Species distributions in a messy world

At the meeting in Zurich (introduced here for those who missed it), species distribution ecologists (like me) and people from the remote sensing community came together to meet. Troughout the discussions we had, an intriguing conclusion surfaced that I found worth mentioning here. To state it boldly: humans are making a mess of species distributions.

To take you back to the theory: where in the world we find a species, is to a large degree defined by its climatic niche, which is the set of environmental conditions in which the species can survive. Is a place too cold or too hot, too dry or too wet, then the species will not be there. Every species has different wishes in that regard, yet all of them have limits. That is what we call the fundamental niche.

There is however something else that defines where in the world will find our species in the end: other species. The interactions with other organisms will work on top of and in interaction with the environmental conditions in defining the so-called realized niche, which is usually only a part of the fundamental niche. For example, alpine plant species might be able to handle the milder climate of a valley, yet they are outcompeted there by other plant species that grow much faster and leave no space for these slow-growing little creatures. If you would give them a helping hand, by planting them in a rock garden, for example, they happily illustrate you how much broader their fundamental niche is.


An alpine species like this Saxifraga can survive and grow in harsh environments

Now there is one organism with a disproportionally huge influence on these realized niches: humans. Like no other species, we influence the landscape, change the land cover, disturb the environment. And inevitably, species are going to appear or disappear following these changes: they might avoid – or not – urban environments, benefit from the edges of fragmented forest patches, or a myriad of other negative ànd positive reactions to all these anthropogenic influences.


Agricultural land looks in no regard like the natural environment that would have been here without human influence.

If one now wants to model where a species actually is (i.e. its realized distribution, an important goal of a lot of our work here on plants), it is obviously crucial to take that human component into account. This is however rarely done, expect for local, regional trials. Most large-scale assessments still focus largely on the abiotic environment, and you can easily see how untrustworthy such predictions would be. The problem is that the human influence on the landscape results in highly heterogeneous conditions, with a lot of variation on a very small scale. And to get good and accurate information on this messy world of humans, is complicated.


Cities, like Mechelen (Belgium) here on the picture, are good for a very heterogeneous environment, due to the wide variety of structures, surfaces, and human disturbances on a small area.

Yet times are a-changing. Recent years have seen an increasing availability of highly accurate data on human land use and the accompanying land cover, thanks to rapidly developing remote sensing techniques: satellite images are improving with every launch, drones are becoming more accessible, and the accuracy of our species distribution models is rapidly following.

So yes, humans are messing with species distributions, yet by joining forces between distribution ecologists and remote sensers, we will now soon be able to assess accurately how bad this is for our species.

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2 Responses to Species distributions in a messy world

  1. How interesting – your blog posts and your line of work! I wish I’d studied something like this when I was younger. Thanks for your posts, I really enjoy reading them! 🙂

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