This paper presents a comprehensive analysis of the dynamics of forest biodiversity through a model representing a disease–food web system, focusing on the interactions among four animal species within a forest ecosystem. The relationships between predators and prey, as well as the transmission of diseases within this system, provide valuable insights into the functioning of such ecosystems. If predator species are not present, it is proposed that the prey population will experience logistic growth. The hypothesis suggests that the infected prey consume healthy prey, utilizing a Holling type II functional response. This analysis focuses on maintaining non-negative solutions, ensuring that solutions remain within a specific range, and preserving non-negativity over time from initial conditions. These considerations are essential for comprehending the system's behavior and stability. Also, it involves assessing the stability of equilibrium points, which are states where the system remains unchanged over time, and evaluating how the system behaves under different conditions, such as varying environmental factors. Here, local stability is determined by examining the eigenvalue distribution. By investigating the effects of the factors on the model parameters, the study aims to understand how changes in the environment can impact the dynamics of the ecosystem. Thus, by exploring these aspects, the numerical findings of infection rate and predation rate contribute to a deeper understanding of ecological models. This model can be utilized to study and protect forest biodiversity, especially in the face of challenges posed by environmental changes.