Discussion Question 1: Coupled Human Natural Systems

What does characterize a city as a coupled human natural system? What are some key qualities that differentiate the city from other ecosystems?


  1. All that has to be established in order for a city to be characterized as a coupled human-natural system is the presence of humans. The natural state, in any form (ocean/land/jungle/urban city), is existing with diverse biota with or without human presence. However, the levels of human interaction, dominance, disruption, innovation, and ultimately influence can vary. The exchanges of intra-city and inter-city flows within communities define the complexity of the coupled system and scale the impacts on all species and nature, including humans. One of the key qualities that differentiate the city from other ecosystems in human dominance. Not only are humans present, but most likely, they are acting as the primary force for system movement or stability. These coupled systems cannot be defined in the same boundaries as we define nature-only ecosystems as they are far more complex and have higher demands on the natural environment (consequently, greater opportunities for change and innovation as well).

  2. The distinctive features of a coupled human natural system in a city are the new ecosystem components that are created by the presence of the built environment. (Thinking about what Seattle was like before it was built…for example.) These would be features such as buildings and structures instead of forests, removal of soils and vegetation for paving and infrastructure, altering surface morphology (e.g., hill/slope removal/filling), redirecting and containing waterways and/or streams/drainage underground, etc. The changes that are made form the new ecosystem and change the functioning and distribution of material in and out of the city. Both systems (before and after) interact as an ecosystem through their elements with cycles of seasons, water, atmosphere, and organisms, yet differently depending on the concentrations and composition of life and structures. The key difference is how elements of each ecosystem functions within earth’s spheres. Replacing ecosystem elements, such as forests with buildings, or streams with pavement alters the ecosystem services available to people in cities. When elements such as paved surfaces are made pervious, the city is able to behave more like its previous counterpart ecosystem, but its contents sets the city apart from the forest ecosystem.

  3. The guiding principle behind the notion of a coupled human-natural system is the inherent interconnectedness between the two primary actors. To understand how ecologies within cities operate, it is necessary to consider the dependency of one on the other. Human development is both dependent upon and directly affects natural processes within a spatial unit and vice versa. This speaks to the need to take an interdisciplinary approach to studying urban ecological systems, incorporating anthropological/social sciences and ecological/natural sciences, as no one school of thought can present a complete perspective. As Alberti asserts in Advances in Urban Ecology, “no single discipline can provide an integrated perspective without bias.”

    Cities present unique conditions for study in the levels of human influence. Urbanization, industrialization, sprawl and population growth have shifted the level and consequence of interaction between human and natural systems, creating new paradigms that have never been experienced and have not been properly evaluated. This shift in dynamics is the driving force in the need for integration of theory and a coupled approach.

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  5. A coupled human-natural system is not merely a combination of human and natural systems, but rather an integration and "co-evolution" of the two, as Alberti discusses in her research. Cities are characterized as coupled human-natural systems because of the significant amount of human influence on the natural environment in these areas. In fact, humans are a dominant player and driver of change in cities, generating new patterns and feedback loops not seen in more natural ecosystems. For example, large amounts of human materials in urban areas, such as concrete and asphalt, lead to urban heat islands (localized climatic responses to human factors), which in turn affect human health.

    Additionally, cities are different from ecosystems because urban functions and human-ecological interactions (such as shoreline development) are directed by governmental and regulatory systems. Ecosystems are largely governed by natural selection, not by organisms acting in the system. Human governance and regulation offers a unique opportunity (and poses a significant challenge depending on the governing body) for cities to shape and guide responses to future scenarios and challenges.

  6. A city should be characterized as a coupled human natural system because it arises out of complex interactions between people (human systems) and nature (ecological systems). Quite literally, cities have roots in the hybridization of these two systems. Cities/urban density can be viewed as an "emergent properties" that came about as trading networks and drives toward resource efficiency connected nature (ecological systems & resources) to people (human systems) in more complex ways over time. Through the increasing complexity of interactions that cities facilitate both between people and people's ability to utilize resources and create new values (tradable & investable ones as well as human), the new emerging properties, or externalities, of urbanization has reached an unprecedented scale and is now one of the most significant drivers of evolution on earth.

    I would argue that there is no such thing as a non coupled human-natural system on planet earth, nor has there been for some time. Human ecological systems have been co-evolving for for most of human history. To some extent, humans have been driving evolution and land change patterns on earth for quite some time, however, the current trend toward urbanization (or an urbanizing planet) is having impacts on global ecology at an unprecedented rate and scale. The key qualities that differentiate a city from other coupled human natural systems is the degree of complexity in the interactions between the systems (complexity begetting complexity in the human system and significant unpredictability in the ecological system in terms of being disrupted toward alternate regimes), and therefore the possibility and probability of uncertainty in the entire system.

    Another side-note on cities and evolution is that they allow for the upward mobility of connectivity to emerge across the globe in terms of urban planning and policies. Toward the end of Eleanor Ostrom's life, she was looking at polycentriCITY (kidding, I don't think she was trying to make a pun) and the possibilities for global networks/regulation/environmental markets to emerge as the result of connecting locally emerging policies (patters/properties) at the global scale. She was theorizing about carbon markets, but I think her theory can be applied to policies and planning decisions at large. The capacity for innovation at the city level and the potential ripple effects that can have in other locals is another key quality of a city.

  7. Coupled human-natural systems are defined by Liu et al. (2007) as integrated systems in which people interact with natural components. Alberti (2016) describes cities as hybrid human-natural systems that operate on multiple scales and exhibit feedback properties that enable multiple possible equilibria. We can see evidence of these types of complex social/biological interactions in many of the issues that are central to the task of planning in urban environments, for example water quantity/quality management, urban forest/open space management, and air quality control. Actions and behaviors of human social systems affect natural systems in urban environments, and vice versa.

    One quality in particular that differentiates cities from other ecosystems is the relative rigidity and material permanence of urban infrastructure (buildings, roadways, utilities) and related implications for mismatch between the time scales of the social and physical evolution of cities. The built environment outlasts social variability, which might include the desire to modify the physical urban environment in response to human-natural interactions. However, our ability to change and adapt the built environment in the short term is limited because of complex feedback loops that are driven by various economic and social factors at play (e.g. private property ownership, commercial transportation patterns, reliance upon SOVs for mobility). Cities comprise dense concentrations of this infrastructural hardscape, and their socio-political processes have long-term legacy effects on landscape patterns that reach far beyond the city itself (Liu et al. 2007). In contrast, natural infrastructure in biological systems is more flexible, relatively impermanent, and creates a lighter footprint in terms of affecting other participants in the ecosystem (think of beaver dams, bird nests or beehives). Gunderson and Holling (2002) note that ecological systems have the resilience to experience wide change and still maintain the integrity of their functions. One could argue that cities exist within a state of more delicate balance due to our reliance on more rigid, brittle and permanent physical environments.

  8. Coupled human natural systems are not humans embedded in ecological systems or the other way around (Westley el. Al, 2002) but as Alberti (2003) suggests, a hybrid system emerges from interactions between human and ecological systems. Cities are an example of a couple human-ecological systems that is processes in time and space.

    Co-evolution and control is a unique characteristic of a of human and ecological systems in cities. Natural systems can change over long periods of time (e.g. animal evolution, formation of the Grand Canyon) or due to an extreme shock (e.g. earthquakes, hurricanes, flooding) however, in a couple systems, humans can control the co-evolution by introducing technology that interacts with both systems. For example, a floodplain is a water source for humans to extract natural resources or is a transportation system. It facilitates of the movement of water and soil for natural processes. A well-managed floodplain allows for natural shocks to the system with minimal losses to natural or human environments as well as the flexibility to change and adapt over time and space.

  9. Cities are coupled human-natural systems, where human and nature interact and co-evolve with each other (Liu, 2007; Alberti, 2016). It reflects an integrated as well as an opposing relationship between human and other natural components, if we consider human and nature are distinct systems. So cities become an interface where human and nature confront and co-exist, rather than a functioning part of a holistic ecosystem.

    Compared with other natural systems, humans have conscious learning objectives, social and technological capacity, and shorter adaptive cycles in making prompt adjustments to cope with disorders or interruptions in the coupled systems. Despite of the high unpredictability of natural feedbacks and possible unintended consequences of inferences, the dynamics of coupled human-natural systems will allow humans to find balanced and stable points through a trial-and-error process, and such process could be shortened and errors alleviated by human efforts.

    Another difference lies in the underlying interests of variable systems. While other natural components are evolving towards an ultimate biosphere prosperity and moderate functioning of the whole planet, development of human will be one priority in coupled human-natural systems. It is undeniable that humans are competing with other creatures for living resources, and such competitions have adversely influenced natural systems in the past. It is also beyond doubt that natural systems could evolve without human, while we cannot say vice versa.

  10. From hunting and horticulture to smokestacks and skyscrapers, we humans have been tightening our grasp on the fickle silly putty of our planet’s ecosystem for millennia. There’s always been a lot of putty, but we’ve made a lot of hands too over the years. So many hands, in fact, that we are quickly warming the silly putty and covering it in moisture and oils. The interaction of human and nonhuman ecological systems has long been a global process transcending individual cities or settlements. Take the lifecycle of our petroleum products: drawn up from below ground, transported, refined, processed, transported some more, used, and expelled—as a puff of greenhouse gas, or perhaps just another lonely plastic kazoo floating in the North Pacific Gyre (Fisher-Bruns 2010). Maybe even as literal silly putty, though I’m not sure what silly putty is made of.
    But as Alberti’s conceptualization suggests, it does us little good to just stand back and gee-whiz about these complex interactions; rather, it is imperative that we understand them analytically. In that regard, it can be useful to distinguish between geographic areas in which human habitation is dominant—i.e., our cities—and those areas in which our ecological havoc is a bit more attenuated or indirect. Extensive geoengineering, hydroengineering, and the substitution of nonhuman habitats with relatively dense human housing, commerce, and recreation mark, at least in a qualitative way, the existence of a city system. Cities interact within themselves in complex ways, and with each other in additional complex ways, and the high volume of resource and exhaust flows between city and hinterland presents another set of interactions. We often conceptualize a dichotomy between “human” and “natural” systems, between hand and silly putty, but there is (or, at least, is no longer) a true separation. But to analyze we must rasterize; the household, the neighborhood, and the city are hierarchical patches in a complex system, representing loci of human activity; analyzing these areas with respect to the world around them will help us understand the many ways that human habitation influences a unitary, hybridized ecosystem.


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