Circular economy (CE) principles distinguish between technical and biological cycles. Technical cycles involve the management of stocks of non-renewable abiotic resources that cannot be appropriately returned to the biosphere, whereas, biological cycles involve the flows of renewable biotic resources that can safely cycle in and out of the biosphere. Despite this distinction, existing CE monitors are typically developed for technical cycles, and focus mainly on the extent to which resources are looped back in the technosphere. These monitors seem less apt to assess the circularity of biological cycles. This study aims to identify this gap by critically reviewing the CE monitoring criteria and CE assessment tools, and evaluate if they include the four key characteristics of biological cycles.

Firstly, biotic resources, although renewable, require to be harvested sustainably. Secondly, while abiotic resources can be restored and recycled to their original quality, biotic resources degrade in quality with every subsequent use and are, hence, cascaded in use. Thirdly, biotic resources should safely return as nutrients to the biosphere to support the regeneration of ecosystems. Fourthly, biological cycles have environmental impacts due to resource extraction, resulting from land-use and resource-depletion and biogenic carbon flows. The CE monitoring criteria lack in thoroughly assessing these characteristics. With the growing demand for biotic resources, the gap in the assessment could exacerbate the overexploitation of natural resources and cause the degradation of ecosystems. The study discusses measures to bridge this gap and suggests ways to design a CE assessment framework that is also apt for biological cycles.

循环经济（CE）原理区分技术循环和生物循环。技术周期涉及无法适当地返回生物圈的不可再生非生物资源的管理，而生物周期涉及可安全地循环进出生物圈的可再生生物资源的流动。尽管有这种区别，现有的CE监视器通常是针对技术周期而开发的，并且主要关注于技术圈中资源循环的程度。这些监测器似乎不太适合评估生物循环的循环性。这项研究旨在通过严格审查CE监测标准和CE评估工具，并评估它们是否包括生物周期的四个关键特征，来找出这一差距。

首先，生物资源虽然可再生，但需要可持续地进行收获。第二，虽然非生物资源可以恢复并循环利用到其原始质量，但生物资源的质量在随后的每次使用中都会下降，因此在使用中会被级联。第三，生物资源应作为养分安全返回生物圈，以支持生态系统的再生。第四，由于资源利用，生物循环会对环境产生影响，这是由于土地利用和资源枯竭以及生物碳流所致。CE监控标准缺乏对这些特征的全面评估。随着对生物资源需求的增长，评估中的差距可能加剧自然资源的过度开发并导致生态系统退化。