What is an Ecosystem Model?

If I say the words “model” or “modeling” to most people their first thought is probably good looking people, fashion, or maybe the movie Zoolander.  However, when scientists talk about modeling they are talking about something totally different so I am writing this blog post to explain what ecological modeling is and why we use them.  

A model, in the most general sense, is something used to represent something else.  Like a model airplane is a miniature representation of an actual airplane.  An ecosystem model is a representation of an ecosystem that is made up of mathematical expressions contained in a computer program.  Our goal when we build ecosystem models is to better understand how they function.  

I am new to ecosystem modeling and I wasn’t so sure I would like it at first.  I became an ecologist because I love doing field work.  I love the outdoors and I am happiest at my job when I am in my waders standing in the middle of a river collecting some samples.  However, no matter how much field work I and my colleagues do we can only take so many samples and measure so many things.  This means that when we have results they only represent certain points in space and certain points in time.  One of the best things about having and using an ecosystem model is that it helps us to fill in the holes between those points, both in time and in space.  

One of the things I’ve realized by learning to develop and use ecosystem models is the deep level of understanding we must have of a system and a process to be able to describe it in mathematical functions.  Ecosystems are natural complex systems and so it is difficult to describe and predict their behavior.  As a scientist, I am really enjoying this challenge.  Once we have developed a model, we check the results it gives us, or its output, with as much real world data as we can to make sure it is working properly.  We call this process model validation.  After the model has passed this test we can use the model to test hypotheses and look at future scenarios.  

Ecosystem models are not crystal balls and they cannot tell us for sure what the future holds but they are the best tool we have to estimate what the future might look like under certain conditions and to evaluate the effect of a disturbance without actually disturbing the ecosystem.  With an ecosystem model we can say, given our best knowledge of our ecosystems, how our water quality will be affected if we double the population of NH, or there are more frequent big rain storms in the future, or we double the amount of land used for agriculture.  We can also see how an ecosystem recovers if a stress is reduced or removed.  

For the ecosystem and society project, we are using models of both terrestrial and aquatic ecosystems to see how climate change and land development in NH will affect these ecosystems and the services they provide for us.  By producing maps of water quality under different scenarios we are making the future consequences of our current decisions a bit more real.  We are providing this information to the public and policy makers so they may make more informed decisions regarding the management of our natural resources and land. 

Posted by Madeleine Mineau, Research Scientist, Earth Systems Research Center, University of New Hampshire