One of the most evident and massive changes in the world’s ecosystems caused by global warming is the fact that many species, both animals and plants, are abandoning their original habitats to seek more favorable climatic conditions.
What happens, however, when multiple species are “connected” to each other at an ecosystem level, but have different needs and therefore migrate in different directions? This is what risks happening to butterflies, explains a study by the University of Helsinki which demonstrates how climate change is rapidly “driving away” many butterflies from the plants on which they depend.
Ideal temperature. Every species on the planet (or almost) needs to stay within a certain temperature range to survive. Butterflies, in particular, almost always need cool air, and cannot tolerate extreme heat: this is why they are moving to latitudes or altitudes higher than the current ones. The problem is that, obviously, wherever butterflies move they need to eat: they need plants, in short.
Simulation. And not all plants are following the butterflies on their migration to cooler climates. Jin Chen, author of the study, built a model that simulates the habitat shifts of 24 species of Southeast Asian butterflies in response to a high emissions scenario.
The species were selected to be representative of the continent: some live in lowland forests, for example, while others on mountain heights; some have a very vast range, others are more sedentary; some depend on a single plant, while others have a wide choice.
The decoupling problem. The results of the simulation say that 17 out of 24 species are undergoing a “decoupling” from the plants on which they depend: the habitat shared between butterflies and plants will reduce, in the coming years, by a percentage between 6 and 39%, depending on the species. Those most affected by this phenomenon are the butterflies that live in lowland areas, and who are moving higher and higher in search of fresh air, thus “losing” the plants on which they depend.
There is another problem related to altitude and low temperatures: many butterflies that migrate towards cooler temperatures find that plants have a harder time growing, and essentially there isn’t enough food to survive. The only good news concerns the other 7 species: for them, the forecast is that the habitat will expand between 1 and 42%, in response to the fact that, when it is warmer, many plants expand their range.