Using endangered grassland species to create beautiful native wildflower meadows in urban centers

Urban roads may seem like an unusual place to preserve endangered grassland species. But my new research shows that plants from these ecosystems can be used to create beautiful, biodiverse urban wildflower meadows. This means that cities can also help restore nature.

Species-rich grass ecosystems are among the most endangered plant communities on Earth. Grassy ecosystems occupying flat land that is easy to develop are routinely sacrificed as cities expand.

In southeastern Australia, the volcanic plains that underpin the northern and western suburbs of Melbourne were once wildflower-studded meadows that, according to early explorer Thomas Mitchell, “resembled an aristocratic park on a vast scale. “I was there,” he said. However, these extremely diverse and endangered ecosystems have been reduced to less than 1% of their original area. What little remains continues to be lost to urban development and weed invasion.

Unfortunately, efforts to restore grasslands around Melbourne have had mixed results. In 2020, the City of Melbourne took matters into its own hands. Recognizing that providing low-growing native plants can enrich the diversity of birds, bats and insects, the council has set a goal of increasing understory vegetation on land it manages by 20%. Set.

Creating a vast natural grassland in the inner-city Royal Park will help achieve this goal. We adapted techniques used by wildflower meadow designers to sow one million seeds of more than 24 species from endangered grasslands around Melbourne. All but one of these species became established in the resulting native wildflower meadow.

What were the challenges at this site?

Existing restoration techniques remove nutrient-rich topsoil packed with weed seeds before sowing native seeds. Targeted plant communities can be established with less competition from weeds that require nutrients.

However, this approach could not be used on the Royal Park grounds. Topsoil removal cannot be used in many urban areas where the soil is contaminated or there are underground utilities. Reducing weed competition while minimizing soil disturbance requires a different approach.

I found a possible answer in the horticultural approach used to create planned wildflower meadows.

Although still a rarity in Australia, designing wildflower meadows can increase the amenity and biodiversity of urban environments. It also reduces the cost of grass management and mowing. These pastures are designed to not be heavily mowed or burned.

Wildflower meadow designers typically use an international range of species that can be established from seed and persist without fertilizer or regular irrigation. People are more accepting of “messy” vegetation when there are lots of flowers. Recognizing this, designers choose combinations of species that can bloom for as long as possible throughout the year.

To reduce competition with weeds, these meadows are often created on top of a layer of sand covering the soil of the original site. The low-nutrient sand creates a seeding surface that buries weed seeds and prevents weed invasion from the surrounding terrain.

However, grasslands around Melbourne grow on clay soils rather than sand. Will these techniques work for plants in these ecosystems?

Deep sand layer suppresses weeds and slugs

To find out, we sowed more than one million seeds in two depths of sand (10 mm and 80 mm) and in the absence of a sand layer in the Royal Park. Within a year, 26 of the 27 sown species were established and formed dense flowering meadows at all sand depths. These plants included three endangered species.

Importantly, the deepest sand layer reduced the number of weeds, resulting in less time spent weeding.

Interestingly, slugs played a role in determining the diversity of native pastures. Most of the grasslands of southeastern Australia evolved without slugs. As a result, seedlings lack chemical or physical protection against slug feeding damage, which can significantly reduce the species diversity of native pastures.

Again, sand provided a huge advantage. There were fewer slugs in the deepest sand layer than in the bare ground. The suggestion that sand can deter slugs is consistent with research on European pastures.

Let’s restore nature in all our cities now

Our research provides another technique for restoring endangered plant communities. This can be used to bring nature back into city parks and streets.

Working in a city has other benefits as well. Easy access to irrigation until pastures are established and to a community committed to caring for the natural landscape. Creating native wildflower meadows in cities also helps support the survival of native animals, including endangered species, that call cities home.

People will be able to come into contact with beautiful native plants that are now rare in urban areas. Enriching our natural experiences improves our health and well-being.

My colleagues and I have trialled these approaches with support from the City of Melbourne. We continue our research to improve the scale and sustainability of native wildflower meadows in other municipalities.

Native wildflower meadows and grassland restoration projects could truly help Australia meet its commitment to restore 30% of degraded landscapes. But first we need to invest more in seed production. Reintroducing native species to degraded land requires large quantities of seeds.

With a more reliable supply of seeds, we can restore native biodiversity and beauty to streets, parks and protected areas across the country.

I would like to express my gratitude to the Wurundjeri and Bunurong peoples of the Kulin Nations, the traditional custodians of the land on which this project took place, and pay my respects to their elders past, present and emerging. . Also listed as co-authors of the research paper on which this article is based are my colleagues: urban ecologists Nicholas S.G. Williams and Stephen Livesley, and seed ecologists Megan Hurst and John・I would also like to thank Mr. Delprat.

This article is republished from The Conversation under a Creative Commons license. Read the original article.