Ecosystems

, Volume 14, Issue 5, pp 776–790

The Role of Abandoned Channels as Refugia for Sustaining Pioneer Riparian Forest Ecosystems

  • John C. Stella
  • Maya K. Hayden
  • John J. Battles
  • Hervé Piégay
  • Simon Dufour
  • Alexander K. Fremier
Article

DOI: 10.1007/s10021-011-9446-6

Cite this article as:
Stella, J.C., Hayden, M.K., Battles, J.J. et al. Ecosystems (2011) 14: 776. doi:10.1007/s10021-011-9446-6

Abstract

In disturbance-prone ecosystems, organisms often persist in spatial refugia during stressful periods. A clear example is the colonization of abandoned river channels by pioneer riparian trees. Here, we examine the prominence of this establishment pathway for a foundation tree species (Fremont cottonwood, Populus fremontii) within the riparian corridor of a large river, the Sacramento River in central California. We quantified the total proportion of forest that initiated as a result of channel abandonment for a 160-km reach, analyzed concurrent patterns of tree establishment with floodplain accretion and sedimentation history, and developed a conceptual model of biogeomorphic evolution of abandoned channels. Historical air photo analysis indicated that stands associated with abandoned channels comprised more than 50% of the total extant cottonwood forest area. Tree-ring evidence showed that cottonwood stands commonly developed immediately following abandonment, and the recruitment window ranged from 4 to 40 years, but was less than 10 years at most sites. Rates of floodplain rise and fine sediment accumulation were high in young sites and decreased logarithmically over time. Together, these results suggest that abandoned channels are an important refuge for cottonwood recruitment, that the greatest opportunity for colonization occurs within a short period after the cutoff event, and that sedimentation processes influence the duration of the colonization window. On rivers where tree recruitment along the active channel is severely limited by hydrologic regulation and/or land management, abandoned channel refugia may play an even more important role in sustaining an ecologically functional riparian corridor. Preserving bank erosion, active meander corridors and forest regeneration zones created by cutoff events are therefore key conservation measures on shifting rivers.

Key words

abandoned channel cottonwood Salicaceae floodplain recruitment refugia riparian Sacramento River dendrochronology oxbow persistence strategy 

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • John C. Stella
    • 1
  • Maya K. Hayden
    • 2
  • John J. Battles
    • 2
  • Hervé Piégay
    • 3
  • Simon Dufour
    • 4
  • Alexander K. Fremier
    • 5
  1. 1.Department of Forest and Natural Resources ManagementState University of New York College of Environmental Science and ForestrySyracuseUSA
  2. 2.Department of Environmental Science, Policy, and ManagementUniversity of CaliforniaBerkeleyUSA
  3. 3.CNRS UMR 5600 EVS/Site ENS LyonUniversity of LyonLyon Cedex 07France
  4. 4.COSTEL-CNRS LETG UMR 6554, Département de GéographieUniversité Rennes 2Rennes CedexFrance
  5. 5.Department of Fish and Wildlife ResourcesUniversity of IdahoMoscowUSA

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