Table 1 Median bedrock water storage capacity for combinations of biomes and Köppen climate types
Full size table

Supplementary information

Source data

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

McCormick, E.L., Dralle, D.N., Hahm, W.J. et al. Widespread woody plant use of water stored in bedrock. Nature 597, 225–229 (2021). https://doi.org/10.1038/s41586-021-03761-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-021-03761-3

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing