Center for Embedded Network Sensing

Seasonal tropical forests are currently experiencing rapid deforestation and changing land management practices, which in turn may permanently transform mature forests into more shrub-herbaceous dominated plant communities and planted pastures. Effective restoration efforts are therefore essential for maintaining the biodiversity and ecosystem functioning in seasonal tropical forests, yet before implementing restoration efforts we need to better understand mechanisms influencing secondary plant succession. The main objective of this study was to investigate the ecological significance mycorrhizae, the symbiotic association between plant roots and specific fungi, may have during secondary plant succession. In 2004, we selected a chronosequence of five distinct stages of secondary succession ranging from recently disturbed areas to more mature forest at El Eden Ecological Reserve in northeastern Yucatan. We determined the plant community composition, as well as, the percent vesicular-arbuscular mycorrhizae (VAM) colonization and VAM spore diversity for each of the distinct stages of succession. Based on preliminary data we found a relatively low Sorenson index for plant species composition among the different stages (0.24-0.430) compared to within specific stages (0.50- 0.789), suggesting that plant communities are changing during secondary succession. On the other hand, we detected no significant difference in vesicular-arbuscular mycorrhizal (VAM) infection among the chronosequence, with an overall average infection of 16.94%. Nevertheless, we did observe a change in VAM species from small-spored Glomus species in earlier stages of succession to larger-spored Gigaspora and Acaulospora species as the forest matures. It therefore appears that in order to maintain the biodiversity and ecosystem functioning of seasonal tropical forest attention must also be give to below ground processes such as mycorrhizal fungi.