Many city parks follow a familiar formula: tall trees above neatly mown lawns, with very little growing in between. New research from the University of Queensland argues that this visually tidy design leaves out an important ecological layer — midstory vegetation.

Published in BioScience, the study examined why shrubs and small trees between roughly 1 and 10 metres in height are often absent from urban public spaces, and why restoring them could improve biodiversity, strengthen urban ecosystems and create more varied experiences for people.

The Missing Middle Layer

Midstory vegetation includes shrubs, dense bushes and smaller trees that sit between groundcover and the upper tree canopy. According to ecologist Dr Nicola Sockhill, this layer has been systematically reduced in many parks shaped by an English landscape-inspired aesthetic that has favoured openness and neatness since the 19th century.

That design may look orderly, but it can be ecologically sparse.

Small birds and other animals often depend on dense vegetation for food, shelter and safe movement through the landscape. In cities, where development and urban expansion are already reducing natural habitat, the absence of this middle layer can leave wildlife with fewer places to feed, hide and travel.

The researchers argue that a park can therefore contain plenty of grass and mature trees while still offering relatively poor habitat.

Why It Matters For People

The issue is not only about biodiversity. Urban green spaces also shape everyday human contact with nature.

More than half of the global population now lives in cities, and for many people a local park may be their main daily encounter with a natural environment. That makes the quality and complexity of urban vegetation increasingly important.

The study draws on existing evidence showing that exposure to nature has been associated with benefits including lower stress, restored attention and improved mental well-being.

Denser planting may also make green spaces feel more immersive. Instead of seeing only open lawns and isolated trees, visitors can experience different textures, heights, habitats and degrees of enclosure within the same park.

Safety Does Not Require Bare Parks

One common argument against dense shrubs is that they may reduce visibility and make public spaces feel less safe.

The researchers do not suggest filling every park with thick vegetation. Instead, they propose strategic planting.

Good lighting, clear sightlines and careful selection of plant species can allow denser areas to coexist with open recreational spaces. People who prefer lawns and broad views can still use them, while others can move through more enclosed, nature-rich areas.

The goal is variety rather than replacing one uniform design with another.

Native Plants May Need Less Work

Professor Richard Fuller, a study co-author, also pointed to a practical advantage: established native midstory vegetation may require less intensive maintenance than conventional lawns.

Lawns need repeated mowing, irrigation and staff time. Native shrubs and small trees, once established, can demand fewer resources while supporting a more complex ecosystem.

The choice of species matters. Fuller argued that plants native to an area are often particularly valuable because local wildlife is already adapted to use them for shelter and food.

The study highlights Kings Park in Perth as an example of a major urban park that successfully combines public recreation with substantial areas of dense bushland.

Not Every Park Should Look The Same

One of the study’s strongest recommendations is to stop treating urban green space as a single design category.

Instead of giving every park the same mixture of grass and tall trees, cities could create a network of different spaces: open recreation grounds, shaded lawns, densely planted refuges and biodiversity-focused areas.

Sockhill described this as a citywide patchwork approach, where different parks perform different ecological and social roles.

That could make urban landscapes more resilient while giving residents a broader range of experiences.

The findings do not mean that open lawns have no place in cities. They remain useful for sport, gatherings and recreation. The argument is that they should not dominate every green space.

A richer urban park may need more than trees and grass. By restoring shrubs and smaller trees, planners could create places that are more useful to wildlife, more interesting for people and, in some cases, easier to maintain over time.