Effect of mulching with compost on growth and physiology of ulmus 'FL634' planted in an urban park

The effects of mixed compost as mulching material on growth and physiology of newly planted elm trees were evaluated over a three-year period after planting in an urban park. Trees mulched with compost generally had greater height (+10% and +19% for 5 cm layer and 10 cm layer treatments, respectively, if compared to control), trunk diameter (+13% and +29%), and current-year shoot growth (+46% and +56%). Limited effects were found with regard to carbon assimilation when considered on a per unit-leaf-area basis (-0.1% and +0.3%), but whole tree carbon assimilation increased in mulched trees (+7% and +59% for 5 cm and 10 cm treatments, respectively, if compared to control) because of the larger total tree leaf area of mulched plants. Mulching also increased chlorophyll content (+4% and +7% for 5 cm and 10 cm treatments, respectively). The results obtained in this study show how mulching with compost increased growth, carbon storage, and improved water use efficiency of trees planted in an urban environment characterized by hot dry summers.