Journal Article

Boxelder water sources and physiology at perennial and ephemeral stream sites in Arizona

Thomas E. Kolb, Stephen C. Hart and Ronald Amundson

in Tree Physiology

Volume 17, issue 3, pages 151-160
Published in print March 1997 | ISSN: 0829-318X
Published online March 1997 | e-ISSN: 1758-4469 | DOI:
Boxelder water sources and physiology at perennial and ephemeral stream sites in Arizona

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To assess the influence of stream water on leaf gas exchange and water potential in different sized boxelder trees (Acer negundo L.), we compared these characteristics in trees growing beside a perennial stream and a nearby ephemeral stream in a montane–riparian forest in northern Arizona. Patterns of tree water use were quantified by stable isotope analysis (δ18O). Physiological characteristics were similar for large and small trees. Similarity between sites in predawn and daytime water potentials and xylem δ18O indicated that stream water was not a physiologically important water source. Seasonal and site variations in light-saturated net photosynthetic rate were significantly related to leaf-to-air vapor pressure deficit (r = –0.691) and foliar nitrogen concentration (r = 0.388). Although deep water was the dominant water source, surface soil water was utilized following precipitation, especially by small trees. We conclude that net carbon gain and severity of water stress are only weakly coupled to stream water availability.

Keywords: Acer negundo; nitrogen; photosynthesis; riparian forests; stable isotopes; stomatal conductance; water relations

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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