Biodiversity offset in the Awudua Forest of Ghana: Effects on tree diversity, abundance, carbon stock and conservation value

Unofficial AI-generated summary based on the public title and abstract. Not an official translation.

🔬研究者:Provides a rare longitudinal comparison of offset and reference sites for biodiversity and carbon in a tropical forest.

🏢実務担当者:Demonstrates that active restoration can enhance carbon storage and tree diversity, useful for corporate offset projects.

🏛政策担当者:Supports the inclusion of biodiversity offsets in national climate and conservation policies with quantified outcomes.

This study compared trends in tree species diversity, abundance, carbon stock, and conservation value between a biodiversity offset site and a disturbed reference site within the Awudua Forest from 2017 to 2023, using a paired-site repeated-measures design. The offsite site is managed by Ghana Rubber Estate Limited (GREL) through active restoration activities, including replanting native tree species, removing invasive plants, and creating corridors to connect forest patches. The nearby reference site, on the other hand, continues to experience a variety of anthropogenic disturbances. Over six years, various vegetation attributes were assessed during the dry season (November–March) at two-year intervals, using a systematic grid-based sampling design with 20 permanent plots (25 m × 25 m each) per site, spaced 100 m apart to ensure independence. All trees ≥ 10 cm DBH were identified and enumerated, and tree biomass carbon was estimated using species-specific allometric models. Species richness in the offset increased from 63 to 68 over the study period, with that of the reference site increasing from 37 to 41. Shannon diversity index values improved from 2.12 to 2.50 at the offset site, but remained lower at the reference site (1.02–1.49). Stand basal area of live trees (≥10 cm DBH) increased by 112% at the offset site, reaching 25.91 m²·ha⁻¹ by 2023, but increased by 19% at the reference site. Estimated total (above- plus below-ground) tree biomass carbon stock increased from 33.54 to 60.35 Mg C·ha⁻¹ at the offset site and from 7.02 to 16.15 Mg C·ha⁻¹ at the reference site. Over time, the floristic composition diverged between the two sites, with the offset developing a richer, structurally complex vegetation comprising, among others, one Endangered, seven Vulnerable and seven Near Threatened tree species than the reference site. These findings, although from a single offset-reference pair imposed by the unavailability of similar offset sites, highlight the importance of continued monitoring and adaptive management. They also suggest that, within this concession, restoration and connectivity enhancement were associated with higher tree diversity and increasing tree biomass carbon stock relative to the disturbed comparator. When available, replications across multiple sites may allow broader inference.

• openalex https://doi.org/10.1016/j.gecco.2026.e04278first seen 2026-06-17 05:16:55 · last seen 2026-06-17 07:13:31