This paper presents a methodology for evaluating the performance of wireless sensor network (WSN) protocols in different tree-obstructed propagation environments. To create this methodology, practical RF propagation models that include many of the substantial features of different tree-obstructed propagation environments are utilized, and radio energy models for different tree-obstructed propagation environments are developed. Moreover, the presented simulations are compared with each other so that the differences in the performance of WSN in various tree-obstructed propagation terrains can be identified. The results obtained through the comparison of these dissimilar outdoor propagation environments reveal significant differences in the lifetime and throughput. Furthermore, generated results using these practical RF propagation models are compared with the results using free space and two-ray propagation models to demonstrate the imprecision of these theoretical propagation models in evaluating the performance of WSN in tree-obstructed environments.