The concentrations and ratios of plant C, N, and P serve as important indicators of ecological processes. However, how plant and soil C:N:P relationships and ratios change with forest stand types remain unclear. Here, we analyzed the ecological stoichiometric characteristics by measuring leaf and soil organic C, total N and P contents in four stand types in Liaocheng, including Populus tomentosa pure forest, Populus tomentosa-Robinia pseudoacacia mixture forests, Platanus orientalis pure forest, and Salix matsudana pure forests. We find that: (1) The N and P leaf contents varied significantly across the four forest stands, with Populus tomentosa-Robinia pseudoacacia mixture forests having higher P levels. Platanus orientalis pure forests had lower C and N but higher P levels compared to others. (2) Uncoupled cycling of P in leaf-soil systems due to environmental influences, but C and N elements showed coupled cycles in some forest stands. (3) All forest stand types were limited by N and P elements. Overall, environmental factors, in addition to species variations, influence the C, N, P, and C:N:P ratios in leaves and soils of different forest stand types. Enhancing conservation and efficient use of N and P elements is crucial for sustainable plantation forest management to promote optimal growth in the region.