Catherine Mosbach

Design of the Biosphere

Bird's eye view of the parc du Louvre Lens. Photo: Philippe Fruitier

How can we move beyond man’s position of dominance over nature? In what way can the living be articulated so as to improve the city? How can we create a dialogue between architecture and landscape? The work of the landscaper Catherine Mosbach represents natural environments—through the recomposition of layers of landscape—collapsing any distance between the public and the object being observed. She recreates environments in the city by playing with a set of parameters including plants but also topography, hygrometry, soils, and environmental pollution, in such a way as to counterbalance urban extremes and create islands of coolness and comfort, but also to provide paths and spaces for sociability. Within this approach, landscape and technology become complementary levers. The landscaper’s drawing must allow the hosting of events by giving up full control. In a similar fashion, architecture can no longer be so attached to the monumental envelope—form and frontier—so as to provide refined interfaces with the landscape, create porosities, and welcome transitions between the inside and the outside.

One of your flagship projects is the botanical garden of Bordeaux, where you magnify the ground as an element that is both living and inert. How did you work on the “galerie des milieux”?

This cultural facility included the construction of buildings, greenhouses, and offices, complete with a dedicated landscape architect. Its objective was to represent various types of landscapes—cultural, spontaneous, exotic landscapes, and so on. The idea was to design a botanical garden with four highlights: the first one is the ethnographical dimension, that is, the relation between people and plants—as food, medicine, derivative products, etc.; the second one revolves around the singular landscapes of the world’s climates in greenhouses; the third is a pond on the east side of the park, which relates to the Garonne river; and finally, a space dedicated to the landscapes of the Aquitaine Basin.

The most challenging task was to represent the natural areas of the Aquitaine Basin on two hectares of land, due to the issue of scale, but also in a way that does not resort to museographic terminology. Distancing the public from the object under observation was out of the question; the public was to be included within it. In the Western view, humans are always placed outside of systems, or more often than not, above them, when we are in fact part of the landscape just as any other beings. For this reason, I approached the question of the landscapes of the immense Aquitaine Basin in the form of vertical sections. I wanted to consider everything that exists and not simply what can be seen at surface level. We recreated mounds with materials collected from the environments that they represent and then allowed visitors to stroll among them. These are of course representations in the literal sense—in other words, figurative objects, or images of realities. The layers that make up the mounds, a practical application of stratigraphic principles, are proportionally thinner than those that can be found along the Aquitaine Basin. The objective was to make visible the relation between the surface landscape and the substrate, but also the thickness of the nourishing factor. This galerie des milieux (gallery of milieus/environments) echoes the cabinets of curiosities of the nineteenth century. In the same way, the aggregation of all these transplanted gardens that operate on a miniature scale provides a patchwork of landscapes right in the city center.

The shift in scale exceeded our expectations. I have been using this method ever since, in different forms depending on the projects. Miniaturization makes it possible to redeploy imagination at various scales, and the public’s reactions are edifying: some people believe that we have extracted entire chunks of landscapes and do not get the fact that they are recomposed. The more open the project is to a temporal process, the more imagination surreptitiously weighs in, whatever the season.

What is interesting is that you reveal the stratification of geological layers, and thus also lay bare the time that settled there. What is your relationship to time like as a landscape architect?

Landscape planners of different creeds disagree about the idea of spontaneity, of all-comers, with regard to the scripted, or even over-designed, project. In my practice, design instates a dialogue between the project and the program. I find it crucial to have an extremely precise design precisely in order to allow the temporal dimension to fulfill its role in terms of transfiguration and transformation by interfering in the design, augmenting it without annihilating it. We have to begin with an assumption of some sort, even though many parameters remain unpredictable. This hypothesis must therefore be as precise as possible in order to navigate through the timescales of a landscape that is intrinsically undergoing perpetual change. I designed the Bordeaux Botanical Garden as a highly scripted piece. The action of the gardener and of the artificial hand on the tree, shrub, and herbaceous layers, is essential to create the impression of a large scale. A garden is like a body: it deteriorates if it isn’t maintained properly and will eventually die off. The perception of its duration is primarily a cultural issue.

Louvre Lens © Iwan Ban

You were also awarded the Taichung Gateway Park in Taiwan, along with the architects Philippe Rahm and Ricky Liu. In an environment where the subtropical climate and pollution drives local inhabitants to seek refuge in air-conditioned spaces and to only enjoy public spaces at night time, you designed a park that could “rehabilitate daytime.” To do so, the project considered a certain number of parameters—including humidity levels, pollution, and the outside temperature—and invites users to use the space differently depending on the comfort levels achieved. Can living systems play an active part in improving urban atmosphere and comfort?

Plants are one of the parameters of urban comfort. An element or a situation must, in my opinion, have a variety of functions and never only serve one objective. Philippe Rahm designed devices that control the atmosphere: mist blowers, dehumidifiers, and reflectors. We reworked the topography over 70 hectares, as well as the quality of the soil and the water. The stormwater runoff from the 250 hectares of impervious surfaces of Stan Allen’s new district had to be managed, all the more so given the humid subtropical climate in which the monsoon has a major impact on urban areas. Like most recently designed urban parks, this one is intended to be a “sponge” in the very heart of the city, in order to mitigate flood risks.

The easiest way to soak up water is to create mounds and troughs in order to capture the water as close as possible to where it falls. When rainwater does not rapidly soak into the soil, the raindrops rapidly go from trickle to torrent. The trough-like swales collect the runoff and act as retention basins; they also form cool spaces. We were required not to transfer any excavated material out of the park; the merit of the project was therefore to make the best use of the existing resources. We brought in macro and micro topographies with earthworks that introduce “hills” and “mountains” that are up to fifteen meters high. This topography will offer a welcome escape from the future skyline of the neighboring business district, which will loom large over the park, but also provide overpasses and underpasses to separate various traffic flows. Other macro topographies form “draperies,” up to two hectares in size, that offer refuge from the sun. These areas provide a cool respite from the heat similar to that of a cathedral or a cave during the summer.

The project acts on a variety of parameters, ranging from temperature/humidity and pollution to site topography and soil characteristics, which are are put to use for rainwater management purposes. Comfort zones were distributed, among other things, according to the impact of the skyline of the future business district on temperature—in terms of shadow effects and air flows—as well as the tree belt and the swales used for stormwater collection. All of this aims to mitigate heat stress. To do so, we have chosen trees with very large leaves and wide canopies, which provide dense, cool shade. Other trees, such as Phellodendron amurense, grow cork that mitigates the noise pollution of car traffic, while the downy trichomes of the leaves and stems of some species such as Paulownia x taiwaniana collect air pollution particles. A plant cannot in itself reduce air humidity but acts as a vector of transit and transformation, in accordance with its particular physiognomy. The stipes of the tree fern and the aerial roots of the fig trees soak in the ambient humidity but, if only for the local wind effects and climatic variations, which are now very numerous, any precise control in an open urban environment is a pipe dream; in contrast, this can be achieved in a closed air-conditioned space. In this case, the extremes are mitigated thanks to the crude outline of the design but not eliminated altogether. Lastly, the palette of the tree and shrub layers of the swales, which boast more than 40,000 plants, uses phytoremediation to treat the polluted surface waters.

The types of plants are thus combined with a variety of parameters and cannot deliver a service in an isolated or solitary manner. The tree layer, made of roughly 12,000 plants, interfaces with the design of the atmosphere and that of the lithosphere. Inevitably, these two strata complement one another and introduce cool areas away from the sources of pollution as well as water bodies. Paths with different purposes connect these places to one another. The most mildly polluted paths are given over to young children, families, and games. The most heavily shaded paths are conducive to leisure activities, encounters, and kiosks, and those that remain unflooded, even when 80 percent of the park is under water, accommodate athletic activities.

Your work as a landscape architect, therefore, leads you to compose with the substrate, water, sunlight, and even technology, as much as you do with plants as such. In a way, is it less a matter of arranging or conducting living systems than of implementing the conditions required for them to develop properly?

Natural environments intrinsically operate as systems in which it is impossible to carry out a monospecific task. In Taichung in particular, and as a general rule, landscape and technology are complementary. Even though the “climatic” stations, as Philippe Rahm calls them, have been removed from the project by the contracting authority, we suggested new machines that are linked to bodily experiences and to the twelve senses put forward by the precepts of Steiner’s theory of the senses. The city should be putting them to use as educational tools in schools. The spurious dichotomy of natural and artificial stems from a counterproductive binary approach, just as a city cannot be “fully mineral.” As a landscape architect, the way my body is enmeshed in the living world that surrounds me in my domestic environment is crucial for my brain to operate properly. It’s a chemical thing, something purely physical. Being in contact with nature, seeing living systems develop over time is a source of inspiration.

The pond of the Bordeaux Botanical Garden, for example, literally became a lake. Herons, frogs, ducks, and fish spontaneously find a haven there, not to mention the people who swim there despite the fact that this water body isn’t up to urban standards. I would never have dared to imagine a mountain lake right in the center of a city. Observing the unexpected ways in which people take ownership of spaces, the way they have fun, let their imagination run free, challenge the so-called prescribed “urban” behaviors, and so on comes as a huge reward that makes up for all the hassles I put up with during the project process.

A design’s potential lies in its capacity to accommodate such unscripted events. Our Western culture indoctrinates us into a cult of stability even though individuals and landscapes change on a daily basis. The fact that review boards of architectural competitions continue filling out tables of ratings based on standards that exclude anything that cannot be scripted in advance, as well as anything experimental or creative. Accepting the idea of interconnections, randomness, and happenstance, and abstracting ourselves from the idea of complete control would be a huge step forward. The greatest service that a landscape architect can offer is to reveal that this isn’t a utopia, but to do so it is necessary to chance upon a bold sponsor.

The dialogue between city and park, between natural and artificial worlds, the inside and the outside, is a fertile ground for the emergence of optimal living conditions. Architecture must not be considered a separation anymore but a filter, a transition between the inside and the outside. It benefits from providing a very fine interface with the landscape. SANAA, the architect of the Louvre Lens Museum, fully understood this. In Japanese culture, the inside and the outside aren’t opposed as they are in the West. SANAA took an extremely humble stance on the issue, one that is very much opposed to self-centered monumental architecture. Its reflective facade causes the building to blend almost seamlessly in the landscape. Not giving any importance to the building as an envelope and only considering what it gives access to, both on the inside and on the outside, is a strong moral and intellectual choice. The way architects and landscape designers pool intertwined concepts together and perform in unison are critical. The mix of mineral elements and plants, inert substances and living systems, accommodates things that weren’t anticipated, leaves room for randomness, provides porosities. This is one of the ways that a potential dialogue between architecture and landscapes can be ushered in.

This article was initially published in Stream 04 - The Paradoxes of the living in November 2017.

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