Ecosystems interacting between themselves is a fascinating process to study. What fascinates me about this subject is the sheer variety of interactions that can be produced between any two ecosystems. The interaction between an ecosystem and its environmental factors are also of interest within this field of ecology. In this post, I’m going to try and illustrate a few examples of interacting ecosystems in the real world, and impress upon the absolute need to study landscapes.
What is a landscape?
Do you remember drawing something like this when you were a kid? If you grew up in India, chances are this was the first ever piece of art you were likely to have made. We would simply title it- “Landscape” (I never imagined I’d come back to this one day).
While the title for that picture is appropriate, the term landscape encompasses so much more. Scientifically speaking, landscape is defined as “an area that is spatially heterogeneous in at least one factor of interest”. The definition, in one sentence, brings in so many elements…
“Spatially”– this clearly indicates that landscape is a study of space; the processes happening in that space and the changes that happen in that space over time.
“Heterogeneous”– this term signifies the importance of having a variety in the area that you are study. Variety in terms of the features that you observe.
“Factor of interest”– can be anything from species composition, patches of land visible, colors of the land, different types of landforms, different topography, etc.
This definition clearly does not put a lower or upper limit of the scale of study; this always depends on the purpose of your study. So a small patch of grass-
can also be considered a landscape, considering it is heterogeneous in the differently colored patches of grass present in that space (commonly called microlandscape). Traditionally though, landscape are considered as large areas in the range of a few hundred meters to a few kilometers. Let me illustrate with the help of some examples-
Examples of interactions between ecosystems: the core of landscape ecology
- Forest fires
My first example is from something that I have written about; forest fires. It is a classic example of a natural process that transcends ecosystem boundaries; a fire can spread from one ecosystem to another and sweep across forests in a short time. A fire is a great leveler. It puts the forest back to square one and allows a community of organisms to grow from scratch. This is on a “first come, first served” basis. The seeds of a species that can colonize the razed area first will establish itself. This process allows for intermixing of species between two separate forest ecosystems.
A more relevant example is the effect that a forest fire could have on residential areas nearby; this is an example of interactions between a natural and man-made ecosystem. The massive amount of smoke produced by a fire has a significant impact on the air quality of surrounding areas (often extending for kilometers in every direction). Also, it causes massive damage to human life and property, as was the case in the recent Fort McMurray fire.
- Dams affecting ecosystems upstream and downstream
Another example is from something I’m working on for a literature review. Dams are a major influence on the landscape around it. This is another example of a human-natural ecosystem interaction. It can affect and alter ecosystems both upstream and downstream; sometimes all the way to the start and end of the river. Rivers are extremely sensitive zones that host a transition between a terrestrial and aquatic ecosystem. Dams play a major role in influencing this distribution by affecting the sediments supplied by the river to all the ecosystems downstream, by hampering the ability of aquatic organisms to freely move up and down the stream. It changes the spatial patterns by (1) submerging entire forests upstream and (2) reducing the floodplain size downstream.
- Wildlife movements
A more natural interaction between ecosystems is the movement of animals across huge distances. Animals, especially predators, move large distances in search of food and to mark territories. This can often span areas that involve many ecosystems. The influence food chains in each of these ecosystems, they influence nutrient cycling because of their droppings and facilitate pollination when pollen sticks to their coats as they move around.
A landslide is unique in the sense that it affects ecosystems across an elevation gradient. The forest composition and human habitation changes with different elevations along the slope of a mountain, and this natural disturbance can affect/destroy all of these ecosystems along this gradient.
Wetland drainage affecting wildlife populations, acid rains originating from distant industrial areas affecting pristine forests kilometers away, dust storms sweeping across the desert and decimating an oasis are all examples where more than one ecosystem are linked are interacting.
Landscape level interactions between different ecosystems are complex, and extremely relevant in today’s world. As I mentioned in my previous post on landscape ecology, human interactions are increasing at the landscape level. Many of the examples I gave above are relevant in this respect; disaster management, wildlife conservation and human manipulation of natural systems. Understanding these interactions is both a way to satiate scientific curiosity and help mitigate a lot of our impacts on the environment.