The Index of Biodiversity Potential tool: How to implement it in forest management?

OG Douglas Index 1. What is the Index of Biodiversity Potential Index (IBP)? .......................... 4 2. Why care about forest biodiversity? ............................................................ 4 3. Where does the IBP tool come from? .......................................................... 6 3.1. How to use the IBP tool? ............................................................................. 6 4. References ........................................................................................................ 9 More information .................................................................................................... 9 Appendix ................................................................................................................. 10 Index of figures Figure 1. Old beech trees in nature reserve in Northern Bavaria (Franconia) (Source: Klaus-Peter Janitz) ..................................................................................... 5 Figure 2. From the IBP practical recommendations (Source: Emberger et al. 2023, p. 4) .................................................................................................................... 8 Figure 3. Comparison of IBP survey methods (Source: Gonin & Larrieu 2025, p. 4) ............................................................................................................................. 10 The Index of Biodiversity Potential tool: How to implement it in forest management? 1. What is the Index of Biodiversity Potential Index (IBP)? The Index of Biodiversity Potential is a scoring tool to assess the biodiversity potential of forest stands according to 10 factors related to animal, plant and fungal species. Biodiversity refers to the diversity of living organisms in a broad sense and includes the diversity of habitats at landscape level, the diversity of species within an environment, and the genetic diversity and variability of individuals within a species. The IBP tool focuses only on species diversity. The IBP helps forest managers to identify the elements favourable to biodiversity to be preserved, in particular the trees of biodiversity interest. A radar diagram makes the biodiversity potential visible. With this, it highlights the factors that could be improved. The IBP documentation also proposes how each of the highlighted factors can be improved. 2. Why care about forest biodiversity? Forests are full of life. Often hidden under the cover of trees, tens of thousands of species of plants, animals, fungi and microscopic organisms interact. Species diversity affects plant regeneration, tree growth, protection against insect pests, and is important for forest resilience. Forest ecosystems, however, are not necessarily pristine habitats but exposed to different pressures incl. demand for forest products and climate change. Assessing the perhaps unimagined and fragile biodiversity of forest ecosystems recognizes the intrinsic value in all living things. Species diversity is an essential condition for forests to function properly and has economic benefits, incl. soil fertility and wood volume, reduction of costs for seedlings and planting, stand resistance and resilience, and protection against natural hazards. Europe is committed to conserving biodiversity through international agreements. This led to adoption of the Nature Directive, the EU Biodiversity Strategy, the Nature Restoration Law, as well as the funding of numerous LIFE and other projects to protect nature and halt biodiversity loss. The IBP tool makes forest biodiversity visible and provides reliable data for monitoring. It is useful for educational purposes and communication with the public, for road building in forests and landscape planning. Figure 1. Old beech trees in nature reserve in Northern Bavaria (Franconia) (Source: Klaus-Peter Janitz) 3. Where does the IBP tool come from? The methodology for the IBP was designed at the National Forest Ownership Centre – Institute for Forest Development (CNPF-IDF) by Laurent Larrieu and Pierre Gonin in 2008. They started from the idea that no simple indicator allows for a quick assessment or routine monitoring of forest stand or plot biodiversity, and have therefore proposed a tool of indirect evaluation of biodiversity to forest managers that can be likened to a composite index. Since 2008, a Research & Development programme to improve IBP, integrate new knowledge and meet the needs of users is conducted at the CNPF and the French Research Unit “Dynamics and Ecology of Paysage Agriforestiers” (INRAE UMR Dynafor). This programme brings researchers, owners, professionals, teachers together. It received support from the French Ministry of the Environment and other entities. The IBP was included in the French Strategy for Biodiversity in 2011. In later years, it was translated and adopted in Italy and Spain (Catalonia). A programme to extend and test the IBP is currently being led in 17 countries across Europe and the Mediterranean Basin. In the frame of the FOREST4EU project, the IBP was met with interest from forestry stakeholders in other countries incl. Finland, Germany, Latvia, and Slovenia. 3.1. How to use the IBP tool? The Index of Biodiversity Potential identifies ten factors to assess the carrying species diversity of forests. Factors A-G are directly dependent on the evaluated forest stand and its management, while factors H-J are context-dependent: A. Diversified native tree species: Animals, plants and fungi in the forest depend on the characteristics of the tree. The more different species there are in a forest, the more likely it is to support the diversity of species specific to each, in addition to more generalist species B. Vertical structure of the vegetation: There are different layers (herbaceous, shrub, tree). Each provides specific habitats (food, shelter etc.), which supports species with different requirements C. (D) Abundant and diversified large deadwood: More than 25% of forest species depend on deadwood or on tree-related microhabitats incl. decaying wood. A wide variety of deadwood (species, size, decay stage, position) supports a diversity of associated species E. Presence of very large living trees: Large-diameter trees, tall and old, provide varied tree-related microhabitats, large branches form platforms for fauna F. Numerous and diverse tree-related microhabitats: Refers to morphological features of trees (cracks, cavities), which are essential places for shelter, reproduction, hibernation and nutrition for many species. G. Flowers-rich open areas in appropriate amount: In permanent or temporary open areas, conditions differ from those inside the stand. There are more numerous flowers, greater variations in temperature and light, etc., which increases forest biodiversity. H. Forest continuity over time: The history of a forest influences its biodiversity. Recently established forest on former agricultural land does not support the same species as land that has been wooded for many centuries. I. (J) Aquatic and rocky habitats: Rivers, ponds, peat bogs, boulders, crags and escarpments are habitats for various species. Tool users are equipped with a survey to score the biodiversity of forest stands. This is done by walking through a given stand and counting the items related to each of the ten factors (e.g., number of large dead trees or forest layers). Based on these observations, a score between 0 and 5 is given to each factor. Adding together these scores gives the IBP and characterises the stand on a gradient of low to high carrying capacity. It also makes it possible to identify features within a stand that are favourable to species diversity or, conversely, those that are insufficiently represented and which should be favoured during management activities. The IBP survey provides a systematic approach to assess the species hosting capacity of a forest stand without making prior judgements of the biodiversity actually present in a given stand. The survey identifies the factors already favourable to biodiversity and those that can be improved through management. There are four survey methods: site coverage (complete, partial), typological sampling, and systematic survey. The choice of the appropriate survey method depends on, among other, the planned diagnoses, area and characteristics of stand, purpose and required level of precision, and available resources. The Appendix provides a table that compares the four survey methods. As a rule of thumb, a complete site coverage should be conducted in small stands (≤ 1 ha) whereas the partial and typological coverage methods should be applied in larger stands (≥ 10-20 ha). Typological sampling is a quick and non-exhaustive survey method. Some prior familiarity basic vocabulary and its application is needed to apply the IBP survey. The index inventors of the index have issued the 2nd edition of the guideline “The key factors for species diversity in forests. Understanding the Index of Biodiversity Potential” in 2023. It explains important terms and how to arrive at management recommendations from scoring the biodiversity potential with the IBP factors. Figure 2. From the IBP practical recommendations (Source: Emberger et al. 2023, p. 4) 4. References Emberger C., Larrieu L., Rotiel S., Gonin P.(2023) Our forests are full of life! Discovering the Index of Biodiversity Potential (IBP). CNPF, INRAE Dynafor, 4 p. Emberger C., Larrieu L., Rotiel S., Gonin P. (2023) Ten key factors for species diversity in forests. Understanding the Index of Biodiversity Potential (IBP). 2nd edition. Paris: CNPF-IDF, 2023, 62 p. Gonin P., Larrieu L. (2025) Index of Biodiversity Potential (IBP): survey methods. CNPF, INRAE Dynafor, 28 p. Gonin P., Larrieu L., Baiges T., Corezzola S., Marty P., Miozzo M., Palero N. (2025) - Index of Biodiversity Potential for forests in temperate Europe and the Mediterranean Basin (IBP EUR.MED v3.1): definition and survey sheets. CNPF, INRAE Dynafor, CPF, DREAm Italia, 24 p. Larrieu L. & Gonin P. (2008) - L’indice de Biodiversité Potentielle (IBP) : une méthode simple et rapide pour évaluer la biodiversité potentielle des peuplements forestiers. Rev. For. Française, LX 6-2008, p. 727-748 More information More information about the IBP in practice, how to document forest species diversity, R&D to improve the tool, bibliographic resources, and contacts can be retrieved via: https://www.cnpf.fr/ibp (last accessed 04.04.2025). The referenced brochure, guideline, survey method explanations and sheets can be downloaded via: https://cloud.cnpf.fr/index.php/s/DP9gB8wg9sgq7gH (last accessed 04.04.2025). The documents are available in English, French, Italian and Spanish. The survey sheets are also available in Catalan.