Restoration and Mycorrhizae in Seasonal Tropical Forest in Mexico

Edith Allen

UC Riverside
Dept. of Botany & Plant Sci.
Riverside CA 92521-0124 USA
tel: (909) 787-2123
fax: (909) 787-4437

Arturo Gómez-Pompa

UC Riverside
Dept. of Botany and Plant Sciences
Riverside CA 92521 USA
tel: (909) 787-4686
fax: (909) 787-4748


Michael F. Allen

San Diego State University
Dept. of Biology & Systems Ecology Group
San Diego CA 92182 USA

The proposed research combines two areas of research, mycorrhizae and restoration ecology, that have special relevance to the tropics. The dry seasonal tropical forests have received less attention than the humid tropical forests, but they have been destroyed at a greater rate.

Less than 10 percent of the Mesoamerican seasonal tropical forest remains, so restoration must supplement conservation for the protection of diversity and ecosystem functioning. We propose to set up forest restoration research plots at two seasonal tropical sites in Mexico, one on the central west coast at the Chamela Ecological Reserve and one on the east coast at the El Eden Ecological Reserve in northern Quintana Roo.

Many of the Pacific Coast forests have been converted to pasture, and the remaining Quintana Roo forests are subject to hurricanes and frequent fires. Pteridium aquilinum (bracken fern) has been invading the burned sites and slowing the time for natural succession. The sites have many plant species and genera in common and a similar seasonal dry climate, but have very different soils.

The Yucatan Peninsula has calcareous, phosphorus-fixing soils, while the Chamela area has geologically young soils with high available P. This suggests that mycorrhizae may be more important for P nutrition at El Eden than Chamela. Our preliminary surveys show that the bracken fern fields have very low mycorrhizal activity immediately after a fire, and Chamela pastures have changed species composition of mycorrhizal fungi.

Thus we propose to examine the role of mycorrhizal inoculation and tree planting on succession during three years. Our field experiments will be replicated at both reserves, with 10 tree species from each reserve planted into fields that have been experimentally burned. Different sources of inoculum will be used, including forest, field, and commercial inoculum, as well as an noninoculated control.

A greenhouse experiment will be done at the Chamela Reserve using local seeds and soil from both reserves in pots inoculated with the same mycorrhizal treatments as in the field. We will monitor naturally occurring species of mycorrhizal fungi and root infection in different disturbance types at each reserve, mycorrhizal and plant recolonization into the restored and control plots, and measures of soil nutrient pools and turnover of N over time.

In addition, we will study tree growth and succession after anthropogenic disturbance, both of which are little understood for these forests.