This study was an attempt to identify adequate maintenance regime for trees in the planting sites of city parks. The lifetime of trees that received 7 types of maintenance regimes was compared using a numerical model described by Watanabe (2011), to which some revisions were made. Tree density, soil texture, site preparation, and maintenance regimes were identified as factors that influence the lifetime of trees, decided 3 levels on 4 factors, and 34=81 simulated cases of planting sites that received the 7 types of maintenance regimes (in combination with pruning, litter removal, and trampling) were evaluated. The results were as follows: (1) To increase the lifetime of trees in the planting sites of city parks by using maintenance regimes, it was valid to reduce the intensity of pruning gradually by 40-60 years after planting and then accelerate loosing the surface soil in the absence of litter removal and trampling by 70-90 years after planting. (2) The lifetime of trees in the planting sites of city parks was influenced by parameters in the following order: pruning > site preparation > litter removal > tree density > trampling. (3) This study and that by Watanabe (2011) showed that the most important factor for tree growth rate was site preparation, but the most important factor for increasing the lifetime of trees was pruning in the planting sites of city parks.
