Climate change and shifting ecosystems: understanding the impact of altitudinal and latitudinal shifts

Worldwide, climate change is leading to changing weather patterns and increasing frequencies and intensity of extreme weather events, such as heatwaves, droughts, and floods. The European continent is particularly affected by climate change, as mean temperatures have increased almost double compared to the global average rate. Plant and animal communities are changing as a response to these dynamics. One way ecosystems respond is by shifting their ranges along latitudinal and altitudinal scales, i.e., northward and upward. This article explores what this means and why it is important.

Shifting ecosystems – latitudinal and altitudinal shifts

As temperature rises, species unable to adapt to changing conditions migrate to more favorable conditions. This often means migrating northward to cooler climates or to higher altitudes where temperatures are more suitable. Researchers found that, generally, species distributions have shifted to higher latitudes at a median rate of 16.9 kilometers per decade, and to higher altitudes at a median rate of 11.0 meters per decade.

Northward shifts

In Europe, many species are moving toward the Northpole. For example, certain butterfly species, such as the Tortoiseshell (Nymphalis xanthomelas) are now increasingly expanding their ranges towards northern regions. This trend has been found for many other butterfly species in many countries, for example in North-West England and Sweden. 

Not only butterflies are moving northwards, but also many bird species, such as the greylag goose, the common shelduck, and the white-tailed eagle, are shifting their range towards the Northpole. For birds, climate change creates extra complications as it more often creates a mismatch between the egg-laying season and the growth season of caterpillars, leading to lower survival chances for the chicks. This might be one of the factors driving bird species ranges more northward to reharmonize the egg-laying and caterpillar season. So far, most research has been done on only a small selection of taxa (birds, butterflies, and plants). But, now it is clear that many vertebrate and invertebrate species are also moving northwards.

Upward shifts

Alpine plants are migrating upwards as temperatures increase at higher elevations. This is especially clear in mountain ranges across Europe, where species that once thrived at lower elevations are now found at higher altitudes. For example, the viviparous knotweed (Polygonum viviparum) and the alpine forget-me-not (Myosotis alpestris) are species that increased their ranges upwards.

This shift is not limited to plants; many animal species, including insects and small mammals, also migrate to higher altitudes. Animals shift their habitats upwards at a higher rate than plants. Animals increase their upper range limit with +47 to +91 m per decade, whereas plants move upwards with +17 to +40m per decade.

Biodiversity loss and invasive species

These ecosystem shifts do not come without consequences. One concern is the potential for biodiversity loss. Species that cannot migrate or adapt quickly enough to changing conditions face the risk of extinction. For example, specialized alpine plants and animals that depend on cold, high-altitude environments find their habitats shrinking. At some point, there will be nowhere left to go when the mountain summit is reached. The glacier buttercup (Ranunculus glacialis) is such a specialist as one of the highest-growing vascular plants in the Alps. It is increasingly threatened as competitors now move upwards into its habitat range.

Conversely, more generalist species or species better able to disperse may thrive and expand their ranges. However, these species could become invasive in other areas, outcompeting local species and disrupting local ecosystems.

Ecosystem Services and Human Impact

Changing species distributions also impacts ecosystem services that humans rely on, such as water regulation, soil fertility, and pollination. Changes in plant and insect populations can affect agricultural productivity and food security. For example, butterflies act as important pollinators of farming crops. Changes in their ranges may negatively affect their role as local pollinators.

Mitigation and adaptation strategies

To mitigate these impacts, conservation strategies must consider the dynamic nature of ecosystems under climate change. This includes creating and maintaining ecological corridors to facilitate species movement and improve habitat connectivity. 

This is what the project LIFE Apollo2020, in which EWS is a partner, is doing for the mountain butterfly Parnassius apollo. Within this project, the existing P. apollo habitats are improved by conservation measures such as debushing and planting of feed and host plants. And, to adapt to climate change scenarios, ‘stepping stone’ sites are created to facilitate species dispersal and migration.

In conclusion, climate change impacts plant and animal communities and ecosystem dynamics, leading to altered species distributions and challenges for biodiversity. These changing dynamics should be considered when developing effective conservation and restoration strategies for European natural areas.