Effects of stand condition and root density on fine-root dynamics across root functional groups in a subtropical montane forest

Abstract

Fine roots play key roles in belowground C cycling in terrestrial ecosystems. Based on their distinct functions, fine roots are either absorptive fine roots (AFRs) or transport fine roots (TFRs). However, the function-based fine root dynamics of trees and their responses to forest stand properties remain unclear. Here, we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment. Mean (± SE) annual production, mortality, and turnover rate of AFRs were 7.87 ± 0.17 m m−2 a−1, 8.13 ± 0.20 m m−2 a−1and 2.96 ± 0.24 a−1, respectively, compared with 7.09 ± 0.17 m m−2 a−1, 4.59 ± 0.17 m m−2 a−1, and 2.01 ± 0.22 a−1, respectively, for TFRs. The production and mortality of fine roots were significantly higher in high root-density sites than in low-root density sites, whereas the turnover of fine roots was faster in the low root-density sites. Furthermore, root density had a larger positive effect than other environmental factors on TFR production but had no obvious impact on AFR production. Tree species diversity had an apparent positive effect on AFR production and was the crucial driver of AFR production, probably due to a complementary effect, but had no evident impact on TFR. Both tree density and tree species diversity were positively correlated with the mortality of AFRs and negatively related to the turnover of TFRs, suggesting that higher root density caused stronger competition for rooting space and that plants tend to reduce maintenance costs by decreasing TFR turnover. These findings illustrated the importance of root functional groups in understanding root dynamics and their responses to changes in environmental conditions.

Contrasting Spatio-temporal Variation of Fine Root Dynamics in Nearby Evergreen Korean Pine and Deciduous Oak Forests and Their Potential Impact on Soil Properties

“…While TBK exhibited greater total length production in the minirhizotron, TCK showed similar area production and a larger volume (Table 2). In general, larger ne root length and surface area indicate advantages in nutrient and water acquisition by increasing soil occupation, while a larger root volume is associated with carbon sequestration (Huang et al, 2023;Jackson et al, 1996;Pinno and Wilson, 2013). Therefore, the more pronounced peaks in length and surface area of TBK during the summer growing season may re ect their higher ability to e ciently forage for nutrients within a shorter period of time, before leaf senescence.…”

Enhancement effects of mangrove restoration on blue carbon storage in Qinzhou Bay

“…The average carbon stocks of belowground and total culms in all sampling sites were calculated. Spearman's rank correlation analysis was employed from the R "corrplot" package to preliminarily examine the covarying environmental factors and the relationship between all environmental variables and carbon storage in different components (Huang et al, 2022). Linear regression analysis was used in this study to analyze the relationships between the environmental variables and carbon stocks in different components.…”

Fine root decomposition in forest ecosystems: an ecological perspective

“…They actively interface with the environment play key roles in terrestrial ecosystem processes, and make up 33% of the world's annual NPP (Li et al, 2019). Fine roots components can be divided into long-lived transport fine roots (TFRs) and short-lived absorptive fine roots (AFRs) (Figure 1) (Huang et al, 2023). TFRs (root orders 4 and 5) help with long-distance transport and hydraulic conductivity by moving water and nutrients from the soil to above-ground plant components.…”