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Mycorrhizal Status of psamophilous meadows in sand dunes of
Venezuela
Poster Session: Mycorrhizas in Stressed Ecosystems
ALARCON, CLARA1 & GISELA CUENCA2
1Postgrado de Botánica, UCV - CIEZA,
UNEFM, Venezuela
2Centro de Ecología, Instituto Venezolano
de Investigaciones Científicas. Apartado 21827.
Caracas 1020-A Venezuela.
ICOM1 Abstract
Colonization percentage by mycorrhizal of the most
abundant herbaceous and arbustives plant species was
determined in the psamophilous meadows of the coastal sand
dunes in Paraguan‡ Peninsula, Venezuela. The presence of AM
fungi in soils was quantified by measuring mycorrhizal
colonizations within fine roots with a light microscope
using a clearing and staining procedure. Samples of
rootlets were taken in twelve plant species: Acacia
tortuosa, Argusia gnaphaloides, Croton punctatus, C.
ramifolium, Egletes postrata, Fimbrystilis cymosa,
Leptothrium rigidum, Melochia crenata, Panicum vaginatum,
Scaveola plumieri, Sporobolus virginicum and Suriana
maritima. Colonization percentage by mycorrhizal was
evaluated by Trouvelot et al (1986) method, which
considers both arbuscules and vesicles. Pelotons and hyphae
were also evaluated. C. ramifolium had the highest AM
colonization frecuency (92.0 %), when compared with L.
rigidum and F. cymosa which had very low mycorrhizal
colonization frecuencies. These frequencies varied from
49.3 to 86.0 % for the other species. The psamophilous
meadows had 68.8% and 7% of average frequency and
intensity of mycorrhizal colonization, respectively. When
our results are compared with other tropical ecosystems, we
can conclude that the frequency of mycorrhizal colonization
in the meadows sand dunes in northern Venezuela is similar
to other tropical natural ecosystems like herbaceous
savannas, but their colonization intensity by mycorrhizal
is typical of perturbed ecosystems.