Seasonally dry tropical forests (SDTF) account for nearly half of the world’ s tropical and subtropical forests but remain one of the most endangered habitats. High rates of forest clearing for pasture, frequent fires, and pressure from population growth have all contributed to severe fragmentation and degradation of SDTF. Most conservation efforts to date have been directed toward specific plant taxa or areas that contain high levels of plant endemism. Although valuable, this approach overlooks less obvious targets for conservation, such as fungi, that are critical to plant growth (mycorrhizal fungi) and ecosystem function (decomposer fungi).

Our studies have examined ectomycorrhizal (ECM) diversity in oaks (Quercus oleoides) in Costa Rica, and arbuscular mycorrhizal fungal (AMF) and lignin-degrader communities in the Yucatán in Mexico.  In Costa Rica, we identified 37 ECM species. The community was dominated by one species (Thelephora) but more than half of all ECM species were rare and found only once. In the Yucatan, lignin-degrading fungal communities are species-rich (more than 400 species) and very dynamic.  In a two-year study, we found that one group of fungi (Trechisporales) occurred in both years and seasons (dry, wet).  Apart from this group, the entire fungal community shifted in composition from year to year, and between wet and dry seasons.  We also found that AMF communities were species-rich (140 species) but that most species (120 AMF) were rare.  Communities also showed strong seasonal shifts and potential specificity to certain tree species. These results highlight the need for a comprehensive survey of fungal diversity, and the need to identify and prioritize rare fungal species for conservation.

Students: Morgan, Ross