Title: Hydraulic redistribution in a Douglas-fir forest: lessons from system manipulations.
Author: Brooks, J. Renée; Meinzer, Frederick C.; Warren, Jeffery M.; Domec, Jean-Christophe; Coulombe, Rob.;
Source: Plant, Cell and Environment. 29: 138-150
Publication Series: Miscellaneous Publication
Description: Hydraulic redistribution (HR) occurs in many ecosystems; however, key questions remain about its consequences at the ecosystem level. The objectives of the present study were to quantify seasonal variation in HR and its driving force, and to manipulate the soil-root system to elucidate physiological components controlling HR and utilization of redistributed water. In the upper soil layer of a young Douglas-fir forest, HR was negligible in early summer, but increased to 0.17 mm day-1 (20-60 cm layer) by late August when soil water potential was approximately -1 MPa. When maximum HR rates were observed, redistributed water replenished approximately 40% of the water depleted from the upper soil on a daily basis. Manipulations to the soil or to the soil/plant water potential driving force altered the rate of observed HR indicating that the rate of HK is controlled by a complex interplay between competing soil and plant water potential gradients and pathway resistances. Separating roots from the transpiring tree resulted in increased HR, and sap flow measurements on connected and disconnected roots showed reversal of water flow, a prerequisite for HR. Irrigating a small plot with deuterated water demonstrated that redistributed water was taken up by small understory plants as far as 5 m from the watering source, and potentially further, but the utilization pattern was patchy. HR in the upper soil layers near the watering plot was twice that of the control HR. This increase in HR also increased the amount of water utilized by plants from the upper soil. These results indicate that the seasonal timing and magnitude of HR was strongly governed by the development of water potential differences within the soil, and the competing demand for water by the above ground portion of the tree.
Keywords: Pseudotsuga menziesii, deuterium labelling, hydraulic lift, seasonal variation, soil water utilization, soil water potential, trenching, water transport
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- You may send email to email@example.com to request a hard copy of this publication. (Please specify exactly
which publication you are requesting and your mailing address.)
XML: View XML
Brooks, J. Renée; Meinzer, Frederick C.; Warren, Jeffery M.; Domec, Jean-Christophe; Coulombe, Rob. 2006. Hydraulic redistribution in a Douglas-fir forest: lessons from system manipulations. Plant, Cell and Environment. 29: 138-150
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility