How variation among field assessments can affect biodiversity offset outcomes
Abstract Biodiversity offsetting aims to balance biodiversity loss at development sites with gains at offset sites. Measurement of loss and gain relies on transparent and repeatable estimates of biodiversity values. However, these estimates are often derived from field assessments by people who diff...
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| Format: | Article |
| Language: | English |
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Wiley
2025-08-01
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| Series: | Conservation Science and Practice |
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| Online Access: | https://doi.org/10.1111/csp2.70096 |
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| author | Peter Contos Emma Gorrod Karen Caves Ian Oliver Josh W. Dorrough |
| author_facet | Peter Contos Emma Gorrod Karen Caves Ian Oliver Josh W. Dorrough |
| author_sort | Peter Contos |
| collection | DOAJ |
| description | Abstract Biodiversity offsetting aims to balance biodiversity loss at development sites with gains at offset sites. Measurement of loss and gain relies on transparent and repeatable estimates of biodiversity values. However, these estimates are often derived from field assessments by people who differ in their interpretation and measurement of biodiversity, either randomly or systematically. Variation among people during field assessments may therefore impact offset outcomes and contribute to uncertainty around the effectiveness of biodiversity offset schemes. Here, we describe variation in loss, gain, and offset outcomes using concurrent assessments by five assessors on eight sites using a multi‐metric biodiversity valuation method from New South Wales, Australia. We found variation among assessors was high for field estimates but substantially decreased for current biodiversity valuations. However, variation increased for the prediction of future biodiversity gains, in the calculation of the required offset area, and contributed an average of 19% variation in development credits (biodiversity loss) and 34% variation in offset credits (biodiversity gain). Evidence of systematic bias among observers for some attributes added further uncertainty to offset outcomes. Our study reveals the need for improved assessor training and field methods to improve assessment consistency, transparency, and reduce offset outcome variability. |
| format | Article |
| id | doaj-art-e9f78732423e48078e8d7ff5223e978d |
| institution | Kabale University |
| issn | 2578-4854 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Conservation Science and Practice |
| spelling | doaj-art-e9f78732423e48078e8d7ff5223e978d2025-08-20T04:01:48ZengWileyConservation Science and Practice2578-48542025-08-0178n/an/a10.1111/csp2.70096How variation among field assessments can affect biodiversity offset outcomesPeter Contos0Emma Gorrod1Karen Caves2Ian Oliver3Josh W. Dorrough4Conservation and Restoration Science Branch Department of Climate Change, Energy, The Environment and Water Sydney New South Wales AustraliaConservation and Restoration Science Branch Department of Climate Change, Energy, The Environment and Water Sydney New South Wales AustraliaNature Markets and Offsets Division Department of Climate Change, Energy, the Environment and Water Sydney New South Wales AustraliaConservation and Restoration Science Branch Department of Climate Change, Energy, The Environment and Water Sydney New South Wales AustraliaConservation and Restoration Science Branch Department of Climate Change, Energy, The Environment and Water Sydney New South Wales AustraliaAbstract Biodiversity offsetting aims to balance biodiversity loss at development sites with gains at offset sites. Measurement of loss and gain relies on transparent and repeatable estimates of biodiversity values. However, these estimates are often derived from field assessments by people who differ in their interpretation and measurement of biodiversity, either randomly or systematically. Variation among people during field assessments may therefore impact offset outcomes and contribute to uncertainty around the effectiveness of biodiversity offset schemes. Here, we describe variation in loss, gain, and offset outcomes using concurrent assessments by five assessors on eight sites using a multi‐metric biodiversity valuation method from New South Wales, Australia. We found variation among assessors was high for field estimates but substantially decreased for current biodiversity valuations. However, variation increased for the prediction of future biodiversity gains, in the calculation of the required offset area, and contributed an average of 19% variation in development credits (biodiversity loss) and 34% variation in offset credits (biodiversity gain). Evidence of systematic bias among observers for some attributes added further uncertainty to offset outcomes. Our study reveals the need for improved assessor training and field methods to improve assessment consistency, transparency, and reduce offset outcome variability.https://doi.org/10.1111/csp2.70096biodiversity offsetsenvironmental policyinter‐observer variationno net lossobserver variationoffset schemes |
| spellingShingle | Peter Contos Emma Gorrod Karen Caves Ian Oliver Josh W. Dorrough How variation among field assessments can affect biodiversity offset outcomes Conservation Science and Practice biodiversity offsets environmental policy inter‐observer variation no net loss observer variation offset schemes |
| title | How variation among field assessments can affect biodiversity offset outcomes |
| title_full | How variation among field assessments can affect biodiversity offset outcomes |
| title_fullStr | How variation among field assessments can affect biodiversity offset outcomes |
| title_full_unstemmed | How variation among field assessments can affect biodiversity offset outcomes |
| title_short | How variation among field assessments can affect biodiversity offset outcomes |
| title_sort | how variation among field assessments can affect biodiversity offset outcomes |
| topic | biodiversity offsets environmental policy inter‐observer variation no net loss observer variation offset schemes |
| url | https://doi.org/10.1111/csp2.70096 |
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