Increase of Tree Species Mingling enhances the resistance of <i>Pinus armandii</i> forests to <i>Dendroctonus armandi</i> infestation

<i>Pinus armandii</i> Franch., a key native conifer in China, faces severe <i>Dendroctonus armandi</i> infestation, threatening forest ecosystems. Reducing infestation probability and enhancing resistance are essential for transforming <i>Pinus armandii</i> forests. This study investigates the correlation between stand structure, topographic factors, and the probability of <i>Pinus armandii</i> infestation by <i>Dendroctonus armandi</i>. Based on these correlations, it selects suitable mixed-species combinations of native tree species with low infestation probabilities that are adapted to regional characteristics. A random survey was conducted in 58 plots (6,021 trees) in Shennongjia. Logistic regression and analysis of variance (ANOVA) revealed: (1) Infestation rate increased with elevation, peaking at 84.38% above 2,000 m; between 1,500-2,100 m, probability rose 4.3% per 100 m elevation gain; (2) Steeper slopes (> 25°) reduced infestation (46.03%), with risk decreasing 1.9% per 1° slope increase (0°-40°); (3) Larger DBH (> 30 cm) trees had higher infestation (82.93%), increasing 4.5% per 1 cm DBH; (4) Higher species mingling (four neighboring non-Pinus trees) lowered infestation to 63.39%, reducing risk by 54.3% per mingling unit; (5) Healthy <i>Pinus armandii</i> were frequently neighbored by <i>Litsea pungens</i>, <i>Carpinus cordata</i>, <i>Phellodendron chinense</i>, and <i>Betula platyphylla</i>. Prioritizing slopes > 25° and elevations < 2,000 m for afforestation, mixed with <i>Litsea pungens</i>, <i>Carpinus cordata</i>, or <i>Betula platyphylla</i>, can mitigate infestation. These findings provide actionable strategies to enhance <i>Pinus armandii</i> forest resilience against <i>Dendroctonus armandi</i> threats.