Decoding the interplay between tree traits, seed production, and cone-boring insect damage using advanced modeling to unveil the intricacies of Atlas cedar ( Cedrus atlantica ) forests

This study aimed to (i) determine the influence of the factors “aspect” and “cone orientation within the tree crown” on cone morphometric traits of Atlas cedar, (ii) determine the relationship between these traits and seed production; and (iii) estimate the damage caused by insects to cones and seeds and the spatial distribution of cone and seed infestations. Within each of the four selected stations, 25 cones were randomly collected from five trees. The parameters determined were: cone morphometric traits, seed yield per cone, number of bores per cone, healthy and infested seeds, and seed damage rates. Despite the variation observed, aspect and orientation had no significant effect ( p > 0.05) on cone morphometric traits (length, width, weight and volume); nor on seed production, number of insect exit holes and resin exudation levels. Generalized linear models (GLM) revealed that the number of seeds per cone varied significantly and differently according to cone morphometric traits, site aspect, cone orientation and their interactions. Seed production increased significantly ( p < 0.001) with increasing cone length, width, volume and weight in south-facing versus north-facing sites. This increase varied with tree crown position. The variation in seed cropping size among aspects and cone orientations was not significant. The number of healthy seeds per cone was significantly higher ( p < 0.001) than the number of infested seeds. GLM showed that seed infestation rates responded positively to southern exposure and infestation indicators (number of holes per cone and level of resin exudation). Seed damage rates were not influenced by cone length, width, volume and cone orientation. The variations observed in seed damage seem to be related to intraspecific variation, tree age, and site-specific trophic conditions. While aspect and cone orientation had limited impacts, the research highlighted significant links between seed yield, cone traits, and site characteristics. Seed damage showed intricate relationships with the studied variables. These insights offer valuable guidance for forest management and suggest avenues for investigating genetic and ecological variations to enhance conservation strategies.