As Los Angeles has evolved over the last 150 years, so has its ecology. Once a pristine mixture of ecotones, including chaparral, coastal sage scrub, and annual grasslands, it is now dominated by a naturalized urban forest and a blanket of concrete. Humans have introduced a variety of fantasy landscapes from faux-tropical paradises to Midwestern suburbs, and created the layered, modified landscape we are all familiar with today.
As Los Angeles has become the densest city in the United States, it has maintained its status as a biodiversity hotspot due in part to these complex microclimates and its location in the western hemisphere migration. However, development of the city has led to a critical loss of open space threatening flora and fauna diversity. Recognizing this issue, members of the Los Angeles City Council passed a motion last year to support biodiversity. City agencies have since come together to develop a biodiversity plan, starting with an index of existing ecology and leading to implementing policy and action. The index, presented at the end of April by the Bureau of Sanitation, is based on the Singapore Index. It quantifies indicators of ecological health such as natural areas, pervious surfaces, urban forest canopy, and native birds in built areas. By evaluating these criteria, they hope to support both ecological and human health in Los Angeles.
It is necessary to understand the impacts of historical and current land use changes caused by humans. By replacing open space with buildings and infrastructure, we are removing the benefits provided by soil, water infiltration, tree canopy, and wildlife. Los Angeles’ signature sprawl, which admittedly has its own issues, has also allowed for a complex patchwork of open spaces from private yards to the sides of freeways to vacant lots. These spaces play an important role in the ecology of the city, but are being lost to urban infill.
In the course of the city’s history, green open space and tree canopy have favored the white and wealthy. Poor and working class neighborhoods of color are still tremendously lacking in tree canopy and parks, and these ecological deserts create physical and mental health disparities. By focusing on improving biodiversity especially in these communities, habitat becomes an issue of environmental social justice. But establishing a value for biodiversity and native ecology, without monetizing these life essentials, is difficult. How can the city evolve to support population growth, a healthy ecology, and environmental equality?
While we cannot restore all species to their pre-1850 populations, we can better support those that have adapted to urban spaces, and lure back some that might be able to adapt. The presentation at the Bureau of Sanitiation last month was titled “Conserving Biodiversity when Land is Developed” and several presenters discussed the varied methods of considering how non-humans use our shared space. The presentation focused mainly on birds as indicator species for overall habitat health. Los Angeles is the “birdiest” county in the United States, with 527 recorded species. The birds have complex seasonal roles, using our region for wintering, breeding, as a stop-over, or a year-round home. Some require large contiguous areas of open space while some are happy in urban fragments. Scientists are currently studying bird habits and the connections between them, plant species, and insects. This important information will then guide policy as well as design of open spaces to support those complex avifauna behaviors.
The 2018 Biodiversity Report is the start of a very important conversation that landscape architects will play a huge role in. As we work on commercial, residential, and civic developments, we can advocate for design that values natural systems and their performance benefits. One of our greatest influences is in the design of schools, introducing kids to nature as early as possible. The city must also institute policies that support a diverse density and not just a capitalist drive towards development. An interdisciplinary approach, using engineering, green infrastructure, policy and cultural awareness will enable Los Angeles to thrive in a changing climate and evolve into a healthy city for humans and wildlife.