Huang Lin, Zhao Rudong, Zhao Xiaoxiang, Tian Qiuxiang, Yue Pengyun, Liu Feng
CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074 People's Republic of China.
University of the Chinese Academy of Sciences, Beijing, 100049 People's Republic of China.
J For Res (Harbin). 2023;34(3):665-675. doi: 10.1007/s11676-022-01514-0. Epub 2022 Jul 23.
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 a, 8.13 ± 0.20 m m aand 2.96 ± 0.24 a, respectively, compared with 7.09 ± 0.17 m m a, 4.59 ± 0.17 m m a, and 2.01 ± 0.22 a, 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.
The online version contains supplementary material available at 10.1007/s11676-022-01514-0.
细根在陆地生态系统的地下碳循环中起着关键作用。基于其不同的功能，细根可分为吸收性细根（AFR）和运输性细根（TFR）。然而，基于功能的树木细根动态及其对林分特征的响应仍不清楚。在此，我们基于一项为期两年的根窗实验，研究了亚热带山地混交林中AFR和TFR的动态及其对林分条件和根密度的响应。AFR的平均（±标准误）年生产量、死亡率和周转率分别为7.87±0.17 m m a、8.13±0.20 m m a和2.96±0.24 a，而TFR的相应值分别为7.09±0.17 m m a、4.59±0.17 m m a和2.01±0.22 a。高根密度位点的细根生产量和死亡率显著高于低根密度位点，而低根密度位点的细根周转率更快。此外，根密度对TFR生产量的正向影响大于其他环境因素，但对AFR生产量无明显影响。树种多样性对AFR生产量有明显的正向影响，是AFR生产量的关键驱动因素，可能是由于互补效应，但对TFR无明显影响。树木密度和树种多样性均与AFR的死亡率呈正相关，与TFR的周转率呈负相关，这表明较高的根密度导致对生根空间的竞争加剧，植物倾向于通过降低TFR周转率来降低维持成本。这些发现说明了根功能组在理解根动态及其对环境条件变化的响应方面的重要性。
在线版本包含可在10.1007/s11676-022-01514-0获取的补充材料。
