NONLINEAR EFFECTS OF ENVIRONMENTAL FACTORS ON SPECIES RICHNESS IN THE WESTERN TIEN SHAN USING A GENERALIZED ADDITIVE MODEL
Keywords:
species richness, sampling effort, GAM, biodiversity hotspot, Western Tien ShanAbstract
This study evaluated the nonlinear effects of environmental factors on species richness in the Western Tien Shan using a Generalized Additive Model (GAM) with a Negative Binomial family. Species richness was analyzed at the 5 × 5 km grid-cell level, with sampling effort included as a control variable. The final model explained 97.9% of the total variation (Adjusted R² = 0.956), with sampling effort identified as the strongest predictor of species richness (edf = 3.88; p < 0.001). After correcting for the sampling effect, only annual precipitation (BIO12) retained a small but significant independent effect (p = 0.039). These findings show that sampling density is critical for interpreting real species richness patterns and must be explicitly considered in biodiversity hotspot assessment.
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References
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