A two-year project with Resource Management Service (RMS), one of the world’s largest and most experienced providers of timberland investment services, utilised RSK Wilding’s skills and expertise across nature gain policies and global ecosystem valuation methods. Working across Nature Positive and with experts at RMS, an innovative and bespoke method to enable an assessment of contributions to the state of nature on operational land was created.
RMS have created a Biodiversity Roadmap for its Evergreen Fund which comprises approx. 400,000 acres of timberland across 8 States within the south-eastern US. This integrates The Taskforce on Nature-Related Financial Disclosures’ (TNFD) Locate, Evaluate, Assess and Prepare (LEAP) approach to contextualise where and how the Fund addresses nature-related impacts and dependencies and how it delivers positive contributions to biodiversity.
Our collaborative approach developed an Ecosystem Integrity Index (EII), and involved:
- Desk-based review of existing ecosystem valuation methods,
- Assessment of specific needs for operational timberland,
- Data efficacy, accessibility and relevance assessment,
- Setting of Core Principles for any tool,
- Building functionality across scales – keeping granularity and relevance at the Fund level; and,
- Interrogatable GIS and communication to non-technical teams.
While a directly applicable tool was not available, the initial desk-based review identified the key attributes of ecosystem integrity which would go on to form the basis of the bespoke tool: ecosystem structure, ecosystem composition, and ecosystem function.
Core principles for the EII were set at an early stage to govern future use of the tool and address its limitations. These principles state that the EII should be based in scientific integrity, be accessible, scalable, with clear and transparent methods. They recognise that any output is indicative of real-world conditions and not absolute as well as ensuring the EII has the capacity to improve as new methods become available.
RSK Wilding developed an initial list of ten bespoke measures of ecosystem structure, composition and function for potential inclusion in the EII, and this was refined to four final measures through testing and discussions with experts at RMS.
These four final measures comprised: Forest Structure, Connectedness, Species Assemblage, and Wetland Integrity. Each of these is comprised of two or three bespoke component indicators selected to enable consideration of multiple factors within each measure, thereby allowing for robust and nuanced assessment. Each indicator was informed by a different dataset and provided a score from 0 (lower integrity) to 1 (higher integrity).
Indicators ranged from the structure provided by managed pine age class diversity to the proximity of areas of the Fund to known corridors or areas of high biodiversity value and the permeability of the landscape to promote species movements. Each indicator score was aggregated to derive the measure score, and each measure score was aggregated to derive the EII score.
The RSK Digital and Geospatial Team assessed this data and used ESRI Webmap functionality to dashboard the analysis findings. The team built a script to define Minimum Assessment Units (MAU) across the Fund and then one that applied each measure methodology. The output was a Webmap which displayed each MAU with its indicator, measure, and EII score. This Webmap also aggregated the MAU scores at different scales, showing scores for watersheds, RMS properties, US States, and the whole Fund. By using a GIS based approach, the EII project team were able to make rapid adaptations to refine the EII following engagement with RMS and their internal stakeholders, and it allows the EII to be adapted to answer a range of different questions.
EII (1st Ed) was presented at RMS investor events in London and Amsterdam in 2025 and 2026. This enabled the project team to synthesise the work undertaken to date for a non-ecological audience and engage with timberland investors to present the direction of travel for the industry and receive constructive feedback on their thoughts of the EII.
The EII can demonstrate to RMS, stakeholders and their existing and potential investors how the Evergreen Fund performs. Due to how the EII was developed it enables comparison both geographically, i.e., how different regions compare, and temporally, i.e., how the ecosystem integrity of an area has improved over time, supporting improvements in asset management and acquisition by considering ecosystem value in decision-making and allowing the impacts of potential interventions to be tested prior to implementation.
The EII has proven to be a differentiator for RMS in their capital raising efforts with investors including pension funds, private equity impact funds, and insurers, by providing investors with a way to quantify the extent of biodiversity uplift relative to their total investment and support impact reporting obligations.
Whilst there are many frameworks and metrics which propose various ways to measure biodiversity, there is still a lack of an agreed approach for measuring biodiversity gain within in working forests. On the back of this work, RMS seeks to substantially advance progress within the forestry sector, with initial steps in this direction including the engagement of a conservation charity in the US to appraise the EII to provide additional comment and third-party assurance.
As such, the EII provides a tangible framework to help RMS, their investors, and the forestry sector as a whole to make investments in measurable outcomes aligned with SDG 15.