Preliminary Study on the Endomycorrhizal Arbuscular Potential in Some Soils from the Ecological Reserve "El Edén", Quintana Roo, Mexico

Sergio Palacios Mayorga

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 propagules.

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.

(5) soils 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.

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