Tuesday, August 4, 2009 - 10:50 AM

COS 24-9: The role of elevated selenium in leaf litter decomposition

Colin F. Quinn and Elizabeth A.H. Pilon-Smits. Colorado State University

Background/Question/Methods

Some plant species hyperaccumulate the element selenium (Se) up to 10,000 mg Se kg-1, or around 1%, dry weight. Recent research has focused on the functional significance of this rare phenomenon, specifically the role Se hyperaccumulation plays in protection from herbivore and pathogen attacks. Elevated levels of Se protect plants from a variety of both herbivores and pathogens. Since many herbivores and pathogens are Se sensitive, it has been hypothesized that decomposing communities may also be Se sensitive, and that leaf litter with elevated Se will decompose slower than leaf litter with low Se. However, the role Se plays in leaf litter decomposition, and the surrounding microbial community, has yet to be investigated. In this study the decomposition rates and quality of leaf litter with varying Se concentrations were compared in a seleniferous habitat. In addition, the bacterial, fungal and micro-arthropod communities were analyzed in each leaf litter treatment.

Results/Conclusions

Interestingly, leaf litter with high Se decomposed faster than leaf litter with low Se. More bacteria, fungi and micro-arthropods were present in leaf litter with high Se, and the microbial community varied for each leaf litter treatment. This study suggests that decomposing communities in seleniferous habitats can tolerate, and may prefer, elevated Se, and, as a result, leaf litter with elevated Se may decompose faster than leaf litter with low Se.