Ecological Resilience: Regaining the Planet’s Biodiversity

This article originally appeared in the semi-annual journal, RI-Vista: Research for Landscape Architecture. Read the full article here.  This article is the second in a four-part series. Read Part 1, Part 3, Part 4. Download the full issue of Ri-Vista here.

By the end of the 21^st century, the Center for Biological Diversity estimates that more than 50% of the planet’s species will be extinct. A recent report by the United Nations calculates that over 1 million distinct species are already at the brink of extinction. What all this means is that the Earth is currently losing animal species at 1,000 to 10,000 times the natural rate. Unlike mass extinctions of the past which can be traced to external disturbances like a giant asteroid striking the planet, our current extinction crisis is almost entirely caused by humans.

Before we get into causality, however, let’s begin with some basic definitions. “Ecology” is generally understood as the study of the relationships of organisms with their environment and each other. It is all-encompassing and has a strong focus on system complexity without biasing or favoring any specific species or elements of the larger ecosystem. In general, an ecosystem is more stable and resilient to disturbance when system complexity increases, such as species richness and landscape heterogeneity. “Ecological resilience,” on the other hand, refers to the amount of external disturbance that an ecosystem can withstand and recover from, without fundamentally altering its vital processes and structures.

Individual species or components of an ecosystem might undergo dramatic elasticity, although the system as a whole retains its integrity. This ecological resilience might not always be favorable to our current societal preferences. A simple example is our propensity for manicured landscapes. These landscapes require constant weeding and pruning, favoring the few plant species that have aesthetic value for humans at this particular moment in time. This intentional weeding, pruning, and termination of vital insects is an external disturbance to the ecosystem whose inherent resilience exerts its power to bring complexity and chaotic order back to the landscape.

Disturbances are ubiquitous in nature, and changes are critical to many vital biogeochemical processes. Most ecosystems can withstand disturbances until a certain threshold is reached, whereby irreversible changes may lead the ecosystem to a fundamentally different state or even collapse. The theory that nature is permanently in balance has been largely discredited in the late 20^th century. What becomes difficult to predict with perfect accuracy, however, is exactly how ecosystems will respond to climate change. Shifts in temperature may cause entire plant communities to shift, or result in an unexpected patterns of species migration. Excessive rain or sustained drought might have similar impacts.

Currently, we’re working in China on the master plan for the Chengdu Panda Reserve—a 69 square kilometer site with the ultimate goal of releasing bred-in-captivity juvenile pandas back into the wild. Although recently upgraded from endangered to threatened by the International Union for the Conservation of Nature (IUCN), the giant panda remains one of the most vulnerable species on Earth due to habitat loss and fragmentation. With a wild habitat range restricted to the mountains of the Tibetan Plateau, the panda’s core habitat lies within a few hundred miles of Chengdu–one of the world’s fastest growing cities. This habitat will be vastly impacted by climate change, as pandas are sensitive to fluctuations in temperature and humidity. They also rely on a consistent source of freshwater, and eat only certain species of bamboo which require specific conditions to grow and are affected by a few degrees difference in temperature or changes to soil moisture and pH. This very bamboo is also a critical component in large-scale carbon storage. Well-managed bamboo forests can sequester carbon at nearly 13 tons per hectare per year—a higher rate than many tree species. To protect the panda, we must protect its entire ecosystem—an ecosystem which is already highly vulnerable to climate change.

Currently, there are an estimated 1,864 adult pandas remaining in the wild. While an additional 300 giant pandas live in captivity and supports the gradual recovery of the species, wild populations continue to be negatively impacted by human presence. Founded in 1987, the Chengdu Panda Reserve was originally commissioned as a research center to advance efforts to breed pandas in captivity. Because of the scientific discoveries made at the Reserve, captive giant panda populations have increased, and the Reserve has expanded beyond its initial research mission to include a broader spectrum of ex situ conservation efforts including education and public outreach programs. With over 18 million people expected to visit the Chengdu Panda Reserve each year, the city has a tremendous responsibility to advance its development in a manner that is mindful of protecting the panda’s native habitat.

Overall, three disparate sites comprise the 26 square mile (69 square kilometer) Chengdu Panda Reserve. Organized by their primary functions, as well as by the level of human interaction and disturbance they allow, each site integrates a complex yet complimentary program that offers the highest standards in captive animal facilities, support facilities including research laboratories and a veterinary hospital, and educational and public outreach facilities. The first of the three sites is the existing Beihu Panda Park, which is located in a suburban area seven miles northeast of Chengdu’s city center and currently serves as the main research hub. The second site is located within the 492 square mile Longquanshan Forest Park, providing an opportunity to experience pandas in a much larger native habitat. The third and most remote site is Dujiangyan, which is situated 35 miles northwest of Chengdu in the foothills of the Tibetan Plateau and serves as the site for pre-release training for bred-in-captivity juvenile pandas prior to their release into the wild. All three sites work together to support the Reserve’s overarching goals of research, education, public outreach, and environmental stewardship.

From a conservation perspective, the giant panda is considered an ‘umbrella species’ where the protection of their habitat benefits additional endemic and threatened species. Noted as a global biodiversity hotspot, the temperate mixed conifer and broadleaf forest ecosystem of the giant panda’s habitat range is noted for its species richness and diversity, containing over 5,000 plant species, 365 bird species, and 109 mammal species including red pandas, clouded leopards, and golden snub-nosed monkeys. While designed habitats within the Reserve’s expansion include areas just outside of the giant panda’s habitat range, the design focuses on a restoration approach for the three sites to (1) create optimal habitat conditions for the giant panda and companion species building off of each site’s existing resources and microclimates; (2) restore the function and diversity region’s mixed conifer/broadleaf forests and bamboo-dominated understory on each site; (3) provide visitors with a more in-depth and interactive learning experience emphasizing the conservation of the giant panda as an umbrella species for other mammals, birds, and amphibians which share the region’s diverse forest habitat; and (4) demonstrate innovative economic and low impact development models to reduce habitat impacts in situ.

To advance this approach, a rigorous site analysis process examined existing topography, drainage patterns, and land cover to provide an understanding of each site’s buildable land area, which was based on criteria of preserving/restoring steep slopes, redeveloping existing development sites, and maintaining a sufficient buffer from streams. The analysis also scrutinized each site through a habitat suitability lens, drawing upon criteria noted in peer-reviewed literature of GIS applications evaluating the habitat of giant pandas. A GIS overlay analysis was then developed to identify the most suitable areas for giant panda habitat enclosures and pre-release training. Informed by this comprehensive understanding of habitat requirements, proposed improvements included a range of native tree species and structural compositions, paying close attention to the type and density of bamboo occurring with the restored forests. Across their range, pandas consume about 60 bamboo species, and habitat carrying capacity is based on the seasonal availability of the most nutritious part of various bamboo species throughout the year. While this is typically influenced by elevation and topography, each site’s “panda kitchen” ensures the full nutritional requirements of the giant pandas are met. In addition to planting design, enclosure configurations avoid steep terrain (>30% slopes) that can be difficult for pandas to traverse. Since giant pandas do not hibernate and prefer a cool to moderate climates, enclosure locations maximize the benefits of each sites’ microclimate, siting most facilities on cooler, densely vegetated north-facing slopes near natural streams.

Building upon the Reserve’s existing facilities, Beihu Panda Park offers an expanded research and education center to accommodate those seeking a more informative experience. Close to downtown and linked to the city by public transit, this urban destination introduces the giant panda to the millions of people who come to Chengdu each year. Here, visitors learn about the daily lives of pandas and their companion species, their shared habitat, and get a glimpse into ongoing research. Based on the habitat suitability analysis, all new giant panda enclosures are sited on north and east facing slopes to maximize the benefits of the cooler microclimate with access to prevailing northeast winds.

Located near Chengdu’s new International Airport, the Longquanshan Panda Village provides an abbreviated introduction to the giant panda and regional conservation efforts. Nestled into a low valley and offering scenic beauty and climate comfort, the Panda Village Zoological Park is conveniently positioned as a gateway to Chengdu. Working with the topography of the site, facilities are positioned within the mountain landscape to reduce noise and light impacts from nearby urban areas, situating animal enclosures along shaded northeast-facing slopes.

The most remote of the three sites that comprise the Chengdu Panda Reserve is the Dujiangyan Panda Wilderness. Located in the foothills of the Tibetan plateau and adjacent to the giant panda’s natural range, the program focuses on wildlife reintroduction. As one of the gateways into China’s newly established Giant Panda National Park, pre-release training acclimates born-in-captivity juvenile pandas prior to final release into the wild. With a significant expansion of animal exhibits planned, the proposed configuration of house/enclosure is organized into three zones – an expanded visitor experience, a research cluster, and wildlife immersion that presents conditions similar to what giant pandas would find in the wild to facilitate pre-release training.

The plan for the Chengdu Panda Reserve by no means strives for perfection, but its goals for habitat protection are ambitious, and hopefully will inspire other regional planning efforts around the world to shape their desired outcomes with a wider lens.

 To read the next article in the series, click here.