HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by McCarron, J. K. Articles by Knapp, A. K. Search for Related Content PubMed Articles by McCarron, J. K. Articles by Knapp, A. K. Agricola Articles by McCarron, J. K. Articles by Knapp, A. K.

C₃ woody plant expansion in a C₄ grassland: are grasses and shrubs functionally distinct?¹

²Division of Biology, Kansas State University, Manhattan, Kansas 66506 USA

The expansion of C₃ shrubs into C₄-dominated tallgrass prairies represents a fundamental shift in growth-form dominance accompanied by changes in resource acquisition and use. We assessed these changes by comparing the ecophysiological traits of the dominant C₄ grass Andropogon gerardii, with traits of three C₃ invasive shrub species, Cornus drummondii, Prunus americana, and Rhus glabra. We tested the hypothesis that ecophysiological traits of the shrubs would be similar within this growth form but distinct from grasses and that these species would conform to the two-layer soil water model. Photosynthetic rates in R. glabra were similar to A. gerardii and higher than in the other two shrubs, while water use efficiency was markedly greater in A. gerardii. Among all species, midday xylem pressure potentials (XPP) were distinctly lower (70%) for P. americana, but were similar among the other species. Predawn XPP was related to soil water at shallow depths for A. gerardii (r² = 0.59) and P. americana (r² = 0.62), and to deeper soil moisture for R. glabra (r² = 0.63); there was no relationship for C. drummondii at any soil depth. Thus, a simple two-layer soil water model for partitioning shrub/grass resource acquisition was not appropriate for this grassland. We conclude that these shrubs could not be considered functional equivalents from an ecophysiological perspective, nor were they, as a group, distinct from A. gerardii in resource acquisition and use.

Key Words: C₃ and C₄ photosynthesis • shrub • tallgrass prairie • two-layer soil water model • water use efficiency • woody expansion

This article has been cited by other articles:

				J. L. Heisler, J. M. Briggs, and A. K. Knapp Long-term patterns of shrub expansion in a C4-dominated grassland: fire frequency and the dynamics of shrub cover and abundance Am. J. Botany, March 1, 2003; 90(3): 423 - 428. [Abstract] [Full Text] [PDF]