微根管法和同位素法在细根寿命研究中的应用及比较

细根的生产和周转在陆地生态系统的碳和养分循环中起着重要作用,并且对全球环境变化具有一定的指示意义。细根寿命是估计细根周转的关键,其长短决定了养分和碳消耗与循环的速度。由于采用的研究方法不同,导致所得细根寿命估计值存在较大差异,目前最新的同位素和微根管2种方法之间寿命估计值差异可达10倍以上。本文对这2种研究方法的原理和优点进行了阐述,并从细根定义、细根寿命理论分布假设、细根取样误差等方面对导致这2种方法研究结果存在差异的原因进行分析,以期有助于今后根系研究的发展。

Minirhizotron and radiocarbon methods: Their application and comparison in estimating fine root longevity

The production and turnover of fine root plays an important role in terrestrial C- and nutrients cycling of terrestrial ecosystem, and is of significance in indicating global environmental changes. Fine root longevity is a key parameter in estimating fine root turnover, which determines the velocities of C- and nutrients consuming and cycling. However, the estimated longevity of fine root had a larger difference, owing to the discrepancy among the methods adopted. As for the newest estimation methods minirhizotron and radiocarbon (e.g., bomb 14C, and FACE 13C), there was a 10 times more difference of estimated value between them. This paper introduced the principles and advantages of these two methods, and analyzed the reasons inducing such a difference of estimation results from the aspects of fine root heterogeneity, mortality pattern, and sampling errors, which would benefit the future study in this field.