What is Open Mosaic Habitat (OMH)? BNG Definition & Examples

Quick Answer: OMH Definition

Open Mosaic Habitats (OMH) are complex brownfield habitats that mix bare ground with patchy vegetation, creating a "mosaic" pattern. Under BNG regulations, OMH is classified as high-distinctiveness habitat, making it challenging and expensive to replace when lost to development.

What Are Open Mosaic Habitats?

Open Mosaic Habitats (OMH) are a unique type of habitat found predominantly on brownfield sites. They consist of a complex mix of unvegetated or sparsely vegetated surfaces, interspersed with more densely vegetated areas. This creates a dynamic ‘mosaic’ of habitats that can support a diverse range of species. OMH is recognised for its high ecological value, particularly within the context of BNG requirements.

Key Characteristics of OMH:

• Location:

  Primarily found on brownfield sites.

• Structure:

  Mix of bare ground (30-70%) and patchy vegetation.

• BNG Classification:

  High-distinctiveness habitat.

• Biodiversity Value:

  Supports rare insects, plants and specialised wildlife.

Why OMH Matters for BNG Compliance

OMH might not always be aesthetically pleasing or immediately recognisable as a valuable habitat, but it plays a crucial role in supporting biodiversity. The combination of bare and vegetated patches provides essential conditions for various species, including rare insects and plants, that might struggle in more uniform environments. These habitats offer critical resources such as nesting sites, foraging grounds, and basking spots for specialised wildlife.

OMH provides:

• Nesting sites for ground-nesting birds and insects

• Foraging grounds for specialised species

• Basking spots for reptiles and invertebrates

• Refuge areas during different seasonal conditions

The OMH Challenge for Developers

The recent introduction of BNG regulations has highlighted some significant challenges regarding OMH:

Regulatory Conflicts: BNG requires that losses of high-distinctiveness habitats, such as OMH, must be replaced with habitats of equivalent value. However, replicating OMH can be complex and often unfeasible on-site due to the specific conditions required for its formation.

Scarcity of Off-Site Solutions: Finding suitable off-site locations to replace lost OMH can be challenging due to the unique conditions that support these habitats. This scarcity can lead to developers resorting to purchasing statutory biodiversity credits, which can be costly and may not always lead to immediate ecological benefits.

Urban Regeneration vs. Habitat Preservation: There is a growing conflict between the need to regenerate brownfield sites and the preservation of OMH. Developers can face challenging dilemmas when trying to balance urban development with the need to protect or replace these valuable habitats.

Solutions for OMH in BNG Projects

1. Designated OMH Sites: Identifying and designating specific brownfield sites for OMH conservation could provide a structured approach to managing and maintaining these habitats. Such sites could be integrated into urban planning processes and managed as urban nature reserves.

2. Strategic Partnerships: Collaborations between organisations, such as Natural England and national infrastructure bodies, could facilitate the provision of OMH on a strategic level. For example, using railway land or other large estates for OMH creation may be a viable option.

3. Viability Considerations: Introducing flexibility in the BNG framework to consider viability and regeneration needs could help balance the preservation of OMH with broader urban development goals.

Frequently Asked Questions about OMH

• What does OMH stand for?

  OMH stands for Open Mosaic Habitat - a type of brownfield habitats with mixed bare ground and patchy vegetation.

• Is OMH considered high-distinctiveness habitat?

  Yes, under BNG regulations, OMH is classified high-distinctiveness habitat, meaning it has high biodiversity value and is difficult to replace.

• Can OMH be created on-site?

  Creating OMH on-site is challenging because it requires specific conditions that develop naturally over time on brownfield sites. Most OMH replacement happens off-site or through statutory credits.

• Why is OMH important for biodiversity?

  OMH supports specialised species that need the unique combination of bare ground and vegetation patches - conditions that are rare in more managed landscapes.

Getting Help with OMH and BNG

OMH is a crucial habitat that contributes significantly to biodiversity, despite its often overlooked appearance. As BNG regulations evolve, it’s essential for developers and stakeholders to understand the complexities of OMH and work towards practical solutions that support both ecological preservation and sustainable development.

At Integrated Land Management (ILM), we are committed to providing expertise and solutions for navigating the challenges of BNG, including the complexities surrounding OMH. For tailored advice and support on BNG and habitat management, contact us today.