© 2007 Heron Publishing—Victoria, Canada
Can fog contribute to the nutrition of Chamaecyparis obtusa var. formosana? Uptake of a fog solute tracer into foliage and transport to roots
I-Ling Lai (1), Walter H. Schroeder (2, 3), Jiunn-Tzong Wu (1, 4), Ling-Long Kuo-Huang (1), Carola Mohl (2) and Chang-Hung Chou (5)
1. Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 106, Taiwan / 2. Phytosphere Institute, ICGIII, Research Center Jülich, 52425 Jülich, Germany / 3. Corresponding author (w.schroeder@fz-juelich.de) / 4. Research Center for Biodiversity and Institute of Botany, Academia Sinica, Taipei 115, Taiwan / 5. Research Center for Biodiversity, China Medical University, 91, Hseuh-Shih Rd., Taichung 404, Taiwan / Received February 24, 2006; accepted November 6, 2006; published online April 2, 2007
Summary
Yellow cypress (Chamaecyparis obtusa (Siebold & Zucc.) Endl. var. formosana (Hayata) Rehder) is the predominant tree species of Taiwan's nutrient-poor, mountain fog forests. Little is known about the
potential contribution of solute uptake from fog to the overall nutrition of these trees. Shoots of yellow cypress seedlings
were misted with artificial fog containing the tracer rubidium (Rb) in laboratory and field experiments to determine if there
is solute uptake from the fog. After misting shoots for six weeks, substantial amounts of tracer were detected in unexposed
roots by inductively coupled plasma mass spectroscopy bulk analysis.
Possible routes of entry were examined by element imaging with energy dispersive X-ray analysis. Direct uptake of the tracer
into leaves across the cuticle and epidermis was small, excluding this as the major uptake path. Accumulations of Rb were
found on leaf surfaces along the edges of the leaves. The almost daily changes in fog coverage and air humidity may enhance
the accumulation of fog solutes at leaf edges. Accumulation of Rb was also found in narrow clefts between opposite leaves
and between the outermost and underlying alternating stacked leaves. The clefts provide a direct passage from the leaf surface
to the space beneath the imbricate leaves and the underlying alternate leaves, possibly facilitating solute uptake from fog,
which in turn may contribute to the nutrition of yellow cypress.
Keywords:
EDXA, ICP-MS, nutrient-poor forest, rubidium.
