, Volume 17, Issue 4, pp 351–358 | Cite as

Drought stress and recovery of riparian cottonwoods due to water table alteration along Willow Creek, Alberta

  • Nadine M. Amlin
  • Stewart B. RoodEmail author
Original Article


A 5-m-deep gravel pit was excavated from 1996 to 1998 in the floodplain between Willow Creek, Alberta, and a grove of balsam poplars ('cottonwoods', Populus balsamifera L.) and water level at the pit was lowered 2.5 m through pumping. This interrupted the infiltration of stream water into the riparian groundwater and imposed drought stress on the cottonwoods. Trees in the drought-affected grove displayed extensive leaf senescence and abscission in late August 1998, while trees in nearby control groves remained green until autumnal senescence in late September. The precocious senescence was accompanied by a two-thirds reduction in leaf stomatal conductance (g s) but mid-day leaf xylem water potentials (ψl) were only slightly reduced (−1.55 vs 1.42 MPa). Pumping ceased in 1999, the pit was partially refilled, and the hydraulic linkage between the stream and the riparian zone recovered. Subsequently in August 1999, g s and ψl were similar for trees in the affected and control groves and senescence phenologies were similar in 1999 and 2000. Annual branch growth increments varied 3-fold across years between 1994 and 1999, but there was no reduction in these growth increments in the drought-affected trees in 1998 or 1999. This study supports the hydraulic linkage between a stream and the adjacent riparian zone in a semi-arid region and demonstrates the vulnerability of riparian cottonwoods to drought due to water table depletion. It also indicates rapid physiological recovery of cottonwoods following restoration of water availability.


Cottonwoods Drought Populus balsamifera Stress Water relations 



This research was funded by a Natural Sciences and Engineering Research Council (NSERC) of Canada scholarship to N.M.A., NSERC research grants to S.B.R. and a research contract from Alberta Environment. This study comprised a part of N.M.A.'s University of Lethbridge M.Sc. Thesis and the inputs from committee members J. Mahoney (Alberta Environment, Lethbridge), C. Goater and R. Rogerson (University of Lethbridge) and external examiner M. Scott (USGS, Fort Collins) are gratefully acknowledged. Thanks are also extended to Alberta Infrastructure, Ron May and the Brown Family for permitting research on their lands, Damian Gilbert and Cathy Metzler for assistance with field work and Lori Gom for assistance with manuscript preparation.


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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of Biological SciencesUniversity of LethbridgeAlbertaCanada

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