PS 19-179 - Modelling the effect of within-stand spatial structure on mixed boreal forest succession

Background/Question/Methods

The spatial configuration of individual trees can affect their growth and survival at a fine scale and change the forest composition and structure at the landscape scale. Thus, understanding the stand spatial dynamics at a fine scale is crucial for forest management. The use of SORTIE-ND allows predictions of the growth, mortality, and recruitment of individual trees at a stand scale by emulating gap dynamics. Our research aims to determine the changes in the spatial structure of forest stands using SORTIE-ND and evaluate the model accuracy by comparing the spatial structure of simulated and observed stands. We conducted and validated the simulation with two sets of empirical data from stands located in the boreal mixedwoods of eastern Canada. These stands were formed after eight wildfires since 1760 and represent a chronosequence of 249 years. From this chronosequence, we used the stands on early to mid successional stages as input data and the stands on mid to late successional stages as validation data. We calculated Ripley's L function of spatial structure for each simulated stand and compared it to Ripley's L function for an observed stand of similar age to see how well SORTIE-ND can reproduce the observed spatial structure.

Results/Conclusions

SORTIE-ND produced a similar spatial pattern for single species and pairs of species for the three most common species (Abies balsamea, Populus tremuloides, and Picea glauca) in the observed stands. We can affirm that the SORTIE-ND model provides a realistic representation of the fine-scale spatial pattern for these above-mentioned tree species. The model’s ability to predict at a fine-scale would make it useful for mixedwood boreal forest management from the landscape to fine-scale. However, the study did not focus on all the tree species of the boreal mixedwood and future research on the model performance for other species needs to be evaluated.