Graefe, S.; Leuschner, C.; Coners, H. & Hertel, D. (2011): <b>Root functioning in tropical high-elevation forests: Environmental vs. biological control of root water absorption</b>. <i>Environmental and Experimental Botany</i> <b>71</b>(3), 329–336.
Resource Description
Title:
Root functioning in tropical high-elevation forests: Environmental vs. biological control of root water absorption
FOR816dw ID:
1272
Publication Date:
2011-02-15
License and Usage Rights:
PAK 823-825 data user agreement. (www.tropicalmountainforest.org/dataagreementp3.do)
email:
dhertel <at> gwdg.de
Georg-August University Göttingen
Albrecht-von-Haller Institute of Plant Sciences
Grisebachstr. 1
Plant Ecology
37077 Göttingen
Germany
Abstract:
Lowered temperatures may reduce the root water uptake of tropical trees at high elevations through several mechanisms; however, field studies to test their relevance are lacking. We measured sap flux density (J) in small-diameter tree roots across a 2000-m elevation transect in a tropical mountain forest for quantifying the effects of temperature, VPD and soil moisture on root water flow and uptake at different elevations. Recently developed miniature heat balance-sap flow gauges were applied to roots<br/>
of about 10mm in diameter in mountain forest stands at 1050, 1890 and 3060m a.s.l. in the Ecuadorian<br/>
Andes and the measured flow was related to anatomical properties of the root xylem. Between 1050 and 3060 m, mean J decreased to about a third. VPD was the most influential environmental factor controlling J at 1050 and 1890 m, while Ta was the key determinant at 3060 m. Large vessels were absent in the root xylem of high-elevation trees which resulted in a 10-fold decrease of theoretical hydraulic conductivity (kh theor) between 1050 and 3060 m. We conclude that both physical limitations (reduced VPD, increased viscosity of water) and biological constraints (large decrease of kh theor) result in a significantly reduced J and root water uptake of the trees in high-elevation tropical forests.
