Posts tagged ecology

Image Credit: Jenni Zell

AHBE interns, W. Zhou (left), Y. Tian. Image credit: Linda Daley

This past summer we had the pleasure of working with our interns to develop a speculative proposal to advance the Rio Hondo Confluence, which is a signature strategy identified in the Lower Los Angeles River Revitalization Plan (LLARRP). The LLARRP is an important document that will guide the transformation of the Lower Los Angeles River for decades. Our independent speculative project, outlined below, integrates strategies providing green infrastructure, ecological habitat, recreational and cultural use.

We selected one opportunity area identified in the LLARRP, the confluence of the Lower Los Angeles River and the Rio Hondo in the city of South Gate, as the focus of our separate investigation and developed a proposal which we entitled River Commons. The Rio Hondo Confluence is a place that presents significant possibilities to transform into both a cultural and ecological asset for the community.

Credit: Regional context and other graphics in post are by AHBE.

The 254-acre site has a complex history. In addition to hydrologic flows converging at this location, transportation and energy flows converge along the 710 Freeway and Imperial Highway. Although it is within a 30-minute walk of several cities including Compton, Lynwood, and Paramount, the flows of traffic, power and water have isolated people and adjacent communities from one another and from the natural resource of the Los Angeles River.

Image Credit: Calvin R. Abe

Located in a landscape where grizzly bears once fished for steelhead trout, the seasonally riparian and upper terrace upland habitat of the Rio Hondo Confluence provided critical habitat functions of the Los Angeles River ecosystem. Our River Commons proposal outlines building blocks to re-connect people and nature by interweaving cultural and natural systems. In addition, the proposal prioritizes the establishment of physical connections, habitat connections and ecological functions to the site while also providing support for wildlife species, stormwater capture and cleaning and new recreational amenities.

The concrete lined river channel has provided flood protection for decades and adjacent freeways have sped up the transportation of people and goods, but the benefits come at the tremendous cost of dividing communities, destroying significant habitats, and breaking ties of the surrounding people to the historic cultural and natural resource of the waterway for food, leisure and health. River Commons tackles the seemingly intractable problem of choosing between flood protection and economic progress and ecological and community health and vitality. Transforming what is currently a single purpose flood control channel into a civic asset, River Commons proposes to advance a signature strategy identified in the LLARRP.

Building Blocks Approach

The building blocks we explored in River Commons can be tested at the Rio Hondo confluence site and adapted and applied to other Los Angeles River and adjacent sites. We identified four key building blocks in our proposal.

  • Temporary and seasonal in-channel recreation is the first building block, which will build momentum for future projects. It will increase awareness of the river channel as a community resource and provides unique experiences not currently available in nearby parks.

  • Levee terracing will provide seasonal access to the river channel during dry weather and new in-channel habitat spaces.

  • Low-flow channel modifications: Creating meandering and multiple crossings of the low-flow channel create water movement and attraction to the water’s edge. Installing ecological concrete and widening the channel enhances biological value by supporting the growth of organisms including targeted fish species.

  • Bridge crossings to connect pedestrian, equestrians and bicyclists: Multi-modal channel crossings provide much needed connections of communities to one another, the river and river adjacent regional trail systems, along with viewing opportunities of local mud swallows.

Site Specific Design Strategies

Charles S. Dwyer, USACE. Credit: Linda Daley

Hydrological modeling and engineering principles were integrated into the analysis and design phase for our selected area through collaborations with local civil engineers and the US Army Corps of Engineers (USACE). We acknowledge and thank USACE’s Charles S. Dwyer (shown at right) and Reuben Sasaki for giving generously to our investigation in terms of their time, LA River knowledge, and technical review and feedback.

By closely collaborating with hydraulic and civil engineers, we received feedback on the draft building blocks to determine the feasibility of our proposals. This collaboration was critical in identifying and evaluating potential design strategies, a few of which we share below.

  • Treating stormwater before it enters the river is key to improving water quality in the river and ocean. River adjacent properties can be utilized to collect and filter runoff while also increasing habitat and at some sites, recharging underlying aquifers.

  • Expanding the river channel to the bend in the 710 freeway presents a unique opportunity for adding substantial new habitat areas hydrologically connected to the LA River ecosystem. This area would flood during design storm events, but regenerate naturally.

  • Taking advantage of the water collected by a downstream rubber dam and utilizing control gates and drainage lines through the levee, river adjacent fisheries can be created to move water and create a hydraulic connection to the river.

  • Horse Camp at the Hollydale Park expansion builds on the rich equestrian culture in the area and provides a revenue source and river trail rides, connecting people and nature to one another and their river.

In developing our design solutions, we were guided by cultural investigations which foster an interconnectedness between the surrounding community’s citizens, environment, and cultural resources. By linking public health, air quality improvements, energy and water demands and supply, accessibility and mobility improvements with sound green infrastructure strategies, the River Commons proposal is an additional resource for community members and agencies to help visualize and build support for future projects.

Image credits: Wendy Chan (above left) and Jenni Zell (right)


All photos: Katherine Montgomery

I cannot remember the first time I saw a monarch butterfly, nor can I recollect exactly when my mom planted milkweed in our backyard. But there are photos of me holding recently hatched monarchs dangling on my hair.

As a kid, I probably misread their docility and fatigue from metamorphosing for affection, adoring the opportunity to be so close to something I would otherwise never be able to grasp. My mom’s decision to lure and then raise monarchs stemmed from her own love of nature and wanting to share it with both of her kids, alongside her 5th grade students. She planted milkweed at home and at the urban schools where she taught, leaving a trail for the monarchs to find. We had numerous seasons of caterpillars eating, pupating, hatching, and flying away. The experience instilled in me a sense of wonder and scientific curiosity.

I recall seeing monarchs regularly enough to assume their permanence in the world. However, the last 20 years has seen an 80% decline in their populations, and their annual migration is now threatened. This decline is due to several causes, but mostly related to habitat loss. Native milkweed once filled the spaces along roadsides and in corn fields across North America, but these nodes of habitat have disappeared with the rise of agricultural herbicides like glyphosate (found in Roundup). Also, those attempting to aid monarch butterflies by planting non-native milkweed in their yards have only exacerbated the problem. The widely available milkweed, Asclepias curassavica, or Tropical Milkweed, found at big box stores or garden centers around the country hosts a parasite that transfers to the caterpillar as it eats the plant, infecting the monarch into adulthood. I grew up with Tropical Milkweed too, before becoming aware of the importance of regional species to their lifecycle.

Monarch migration is one of the wonders of our world. The butterflies, usually 3-4 generations removed from those who migrated north, innately know to fly across North America to a specific location in southern Mexico to mate. The typical lifespan of a butterfly is only 4-6 weeks, but those that overwinter in Mexico live 6-7 months. The females fly north again to lay their eggs, while the males die happily after completing their duty, littering the forest floor orange. The succeeding generations of monarchs make their way as far north as Canada before repeating the cycle.

Last fall, my garden was host to a handful of monarch caterpillars. I spotted the first tiny pearlescent egg on the underside of a milkweed leaf. Once hatched, I watched as the hatchlings fattened themselves over the course of a couple weeks. Overnight they disappeared, and I began hunting around the yard for their green, bejeweled chrysalises. One hung gracefully from the arm of an Aloe marlothii, and another nestled into the concave leaf of an Aloe vera right next to my front door. A few attached themselves to small buckwheat branches. I brought one of these in a jar to work, where my coworkers and I excitedly waited for the chrysalis to turn dark, and then clear when it would reveal its black and orange wings folded inside.

Concerned the butterfly might emerge over the weekend, I decided to take it home. During the Metro ride back home I held the jar gingerly, trying to soften the bumps of the train. A wide cross-section of passengers ended up asking what I was cradling – from teenagers to Spanish-speaking older men – each wanting to connect with the tiny bit of nature within my jar. Once they knew it was a monarch butterfly, their faces registered I was transporting something special. Thus, a subway ride became an opportunity for conversations about bugs, ecology, and the environment.

A monarch egg (left) and young caterpillar (right).

The green and gold chrysalis transforms to clear a day or two before the butterfly hatches.

The butterfly emerges with a large abdomen full of liquid which is pumped into its wrinkled wings. It lingers several hours before having the energy to fly away.

Monarch butterflies’ orange and black wings are immediately recognizable, traditionally associated with spring, rebirth, resurrection, and more recently, as symbols of strength and resilience. They are also a sentinel species, warning us about health threats within a particular ecosystem or habitat. If we don’t address overuse of herbicides, pesticides, and abuse of our lands, we will lose the monarch and harm ourselves. The monarch butterfly is more than just a visual icon; these charismatic creatures can also prompt larger conversations about ecosystems, food sources, and the economy. One small critter can lead to educating the public on a variety of world issues.

The Asclepias fasciculatum (narrow-leaf milkweed) in my garden is just beginning to rebound after some winter dormancy. I am hoping my patch of California native milkweed will lure more monarchs this year, permitting me the opportunity to share the wondrous experience again with as many people as I can, just as my mom once did for me.

The bright orange of monarch butterflies disappear like the thin edge of a slip of paper until their wings fold up or open, changing dimension while pausing on a leaf or flower.

As designers with our hands in the landscape, it is our responsibility to support populations like the monarchs, and build habitat into the urban context. These nodes, however small, support a much larger system, providing important moments of connection with the bigger picture, even if just for a moment on a subway ride.


Zootopia Concept Art / Central Station by Matthias Lechner for The Walt Disney Studios

Zootopia Concept Art / Central Station by Matthias Lechner for The Walt Disney Studios

When I first heard Disney planned to make a new feature animation about animals, I was not surprised. But after noticing people – specifically some adults friends – raving about the film, I reluctantly decided I needed to see what all the excitement was all about. Guess what? I’m now one of the raving Zootopians too.

Simply put, “Zootopia” is a movie about dreams and courage. Although the themes of the film are common within the animated genre, the film has been critically applauded for its metaphorical creativity, portraying a cast of animals, or what they called “anthropomorphic mammals”, within urban neighborhoods: Savanna Central (downtown), Tundratown, Rain Forest District, Sahara Square and Bunnyburrow.

Like its real world counterpart, downtown Savanna Central is where different animals live and work in a bustling metropolis. This utopian city comes complete with its own comprehensive municipal infrastructure system complete with different scaled commute facilities to accommodate for each species, a climate control system for cooling down Tundratown to the comfort of its inhabitants, and even a water recycling system for treating rainfalls in the Rain Forest District. Keen eyed architecture enthusiasts might notice the design of the Central Station in “Zootopia” resembles the Atocha railway station in Madrid, famous for its inner garden.

Madrid Atocha Railway Station / Creative Commons photo

Madrid Atocha Railway Station / Creative Commons photo

Most fictional animal films tend to portray beasts in an anthropomorphic style, or conclude with the wild animal finally being tamed at the end (such as in, “How to Train Your Dragon”). The narratives reflect the desire for a harmonious existence with wildlife, but only on human terms. In either case, animals are left as either pets or livestock. “Zootopia”‘s standout narrative feature is avoiding this trope.

Nara deer / Creative Commons photo

Nara deer / Creative Commons photo

Nara, a real city in Japan, is famous for the wild deers lingering everywhere. Under the protection of local residents and visitors, those “wild” deers commonly take over streets and parks, without any serious concerns about shelters and food supply like their wild cousins. The deer-hospitable city reminds me of another movie, one created by Studio Ghibli, “Pom Poko”. The film is a dark comedy about Japanese raccoons known as tanukis trying to protect their homeland from human’s urbanization. The ultimately fail in the end, so the tanukis transform into human being to survive in the city.

In reality, urban designers, architects, and landscape architects have been experimenting with design methodologies with the hopes of finding a balance for urban coexistence between local wildlife and humans for many years. But the reality is that urbanization sacrifices part of the natural ecosystem forever, and it never fully recovers regardless of how many trees we plant or how many more reservoirs we build.

An interesting project being proposed is Maryland-based Working Group on Adaptive Systems’ “Nonhuman Autonomous Space Agency”. The project proposes future space exploration manned with only robots and animals – no human being – essentially sending out a self-developing ecosystem into outer space without any human intervention. A whimsical project for sure, but it could prove an important and humbling reminder that life can continue on with or without the human race.

Urban animals have sacrificed and adapted to the human world, their adaptability possibly attributed to their wild nature. Technically speaking, human beings are also animals: Homo Sapiens – a mammal. So one might wonder, did we also sacrifice and adapt our nature for civilization’s sake?


One of the most dynamic landscapes is currently undergoing a process of plant succession – the ecological process coined by naturalist and writer, Henry David Thoreau, describing the opportunistic progression in which specific conditions favor the growth and proliferation of one species over another during the timeline of a habitat.

Types of plant succession are:

Primary Succession (from non-vegetated > vegetated)
Secondary Succession (from vegetated > changed vegetated)
Old-Field Succession (from abandoned farmland > changed vegetated)

With all the wildfires affecting Southern California this summer, it seems inevitable that ecological succession is constantly occurring. Southern California is experiencing a secondary succession, where the ecology responds to natural disturbances such as fire, flood, strong winds, or human activities such as logging and agriculture.

During a forest fire plants and trees are destroyed, however the soil itself is usually left viable. In time the burnt landscape develops into a grassland, chaparral, then eventually conifers and other hardwood trees may sprout up to repopulate a new forest literally arisen from ashes. Within this forest, short-lived shade intolerant trees die as the larger evergreen trees grow taller and fuller. Succession is a natural process that is necessary for biodiversity. Without succession, certain plant species could die out.

Photo: Julie An

Photo: Julie An

One doesn’t have to venture far to see succession in action. During a recent trip to the San Bernardino Forest I visited the Keller Lookout. Located at the 8,000 ft. elevation peak, Keller Lookout is a fire tower administered by the U.S. Forest Service. It was built in 1926 and has survived several fires. The most recent fire in the area happened in the 1990s, the fire’s mark is still visible as an unusual clearing of mature pine trees at the top of Keller Peak.

Photo: Julie An

Photo: Julie An

One of the most prominent intermediate species growing back into these clearings here in Southern California is the Chinquapin, or Chrysolepis sempervirens, which has edible nuts. Bush chinquapin survive fires by sprouting from the roots, root crown, and stump when aboveground portions of the plant have burned, regrowing from points deep in soil. Opportunistic intermediary species like the the Chinquapin illustrate how a destructive force like wildfire has a place in ecological diversity and reminds us as one door closes on one species, another may be opening for another to thrive.

by-Linda-Daley_pine-trees_horizIf you are like me, you have responded to the state drought mandates by making changes to your daily habits and declaring a broader intention of living sustainably for the good of the planet. Given my curiosity about the social and natural sciences, I thought I had a basic understanding of the causal relationships between human behavior and the environment and that this knowledge would guide me in making the right choices regarding conservation. I have so much more to learn.

“Education is not the filling of a pail, but the lighting of a fire.” — William Butler Yeats, poet

Putting earth stewardship into practice is a journey filled with surprises. The decision to limit irrigation use, for example, may be a big deal for one individual and considered a personal accomplishment once the step is taken. Then the law of unintended consequences kicks in. Tree experts are reporting signs of drought stress in urban trees due to lack of water. We have adjusted our irrigation use without consideration of the watering needs of the trees located within gardens or lawn areas. Additionally, water-stressed trees are susceptible to pest infiltration.


We need trees and forests. They are essential elements for a healthy planet. They contribute positively to climate, biodiversity, air and water quality, health, social environments, and much more. We have to be smarter about how we care for and protect them.

Every action has consequences. Our challenge is to keep ourselves informed and learn from the unexpected results so that we don’t repeat the same mistakes. This is part of our unending education if we are committed to improving the well-being of people and the planet.