So a little bit of background. I am writing a fantasy novel (non-traditional setting), though the ecology is similar to our world so I'm simplifying to just discussing our world for ease of answering.

I've drawn some inspiration from Maoist China, particularly the Four Pests Campaign which practically wiped out the Eurasian tree sparrow and that led to drastic and devastating ecological effects.

Without going into the nuances of the story, I want to know other creatures (non-bird) which are important parts of a given ecosystem, that when pushed/wiped out could cause similar effects.

The biome in my story is more or less a temperate coniferous/mixed leaf forest along a mountainous region. But, feel free to provide examples of creatures that don't exist in this biome, as it might still provide some ideas.

It may also be related (either directly or indirectly) to the introduction of too many/an invasive top tier predator[s], but that's not necessitated.

To be clear, I'm asking ideas of real-world examples, but will probably use the information I receive to adapt it to a new fantasy creature.

This is my first post. Let me know if it needs clarification. Thanks!


closed as too broad by cobaltduck, Hohmannfan, a CVn, bilbo_pingouin, fi12 Apr 8 '16 at 21:52

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ To get you started, google the term "keystone species." The Wikipedia article has numerous examples. $\endgroup$ – cobaltduck Apr 8 '16 at 19:53
  • $\begingroup$ In the US east of the Rockies, the removal of most large predators, which caused an explosion in the whitetail deer population. Or for a reverse case, where effective removal of a species (humans) led to ecosystem recovery, the aftermath of Chernobyl. $\endgroup$ – jamesqf Apr 8 '16 at 20:31

There are many examples of this happening in various parts of the world. Off the top of my head I can think off the following:

There have been pesticide attempts in many countries to take out certain insects. Often these pesticides also kill other insects. These insects levels drop so low they can no longer pollinate the plants they would normally pollinate so the plants die leading to food shortages for many animals.

In Britain there is a type of orcid which used to thrive all over the countries woodlands. This orcid is now unable to reproduce as the fungi which used to be in a symbiotic relationship with the plan and used to help its seeds germinate was wiped out. The death of this plant has caused insects that relied on it to die out.

The opposite, (introducing a species) can have far worse consequences. rhodedendrans have killed native British wildflowers and grey squirrels carry diseases which destroy red squirrel populations. Both these species were introduced from abroad for hunting or as garden plants and then spread out of control. This can also happen as an attempt to remove other species from an ecosystem. I think natterjack toads are an example of this.



Bees are the most important insects when it comes to pollination. Eliminating all bees from an ecosystem would have drastic consequences for the flower bearing plants (including trees). No bees would mean much lesser pollination of flowering plants which would mean there would be lesser food available for herbivorous animals (although many can eat grass, there are several which only eat soft plants).


Grass is the staple food of a lot of grazing animals. Eliminating it would mean you are affecting all the animals in the ecosystem and several herbivorous genera would be wiped out, the carnivores would also suffer severely.


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