Combined effects of environmental conditions and stand age–induced tree size variation on temperate forest carbon pools among stand types in South Korea

Abstract

The conservation of biodiversity and carbon sequestration in forests has global significance. In this study, we aimed to investigate strategies to enhance biodiversity and forest carbon pools in temperate forests. We analyzed soil sample data from 725 plots (400 m² each) collected from the National Forest Inventory of South Korea, categorizing them into three forest stand types: conifer, broadleaved, and mixed stands. Abiotic drivers (topographic and climatic factors, and soil properties), biotic drivers (taxonomic and functional trait diversity, functional trait identity, and stand structural diversity), and forest development stage-related factor (stand age) served as independent variables. We applied a multimodel averaging approach and piecewise structural equation modeling to identify the main drivers and linkages controlling forest carbon pools, including tree biomass, coarse woody debris, and soil organic carbon (SOC) for each stand type. Our findings revealed that stand age–driven tree size variation (i.e., standard deviation of diameter at breast height) influenced each forest carbon pool across all stand types, with different biotic drivers affecting the linkages among carbon pools depending on forest type. Additionally, environmental conditions, especially soil chemical properties, were the main drivers controlling SOC among forest carbon pools. In this study, we suggest that different forest management plans should be implemented to enhance the carbon sequestration capacity and biodiversity of each forest stand type.