> For the complete documentation index, see [llms.txt](https://isbm.savimbo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://isbm.savimbo.com/methodology/zh-cn/ji-xian-ping-gu.md).

# 基线评估

本方法学中的基线情景包括 [对生态系统进行分类](/methodology/zh-cn/ji-xian-ping-gu/ji-xian-sheng-tai-xi-tong-fen-lei.md), [估算生物多样性丰富度](/methodology/zh-cn/ji-xian-ping-gu/ji-xian-sheng-wu-duo-yang-xing-ke-xuan.md)，以及估算……的威胁 [生物多样性丧失](/methodology/zh-cn/ji-xian-ping-gu/ji-xian-sheng-wu-duo-yang-xing-sang-shi-feng-xian.md)。项目必须每五年依据现有数据更新其基线情景， [计算](/methodology/zh-cn/ji-suan/jia-zhi-ji-suan.md) 可能因此发生变化。

在ISBM中，不同于碳项目，VBC核算并非基于一个预测的基线情景、相对于一个预测的项目情景来开展 [（Pollock 等，2020）](https://sciwheel.com/work/citation?ids=10899578\&pre=\&suf=\&sa=0)。相反，本方法学为便于IP和LC直接进入市场而进行了简化。换言之，这些区域并非需要恢复或改进的区域，而是面临遭受扰动或损害威胁的区域。维护这些完整生态系统，而不是改变它们，才是这些项目的适当成果。ISBM基线情景依据所有可公开获取的信息，确立BCP完整生态系统的全球价值及其所面临的威胁。随后，BCP项目情景确立该完整生态系统的计入区域。 

在这种背景下，历史数据和预测数据虽有用，但并非必需，因为其可能极难获取，而且对于在生物多样性丰富地区、缺乏研究资金和原位研究人员支持的、由IP和LC主导的项目而言，获取成本高得难以承受（[附录C](/methodology/zh-cn/fu-lu/fu-lucji-xian-sheng-tai-xi-tong-fen-lei-yang-ben.md)). 

鉴于在完全量化之前需要开展保护，若基线数据不可获得，则可将IUCN生态系统红色名录以及地理分布数据等外部标准作为代理指标。然而，基线情景应每五年重新核实一次，以纳入更新数据。


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