Ponderosa pine (Pinus ponderosa) is a foundational species in dry-forest landscapes across western North America. Ongoing warming and aridification intensify climatic stress across its native range. Prior research on ponderosa pine health is regional in scope and focuses on single disturbances, leaving the combined influence of climate, stand structure, and biotic agents on dieback and mortality poorly understood. To address these knowledge gaps, we surveyed sites across California, Colorado, Idaho, Montana, and Wyoming during 2024 and 2025. At each site, we characterized stand conditions, assessed tree health, and collected tissue samples for pathogen identification. Long-term changes in climate were also recorded at each site to test associations between tree health and biotic and abiotic factors. Recent climate trends included reduced precipitation, elevated mean temperatures, and changes in vapor pressure deficit, indicating the potential for climatic stress on trees. Of the 324 trees surveyed, 25.8% had detections of pathogens and symptoms consistent with pathogen infection. Pathogens were composed of two functional groups: (1) needle and branch pathogens, including the widely distributed endophyte, Sydowia polyspora, primarily associated with trees of moderately poor health status, and (2) vascular stain fungi that were strongly linked to recent mortality. Only S. polyspora showed significant relationships with abiotic conditions in generalized linear models, while non-metric multidimensional scaling revealed clear geographic structuring of pathogen assemblages. In summary, our study suggests that climatic stress is associated with increases in host vulnerability to biotic agents, while fungal pathogens exhibit distinct associations with moderate decline and recent mortality.
Japanese cedar (Cryptomeria japonica) is the most widely planted tree species in Japan; however, Japanese cedar planted forests in cool-temperate regions are highly vulnerable to heavy snowfall. Snow damage reduces the number of healthy, marketable trees, leading to declines in timber-provisioning services and income for forest owners. In contrast, ecological succession following snow disturbance often promotes establishment of deciduous tree species such as Aralia elata, Chengiopanax sciadophylloides, and Kalopanax septemlobus, which produce edible wild shoots that may provide an alternative income source. To evaluate the economic implications of snow disturbance for both timber- and food-provisioning services, we conducted a tree inventory in a Japanese cedar stand severely damaged by heavy snowfall in December 2014 in Gifu Prefecture, Japan, and combined these data with national statistics and online marketplace analyses. The estimated timber income loss caused by snow disturbance was approximately JPY 443,000 ha−1. In contrast, field surveys conducted in spring 2023 indicated that the potential seasonal value of harvestable edible wild shoots reached JPY 83,800 ha−1 year −1. Market analyses showed that these shoots are actively traded as wild delicacies on nationwide online platforms, enabling forest owners to reach a broad consumer base. Overall, our findings suggest that income losses caused by snow-related reductions in timber provisioning may be partially offset over several years by utilizing naturally regenerating edible wild plants. Incorporating edible wild plant harvesting into post-disturbance forest management may enhance the economic resilience and sustainable use of snow-disturbed planted forests.
The pine processionary moth (Thaumetopoea pityocampa) is an important defoliator of circum-Mediterranean pine forests. Females are capital breeders and lay their eggs in a single egg mass, making oviposition site selection potentially important for offspring survival. We examined host-tree selection and within-tree egg mass distribution in three pine stands in southeastern Spain spanning an elevational range of 900–1820 m a.s.l. We recorded the number and position of egg masses and analysed their relationships with tree isolation, tree height, late-afternoon solar direction and local topography. In the primary model, more isolated trees had a higher probability of being selected, whereas taller trees received more egg masses once selected. Egg masses were preferentially located on the side of the tree facing the late-afternoon sun at all three sites, and solar alignment was stronger for downslope positions. The downslope–upslope contrast in the probability of sun-facing placement was greatest at the upper site. Vertical placement also differed among sites: egg masses occurred predominantly in lower canopy positions at the lower site, were more evenly distributed at intermediate, and occurred mainly in intermediate and upper positions at the upper one. Overall, these results indicate that oviposition-site selection operates across multiple spatial scales, from host-tree selection to within-tree orientation and vertical distribution.
