Several species of butterflies, including the Red Admiral (Vanessa atalanta), were surveyed across Finland and the Netherlands to assess their response to habitat amount and fragmentation under climate change. Credit: Richard Bartz
Many species are expected to undergo range shifts due to future climate conditions. How easily these species can shift their ranges will depend in part on the surrounding environment through which they have to move. If the amount of good habitat they must traverse is low, or is highly fragmented, their chances of success are likely to be low.
This ability to move through spatially dispersed habitat can be linked to species traits, such as whether individuals are better adapted to warmer temperatures or cooler ones. Understanding how species traits influence community dynamics, and the rate of species turnover in fragmented landscapes under future climate conditions, can lead to better predictions of which species will be able to persist.
A recent study uses butterflies to better understand how species traits affect colonization and extinction under climate change when individuals move through different levels of fragmented habitat. Starting in 1992 in the Netherlands and 1999 in Finland, 98 species of butterflies were observed at over 1,000 sampling sites across both countries. These species were classified as either warm-adapted or cold-adapted, and the amount of semi-natural habitat and degree of fragmentation were recorded at varying distances from each sampling site. These data were then used to predict climate-driven species turnover based on species traits.
The analysis revealed that both the amount of semi-natural habitat and its configuration had an impact on community dynamics under climate change. There was a faster turnover of communities towards warm‐adapted species in sites that were surrounded by a relatively high cover of semi-natural habitat, and where that habitat had a less‐aggregated configuration. Warm‐adapted species had larger colonization probability when the semi-natural habitat was dispersed, but a larger proportion and higher aggregation of semi-natural habitat decreased extinction risk of cold‐adapted species. These effects were magnified based on species mobility. This directly contrasts with the habitat amount hypothesis, and informs management decisions that focus on how to support range shifts.
Small patches can act as connecting “stepping stones” for individuals to use when moving between large fragments. Credit: USDA.
The study also highlights the value of stepping stones, i.e. small patches of suitable habitat that help connect larger patches, even if they themselves aren’t fully connected. By maintaining and increasing habitat area and connectivity in the form of stepping‐stones, it may be easier for species to shift ranges, especially when they are warm-adapted. In contrast, cold‐adapted species may need a different strategy, since they’re more likely to go extinct when semi‐natural habitat is spatially dispersed and rare. For any species, maintaining a high level of connectivity remains one of the key strategies to support species persistence under climate change.
Resources
Fourcade, Y., WallisDeVries, M.F., Kuussaari, M., van Swaay, C.A., Heliölä, J. and Öckinger, E. 2021. Habitat amount and distribution modify community dynamics under climate change. Ecology Letters 24(5): 950-957.
Habitat fragmentation, habitat amount, and conservation (Part 1) (February 2019)
