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Modelling silvicultural thinning using unsupervised machine learning: Evidence from Pterocarpus santalinus trial plots of Odisha, India

Sanjay Saini, Swayam Mallick

Abstract


Silvicultural thinning is essential for regulating stand density, yet conventional prescriptions rely on fixed rules and subjective judgment that may not fully account for stand heterogeneity. This study applies unsupervised machine learning to support silvicultural thinning decisions in Pterocarpus santalinus trial plots across Odisha, India. Tree-level girth and height data from six plots were analysed using k-means and hierarchical clustering to classify trees for retention or felling. Across all six plots, k-means produced better-separated clusters than hierarchical clustering, with higher silhouette scores (0.53–0.62 versus 0.46–0.61) and higher Caliński–Harabasz index values (approximately 538–2504 versus 200–2334). The clustering approach offers an objective, reproducible, and quantitative framework for characterising intra-stand variability that can complement traditional rule-based thinning and support more consistent, data-informed silvicultural management.


Keywords


K-means clustering; Hierarchical clustering; Pterocarpus santalinus; Silvicultural thinning; Silhouette score; Caliński–Harabasz index

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References


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