As you saw in the introductory video about a food system in Vietnam, food systems incorporate both natural and human components. In fact, because of the ubiquitous need for food, food systems are among the most important ways that human societies interact with the physical and biological elements and processes on earth's surface. Land used in some way for food production already occupies over two-thirds of the ice-free land surface (Ellis, 2011 or similar on anthromes) and the trend is for this proportion as well as for the intensity (roughly, the production from each unit of land area) to increase. Human fisheries and other forms of food production from oceans (for example, kelp farming) are also tending to exploit wider and wider areas. In addition, as seen in the multiple types of food systems presented above in section II of this unit, the interactions of human societies with earth's ecosystems in food production is not governed by a single human process but depends greatly on human priorities, land management and food production knowledge, rationales and prescriptive goals for food systems, and government policies that regulate and reward food system outcomes. Understanding these societal factors is key to improving the sustainability of food systems in their impact on the earth's ecosystems.
To understand the interaction of human societies with the earth's surface, a common and productive framework is that of coupled natural-human systems [Liu et al., 2007]. These start from a relatively simple diagram (Fig. 8.9), in which a generic human system (e.g. a community within a human society) interacts with a generic natural system (e.g. a farming-dominated landscape within a production region). The framework also recognizes that natural and human systems have many internal interactions and processes such as biogeochemical nutrient cycling (e.g. the nitrogen cycle, see unit N.N in this course) or the policies, corporate actors, and markets determining food supply chains (a human factor).
Fig. 8.9. A generic natural-human system that can be applied to the food system in its interactions with earth system processes. Credit: National Science Foundation Coupled Natural Human Systems research grant program
- Click for a text description of Natural-Human system diagram.
Generic Natural-Human system that can be applied to the food system in its interactions with earth system processes
Arrows labeled human to natural coupling and natural to human coupling form a circle between human system and natural system. Those are defined as follows:
Human system: human system internal interactions
Human to natural coupling: Human system impacts and reorganizes natural system
Natural System: natural system internal interactions
Natural to human coupling: Natural system a)presents food production conditions to the Human System b) responds to human management and other drivers in ways that affect the human system (feedbacks)
So, for example, in the video that you watched on the food system from the Red River delta in Vietnam, the river delta is the initial, broad natural system context that presents opportunities for farming, livestock production, and aquaculture to farming households and national/local government policies. Human farming/aquaculture knowledge and practices, markets and government policies are part of a human system that impacts and reorganizes the natural system over time into its current state. Over time the natural system internal interactions and processes may also change, for example, increases or decreases in soil fertility, crop pests, or animal diseases. Because of the evolution over time of the system, it is useful to reorganize the coupled natural-human system as evolving over time (Fig. 8.10).
Fig. 8.10. A coupled natural-human food system developing over time. The initial coupling at time 0 is the natural system presenting itself to human society with its properties for potential food production. The Human system "responds" by reorganizing the natural system for food production (time 2), and feedbacks from the natural system ensue, with impacts on the human system. These feedbacks are either intended consequences (e.g food production and income generation) or unintended consequences (e.g. river and estuary pollution, greenhouse gas emissions). Credit: Karl Zimmerer/Steven Vanek