What Food Webs Tell Us About Our Environment

Deer were an important food source in the ancient Pueblo food web. Human hunting and expansions changed that web. yankane/Shutterstock

Relationships can be complicated, and that's especially true of the relationship we have with our ecosystem. We're all in this together, after all, and that includes every creature and every plant. To keep a relationship healthy, we have to examine it from time to time. How do we examine the relationship that's shared by all walks of life? By using food webs.

A food web is a map that lets us see connections and measure the stability between various food chains and environments, as well as the interactions between all the inhabitants. This allows us to learn how well we function together, and what it looks like if the relationship is a little rocky.

For instance, we can see what an area would look like with or without squirrels, and how that would affect maybe a fox and the way it operates within its environment. Or we could take a look at the way a lack of forestry affects a bird, and how that in turn determines the way the bird makes use of its environment. Food webs basically give us a way to examine a variety of food chain feedback loops. We can look at hypothetical situations, past situations, or current situations to explore what any particular ecosystem might look like when certain parts like animals or crops and plant life are omitted or substituted.

Recent research conducted by a team at Penn State University and published in the Journal of Archaeological Science used food webs to suggest that disturbances of food chains over time could create problems for our ecosystem, reports Phys.org. These problems include the difficulty of human survival — not to mention the survival of just about everything else.

Typically, food webs don't include humans, but this recent research took the human element into account. In fact, omission of species isn't rare. It's what makes food web examination so effective. Usually, researchers use what’s called a "knockout" food web, or one that leaves out certain animals, creatures, critters or crops that would have been present at one point or are present now.

"Knockout food webs are one of the best ways to understand how people interact with the environment," says team leader Stefani Crabtree, postdoctoral fellow of Penn State’s department of archaeology. "Because we can remove something, predator or prey, and see what would happen."

Looking to the past to understand the present

A 3-D modeling of a food web
A sample food web where red nodes represent primary producers, orange nodes primary consumers, yellow-orange nodes omnivores and the true-yellow nodes are true carnivores. The connections between these entities are clearly complicated. Stefani Crabtree/Penn State

The researchers created digital food webs that mirrored three different eras of the ancestral Pueblo southwestern United States.

The team looked at all the common and noninvasive species and crops that inhabited particular ancestral Pueblo areas at various times. Certain elements of the webs both past and present were removed and substituted to show how even the slightest change affects the environment as a whole, giving us a glimpse as to how each environmental shift changes how the food chains and ecosystem function.

Crabtree suggests we look at it like this: "When people show up in the area around A.D. 600, they bring corn," she says. "It takes a while for critters to get used to it, but eventually, everything that eats vegetation, eats corn and prefers it."

When humans come in and plant corn, the previously existent terrain is altered, along with the diet of other creatures. This is turn affects how and where humans and animals get their food. Now we have a food chain that operates differently than before, and these changes can apply to crops and plant life and even more so to prey and predator.

During the ancestral Pueblo periods in the American Southwest, humans turned to deer as a food source. Eventually the number of deer decreased, and humans had to look elsewhere for meat. Thus began the domestication of turkeys. To help keep the domesticated turkeys fed, corn was used.

Now both turkeys and humans have to compete for food and where to find it. This results in alterations to how the food chain works. With every change we make to the environment and food chain, the more we all have to adapt — no matter what type of creature we are. Humans, animals and plants are constantly reworking and reassembling a chain whose links are very tightly interconnected. Whatever the change in the food chain link is, it ultimately impedes the flourishing of critters or crops.

Plucking food web threads

But what did we do when the course of food consumption veers? It’s simple, or at least it use to be. We would migrate, but that’s not really an option these days. We've already moved around many times over many years to find new areas in which we try to create a stable environment that lets us flourish. And of course, any movement would again alter the food chain.

With global temperatures on the rise, this can create serious problems for a stable ecosystem. Ecosystem change is happening, and thus disruptions in the food chain as well. Excessive heat or a major drought caused by human induced global warming is going to make thriving all the more difficult when we have nowhere to go and no way of maintaining a stable food chain.

Crabtree notes that, "We didn't have a long-term plan during the 600 years of ancestral Pueblo habitation in the Mesa Verde region. We don't have a long-term plan today either. We don't even have a four-year plan. Some people are pushing us to look closely at climate change."

This research shows that our decisions actually matter. The ways and places we can flourish are running out, and it looks like the food chains will experience further disruption every time we try something new. It's a good time to ask ourselves: Where do we go from here?