Spartina alterniflora leaf litter bundles were placed in a North Carolina Salt marsh to study the effects of environmental heterogeneity on decomposition and animal Colonization. Sediment type (mud vs. sand), tidal inundation zone (near bay, mid-marsh and upper marsh) and Spartina growth form (tall vs. short) were studied. Tidal zone had the greatest effect on decomposition rate. The main effects of sediment type and growth form were not significant. All treatments affected animal distribution patterns in the leaf bundles. Nearly all common taxa were more common on mud than sand. Most taxa showed a strong association with one tidal zone. half of the taxa were associated with one of the Spartina growth forms. Many interactions among the treatments were also significant. This study demonstrates the significance of environmental heterogeneity in a Spartina marsh both for litter decomposition and animal distributions.