St. Bacchus et al., Soluble sugar composition of pond-cypress: A potential hydroecological indicator of ground water perturbations, J AM WAT RE, 36(1), 2000, pp. 55-65
Citations number
53
Categorie Soggetti
Environment/Ecology
Journal title
Journal of the american water resources association
Pond-cypress, a deciduous conifer, is a dominant canopy species in depressi
onal wetlands of the southeastern Coastal Plain (SCP). Extensive premature
decline and death of pond-cypress trees in central Florida have been attrib
uted to hydroperiod alterations due to excessive withdrawals of ground wate
r from the Floridan aquifer. One factor identified in the decline process i
s basal decay, which may be related to the presence of Botryosphaeria rhodi
na and Fusarium species (nonaggressive, facultative fungal pathogens). Thes
e fungi have been cultured from sapwood tissue of declining pond-cypress as
sociated with ground water mining, but not from pond-cypress away from grou
nd water mining areas. In this experiment, differences in soluble (nonstruc
tural) carbohydrate composition of branch tips were evaluated for one- and
two-year old, nursery-grown (unsheltered) pond-cypress, following a year of
growth under treatment conditions (control, fungal inoculation, water stre
ss, and fungal inoculation plus water stress) in a growth chamber. Results
from two methods of wet chemical analysis were compared (trimethylsilyl met
hylglycoside Method A, and alditol acetate - Method B). Three pentoses (ara
binose, rhamnose, and xylose) and three hexoses (galactose, glucose, and ma
nnose) were identified in branch tips from both age classes. A fourth hexos
e (fucose) also was identified in samples from the younger trees. The acidi
c sugar, galacturonic acid, was identified in both age classes using Method
A. Results suggest that prolonged water stress is correlated with greater
relative concentrations of the neutral soluble sugars rhamnose (P = 0.02),
xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic suga
r galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for
Method B. These results also suggest that in the absence of water stress, t
he fungal pathogen B. rhodina does not penetrate to the sapwood of the tree
s, and that inoculation with this fungal pathogen is not correlated with di
fferences in relative concentrations of nonstructural, soluble carbohydrate
s, based on Method A analysis. Empirical evidence suggests that pond-cypres
s trees in depressional wetlands respond similarly to anthropogenic perturb
ations of ground water, but not to natural periods of drought in the absenc
e of such perturbations. Therefore, pond-cypress appear to be integrators o
f groundwater perturbations. Greater concentrations of the soluble sugars i
dentified in this study in pond-cypress branch tips may be hydroecological
indicators of such anthropogenic perturbations as unsustainable yield from
the regional aquifer and adverse impacts from aquifer storage and recovery
(ASR) activities in the SCP.