E. Martinezmeza et Wg. Whitford, STEMFLOW, THROUGHFALL AND CHANNELIZATION OF STEMFLOW BY ROOTS IN 3 CHIHUAHUAN DESERT SHRUBS, Journal of arid environments, 32(3), 1996, pp. 271-287
Three studies were conducted to examine precipitation-vegetation relat
ionships in the multi-stemmed shrubs Larrea tridentata, Prosopis gland
ulosa and Flourensia cernua in a desert ecosystem. We measured stemflo
w and throughfall as affected by bulk precipitation, canopy architectu
re and stem-angles. Using fluorescent dye, we traced root channelizati
on of stemflow water. Stepwise regression analysis showed that the bes
t one-variable model for stemflow in L. tridentata was canopy volume,
which accounted for 87% of variation. The best one-variable model for
stemflow in P. glandulosa and F. cernua was canopy area, which account
ed for 82% of variation in both species. Stemflow data from winter and
summer months were statistically compared to determine the influence
of leaves on stemflow generation in P. glandulosa and F. cernua. Stemf
low amounts collected during winter months do not differ significantly
from those of summer months demonstrating that in these winter decidu
ous species the absence of leaves during winter months does not affect
generation of stemflow. Analysis of variance showed that the percenta
ge of throughfall was different among species suggesting that variatio
ns in canopy characteristics could explain, in part, these interspecif
ic throughfall differences. Both stem-angle and stem-length had a sign
ificant effect on stemflow generation in F. cernua and L. tridentata,
whereas there was only a significant relationship between stem-angle a
nd stemflow in P. glandulosa. Analysis of rhodamine-B dye distribution
under shrubs indicated that root channels are preferential pathways f
or movement of stemflow water into soil, and that this water is potent
ially the source of soil moisture which allows shrubs to remain physio
logically active under drought conditions. (C) 1996 Academic Press Lim
ited