Although climate change-related concerns have long been raised regarding the sudden dieback of Korean fir (Abies koreana), the event's etiology and subsequent ecosystem processes must be explained. Our study aims to clarify the continuity or transience of mass mortality events within the coarse woody debris (CWD) structure and, if transient, to identify the climatic conditions (1974-2021) that could be responsible for the massive dying phenomena in Korean fir populations. On average, precipitation during the non-growing season (November-April as winter) constituted 18.5% relative to the growth period; in the winter of 1999, it was 4.8% due to an abnormal drought event. The dead stems occurred evenly across all size classes. In the CWD structure, the density and biomass of the dead fir individuals peaked in decay classes II or III. The size distribution of the retained fir was inverse-J shaped across the entire altitudinal range. The abnormal winter drought event, causing root damage by soil frost and heaving, may be one of the factors that increased Korean fir mortality across the entire stem size range. Despite transient cohort senescence, the retained Korean fir individuals transmitted drought-resistant traits into the regional pool following the drought event.

Iodine deficiency is a global public health problem and dietary microgreens represent a possible cost-effective supplement. Bacillus velezensis is a commonly occurring soil bacteria that promotes plant growth. However, little attention has been paid to the effects of B. velezensis on the absorption of iodine by plants. Herein, we demonstrated that B. velezensis accelerates pepper seed germination and growth under 0.01 mmol/L KI supplement, with an 85.9% increase in fresh biomass. B. velezensis induced approximately 2.0 -fold higher iodine absorption. Likewise, colonization by B. velezensis occurred in the microgreens. Consequently, the total thiol, vitamin C, total phenolics, and the antioxidant capacity were increased. This was followed by a marked decrease in the catalase and total superoxide dismutase activities. Furthermore, the combination of B. velezensis and 0.01 mmol/L KI significantly decreased the relative water content and membrane damage (malondialdehyde and relative electrical conductivity). Intriguingly, the transcripts of ethylene biosynthesis genes CaACS10 and CaACO1 were downregulated, whereas CaACO3 expression was upregulated. Thus, the present study showed that B. velezensis accelerated iodine accumulation; improved seed germination and seedling growth; elicited antioxidant bioactivity; decreased membrane damage; and preserved vegetable microgreen quality during storage.