Pang Yue, Tian Jing, Yang Hang, Zhang Kai, Wang Dexiang
College of Forestry, Northwest A&F University, Yangling, Xianyang 712100, China.
Biology (Basel). 2022 Feb 22;11(3):351. doi: 10.3390/biology11030351.
Fine roots make critical contributions to carbon stocks and terrestrial productivity, and fine roots with different diameters exhibit functional heterogeneity. However, the changed characteristics of fine roots with different diameters at different soil depths following thinning disturbances are poorly understood. We investigated the biomass, production, mortality and turnover rate of <0.5 mm, 0.5−1 mm, and 1−2 mm fine roots at 0−20 cm, 20−40 cm, and 40−60 cm soil depths under five thinning intensities (0%, 15%, 30%, 45%, and 60%) in a secondary forest in the Qinling Mountains. The biomass, production and turnover rate of <0.5 mm fine roots fluctuated with increasing thinning intensities, while the 0.5−1 mm and 1−2 mm fine-root biomass significantly decreased. The thinning intensities had no effects on the fine-root necromass or mortality. The change in the fine-root characteristics in deeper soils was more sensitive to the thinning intensities. The principal component analysis results showed that increased <0.5 mm fine-root biomass and production resulted from increased shrub and herb diversity and biomass and decreased soil nutrient availability, stand volume, and litter biomass, whereas the 0.5−1 mm and 1−2 mm fine-root biomass showed the opposite trends and changes. Our results suggest that different thinning intensities exhibit varied influential mechanisms on the changed characteristics of fine roots with different diameters.
细根对碳储量和陆地生产力有着至关重要的贡献，且不同直径的细根表现出功能异质性。然而，间伐干扰后不同直径细根在不同土壤深度的变化特征却鲜为人知。我们研究了秦岭次生林中在五种间伐强度（0%、15%、30%、45%和60%）下，0-20厘米、20-40厘米和40-60厘米土壤深度处直径小于0.5毫米、0.5-1毫米和1-2毫米的细根的生物量、生产量、死亡率和周转率。直径小于0.5毫米的细根的生物量、生产量和周转率随着间伐强度的增加而波动，而直径0.5-1毫米和1-2毫米的细根生物量显著下降。间伐强度对细根死有机质或死亡率没有影响。更深土壤中细根特征的变化对间伐强度更为敏感。主成分分析结果表明，直径小于0.5毫米的细根生物量和生产量的增加是由于灌木和草本植物多样性及生物量的增加以及土壤养分有效性、林分蓄积量和凋落物生物量的减少所致，而直径0.5-1毫米和1-2毫米的细根生物量则呈现相反的趋势和变化。我们的研究结果表明，不同的间伐强度对不同直径细根的变化特征表现出不同的影响机制。
