Introduction

Cities will have to absorb the bulk of global population growth by 2050. In this context, understanding how urban forms influence biodiversity is no longer an isolated academic field: it is a major operational challenge. BAUM Notebook No. 7, published by PUCA in 2025, offers a rare synthesis of the scientific approaches developed to study this link. The implicit conclusion is clear: urban biodiversity cannot be studied, assessed, or certified without a reproducible, independent, and evidence-based method.

1. The complexity of the link between urban form and biodiversity

The document reiterates that the relationship between urban morphology and biodiversity is real, but that it depends on multiple environmental and biotic factors. From the introduction (p. 12), the report emphasizes that the city is a "heterogeneous" environment where the effects of urban forms cannot be isolated without a strict protocol. This is the first key takeaway: no simple metric can draw conclusions about the morphological effect without controlling for variables.

2. The six BAUM projects: diversity of approaches, same structural limitations

The report analyzes six projects: MORPHOBIOT, RÉAUMUR, TRAM'BIOSOL, FRUGACITÉ, BIOREV'AIX and ÉVOLVILLE.

All of them show that:

• qualitative approaches offer a nuanced but difficult-to-replicate reading (MORPHOBIOT, p.55);
• Quantitative approaches require homogeneous data, which is often difficult to obtain at the urban scale (RÉAUMUR, TRAM'BIOSOL);
• Mixed approaches increase methodological complexity (FRUGACITY).

BAUM draws a clear conclusion (p. 41): no method is “better” than another; each method only answers certain questions. Hence the need for an independent framework capable of assembling these building blocks into a coherent structure.

3. Methodological biases identified by BAUM: a critical point for building professionals

3.1. Site selection and “species pools”

Page 70: the notebook reminds us that site choices influence the observable “species pools,” sometimes creating irreversible biases in the analysis. Direct implication: in a real estate project, the initial state must be described using a stable and comparable methodology.

3.2. Confounding Factors

The document emphasizes that pollution, microclimate, disturbances, road structure, resource availability, etc., must be statistically integrated into the models or controlled during the selection of measurement points. Without this, "hasty conclusions and overinterpretation of results" become likely (p. 70).

3.3. Data Quality and Resolution

The summary notes that the spatial representativeness of the data directly influences the robustness of the conclusions. This is one of the most crucial factors for any evidence-based certification.

4. Towards an explicit need for methodological standardization

The document is explicit (p. 73): the program's results must be transformed into operational methods; otherwise, scientific advances will remain confined to research. This transition requires:

• independent scientific governance,
• standardized protocols,
• a reproducible assessment,
• data traceability.

These four pillars constitute precisely the architecture of the IRICE system, which combines:

• an ISO/IEC 17065 accreditation system,
• an independent scientific committee (BSC),
• evidence-based frameworks (Effinature, BPS),
• a homogeneous methodological doctrine for all operations.

5. Contributions of the BAUM program to biodiversity reference frameworks

Reviewing the projects highlights three operational lessons:

5.1. The central role of soil, microclimate and ecological continuities

TRAM'BIOSOL (pp. 22–29) and BIOREV'AIX (pp. 33–35) confirm that soil and road structure are determining factors. Effinature integrates these parameters via:

• the requirements for preserving living soil,
• Structured Biodiversity Area (EBS),
• the control of ecological continuities.

5.2. The need to describe vegetation in terms of configuration, not just quantity

On page 12, BAUM shows that, at equal plant density, different plant configurations offer vastly different ecological opportunities. Effinature translates this point into:

• the ecological plant palette
• the quality of the vegetation layers,
• the analysis of the ecological functions of vegetation.

5.3. The importance of having a multi-biological model evidence system

The six BAUM projects work respectively on: birds, flora, earthworms, road network, etc. No single model is sufficient. Effinature integrates this plurality through a cross-analysis of fauna/flora/soils.

Conclusion

BAUM Notebook No. 7 offers a structuring perspective on urban ecology: urban forms influence biodiversity, but only when confounding effects are controlled, data are robust, and methods are standardized. These findings reinforce the need for independent, evidence-based certification capable of transforming scientific advances into operational tools. This is precisely IRICE's mission: to ensure the consistency, reproducibility, and reliability of biodiversity approaches in real estate projects.