Plant Ecology

, Volume 212, Issue 4, pp 663–673 | Cite as

Droughts, hydraulic redistribution, and their impact on vegetation composition in the Amazon forest

Article

Abstract

Hydraulic redistribution (HR), the nocturnal transport of moisture by plant roots from wetter to drier portions of the root zone, in general can buffer plants against seasonal water deficits. However, its role in longer droughts and its long-term ecological impact are not well understood. Based on numerical model experiments for the Amazon forest, this modeling study indicates that the impact of HR on plant growth differs between droughts of different time scales. While HR increases transpiration and plant growth during regular dry seasons, it reduces dry season transpiration and net primary productivity (NPP) under extreme droughts such as those during El Niño years in the Amazon forest. This occurs because, in places where soil water storage is not able to sustain the ecosystem through the dry season, the HR-induced acceleration of moisture depletion in the early stage of the dry season reduces water availability for the rest of the dry season and causes soil moisture to reach the wilting point earlier. This gets exacerbated during extreme droughts, which jeopardizes the growth of trees that are not in dry season dormancy, i.e., evergreen trees. As a result, the combination of drought and HR increases the percentage of drought deciduous trees at the expense of evergreen trees, and the fractional coverage of forest canopy is characterized by sudden drops following extreme droughts and slow recovery afterwards. The shift of the tropical forest towards more drought deciduous trees as a result of the combined effects of extreme drought and HR has important implications for how vegetation will respond to future climate changes.

Keywords

Hydraulic redistribution Vegetation distribution Drought Plant–water relations 

References

  1. Alo AC, Wang GL (2008) Potential future changes of the terrestrial ecosystem based on climate projections by eight general circulation models. J Geophys Res 113:G01004. doi:10.1029/2007JG000528 CrossRefGoogle Scholar
  2. Baker IT, Prihodko L, Denning AS, Goulden M, Miller S, da Rocha HR (2008) Seasonal drought stress in the Amazon: reconciling models and observations. J Geophys Res 113:G00B01. doi:10.1029/2007JG000644 CrossRefGoogle Scholar
  3. Becker P, Tyree MT, Tsuda M (1999) Hydraulic conductances of angiosperms versus conifer: similar transport sufficiency at the whole plant level. Tree Physiol 19:445–452PubMedGoogle Scholar
  4. Betts RA, Cox PM, Collins M, Harris PP, Huntingford C, Jones CD (2004) The role of ecosystem–atmosphere interactions in simulated Amazonian precipitation decrease and forest dieback under global climate warming. Theor Appl Climatol 78:157–175CrossRefGoogle Scholar
  5. Bonan GB, Levis S (2006) Evaluating aspects of the community land and atmosphere models (CLM3 and CAM3) using a dynamic global vegetation model. J Clim 19:2290–2301CrossRefGoogle Scholar
  6. Brooks JR, Meinzer FC, Coulombe R, Gregg J (2002) Hydraulic redistribution of soil water during summer drought in two contracting Pacific Northwest coniferous forests. Tree Physiol 22:1107–1117PubMedGoogle Scholar
  7. Burgess SSO, Adams MA, Turner NC, Ong CK (1998) The redistribution of soil water by tree root systems. Oecologia 115:306–311CrossRefGoogle Scholar
  8. Burke EJ, Brown SJ, Christidis N (2006) Modeling the recent evolution of global drought and projections for the twenty-first century with the Hadley Center climate model. J Hydrometeorol 7:1113–1125CrossRefGoogle Scholar
  9. Caldwell MM, Dawson TE, Richards JR (1998) Hydraulic lift: consequences of water efflux from the roots of plants. Oecologia 113:151–161CrossRefGoogle Scholar
  10. Costa MH, Biajoli MC, Sanches L et al (2010) Atmospheric versus vegetation controls of Amazonian tropical rain forest evapotranspiration: are the wet and seasonally dry rain forests any different? J Geophys Res 115:G04021. doi:10.1029/2009JG001179
  11. Cox PM, Betts RA, Jones CD, Spall SA, Totterdell IJ (2000) Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature 408:184–187PubMedCrossRefGoogle Scholar
  12. Dai YJ, Zeng XB, Dickinson RE et al (2003) The common land model (CLM). Bull Am Meteorol Soc 84:1013–1023CrossRefGoogle Scholar
  13. Dawson TE (1993) Hydraulic lift and water use in plants: implications for performance, water balance and plant-plant interactions. Oecologia 95:565–574Google Scholar
  14. Delire C, Foley JA (1999) Evaluating the performance of a land surface/ecosystem model with biophysical measurements from contrasting environments. J Geophys Res 104:16895–16909CrossRefGoogle Scholar
  15. Friedlingstein P, Bopp L, Ciais P et al (2001) Positive feedback of the carbon cycle on future climate change. Geophys Res Let 28:1543–1546CrossRefGoogle Scholar
  16. Huete AR, Didan K, Shimabukuro YE et al (2006) Amazon rainforests green-up with sunlight in dry season. Geophys Res Lett 33:L06405. doi:10.1029/2005GL025583 CrossRefGoogle Scholar
  17. Hutyra LR, Munger JW, Saleska SR et al (2007) Seasonal controls on the exchange of carbon and water in an Amazonia rain forest. J Geophys Res 112:G03008. doi:10.1029/2006JG000365 CrossRefGoogle Scholar
  18. Jackson RB, Sperry JS, Dawson TE (2000) Root water uptake and transport: using physiological processes in global predictions. Trends Plant Sci 5:482–488PubMedCrossRefGoogle Scholar
  19. Lee JE, Oliveira RS, Dawson TE, Fung I (2005) Root functioning modifies seasonal climate. PNAS 102:17576–17581PubMedCrossRefGoogle Scholar
  20. Levis S, Bonan GB, Vertenstein M, Oleson KW (2004) The Community Land Model’s dynamic global vegetation model (CLM-DGVM): technical description and user’s guide. NCAR Tech. Note TN-459+IA, 50 ppGoogle Scholar
  21. Malhi Y, Pegoraro E, Nobre AD et al (2002) Energy and water dynamics of a central Amazonian rain forest. J Geophys Res 107:8061. doi:10.1029/2001JD000623 CrossRefGoogle Scholar
  22. Malhi Y, Roberts JT, Betts RA, Killeen TJ, Li WH, Nobre CA (2008) Climate change, deforestation, and the fate of the Amazon. Science 319:169–172PubMedCrossRefGoogle Scholar
  23. Nepstad DC, Decarvalho CR, Davidson EA et al (1994) The role of deep roots in the hydrological and carbon cycles of Amazonia forests and pastures. Nature 372:666–669CrossRefGoogle Scholar
  24. Nepstad DC, Moutinho P, Dias MB et al (2002) The effects of partial throughfall exclusion on canopy processes, aboveground production, and biogeochemistry of an Amazon forest. J Geophys Res 107:8085. doi:10.1029/2001JD000360 CrossRefGoogle Scholar
  25. Oliveira RS, Dawson TE, Burgess SSO, Nepstad DC (2005) Hydraulic redistribution in three Amazonian trees. Oecologia 145:354–363PubMedCrossRefGoogle Scholar
  26. Phillips OL, Aragao LEOC, Lewis SL et al (2009) Drought sensitivity of the Amazon rainforest. Science 323:1344–1347PubMedCrossRefGoogle Scholar
  27. Qian TT, Dai AG, Trenberth KE, Oleson KW (2006) Simulation of global land surface conditions from 1948 to 2004. Part I: forcing data and evaluations. J Hydrometeorol 7:953–975CrossRefGoogle Scholar
  28. Randerson JT, Hoffman FM, Thornton PE et al (2009) Systematic assessment of terrestrial biogeochemistry in coupled climate-carbon models. Global Change Biol 15:2462–2484CrossRefGoogle Scholar
  29. Richards JH, Caldwell MM (1987) Hydraulic lift: substantial nocturnal water transport between soil layers by Artemisia tridentate roots. Oecologia 73:486–489CrossRefGoogle Scholar
  30. Romero-Saltos H, Sternberg LDSL, Moreira MZ, Nepstad DC (2005) Rainfall exclusion in an eastern Amazonia forest alters soil water movement and depth of water uptake. Am J Bot 92:443–455CrossRefGoogle Scholar
  31. Ryel RJ, Caldwell MM, Yoder CK, Or D, Leffler AJ (2002) Hydraulic redistribution in a stand of Atemisia tridentata: evaluation of benefits to transpiration assessed with a simulation model. Oecologia 130:173–184Google Scholar
  32. Saleska SR, Miller SD, Matross DM et al (2003) Carbon in Amazon forests: unexpected seasonal fluxes and disturbance-induced losses. Sci 302:1554–1557CrossRefGoogle Scholar
  33. Samanta A, Ganguly S, Hashimoto H et al (2010) Amazon forests did not green-up during the 2005 drought. Geophys Res Lett 37:L05401. doi:10.1029/2009GL042154
  34. Scott RL, Cable WL, Hultine KR (2008) The ecohydrologic significance of hydraulic redistribution in a semiarid savanna. Water Resour Res 44:W02440. doi:10.1029/2007WR006149 CrossRefGoogle Scholar
  35. Sen OL, Shuttleworth WJ, Yang ZL (2000) Comparative evaluation of BATS2, BATS, and SiB2 with Amazon data. J Hydrometeorol 1:135–153CrossRefGoogle Scholar
  36. Smith DM, Jackson NA, Roberts JM, Ong CK (1999) Reverse flow of sap in tree roots and downward siphoning of water by Grevillea robusta. Funct Ecol 13:256–264CrossRefGoogle Scholar
  37. Wang DG, Wang GL (2007) Towards a robust canopy hydrology scheme with precipitation sub-grid variability. J Hydrometeorol 8(3):439–446CrossRefGoogle Scholar
  38. Werth D, Avissar R (2004) The regional evapotranspiration of the Amazon. J Hydrometeorol 5:100–109Google Scholar
  39. Zeng XB, Dai YJ, Dickinson RE et al (1998) The role of root distribution for land climate simulations. Geophys Res Lett 25:4533–4536CrossRefGoogle Scholar
  40. Zheng Z, Wang GL (2007) Modeling the dynamic root water uptake and its hydrological impact at the Reserva Jaru site in Amazonia. J Geophys Res 112:G04012. doi:10.1029/2007JG000413 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Guiling Wang
    • 1
    • 2
  • Clement Alo
    • 1
  • Rui Mei
    • 1
  • Shanshan Sun
    • 1
  1. 1.Department of Civil & Environmental EngineeringUniversity of ConnecticutStorrsUSA
  2. 2.Center for Environmental Sciences and EngineeringUniversity of ConnecticutStorrsUSA

Personalised recommendations