Species and microsite effects on litter decomposition in a Puerto Rican landslide

Because decomposition is an important ecosystem process and species control of it is an issue in the tropics, we examined how much plant species controlled decomposition compared to environmental conditions on a landslide in Puerto Rico. We chose a landslide because of its extreme special variation in environmental conditions, and found that the landslide center microsite had the greatest variation in temperature and precipitation. Litterbags were filled with single-species leaves of three different plant species and placed in center, border and forest landslide microsites. Bags were collected after 1, 2, 4, 8 and 16 weeks and analyzed for organic matter and various other chemicals. All chemicals showed strong differences among plant species and very little significant environmental variation and. with one exception, organic matter loss followed the same exponential decay pattern for all species and microsites. Interestingly, nitrogen (N) and phosphorus (P) immobilization was seen for all three litter types, and calcium immobilization was seen for two of the three. However, immobilization of N and P were most pronounced for the early successional species. Finally, the dominance of species effects over environmental effects suggests that leaf litter chemistry strongly influences decomposition in landslides. While the soil decomposer biota act similarly along landslide environmental ranges, they are more responsive to substrate quality.