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Ecological networks and their fragility

Ecological networks are networks among the living community that is the world we inhabit.  Different species of animals, plants, fungi, and microbes interact with each other, and the environment in an intricate, complex web.  The nodes are the living species/organisms, and the edges are between two different organisms that have a relationship, such as predator-prey, symbiotic, or parasitic.  In the guest editorial on, “Emergence of ecological networks”, Steve Carpenter of theUniversityofWisconsin, describes the research done by environmental scientists on the nature of these biological networks, and how they have changed over the past 50 years, most notably due to human activity.  Smaller, local events can cause larger changes in the ecosystem, which is coined “greenlash”.  Notable greenlash problems include climate change – unusually large flooding, uncharacteristically long droughts, and invasive species, to name a few.  Most obviously, the release of a few invasive specimens into an ecological system can over a period of time spread around an entire continent.  These invasive species shift the nodes and edges of a long-standing network, often times leading to imbalance.


Some concepts used in ecological network research I found on Wikipedia:

Ecological networks tend to be unstable if the network grows too complicated – the link density (“average number of links per species”).

Networks have a connectance – how many possible links between species are filled up – as a proportion.

Some networks have “keystone species”, which are the important species that are connected to many other species.  If those species have a dramatic change in population, there will likely be a magnified effect on the whole ecosystem.



Many scientists now study the phenomena of ecological networks to find new approaches to combat this greenlash.  The unfortunate part now is that the faster the ecosystems change, the less accurate our predictions are on the effect various greenlash factors have on the biological network, since our knowledge is based on historical data before all this human contamination of the earth occurred.





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