To enhance the PDG-Arena model's ability to simulate species-specific water uptake strategies and nutrient competition, several improvements could be implemented. First, integrating a more detailed representation of root architecture and depth could allow for the simulation of vertical stratification in water uptake. Different tree species often exploit varying soil depths for moisture, which can significantly influence their competitive dynamics. By incorporating species-specific root depth profiles and water extraction patterns, the model could more accurately reflect how mixed species interact regarding water resources.
Additionally, the model could benefit from the inclusion of nutrient cycling processes. Currently, PDG-Arena does not account for competition for nutrients, which is a critical aspect of tree interactions in mixed forests. Implementing a nutrient dynamics module that simulates the availability and uptake of key nutrients (e.g., nitrogen and phosphorus) would allow for a more comprehensive understanding of how nutrient competition affects tree growth and productivity. This could involve modeling the effects of litter decomposition, soil microbial activity, and nutrient leaching, which are essential for capturing the complexity of nutrient interactions in diverse stands.
Finally, incorporating phenotypic plasticity into the model could enhance its predictive capabilities. By allowing trees to adjust their growth strategies based on local resource availability, the model could simulate how species adapt their water and nutrient uptake strategies in response to competition and environmental changes. This would provide a more nuanced understanding of the diversity-functioning relationship in mixed forests.