Researchers at the University of Helsinki wanted to understand which is the dominant factor for species occurrence and abundance: the climate or habitat-related variables, such as their natural state and the share of land shaped by human activity. Solutions to mitigate biodiversity loss depend on the answer to this question.
Contrary to the researchers' expectations, habitat composition offers a better explanation than the climate for the occurrence and abundance of most animal groups. This conclusion highlights the importance of land-use planning in safeguarding biodiversity.
"The habitat proved to be of special importance to butterflies, birds, and small mammals. As for large mammals and moths, the relative importance of the habitat and climate were equal," explains Emy Guilbault, the article's lead author.
The study examined 503 terrestrial animal species, including changes in their occurrence, over a period of 20 years. The data covered the whole of Finland with all its climatic zones. Analysing more than three million observations required the use of advanced statistical methods.
Climate accounts for differences between north and south, while habitats explain local variation
The climate is the best explanation for the observed variation in species communities from year to year as well as between more extensive geographical areas, such as Southern and Northern Finland. Tackling climate change is essential in order to retain the distinctive characteristics of northern and southern fauna.
In contrast, the importance of habitats increases when variation in biodiversity is examined locally and regionally. Forested areas accommodate different species communities than agricultural environments or wetlands, and species are lost if their habitats are altered. Consequently, land-use decisions greatly impact the occurrence and location of species communities.
Species-specific characteristics determine the dominant factor
The study also investigated the impact of what are known as functional traits of species on the results. For example, body size, reproductive cycle rate, and degree of specialisation affect the extent to which the climate and habitat determine species occurrence and abundance.
In almost all taxonomic groups, species with slow reproductive cycles were more sensitive to climatic conditions than species with faster ones. Similarly, small mammals preferring a specific habitat or food were dependent on the climate, while the importance of the habitat was more prominent in larger, less specialised mammalian species.
For birds, butterflies and moths, body size or degree of specialisation had no effect on which – the climate or habitat quality – was more dominant.
Biodiversity decline cannot be explained by climate change only
The researchers believe that biodiversity loss in Finland cannot be attributed to climate change alone.
"In many cases, land use can have an even more decisive impact on species, especially locally and regionally. At the same time, climate change and habitats cannot be completely separated from each other, because it is together that they will determine the state of our species communities in the coming decades," says Guilbault.
The climate and habitats have significant combined effects on biodiversity, as species are forced to simultaneously adapt to the changing climate and habitat degradation.
"To preserve biodiversity, we should put greater effort into the protection and restoration of the remaining habitats. Maintaining habitat diversity is an action that also helps species cope with climate change. Moreover, conservation efforts should take species characteristics, regional differences and temporal variation into account", says Professor Jarno Vanhatalo.
The researchers take comfort in knowing that their results show that land use and habitat protection can be addressed more effectively locally than tackling climate change globally. We have means to protect Finland's species, and the most effective of these are in our own hands.
Original article
Guilbault, E., Antão, L.H., Santangeli, A. et al. Shifting balance between habitat and climate in boreal biodiversity patterns across space, time and taxa. Nature Communications, published 14 October 2026 DOI: 10.1038/s41467-026-78359-2
Additional information
Emy Guilbault, Humboldt Foundation Research Fellow
