Preliminary Study on the
Endomycorrhizal Arbuscular Potential in Some Soils from the Ecological
Reserve "El Edén", Quintana Roo, Mexico
Instituto de Geología
Calle Teja 157
Col. Jardines del Sur
Xochimilco D.F. 16050 México
tel: (5) 622-42-86
fax: (5) 550-84-32
Kumiko Shimada Miyasaka
Eduardo González Quintero
Instituto de Geología, UNAM
The study area forms part of the edapho-ecosystems that
periodically suffer the impact of hurricanes and fires. The purpose
of this study is to determine the impact caused by this type of disaster
on the number of endomycorrhizal
Five sampling sites were chosen around "La Sabana"
research station, with the following characteristics:
(1) middle rainforest
with 12 to 15 meters high, close to the "tintales", and presented the least grade of disturbance.
(2) rainforest ("acahual")
which suffered a fire about 15 years ago and is now under natural recovery.
(3) the "acahual" which suffered
a fire three months ago, where a breach ("guardaraya") was
open by a type of bulldozer machine.
(4) zone that was burnt (at the same time as mentioned
in 3) and which has been subject to reforestation; and finally.
from the burnt zone which were invaded by fern Pteridium. In
all of these cases, the soils correspond to calcimagnesic intergraded
soils, shallow and generally, A0T1C as in site (1), or AC as in soils
disturbed by fire.
Endomycorrhizal arbuscular potential
was evaluated by the most probable number (MPN) of propagules per gram
of dry soil. Plastic trays for seedlings nursery were used and "Rhodes
grass" (Chloris gayana) was the host plant.
Significant differences of some variables were found
among sampling sites. pH was slightly alkaline (7.1-7.7); organic matter
was high in all sites (16.7 to 32.8 percent). Available phosphorous
ranges from 1.5 to 53 ppm. Phosphorous fixation fluctuates from 36 to
97 percent; the higher levels of available phosphorous may have been
as a consequence of fire impact.
Mycorrhizal colonization varied from 5 to 80 percent,
and was detected in most vascular plants, including ferns from burnt
sites. A significant effect on mycorrhizal potential was also observed.
We are very interested in continuing this study in order
to learn more about the role played by arbuscular mycorrhizal fungi
in this kind of edapho-ecosystems, relating its importance to biodiversity
and colonization and effectiveness capacity.