Flower petals can be valuable plant tissue, with high amounts of nitrogen and phosphorus. Coffee (Coffea arabica) flowers synchronously and flowers are only open for a few days before senescing. A pulse of petals to the detrital pool could be important for the decomposer community and decomposition processes.
Our research assessed the magnitude of the pulse of petals in a shaded coffee farm, and the impact of petals on the leaf litter community, and on leaf litter decomposition. We hypothesized that flower petals would accelerate the decomposition rate of leaf litter. While we did not expect the community composition to change, we hypothesized that the abundance of micro-arthropod decomposers would increase where flower petals are added.
Three plots of twelve coffee plants were monitored throughout the flowering period to determine the magnitude of the bloom, as indicated by the number of flowers and the length of time each was open. Pitfall traps were used to assess the leaf litter community before and after flowering. After flowering began, petals were added or excluded from sites to assess how the leaf litter community changed. Finally, litterbags with C. arabica leaves alone and C. arabica leaves with flower petals were used to compare the mass loss of leaves decomposing alone and leaves decomposing with petals.
Results/Conclusions
We quantified the number of petals on each coffee plant in our monitored plots and the number of days they were open during the bloom. The leaf litter community did not change throughout our sampling, indicating that flower petals may not alter the abundances of decomposers, or that community effects may be acting on a longer time scale than the bloom itself. Leaf litter did decompose more quickly in litterbags that also included flower petals, in comparison to litterbags with just C. arabica leaf litter. The direction and magnitude of this result was similar after 1 and 2 months. This suggests that the input of flower petals can accelerate decomposition processes, even if the decomposer community is not responding within the time scale of the pulse.