Influence of health status and environmental factors on the trade-off between aboveground growths of endangered Abies koreana in Mt. Jirisan, South Korea

Understanding resource allocation trade-offs is essential for efficient forest management, particularly for species prone to decline amidst challenging environmental conditions. However, the allocation of resources to aboveground organs under varying health statuses and environmental conditions remains unclear. Therefore, we examined the trade-off relationship between the growth of aboveground organs and influence of environmental factors, particularly in high-altitude regions vulnerable to climate change. Growth of aboveground organs and trade-off between healthy and declining Korean fir trees in subalpine forests was examined. Korean fir demonstrated distinct temporal shifts in the trade-off among aboveground organs based on health status. Healthy trees exhibited the highest relative benefit in needle length. In contrast, declining trees showed the most significant relative benefit in branch length. In post-drought events, healthy trees displayed a recovery in the trade-off among aboveground growth, whereas declining trees did not exhibit a similar recovery. When examining the influence of environmental factors, a high average temperature before the growing season negatively affected the growth of branches and needles, irrespective of their health status. Concurrently, the needle length and tree-ring width of Korean fir trees decreased with a decrease in soil pH and cation content. However, stem growth tended to favor more than needle growth with abundant soil nutrients. Overall, high temperatures preceding the growing season and soil acidification serve as crucial factors influencing aboveground growth and the trade-off relationship in Korean fir trees. These findings are expected to contribute to enhancing forest management strategies for conserving this declining species in their natural habitat.