Species and functional diversities regulate the nutrient allocation of plants to biomass accumulation in logged forests

Abstract

Selective logging is a widely practiced afforestation management strategy aimed at promoting the sustainable utilization of disturbed forests. However, how nutrient allocation strategy between aboveground and belowground regulates community biomass accumulation dynamics after selective logging remains unclear, which becomes a research gap. This study selected six low-intensity selective logging sites and one unlogged site as a control in broad-leaved Korean pine forests located in Northeastern China, representing 6, 14, 25, 36, 45, 55, and 100 years after logging. The nutrient contents of leaf, root, and soil, and plant functional traits of 234 plant species were measured to quantify the nutrient allocation between aboveground and belowground of plants (b_SMA) and the contributions of nutrient allocation to biomass accumulation. Results suggested more stable N utilization in leaves than in roots for trees (b_SMA = 0.80 ± 0.02), shrubs (b_SMA = 0.87 ± 0.03), and herbaceous plants (b_SMA = 0.84 ± 0.02) in logged sites. With increased restoration years after logging, the b_SMA of N increased for trees, shrubs, and herbaceous plants. The community biomass was positively correlated with nutrient b_SMA, which was explained 45 % of the total variation in community biomass. The contribution of nutrient allocation to biomass accumulation was indirectly regulated by functional diversity (0.40) and species diversity (0.33) in selective logging forests. The results emphasize the importance of N allocation strategies of the trees and P allocation strategies of the understory species for biomass accumulation, which closely related with functional diversity. Therefore, this study suggests that forest management should appropriately expand the artificial cultivation of N-fixing plants, especially the understory species to promote the interspecific competition and nutrient cycling in maximizing the carbon stocks in the management of logged forests.

Keywords: Forest management; Functional traits; Nutrient allocation; Plant growth; Selective logging.