Oecologia

, Volume 145, Issue 1, pp 32–40

Soil moisture redistribution as a mechanism of facilitation in savanna tree–shrub clusters

  • C. B. Zou
  • P. W. Barnes
  • S. Archer
  • C. R. McMurtry
Ecophysiology

Abstract

Plant–soil water relations were examined in the context of a selective removal study conducted in tree–shrub communities occupying different but contiguous soil types (small discrete clusters on shallow, duplex soils versus larger, extensive groves on deep, sandy soils) in a subtropical savanna parkland. We (1) tested for the occurrence of soil moisture redistribution by hydraulic lift (HL), (2) determined the influence of edaphic factors on HL, and (3) evaluated the significance of HL for overstory tree–understory shrub interactions. Diel cycling and nocturnal increases in soil water potential (Ψsoil), characteristic signatures of HL, occurred intermittently throughout an annual growth cycle in both communities over a range of moisture levels (Ψsoil=−0.5 to −6.0 MPa) but only when soils were distinctly stratified with depth (dry surface/wet deep soil layers). The magnitude of mean (±SE) diel fluctuations in Ψsoil (0.19±0.01 MPa) did not differ on the two community types, though HL occurred more frequently in groves (deep soils) than clusters (shallow soils). Selective removal of either Prosopis glandulosa overstory or mixed-species shrub understory reduced the frequency of HL, indicating that Prosopis and at least one other woody species was conducting HL. For Zanthoxylum fagara, a shallow-rooted understory shrub, Prosopis removal from clusters decreased leaf water potential (Ψleaf) and net CO2 exchange (A) during periods of HL. In contrast, overstory removal had neutral to positive effects on more deeply-rooted shrub species (Berberis trifoliolata and Condalia hookeri). Removal of the shrub understory in groves increased A in the overstory Prosopis. Results indicate the following: (a) HL is common but temporally dynamic in these savanna tree–shrub communities; (b) edaphic factors influencing the degree of overstory/understory development, rooting patterns and soil moisture distribution influence HL; (c) net interactions between overstory and understory elements in these woody patches can be positive, negative and neutral over an annual cycle, and (d) Prosopis-mediated HL is an important mechanism of faciliation for some, but not all, understory shrubs.

Keywords

Argillic horizon Berberis trifoliolata Competition Condalia hookeri Hydraulic lift Positive and negative interactions Prosopis glandulosa Zanthoxylum fagara 

References

  1. Archer S (1989) Have southern Texas savannas been converted to woodlands in recent history? Amer Nat 134:545–561CrossRefGoogle Scholar
  2. Archer S (1990) Development and stability of grass/woody mosaics in a subtropical savanna parkland Texas, USA. J Biogeogr 17:453–462CrossRefGoogle Scholar
  3. Archer S (1995) Tree-grass dynamics in a Prosopis-thornscrub savanna parkland: reconstructing the past and predicting the future. Ecoscience 2:83–99Google Scholar
  4. Archer S, Scifres C, Bassham CR, Maggio R (1988) Autogenic succession in a subtropical savanna: conversion of grassland to thorn woodland. Ecol Monogr 58:111–127CrossRefGoogle Scholar
  5. Barnes PW, Archer S (1996) Influence of an overstorey tree (Prosopis glandulosa) on associated shrubs in a savanna parkland: implications for patch dynamics. Oecologia 105:493–500CrossRefGoogle Scholar
  6. Barnes PW, Archer S (1999) Tree-shrub interactions in a subtropical savanna parkland: competition or facilitation? J Veg Sci 10:525–536CrossRefGoogle Scholar
  7. Boutton TW, Archer SR, Midwood AJ (1999) Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical savanna. Rapid Commun Mass Spectrom 13:1263–1277PubMedCrossRefGoogle Scholar
  8. Brown RW, Bartos DL (1982) A calibration model for screen-caged Peltier thermocouple psychrometers (Research Paper INT-293). USDA Forest Service, OgdenGoogle Scholar
  9. Burgess SSO, Adams MA, Turner NC, Ong CK (1998) The redistribution of soil water by tree root systems. Oecologia 115:306–311CrossRefGoogle Scholar
  10. Burgess SSO, Pate JS, Adams MA, Dawson TE (2000) Seasonal water acquisition and redistribution in the Australian woody phreatophyte, Banksia prionotes. Ann Bot 85:215–224CrossRefGoogle Scholar
  11. Caldwell MM (1990) Water parasitism stemming from hydraulic lift: a quantitative test in the field. Isr J Bot 39:395–402Google Scholar
  12. Caldwell MM, Richards JH (1989) Hydraulic lift: water efflux from upper roots improves effectiveness of water uptake by deep roots. Oecologia 79:1–5CrossRefGoogle Scholar
  13. Caldwell MM, Richards JH, Beyschlag W (1991) Hydraulic lift: ecological implications of water efflux from roots. In: Atkinson D (ed) Plant root growth: an ecological perspective. Blackwell, London, pp 423–436Google Scholar
  14. Caldwell MM, Dawson TE, Richards JH (1998) Hydraulic lift: consequences of water efflux from the roots of plants. Oecologia 113:151–161CrossRefGoogle Scholar
  15. Callaway RM (1995) Positive interactions among plants. Bot Rev 61:306–349CrossRefGoogle Scholar
  16. Callaway RM, Davis FW (1998) Recruitment of Quercus agrifolia in central California: the importance of shrub-dominated patches. J Veg Sci 9:647–656CrossRefGoogle Scholar
  17. Carter AJ, O’Conner TG (1991) A two-phase mosaic in a savanna grassland. J Veg Sci 2:231–236CrossRefGoogle Scholar
  18. Correll DS, Johnston MC (1979) Manual of the vascular plants of Texas. University of Texas Press, RichardsonGoogle Scholar
  19. Dawson TE (1993) Hydraulic lift and water use by plants: implications for water balance, performance and plant–plant interactions. Oecologia 95:565–574Google Scholar
  20. Dawson TE (1996) Determining water use by trees and forests from isotopic, energy balance and transpiration analyses: the roles of tree size and hydraulic lift. Tree Physiol 16:263–272PubMedGoogle Scholar
  21. Fuentes ER, Otaiza RD, Alliende MC, Hoffmann A, Poiani A (1984) Shrub clumps of the Chilean matorral vegetation: structure and possible maintenance mechanisms. Oecologia 62:405–411CrossRefGoogle Scholar
  22. Fulbright TE, Kuti JO, Tipton AR (1995) Effects of nurse-plant canopy temperatures on shrub seed germination and seedling growth. Acta Oecol 16:621–632Google Scholar
  23. Haase P, Pugnaire FL, Clark SC, Incoll LD (1996) Spatial patterns in a two-tiered semi-arid shrubland in southeastern Spain. J Veg Sci 7:527–534CrossRefGoogle Scholar
  24. Hamerlynck EP, McAuliffe JR, Smith SD (2000) Effects of surface and sub-surface soil horizons on the seasonal performance of Larrea tridentata (Creosotebush). Funct Ecol 14:596–606CrossRefGoogle Scholar
  25. Hibbard KA, Archer S, Schimel DS, Valentine DW (2001) Biogeochemical changes accompanying woody plant encroachment in a subtropical savanna. Ecology 82:1999–2011CrossRefGoogle Scholar
  26. Horton JL, Hart SC (1998) Hydraulic lift: a potentially important ecosystem process. Trends Ecol Evol 13:232–235CrossRefGoogle Scholar
  27. Hubbard J, Archer S, Boutton TW (1997) Rates of root biomass accumulation during succession from savanna to woodland. Bull Ecol Soc Amer 78(4):260Google Scholar
  28. Huebotter NH (1991) Successional processes in a Texas savanna woodland: the role of birds and rodents. MS Thesis, Texas A&M UniversityGoogle Scholar
  29. Hultine KR, Williams DG, Burgess SSO, Keefer TO (2003) Contrasting patterns of hydraulic redistribution in three desert phreatophytes. Oecologia 135:167–175PubMedGoogle Scholar
  30. Hultine KR, Scott RL, Cable WL, Goodrich DC, Williams DG (2004) Hydraulic redistribution by a dominant, warm-desert phreatophyte: seasonal patterns and response to precipitation pulses. Funct Ecol 18:530–538CrossRefGoogle Scholar
  31. Ishikawa CM, Bledsoe CS (2000) Seasonal and diurnal patterns of soil water potential in the rhizosphere of blue oaks: evidence for hydraulic lift. Oecologia 125:459–465CrossRefGoogle Scholar
  32. Johnson RW, Tothill JC (1985) Definition and broad geographic outline of savanna lands. In: Tothill JC, Mott JJ (eds) Ecology and management of the world’s savannas. Australian Academy of Science, Canberra, pp 1–13Google Scholar
  33. Knoop WT, Walker BH (1985) Interactions of woody and herbaceous vegetation in a southern African savanna. J Ecol 73:235–253CrossRefGoogle Scholar
  34. Le Houerou HN, Norwine J (1988) The ecoclimatology of South Texas. In: Whitehead EE, Hutchinson CF, Timmesman BN, Varady RG (eds) Arid lands: today and tomorrow. Westview Press, Boulder, pp 417–444Google Scholar
  35. Loomis LE (1989) Plant–soil relationships in grassland-to-woodland succession. PhD Dissertation, Texas A&M University, College StationGoogle Scholar
  36. Ludwig F, Dawson TE, Kroon H, Berendse F, Prins HHT (2003) Hydraulic lift in Acacia tortilis trees on an East African savanna. Oecologia 134:293–300PubMedGoogle Scholar
  37. Matzner SL, Richards JH (1996) Sagebrush (Artemisia tridentata Nutt) roots maintain nutrient uptake capacity under water stress. J Exp Bot 47:1045–1056CrossRefGoogle Scholar
  38. McAuliffe JR (1994) Landscape evolution, soil formation, and ecological patterns and processes in Sonoran Desert Bajadas. Ecol Monogr 64:111–148CrossRefGoogle Scholar
  39. McLendon T (1991) Preliminary description of the vegetation of south Texas exclusive of coastal saline zones. Texas J Sci 43:13–32Google Scholar
  40. McMurtry CR (1997) Gas exchange physiology and water relations of co-occurring woody plant species in a Texas subtropical savanna. SM Thesis, Texas State University, San MarcosGoogle Scholar
  41. Midwood AJ, Boutton TW, Archer SR, Watts SE (1998) Water use by woody plants on contrasting soils in a savanna parkland: assessment with δ2H and δ18O. Plant Soil 205:13–24CrossRefGoogle Scholar
  42. Miller D, Archer SR, Zitzer SF, Longnecker MT (2001) Annual rainfall, topoedaphic heterogeneity and growth of an arid land tree (Prosopis glandulosa). J Arid Environ 48:23–33CrossRefGoogle Scholar
  43. Mooney HA, Gulmon SL, Rundel PW, Ehleringer J (1980) Further observations on the water relations of Prosopis tamarugo of the Northern Atacama desert. Oecologia 44:177–180CrossRefGoogle Scholar
  44. Mordelet P, Abbadie L, Menaut JC (1993) Effects of tree clumps on soil characteristics in a humid savanna of West Africa (Lamto, Cote d’voire). Plant Soil 153:103–111CrossRefGoogle Scholar
  45. Nelson JA, Barnes PW, Archer S (2002) Leaf demography and growth responses to altered resource availability in woody plants of contrasting leaf habit in a subtropical savanna. Plant Ecol 160:193–205CrossRefGoogle Scholar
  46. Richards JH, Caldwell MM (1987) Hydraulic lift: substantial nocturnal water transport between soil layers by Artemisia tridentata roots. Oecologia 73:486–489CrossRefGoogle Scholar
  47. Ryel RJ, Caldwell MM, Yoder CK, Or D, Leffler AJ (2002) Hydraulic redistribution in a stand of Artemisia tridentata: evaluation of benefits to transpiration assessed with a simulation model. Oecologia 130:173–184Google Scholar
  48. San José JJ, Montes R (1991) Regional interpretation of environmental gradients which influence Trachypogon savannas in the Orinoco Llanos. Vegetatio 95:21–32CrossRefGoogle Scholar
  49. San José J, Farinas M, Rosales J (1991) Spatial patterns of trees and structuring factors in a Trachypogon savanna of the Orinoco Llanos. Biotropica 23:114–123CrossRefGoogle Scholar
  50. Schulze E-D, Caldwell MM, Canadell J, Mooney HA, Jackson RB, Parson D, Scholes R, Sala OE, Trimborn P (1998) Downward flux of water through roots (ie, inverse hydraulic lift) in dry Kalahari sands. Oecologia 115:460–462CrossRefGoogle Scholar
  51. Scifres CJ, Koerth B (1987) Climate, soils, and vegetation at the La Copita Research Area (Report MP-1626). Texas Agriculture Experiment Station Texas A&M University, College StationGoogle Scholar
  52. Smith SD, Herr CA, Leary KL, Piorkowski JM (1995) Soil-plant water relations in a Mojave Desert mixed shrub community: a comparison of three geomorphic surfaces. J Arid Environ 29:339–351CrossRefGoogle Scholar
  53. Smith SD, Monson RK, Anderson JE (1997) Physiological ecology of North American desert plants. Springer, Berlin Heidelberg New YorkGoogle Scholar
  54. Stroh JC, Archer S, Doolittle JA, Wilding L (2001) Detection of edaphic discontinuities with ground-penetrating radar and electromagnetic induction. Landscape Ecol 16:377–390CrossRefGoogle Scholar
  55. Wan CG, Sosebee RE, McMichael BL (1993) Does hydraulic lift exist in shallow-rooted species? A quantitative examination with a half-shrub Gutierrezia sarothrae. Plant Soil 153:11–17CrossRefGoogle Scholar
  56. Watts S (1993) Rooting patterns of co-occurring woody plants on contrasting soils in a subtropical savanna. MS Thesis, Texas A&M University, College StationGoogle Scholar
  57. Whittaker KH, Niering WA, Crisp MD (1979a) Structure, pattern, and diversity of a Mallee community in New South Wales. Vegetatio 39:65–76CrossRefGoogle Scholar
  58. Whittaker RH, Gilbert LE, Connell JH (1979b) Analysis of two-phase pattern in a mesquite grassland, Texas. J Ecol 67:935–952CrossRefGoogle Scholar
  59. Yoder CK, Nowak RS (1999) Hydraulic lift among native plant species in the Mojave Desert. Plant Soil 215:93–102CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • C. B. Zou
    • 1
  • P. W. Barnes
    • 2
  • S. Archer
    • 3
  • C. R. McMurtry
    • 3
  1. 1.Department of Rangeland Ecology and ManagementTexas A&M UniversityCollege StationUSA
  2. 2.Department of Biological SciencesLoyola University New OrleansNew OrleansUSA
  3. 3.School of Natural ResourcesUniversity of ArizonaTucsonUSA

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