Why Biodiversity Is Not a Metric

Executive Summary

Many urban projects report improved biodiversity while simultaneously weakening ecological resilience.

This apparent contradiction arises because biodiversity is frequently evaluated through isolated indicators—such as species richness, planting diversity or habitat area—rather than through the performance of the ecological system as a whole.

Environmental systems function through relationships. Habitat connectivity, hydrological processes, thermal conditions and long-term maintenance determine whether biodiversity can persist, adapt and regenerate over time.

For climate-responsive development, the objective should therefore shift from maximising biodiversity indicators to designing ecological systems capable of sustaining environmental performance throughout the lifetime of a project.

Measuring biodiversity is not the same as designing ecological resilience.

Across Europe, biodiversity has become one of the most common environmental objectives within urban development.

Projects increasingly include biodiversity targets, ecological indicators and habitat requirements. Environmental assessments often report measurable improvements based on species counts, planting diversity or newly created habitat areas.

These indicators are valuable.

However, they do not necessarily describe whether an ecological system will continue to function over time.

A project can achieve excellent biodiversity metrics while simultaneously reducing its ecological resilience.

This is not a contradiction.

It is a consequence of measuring components instead of relationships.

The limitation of indicator-based thinking

Many biodiversity assessments concentrate on questions such as:

How many species are present?
How diverse is the planting palette?
How much habitat has been created?
What percentage of the site is vegetated?

These questions are relatively straightforward to quantify.

They are also relatively easy to communicate.

Yet ecological systems are not defined primarily by the number of elements they contain.

They are defined by how those elements interact.

A landscape with fewer species but continuous ecological processes may outperform a more diverse landscape that is fragmented, heavily irrigated or dependent on intensive maintenance.

Environmental performance is therefore not an additive property.

It is an emergent property.

Ecological performance is created by relationships

From a systems perspective, biodiversity depends on relationships operating across space and time.

Among the most important are:

Habitat continuity

Species require connected ecological networks rather than isolated habitat islands.

Hydrological connectivity

Water movement influences vegetation health, soil biology and habitat quality simultaneously.

Thermal adaptability

Microclimatic variation determines which ecological communities can establish and persist under changing climatic conditions.

Soil continuity

Healthy ecological systems begin below ground. Compacted, fragmented or artificial soils reduce long-term ecological performance regardless of planting diversity.

Maintenance dynamics

Ecological resilience depends on how systems evolve over decades, not simply on how they perform immediately after construction.

Designing systems instead of collections

This distinction fundamentally changes the design process.

Instead of asking:

How much biodiversity can we add?

Projects should ask:

Which ecological relationships are currently missing?
Which processes should be restored?
Which environmental dependencies should be strengthened?
How will the system adapt over the next thirty years?

These questions shift attention away from objects and towards performance.

This is where climate-responsive landscape design begins.

The Criterra Perspective

At Criterra, biodiversity is understood as one component of a broader environmental system.

Species richness alone cannot describe environmental performance.

Instead, biodiversity should be evaluated alongside:

hydrology
thermal behaviour
soil systems
maintenance requirements
landscape connectivity
long-term adaptability

Only by considering these relationships together can projects generate environmental systems that remain functional under changing climatic conditions.

Our decision frameworks therefore evaluate biodiversity not only as an environmental objective, but also as an operational system whose performance depends on multiple interacting variables.

Implications for urban development

As cities face increasing pressure from climate change, biodiversity can no longer be treated as an isolated environmental target.

Projects must balance ecological objectives with flood resilience, urban cooling, operational constraints and long-term maintenance.

This requires moving beyond indicator optimisation towards systems evaluation.

The goal is not to maximise individual metrics.

The goal is to maximise the performance of the environmental system.

Conclusion

Biodiversity is often measured through individual indicators.

Ecological resilience is created through relationships.

The future of climate-responsive urban development will depend less on how many environmental components are added to a project, and more on how effectively they interact over time.

Environmental performance is not designed through accumulation. It emerges through relationships.