Since 1990, externally funded tree-planting activities have taken place in more than 350 Iowa, U.S., communities. The species diversity, survival, size, growth, carbon uptake, carbon storage, and pollution removal of 932 trees planted in 2 1 commu- nities of different sizes and in different parts of Iowa were assessed by repeated measurements over a 4-year period. The sample included 40 tam and was dominated by crabapples (Malw spp.) and green ash (Fraxinw pennsylvanica Marsh.). Species diversity was described using the reciprocal of Simpson's index for the overall population (10.92), by community size, and by location in the state. No differences in species diversity were detected according to community size or location in the state. Overall survival rate for the trees was 91%; no significant differences in survival rate related to community size or location were detected. Estimated carbon stored by all trees was 2,252 kg (4,954 lb), and carbon uptake was estimated to be 568 kg yr¹ (1,250 lb). Total pollution removal by all trees was estimated at 2 kg yr¹ (4.4 lb)