Alliances against invasion

This post first appeared on the MRI mountain blogs

In the discipline of mountain invasion, the enemy has many faces. Some are large and visible, marching uphill in plain sight. Others are small and sneaky, slipping invisibly and unnoticed behind your back. The problem is: it is not always the big and visible enemies that matter most.

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Reindeer herding and migration may increase the rate of pathogen introductions in cold environments, especially under warmer conditions.

It is hard to keep track of all these different faces of the enemy when one stays within his own research discipline. If we want to tackle the global problem of mountain invasion, at least as many different ecologists will be needed as groups of invading species. A recent paper in Biological Invasions describes what might be the world’s first effort ever to use strategic alliances against mountain invaders. The paper shows how 22 scientists with expertise covering all major organism groups and geographic regions joined forces to tackle questions about mountain invasions. Their aim was to find new ways to deal with novel species interactions and the immediate threats posed by emerging invasive species.

The main conclusions of the paper are painfully clear: the main pathways for species invasion into the mountains, whatever the species group, are anthropogenic. This we know very well from the big and visible species groups, like the non-native plants that so clearly follow mountain roads towards higher elevations. It is likely, however, that less visible species like fungi, insects and pathogens also use some kind of human-created pathways. They all have their own (sometimes very devious) ways to hitchhike to the top.


Mycorrhizal mutualism is needed for Pinus contorta to invade in South America. 

The main outcome of all these moving species (as both natives and non-natives are hurrying uphill nowadays) is totally new sets of species in the mountains. These shifts in species composition will have important effects on those species that have to welcome the newcomers, and those that are not as fast to join the uphill rush. For now, the effects of these new species interactions remain largely unexplored. It is likely that negative effects can be expected, for example through the invasion of diseases and pathogens into cold environments.

To tackle these complex problems in a changing world, collaborations are our only hope. As shown by the recent paper in Biological Invasions, steps in the right direction have already been taken. Many scientific questions however remain, so future collaborations should be encouraged. Because as we all know, many watchmen see more than one.


Pauchard et al. (2015) Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation. Biological Invasions. DOI 10.1007/s10530-015-1025-x

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4 Responses to Alliances against invasion

  1. I have been very curious about this trend for a while and hope you can help me on this a bit. When you speak of “invasion”, what is the standard? I get when it’s something new or its crowds out other species, etc. but is there a golden age stasis that is the goal? Humans have indeed created many of the situations that we now find problematic. In the States, for example, you hear the term “invasive species” a lot and sometimes the solutions are worse than the fault! As I know this is your area of expertise, I am genuinely interested in how scientists in your specific field measure these things. (PS, I realize this is probably beyond the scope of a blog but if you have can point me toward some authors/books/sites, I would love to read more. Thanks!!!)

    • Thanks for asking!
      It is important in this case to highlight the difference between non-native and invasive species. Non-native species are those that come from outside that area and are in 99% of the cases transported between those areas by humans. They can have positive or negative effects, or in a lot of cases no effects at all. Only a few of these become invasive: they start reproducing fast, spreading on their own, covering large areas ànd they cause substantial harm in some way to the ecosystem.
      It is also important to realise that we won’t ever be able to go back to some kind of ‘ideal’ nature from before humans influenced the world. That’s not feasible, and not necessary. But that does not mean that we should just let all the changes happen without taking measures, as the invasion of several species does substantial harm to both economy and ecology. And those we should try to battle.
      Unfortunately, every non-native species and every region is a different story, and a lot of trial and error is involved to find solutions that work, which is why some turn out to be not efficient.
      I can happily point you towards the page on Invasion ecology on this blog: where I also refer to a very good book on Invasion ecology from Daniel Simberloff, a leading scientist in the discipline, who happens to write clearly and understandable for a broader audience.
      Hope this answers your questions, always happy to answer more, provide more detail or link to other sources

      • 😀 ! This is a wonderfully detailed and, in my opinion, balanced response! I will look into the sources you mentioned and I thank you again for taking the time to answer me so completely. With climate change already upon us, I agree these issues will only become more pressing and it’s a really good idea to discuss the many implications now.

      • Glad I could help :-). I like to think of it all as ‘global change’, with the changing climate indeed as one of the main issues, but many other things being involved and changing, both for the good and the bad.

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