In Nature, nothing ever exists by itself. There are always relationships to consider. Everything is a system that contains many other systems. Our oceans are aquatic systems that are driven by our sun, gravity, and wind systems. Continents are systems that contain countless ecosystems and non-living structures.
When you stand on the shore of an ocean or a lake, things are much more complex than a simple boundary between water and land. There is no such thing as a dividing line. Instead, there is another system that stands between the water and the land – a juncture of connectivity between adjacent ecosystems. And, that “in-between” system works because it deals with the environment of both the water and the land. Ecologists call this “in-between” system an “ecotone” or an “edge” – a fuzzy and dynamic boundary between two habitats.
Ecotones connect adjacent ecosystems through flows of energy, material and the organisms that cross ecosystem boundaries. Consider the ecological boundary between an oceanic environment and a continent. We know these boundaries as beaches or rocky inter-tidal zones. Here, wave energy, wind energy, weather systems move across the boundary as they move onshore. These inter-tidal zones are affected by both the moon-driven tides and the weather systems of the much dryer onshore terrain environment. Organisms, such as the barnacles that live in this zone, must deal with being both wet and dry. They must also deal with being hot then cold. Some organisms also have to deal with both salt water and fresh water tolerance as well as the forces of wave action. This inter-tidal zone is not a simple dividing line. It is a unique ecosystem that interrelates with at least two other adjacent ecosystems. The boundaries are often nebulous and do change over time.
Another example of Nature’s fuzzy boundaries is at the edges of a coastal lagoon – an estuary. Here we see mangrove plants lining the water’s edge. The mangrove roots are exposed at low tide. Within these roots is an ecosystem that is usually composed of newly born creatures who are seeking both protection and the nutrients from the mangrove detritus. The ecotone shown in this picture is vitally important to the ecological resilience of the larger body of water adjacent to the lagoon – in this case the Sea of Cortez. For, within the roots of the mangrove lie the next generation of life (usually fish and shrimp) that will ultimately live and thrive in the open waters of the sea.
We see much of the same idea in a forest clearing. Here, there is usually a clear line between forest and meadow. Some of the meadows are natural and some are cleared by man. The forest portion of the boundary system offers protection to creatures who feed in the meadow. In some forest/meadow boundaries, we see new Quaking Aspen trees spring up along the edge. These trees are an example of new life that takes advantage of both the forest environment as well as the sunlight of the meadow.
It is important to keep in mind that Nature rarely exhibits a clear and precise dividing line between environments. Instead of clear boundaries, there are “in-between” systems whose role is to interrelate with adjacent ecosystems. It is just as important to recognize and protect these fuzzy borders, the ecotones, as it is to preserve their adjacent ecosystems. By looking for ecotones, we are reminded that everything in Nature is composed of connections to other things.
Why Do I Write These Essays?
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My name is Bill Graham. As a Marine Biologist who has worked in the US and Mexico for 30 years, I am a student of Nature, a teacher, a researcher, and a nature photographer. Through my work, I have acquired an ever growing passion for how everything in Nature is connected. Today, I travel extensively contemplating about, writing about, and photographing Nature’s connections. I also work with conservation projects in the USA and Mexico and mentor talented youth.