> 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-suan/shi-jian-ji-suan.md).

# 时间计算

指示物种的一次观测具有60天的基准持续期。该持续期定义为记录观测日期时间戳之前30天和之后30天。相比之下，该单元的基准持续期为1个月，即30天。因此，一次观测最多产生 *两* 个信用，在前、后各1个。 

该时段经过审慎选择，依据包括原住民和当地社区专家生计生活方式的周期性、原住民和当地社区监测设备成本、跟踪设备电磁场对保护区内全部物种谱系影响尚未充分表征，以及在监测期间狩猎或偷猎可能导致动物种群减少的风险（[附录H](/methodology/zh-cn/fu-lu/fu-luhyuan-zhu-min-zuo-zhe.md)).  

该系统不允许对时间上重叠的观测进行重复计入。观测在整个监测期间连续发生。监测组在工作活动中呈现狩猎采集型周期性。此外，动物的可观测行为存在昼夜和季节变化。该方法学对此予以考虑，通过汇总观测，在空间（[图9](https://isbm.savimbo.com/methodology/zh-cn/ji-suan/pages/a88fa5dc50789c742ced1c5300be355c87f559d4#figure-9.-union-of-observations-which-overlap-in-time-and-space-to-calculate-crediting)）和时间（[图10](#figure-10.-biodiversity-credits-appearing-and-disappearing-over-time-with-different-species-observat)).

1. ）两个维度实现计入标准化。代表观测点所对应已计入公顷数的圆形区域，首先被赋予一个日期范围；在同一时段内，其面积可能与另一观测点重叠，
2. 如果观测在时间上重叠，则按每个日期对观测面积取并集， 
3. 随后，再以项目边界对所得地图进行裁剪，以计算可计入面积，
4. 最后，将时段和地图结果汇总，得出当年可用于计入的总公顷数。 

#### 图9。对时间和空间上重叠的观测取并集，以计算计入量

<figure><img src="/files/49a1bd876f017bf49db78c350333cb7207b7c7fc" alt=""><figcaption></figcaption></figure>

正如对于1公顷面积，即使记录到不止1个物种，也仅计入1次一样；对于同一公顷面积，即使存在多个时间上重叠的目击记录，也仅按1天计入，而非重复计入30天前后。例如，若某次目击发生在同一区域前一次目击后的1天，则仅计入额外的1天，而不是前后30天，因为增量仅为这额外的1天。数学上，该函数称为重叠集合的并集。

#### 图10。不同物种的观测使生物多样性信用随时间出现和消失

<figure><img src="/files/2fc4f3473b93eba56646e51d6d638e91bf5fa1a5" alt=""><figcaption><p><strong>图10。</strong> 随着不同物种的观测，生物多样性信用随时间出现和消失。</p></figcaption></figure>


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